Ingineria · 4 Ingineria Automobilului Automotive Engineering: print edition publication, 2006...

DISTR IBU TED WITH AU TOTEST M AG A ZINEVol. 7, no. 3 / 2013

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INTERNATIONALFEDERATION OFAUTOMOTIVEENGINEERINGSOCIETIES

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IngineriaAutomobilului Society of

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RomanianAutomobileRegister

l Interview with Dana Oprisan – Director of Human Resources at Renault România l Experimental Study of Collision Using Similarity Theoryl The Future of the Piston Engines

INTEGRATED VEHICLE HEALTH MANAGEMENT:THE TECHNOLOGY Author: Ian K. Jennions

The third volume in the Integrated Vehicle Health Management (IVHM) series, this book focuses on the technology that actually supports the im-plementation of IVHM in real-life situationsIt follows two bestsellers, also published by SAE International, whi-ch covered the fundamentals aspects of this new body of knowledge (Integrated Vehicle Health Management: Perspectives on an Emerging Field), and the business justification needed so that investments in the technology make sense (Integrated Vehicle Health Management: Business Case • Integrated Vehicle Health Management: Perspectives on an Emerging Field• Integrated Vehicle Health Management: Business Case Theory and Practice

INTERNAL COMBUSTION ENGINES FOR ROAD VEHICLESMOTOR MECHANISM – CONSTRUCTION AND CALCULATIONSAuthor: dr.ing. Sorin RaţiuMIRTON Publishing House, Techno Collection, Timisoara, 2010

Based on the curriculum of the university subject „Calculation and con-struction of internal combustion engines for road vehicles”, this paper was designed as a manual - course aimed to serve as a training tool for acquiring the engineering skills necessary for understanding and provi-ding solutions to the problems which arise in this field.The material is addressed both to students attending the courses of the Road Vehicles specialization within the Faculty of Engineering of Hunedoara and beyond, and to specialists in the vast field of internal combustion engines.Starting from the idea that the work should reflect not how much a spe-cialist needs to know, but how much a student has to acquire, one of the major objectives was to provide those interested with material containing most useful and up-to-date information structured in a clear, concise and easy-to-remember manner.The theoretical aspects are presented in logical and gradual succession, without unnecessarily complicating the mathematical apparatus, continually seeking the pragmatic aspect, and thus the connection with technical issues of interest

3

Ingineria Automobilului

It doesn’t matter in which language it is to be spelled, this word comes in to the current speak, passes more and more as unremarked, but makes dramatic effects, sometimes irre-

versible. It is, more than ever, fashionable to speak and to write about pollution and a lot of people do so. A simple search with an internet search-ing engine gives tremendous results, no matter of

the used variant. There are a lot of reasons and easy to be further identified why is this thing happened for, some of them trying to clear it up, obviously in order to be as “trends”. Particularly starting with the last century, as result of the advanced industrialization, and a noteworthy growth of population in connection with the growth of its mobility necessities, especially in the ur-ban areas, the air pollution, assigned to the human activities, claims more and more sharp and irreversible forms. In this way, a continuous accumulation of different pollutants is happening, with severe consequences on the human factor, vegetables and animals, buildings, art creations and general landscape, as well. The road traffic generally represents the most important category of air pollution sources in the big urban areas, and the ambient impact generated by the traffic of motor vehicles on the major roads is considerable for the adja-cent suburban and county areas. Pollutant emissions generated by the mobile sources, the road traffic being among them, are very important and extremely complex and contain hundreds of compounds present in the atmosphere as gases, aerosols and particles. In the atmosphere, a lot of those compounds transform themselves in secondary pollutants (indirectly produced) as tropo-sphere ozone (dry smog), acid aerosols and carcinogenic hydrocarbons, be-ing sometimes more harmful as the directly produced forerunners. The major air pollutants emitted by the motor vehicles engines include carbon oxide (CO), inhaling particles, nitrogen oxide (NOx) and a big variety of gaseous organic compounds, especially hydrocarbons (HC) generic called as volatile organic compounds (VOC). The presence of strong reactive multiple ele-ments within VOC emissions, colligated with the NOx emissions, determine their character as being the forerunners of the troposphere ozone (O3).In order to maintain the said desideratum regarding the environmental pro-tection and the rise of life quality of its habitants, the European Union imple-mented and enforces more and stricter normative acts regarding the regula-tion of domains having a possible impact on environment. Thus, in the field of motor vehicles’ construction, the current applicable legislation for heavy duty vehicles is mentioned in the Directives 2005/55/EC and 2005/78/EC. This legislation defines the currently applicable standard emissions (Euro V), and the standard generic named (EEV). Following the established programs and the strategy in the field of air pollution, the European Commission adopt-ed for the heavy duty vehicles the new step (Euro VI) being defined in the Regulation (EC) no. 595/2009 of the European Parliament and the Council of 18 of June, 2009 regarding the type approval of motor vehicles and engines with respect to emissions from heavy duty vehicles and on access to vehicle repair and maintenance information. For the light duty vehicles is already in force the Regulation (EC) no. 715/2007 of the European Parliament and the Council of 18 of June, 2009 regarding the type approval of passenger and commercial light duty motor vehicles with respect to emissions from light duty vehicles and on access to vehicle repair and maintenance information. For the new vehicles, the generic step named Euro 5 is already applicable and

the dates of their entry in force for the Euro 6 step are September 2014, respec-tively 2015 depending on the category and reference masses of the vehicles.For the vehicle already being in use it is applicable the Directive 2010/48/EC of the Commission of 5 of July 2010 on the adaptation on the technical progress of the Directive 2009/40/EC of the European Parliament and the Council on the technical inspection for motor vehicle and their trailers, the last one being under revision. It is mentioned the introduction of sharp and strict stipulations regarding the aspects concerning the administrative organi-zation and technical issues, as well, regarding the uniformity and improve-ment of the periodical technical inspection, at the EU level, for vehicles being already in use. Additionally, there is the Directive 2003/30/EC regarding the vehicles roadside technical check.In the field of the quality of vehicle fuel, starting with 31 January 2007 Eu-ropean Commission proposed new standards for fuels used for transport in order to reduce their contribution to the climate changes and air pollution, including among them the rise of bio-fuel use. The new standards will not cre-ate cleaner crude oil, gasoline and diesel oil, but these standards will allow the putting on the market of less pollutant motor vehicle. It is about to encourage the development of fuels having less carbon, as the bio-fuel, thus resulting a greenhouse effect gases reduction arising from their production, transport and use of 10% between the years 2011 and 2020.The Directive 98/70/EC with the last amendment the Directive 2011/63/EU contains environment specifications regarding the fuels quality, respec-tively gasoline and diesel oils within the Community, generally focused on the sulphur content and at the beginning on aromatics for gasoline. The Member States already currently imposed to the gasoline supplier to deliver on the market gasoline having oxygen of max. 2.7% and ethanol of max. 5%.In the field of renewable fuels, the today transport is generally based on oil. This situation has implications in the energetic policy but has a capital im-portance, as well, from the environment perspective with effect in the climate changes. The action had generally in view a subject regarding alternative fu-els, and especially the bio-fuels. The long term vision regarding the hydrogen as energy source is in the view of an elite group from the hydrogen field and fuel cells, as well. From the environment perspective it is important to have in mind that is not sufficient to find alternative fuels; if we have in intention to develop a sustainable transport system, these fuels must come from regen-erative sources. In a larger perspective, the safer, more efficient and less pol-lutant new technology in the field of motor vehicles belongs to the concept of Intelligent Transport Systems (ITS). Despite of all recent and remarkable progresses in the field of motor vehicles technology, now, it is well known the fact that complying with the requirements of the EU Directives regarding the ambient air quality will be very difficult to be achieved in a lot of urban areas. In the most serious mode, it is our duty, the duty of all involved peoples from different levels and domains, to join efforts and capacities with a view to achieve these targets, having in mind the future of our planet and our chil-dren, and our obligation to make possible them to enjoy of a sunshine, a drop of clean water and a flower, because,Life, la vie, viață…it gives back, exactly in the same order, incomparably more results!

Eng. George-Adrian DincăGeneral Manager – Romanian Automobile Register.

To pollute, a polua, polluer

4


Automotive Engineering: print edition publication, 2006 (ISSN 1842-4074), electronic edition, 2007 (ISSN 2284-5690).New Series of the Journal of Automotive Engineers (RIA), printed in 1992-2000

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REGISTER

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SOCIETY OF AUTOMOTIVE ENGINEERS OF ROMANIAPresident: Conf. Dr. Ing. Adrian Clenci, Universitatea din Piteşti

Honorary President: Prof. Dr. Ing. Eugen Negruş, Universitatea Politehnica din BucureştiVice-president: Prof. Cristian Andreescu, Universitatea Politehnica din Bucureşti

Vice-president: Prof. Anghel Chiru, Universitatea Transilvania din BraşovVice-president: Prof. Ioan Tabacu, Universitatea din Piteşti

General Secretary of SIAR: Prof.Dr. Ing.Minu MitreaPublishing Director or SIAR: Dr.Ing. Cornel Armand Vladu

Editor in chief: Prof. Dr.-Ing. habil. Prof. E. h. Dr. h.c. Cornel Stan Executive editor in chief: Prof. Mircea OPREAN Universitatea Politehnica Bucureşti

Deputy Editors Prof. Gheorghe-Alexandru RADU Universitatea Transilvania Braşov Prof. Dr. Ing. Ion COPAE Academia Tehnică Militară, Bucureşti Conf. Ştefan TABACU Universitatea din Piteşti

Editors Conf. Adrian SACHELARIE Universitatea Gh. Asachi Iaşi Conf. Dr. Ing. Ilie DUMITRU Universitatea din Craiova Lector Cristian COLDEA Universitatea Cluj-Napoca Lector Dr. Ing. Marius BĂŢĂUŞ Universitatea Politehnica Bucureşti Dr. Ing. Gheorghe DRAGOMIR Universitatea din Oradea

Editorial Secretary: Dr.ing. Cornel Armand Vladu, Publishing Director or SIAR

EDITORIAL BOARD

SCIENTIFIC AND ADVISORY EDITORIAL BOARDProf. Dennis Assanis

University of Michigan,Michigan,

United States of America

Prof. Rodica A. BărănescuUniversity of IIlinois at Chicago

College of Engineering, United States of America

Prof. Nicolae BurneteTechnical University of Cluj-Napoca, Romania

Prof . Giovanni CipollaPolitecnico di Torino, Italy

Dr. Felice E. CorcioneEngines Institute,

Naples, Italy

Prof. Georges DescombesConservatoire National

des Arts et Metiers de Paris,France

Prof. Cedomir DubokaUniversity of Belgrade

Serbia

Prof. Pedro EstebanInstitute for Applied

Automotive ResearchTarragona, Spain

Prof. Radu GaiginschiTechnical University

„Gh. Asachi”of Iaşi, Romania

Prof. Berthold GrünwaldTechnical University

of Darmstadt, Germany

Eng. Eduard Golovatai-SchmidtSchaeffler AG & Co. KGHerzogenaurach, Germany

Prof. Peter KucharUniversity for Applied Sciences,Konstanz, Germany

Prof. Mircea OpreanUniversity Politehnica of Bucharest,Romania Prof. Nicolae V. OrlandeaRetired Professor, University of MichiganAnn Arbor, M.I., USA

Prof. Victor OţătUniversitatea din Craiova, România

Prof. Pierre PodevinConservatoire Nationaldes Arts et Metiers de Paris, France

Prof. Andreas SeeligerInstitute of Mining and Metallurgical Machine, Engineering,Aachen, Germany

Prof. Ulrich SpicherKalrsuhe University, Karlsruhe, Germany

Prof. Cornel StanWest Saxon University of Zwickau, Germany

Prof. Dinu TarazaWayne State University, United States of America

5


Summary „Ingineria Automobilului“ No. 27 (vol. 7, no. 3)3 To pollute, a polua, polluer5 Tension and Intensity Tensiune şi intensitate6 Interview with Dana Oprişan Director of Human Resources at Renault România Interviu cu Doamna Dana Oprişan Director Resurse Umane al Renault Romania7 Experimental Study of Collision Using Similarity Theory Studiu experimental al coliziunilor folosind teoria similitudinii10 Performance Evaluation of an Internal Combustion Engine Supercharged with Pressure Wave Compressor Evaluarea performanţelor unui motor supraalimentat cu agregat cu unde de presiune13 The Future of the Piston Engines Viitorul motoarelor cu piston

15 Experimantal Study of the Car Acceleration Equipped with On-Board Computer Studiul experimental al demarajului automobilelor echipate cu calculator la bord19 The Analysis of the Wear Processes per Cycle Using the Thermodynamic Modeling of the Internal Combustion Engines Analiza uzurii pe ciclu folosind modelarea termodinamică a motoarelor cu ardere internă23 Study on Structural and Functional Particularities of EGR Depollution Systems Used on Diesel Engines Studiu asupra particularităţilor constructive şi funcţionale ale sistemelor de depoluare de tip EGR folosite pe motoarele Diesel26 University Research Cercetarea universitară

The principal mis-sion of our maga-zine is to detect

and to propagate the main research and development themes of the worldwide automotive industry, as a contribution to the orien-

tation of the strategies - not directly of the OEM their self, but more of the numerous suppliers of modules, subsystems or parts - but also of those regarding the formation of future experts. One year ago I was stunned when hearing a Ger-man minister speaking to a very numerous audi-ence formed by people from the mechanical and automotive industry in the following manner: who develops and produces still gear wheels, pis-tons or rods should re-orientate in this new time to solenoids, magnets and electric rotors.In the year 2012 in Germany were sold exactly 3000 electric cars, up to one million cars as a target within the next 2 years, there is a long way. The minister would negate today to have said such phrase, which can disorientate and trouble a sector which is hard, complex and full risks.

The tension increase obviously, the cars with electric propulsion are in expansion not only geographically but also regarding their diversity: some days ago BMW presented concomitantly in New York, Beijing and London a 3 billion euro concept which should revolutionize the automo-bile: the electric car i3. The motor has a power of 125 kW, allowing the acceleration 0-100 km/h in 7.2 seconds and a maximum speed of 150 km/h. The CFRP (Carbon Fiber Reinforced Plastic) car body has a weight under 150 kg, which is a real performance. However, the total car weight achieves 1195kg, the battery with 22 kWh having 230 kg. With the energy of 22 kWh the autonomy remains under 160 km. The price: 37,000 euro. The series production of this type will start this year. The French are more pragmatic, the electric car being considered more for the urban traffic: therefore, the Renault Zoe has a motor with lower power - 65 kW, the battery having the same capacity like in the BMW i3. But with the heavier car body - 1503 kg - the autonomy remains in the same range - 150 km - despite the half of propul-sion power. Renault Zoe costs 5000 euro more

than a comparable car with classical engine, Re-nault Clio. The US Americans uplift the tension in market-ing, the target being the supremacy at all parame-ters: the new electric car Tesla S achieves a power of 310 kW, having the dimensions of a Mercedes S. Despite the full aluminum body , the weight of the car cannot be reduced under 2.1 tons, because of the battery, which comprise 85 kWh, which means 4 times more than the batteries of Renault or BMW, the goal being an autonomy of 500 km. However, under real conditions the autonomy remains under 400 km. The price: 100,000 euro.These examples demonstrate an increase of the tension in this domain. I have a high respect and admiration for the assiduous work, for the inge-nuity and creativity of thousands of engineers and technicians who achieved such performanc-es, but the tension must be followed by intensity: the intensity of production and sales. Until then is preferable to not give up the piston production, nor the courses of internal combustion engines.

Prof.Dr.-Ing.habil.Prof.E.h.Dr.h.c. Cornel Stan

Tension and Intensity

6


Renault Romania’s Most Important Asset: Its People Interview with Dana Oprişan

Director of Human Resources at Renault România

Dacia Renault plays an important role on the Eu-ropean car manufacturing world. How do you see the future evolution of Dacia’s car manufacturing?

Indeed, Dacia became a key player on the European market, with a market share of 2.5%. Obviously, this is good news for us, but at the same time it makes us more aware of our responsibility. We have to keep an eye, first of all, on the market’s evolu-tion. In the first semester, this year, the European market, our main export destination fell by 6.6%, the most impacted being the markets in France (-11.2%), Germany (-8.1%), Italy (-10.3%), and the Netherlands (-36%), traditional destinations for our cars. And, there also are our competitors, who target these markets with similar products to ours. Consequently, we have to be very alert to the services we offer, but also costs and car quality in order to keep the advantage we have.

How important are people, human resources to a company such as Dacia?

For a company such as Renault Romania (with over 17,500 employees) its biggest asset is its people. On the one hand, there is the Dacia plant where the manufacturing activities are predominantly manual, and con-sequently people’s training and quality are essential. One can get good quality cars only with good people, who know their job and fulfill their tasks with responsibility.Then, there is, in Romania, an engineer-ing center within which, competences are again, essential.

Your company has concluded partner-ships with universities in Romania. How could this cooperation become more dynamic (in the scientific research area included)?

During the last 10 years, we have built numerous partnerships with universi-ties in Romania, just because human resources are important to us, for the

group’s evolution. We have developed trainings and master’s programs focused on core subjects for us and, for which, the training offer on the market was not adequate. It is the case with a master’s in “Logistics Management” currently supplied by the University of Pitesti, a master’s program in “Noise and Vibration Control”, unique in Romania, devel-oped with the Polytechnic University of Bucharest, or with the master’s programs in car project engi-neering delivered by the Polytechnic University of Bucharest, the Technical University Gh. Asachi of Iasi, the University of Craiova and the University of Pitesti. The 4 master’s programs were launched some years ago and they are the very fruit of the cooperation between the 4 Romanian universities, the University of Compiègne in France and Renault Technologie Roumanie - the engineering center

within Renault Romania. Their aim is to make stu-dents familiar with activities specific to the automotive industry, such as developing skills for project management, team work in an international environment, use of foreign languages in a professional context, etc.Of course, our cooperation with universities does not stop here. We stay in permanent contact with universities, we have a dedicated team, and the purpose is to identify cooperation opportunities beneficial to both par-ties.

What’s your rating of the training students get in universities and how can it be improved?

University graduates in Romania have, generally speaking, a good theoretical background. What they sometimes lack is practical training,necessary for real life, for the labor market: team work, project management, communication and presentation skills. These are the aspects we have been trying to improve via the programs developed and the in-ternships we organize each year. I think it’s a shared responsibility of universi-ties and companies to train the youth as well as possible for their future profes-sional life.

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Experimental Study of CollisionUsing Similarity Theory

Lucian Anton BodorS.C. ASTRA Insurances, Bacău, [email protected]

Radu GaiginschiTechnical University„Gheorghe Asachi“Iaşi, România

Adrian SachelarieTechnical University„Gheorghe Asachi”Iaşi, România

ABSTRACTSimilarity theory was applied for the first time in hydrodynamic studies because the impossibility carried of experimental tests on these condi-tions. So by building scale layouts was followed a resemblance of layouts and processes that are used with real models respecting similarity theory. In the present context it is known that experimental study of collisions involving high costs of real cars, application of similarity theory to study collisions between vehicles will reduce research costs respecting the scientific nature of research.This paper proposes a method to study the col-lisions with fixed barrier using experimental layouts so manufactured as to respect principles of similarity theory both between layout and prototype and for the collision in which are in-volved. It is considered that conditions of per-fect similarity are satisfied when simultaneously satisfied geometry similarity, the kinematics similarity and the dynamic similarity.Keywords: geometry similarity, kinematics similarity, dynamic similarity, layout, proto-type.

INTRODUCTIONPhenomenons of the same nature are described analytical through identical mathematical rela-tions as similar form and content. In order to accomplish the similarity the subjected to ex-perimental research layout marked with ,,m”

and the assimilated prototype marked with ,,p” and whose characteristics must be identical or at least close to the ones of a real vehicle.For these purpose the first condition in order to accomplish the similarity is to have a geometri-cal resemblance [2] between the layout and the prototype characterized through the propor-tionality of counterpart lengths:

(1)

in which: Lp - the prototype’s length units ; Lm - the layout’s length units; kl - the similarity factor.The kinematic similarity [2] is assured by the geometrical resemble of the trajectories and the proportionality between velocities, being defined on the velocity scale in the following manner:

(2)

in which: wp - the prototype’s speed units ; wm - the layout’s speed units; kw - the speed’s simi-larity factor.The dynamic similarity [2] is assured by the kinematic similarities plus the condition that states the dynamic similarity is provided by the mass scale:

(3)

in which: Mp - the prototype’s mass units ; Mm - the layout’s mass units; km - mass similarity fac-tor.The collision that it analyze is similar to a real one, only if they depend the same physical size characterized by same measurement units and the sizes without dimension have the same val-ues both for the layout and the prototype. When it say sizes without dimension it refer our self to those sizes that don’t have assigned measure-ment units attached to them it must establish models or similarity criterion.One feature of the sizes without dimension characteristic to changeable in time phenom-enon is the raport that is named after Stouchal criterion. According to this criterion

the relation between the similarity factors is:

(4)

The second size without measurement that it took into consideration is marked with Ne and it represent the raport between the applied force and the inertial force also called Newton’s crite-rion, according to which the following relation between the similarity scales is defined:

(5)

In order to create a new similarity it is manda-tory to determine the subjected to impact test layout main mass, dimension and deformation features. It go on with determination of the above mentioned characteristics on a proto-type and afterwards it will realize a comparative study of them with the ones of a real car. In order to determine the features regarding the layout’s stiffness it will realize a test a fix barrier in the prior mentioned conditions.

DETERMINING THE LAYOUT’S FEATURESThe determination of the layout’s features is be-ing done through experimental determinations. In order to achieve this goal it have done a test with fix barrier that is actually compounded out of two collision tests: one in which the layout hits the fix barrier with a speed around 50 km/h ( taking into consideration the speed’s similar-ity factor) and the second one is based on the layout’s crash with a fix barrier with a speed that can avoid remanent damages on the deformable structure. Next it will present the conditions in which the experiment was carried out, the lay-out’s features and the gear it used.In the experimental activity there were used:- the layouts subjected to experiment are two cars with radio command. To these cars we have attached on the front side two deformable profiles made out of aluminum. The two layout shave identical characteristics: length 38 cm, width 17 cm, height 12cm, wheelbase 20cm,

8


length deformable profile 9 cm, width deform-able profile 17cm and mass 890 gr; - the surface on which experiment was carried out is a 2 cm thick OSB board with the length of 2,25 m and the width of 1,2 m. In order to determine how the layouts moved it have drawn a vertical and horizontal grid, the distance be-tween two consecutive grids being 2 cm. The fix barrier is a a concrete brick that weights 3 kg and that was caught in a 15 kg tile glue bag in order to avoid its movement during impact;- in order to take photos of collision a Samsung Galaxy S2 smartphone was used, which was implemented a shooting frame by frame Fast Burst Camera program, that was set take photos at 1/20 s. At each photo that was taken, the cam-era attaches the precise moment, in which the photo was taken, in milliseconds.To determine the reduce speed for which there are no deformation (b0) it use footages from fig-ure 1 It can note that the layout moves on a 2 cm distance in 71 ms until it hits the fix barrier. As result the impact velocity for which there are no deformation is b0 = 0,28 m/s.To determine the impact velocity it use the pic-tures from figure 2. The layout’s movement from position one to position two is 8 cm long on the OX axis and the time in which this movement takes place in 55 ms. As result the impact with the fix barrier velocity is w = 1,45 m/s.The amplitude of the deformations in the six points is presented in table 2 and figure 3. The medium deformation is provided by the rela-tion:

(6)So

Knowing that the reduce speed that does not produce damages when hitting the fix barrier, the impact velocity w = 1,45 m/s and the me-dium deformation Cmed = 0,048 m it calculate

the b1 coefficient, b1 = 24,38m/sm = 87,77km/h m with the help of relation:

(7)

To determine stiffness of the model that it have subjected to tests it is necessary to determine in a experimental manner the value that stiffness coefficients have, using the experimental values:

(8)

in which: m is the mass, l* is yhe impact zone’s width; b0 is the reduced speed that does not create deformations when coming into contact with the fix barrier; b1 is a coefficient, w is the impact with the fix barrier velocity.Knowing that the layout’s mass Mm = 0,89 kg, and the deformed surface’s width is l = 0,09 m, it was able for the layput’s stiffness coefficients to be determined:

Calculate the scale factor derived for coefficient making the report corresponding coefficients for the prototype and the layout:

(9)

In order to determine the derived scale for coef-ficient A :

(10)

It determine the derived scale for coefficient of stiffness B:

(11)

The validity of the determined derived scale from above must certify the relation between two parameters and the force on the deforma-

tion’s width unit:

(12)

(13)

The left member of the equation is being calcu-lated (13) by help Strouchal criterion:

(14)

The right member of equation is being calcu-lated (13) by help Strouchal criterion:

By applying the Newton criterion it obtain the same result.

(15)

Because the similarity coefficients verify the existing relation between the deformation coef-ficients and because they simultaneously fulfill the Strouchal criterion, the one of geometrical similarity and Newton’s, it state that a perfect similarity between the layout and prototype was accomplished.

DETERMINING THE PROTOTYPE’S FEATURESIt have known and have calculated the values that correspond to the layout, which will be re-minded:the layout mass - Mm; the layout’s lenght - Lm; the layout’s width - lm; The reduce speed for which does not deformations - b0m = 0,28 m/s; the im-pact velocity with fix barrier - wm; the coefficient

Fig. 1. Scheme for determining the reduced speed Fig. 2. The determination of the impact velocity

Footage t1=46,286 s Footage t2= 46,357s Footage t1*= 23,567 s Footage t2*= 23,622s

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b1 - b1m = 24,38 m/sm = 97,77 km/hm; the stiff-ness coefficient A - Am = 67,5 N/m ; the stiffness coefficient B - Bm = 5877,8 N/m2; the stiffness coefficient G - Gm = 0,388 N; the impact force Fm = 31,47 N .Knowing that the prototype has following char-acteristics Mp = 1354 kg; Lp = 4,28 m, b0p = 11 km/h = 3,06 m/s ; it determine the similarity factors kM = 1521,35; kL = 11,26; kw = 10,93. Using these values it calculate the similarity fac-tors for the coefficients of deformation A and B, the similarity force factors and the similarity fac-tors for coefficient b1: kA = 1433,4; kB = 127,3; kF = 16137,3; kb1 = 0,97.Taking into account the values of the scale fac-tors the prototype will have the following fea-tures:- the protype’s massMp = kM * Mm=1521,35 * 0,89=1354 kg;- the prototype’s lengthLp=kL * Lp= 11,26 * 0,38=4,28 m;- the prototype’s widthlp=kL * lm = 11,26 * 0,17=1,91 m;

- the b0p

b0p=kw * b0m = 10,93 * 0,28 = 3,06 m/s=11 km/h;- the reduce speed for which does not deforma-tionswp=kw * wm = 10,93 * 1,45 = 15,85 m/s = 57 km/h- coefficient b1

b1p = kb1 * b1m = 0,97 * 24,38 = 23,6 m/sm =85 km/hm;- the stiffness coefficient AAp = kA * Am = 1433,4 * 67,5 = 96754,5 N/m;- the stiffness coefficient BBp = kB * Bm = 127,3*5877,8 = 748 243,9 N/m2;- the stiffness coefficient G

- the impact force Fp = kF * Fm 16137,3*31,47 = 507 840,8 N

In conclusion, it consider that the simultane-ous fulfillment of the geometrical resemblance criterion and Newton’s mechanics fundamental similarity criterion together with the Strouchal’s criterion was ensured, therefore it can state the

similarity between the prototype and the lay-out but also the similarity between the process in which they are used has been ensured. Next, making a comparasion between the values of a real car it can observe that the prototype in col-lision with a fix barrier presents geometrical, ki-nematic and dynamic features close if not iden-tical to the ones of the real vehicle Chevrolet Aveo 2007. So, by analogy it can say the similar-ity between the layout used in the experiment and the Chevrolet Aveo 2007 is accomplished. Using similarity theory in collisions expertise between vehicles will give an viable solutions in statements that are introduce risk factors on personnel running these experiments in experi-mental testing Also not be neglected economic side, using thery similarity in the collisions experiments will generate the low-costs experiments while maintaining scientific value of results. Another advantage of using similarity theory in experi-mental reconstruction of collisions is repetabil-ity a collisions under identical conditions.

Mărimea U.M. Macheta PROTOTIP CHEVROLET AVEO 2007

Length m 0,38 4,28 4,28

Width m 0,17 1,91 -

Wheelbase m 0,2 2,26 2,48

Mass kg 0,89 1354 1354

Coefficient b1 Km/h m 87,77 85 94

Stiffness coefficient A N/m 67,5 96 754,5 95 766,1

Stiffness coefficient B N/m2 5877,8 748 243,9 749 812,4

Stiffness coefficient G N 0,388 6255,6 6115,6

REFERENCES[1] Gaiginschi,R., Reconstrucţia şi expertiza acciden-

telor rutiere,Editura Tehnică,Bucureşti 2009;

[2] Iulian Florescu, Mecanica fluidelor, Note de curs

pentru uzul studenţilor, capitol referitor la Teoria simili-

tudinii, Editura Alma Mater, Bacău 2007.

[3] Nathan,A.,R., Stephen,J.,F., Richard,M.,Z.,

Crush Conservation of Energy Analysis: Toward

a Consistent Methodology, 2005-01-1200, SAE

Accident Reconstruction 2005,Warrendale,USA,

2005

[4] Nathan, A.,Stephen,J.,Fenton,M.,Richard,

M., An Examination of the CRASH 3 Effective Mass

Concept. SAE Paper2004-01-1181,SAE ISBN

0-7680-1409-3

Table 1 – Similar features with real vehicle

Fig. 3. The magnitude of the deformation after colliding with the fix barrier

C1 = 8,5-2=6,5 cm C2 = 8,5-5,5=3 cm C3 = 8,5-2,5 =6 cm

C4 = 8,5-2,5=6 cm C5 = 8,5-5=3,5 cm C6 = 8,5-4=4,5 cm

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ABSTRACTThis paper aims on highlighting the pressure wave supercharger superiority over turbocharg-er by simulating two engines using those type of superchargers. Among the most disputed world problems, in term of building powerful and efficient internal combustion engines, are emissions. The internal combustion emissions are the product of inefficient and incomplete burning process. A complete burning process assumes an air intake with a fixed ratio of inject-ed fuel mass. The pressure wave supercharger eliminates the shortcomings of the turbocharg-er, in term of air intake at low engine speed. This fact is highlighted in this article. The simulations were accomplished using AVL Boost software, version 2010.Key words: supercharging, pressure, intake, compressor, engine.INTRODUCTIONGlobal mobility is increasingly emphasized in recent years, which has led to an exponential increase in the number of vehicles and also the quantity of pollutants emitted into the environ-ment by them. More evidences are appearing re-garding on climate change and extreme weather events that are actually a result of the interven-tion of the human society. The internal combus-tion engines and its annexes were also major contributors to this issue of environmental deg-radation, through emissions [7, 10].An important aspect that must be considered in the problem of increasing the efficiency of in-ternal combustion engine is to reduce losses in its operation. A continuous variation of advanc-ing resistances occurred during movement of a vehicle force the engine to run at partial loads and uneven and variable speeds, which lead to increased fuel consumption and pollutant emis-sions due to this transitional regime. Adopting a lower unit displacement leads to a decrease in

engine mass and a re-duction in friction and pumping losses. This reduction forces the „weaker“ engine to work at higher loads. Decreasing the num-ber of cylinders of internal combustion engine automatically leads to lower friction loss mentioned above [3, 9 and 10].Along with reducing total displacement and number of cylinders, the energetically per-formance of the engine is also diminished. The most common way to compensate this issue is to implement a su-percharging solution. Analyzing the thermody-namic cycles of the two constructive solutions in Figure 1, it can be seen that the mechanical work of the supercharged one is theoretically higher, this fact is due to a mean effective pressure per cycle higher, and also to the addition of the pumping mechanical work (area 0-1-7-8), which is positive on the supercharged engine [5, 10].

Supercharging with mechanically driven com-pressors and with the exhaust gases driven com-pressors are two of the most known and used methods by the manufacturers of internal com-bustion engines. The first solution uses a me-chanically driven unit directly from the engine crankshaft. This version has the advantage of al-most instant throttle response and can provide a

Performance Evaluationof an Internal Combustion Engine

Supercharged with Pressure Wave Compressor

Drd. Ing. Atanasiu Cătălin GeorgeUniversitatea Transilvaniadin Braş[email protected]

Fig.1. Comparison between engine cycles [4]: a. Naturally aspirated, b. Supercharged

a. b.

Fig. 2. Pressure wave compressor [1]:1 – fresh air intake, 2 – compressed air exhaust, 3 – exhaust gases intake, 4 – exhaust gases evacuation, A – the “hot” side, B – rotor,

C – mechanical drive, D – the “cold” side

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boost pressure over the engine’s need. In terms of energy, the mechanically driven compressor is a power consumer, which negatively affects fuel consumption [3, 4].THE PRESSURE WAVE SUPERCHARGER (COMPREX)The supercharging using the pressure wave su-percharger (Comprex) is powerful supercharg-ing equipment that eliminates some of the drawbacks of the turbocharger, because the inlet pressure depends directly by the exhaust gases pressure and not by the flow quantity. In this way, very high supercharging coefficients can be achieved, even at low engine loads and speeds [6, 9, 10].Like the turbo charging equipment case, the fresh air compression is done with the help of

the exhaust gases. The principle of operation, however, is slightly different. It is based on the following assumption: by putting in contact two fluids with different pressures, the pressure equalization occurs before mixing [1, 9].The power of the pressure wave supercharged comes from the engine crankshaft via a belt (old-er models), but the fresh air compression is done by the exhaust gases. The newer experimental models have electric drive for the rotor, instead of mechanical drive from the crankshaft [2].The Comprex pressure wave compressor can achieve very high compression ratios (2 – 2.8 bar), being an attractive solution with presents a high developing potential in scope of obtaining high performance engines [9].EXPERIMENTAL DESCRIPTION

The AVL package is a complete software bun-dle used for simulating the internal combustion engines, which can include codes like: Boost, Cruise, Excite and Fire [8].In the present study the v2010 AVL Boost was used, which is software for thermodynamic calculation of engine operating cycles and AVL Impress, an instrument for graphical processing of results.In figure 3 is presented the schematic for turbo-charged engine operation, and in figure 4 is pre-sented the schematic for pressure wave super-charged engine, used through the whole process of the virtual investigations.These models were created using the library models defined in AVL Boost, which consist of: C1, C2, C3, C4 – engine cylinders; PL1, PL2 – plenums; TH1 – throttle (deactivated in case of diesel engine, flow coefficient used: 1); CO1 – intercooler; CL1 – air filter; TC1 – tur-bocharged; PWSC1 – pressure wave compres-sor; CAT1 – catalyst; MP1 to MP5 – measuring points; R1, R2 – flow restrictions (used for sim-ulating the EGR and for knocking turbocharged out of use); SB1, SB2 – system boundaries; J1 to J14 – pipe intersections; 1 to 42 – connecting pipes [8].The simulation was made using the following premises:- Engine displacement: 1.8 liters, direct injec-tion, diesel;- Engine speed: 1500 rpm;- Load applied: 100%;- Ambient temperature: 20 degrees C.RESULTSConsidering that the thesis has not been made public yet, the results are displayed as percent increase (or loss) in terms of performance.Notations in graphics:- PWS: pressure wave compressor (or Com-prex);- Turbo: turbo charging equipment;- Turbo+VVT: turbo charging equipment cou-pled with variable valve timing for exhaust valve. CONCLUSIONSThe pressure wave compressor has a big impact over internal combustion engine performances. The simulated diesel engine has a positive in-crease in power and torque at low speed (city driving conditions) and also a net superior tran-sient response over a turbocharged engine.An engine supercharged with pressure wave compressor has a gain in weight of approxi-mately 20-25 kg (estimated) over an turbo-charged engine [5]. This gain is due to bigger

Fig. 3. Turbocharged engine model

Fig. 4. Pressure wave supercharged engine model

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supercharging unit and also due to larger intake and exhaust pipes. Considering that an pressure wave supercharged engine has approximately 30% performance improvement in terms of torque and power over a turbocharged engine, the increase in weight of the engine, and thus of the vehicle, does not have a negative impact.

INTERNATIONAL SUPPORTThis paper is supported by the Sectoral Opera-tional Programme Human Resources Develop-ment (SOP HRD), financed from the European Social Fund and by the Romanian Government under the contract number POSDRU ID76945.

REFERENCES:[1] Gyarmathy George, How does the Comprex pressure-wave supercharger work [C], SAE paper 830234.1983:pp. 91–105; [2] Weber F, Guzzella L. Control oriented modeling of a pressure-wave su-percharger (PWS) to gasoline engine[C]. SAE paper 2000-01-0567. 2000; [3] Stone R., Introduction to Inernal Combustion Engines, Third Edition, SAE 1999, ISBN: 0-7680-0495-0; [4] Heisler H, Advan-ced engine technology, 1995, ISBN: 978-1560917342; [5] Hermann H., Peter P., Charging the internal com-bustion engine, Springer Wien New York, 2003; [6] Spring P, Onder CH, Guzzella L. EGR control of pressure-wave supercharged IC engines. Control Engine-ering Practice [J] 2007; vol. 15:1520–32; [7] Willard W. Pulkrabek. Engineering Fundamentals of the Inter-nal Combustion Engine [M]. New Jersey: Prentice Hall, 2003; [8] AVL Boost 2010, user guide pdf book; [9] Teza de doctorat, Dr.Ing. Leahu Cristian-Ioan, Optimizarea funcţionării motoarelor cu aprindere prin comprimare cu agregatele de supraalimentare, Braşov, 2011; [10] Teza de doctorat, Dr.Ing. Hirceaga Ma-rius Ciprian, Studiul fenomenelor dinamice din gaze cu aplicaţie la supraalimentarea motoarelor cu ardere internă, Braşov, 2012.

Fig. 5. Cylinder pressure evolution. Maximum pressure value:Turbo: 100%, Turbo+VVT: 108%, PWS: 143%

Fig. 7. Mechanical work evolution. Mechanical work average over one engine cycle:Turbo: 100%, Turbo+VVT: 103%, PWS: 121%

Fig. 6. Cylinder temperature evolution. Maximum cylinder temperature:Turbo: 100%, Turbo+VVT: 102%, PWS: 99%

REZUMATAceastă lucrare are ca obiectiv evidenţierea superiorităţii agregatului cu unde de presiune printr-o comparaţie simulată între un motor supraalimentat cu turbosuflanta şi unul supraalimentat folosind agregatul menţionat mai sus. Printre problemele mondiale cele mai disputate, în ceea ce priveşte construcţia de motoare performante şi eficiente sunt emisiile poluante. Emisiile sunt rezultatul arderilor ineficiente, incomplete. O ardere completă presupune un aport de aer aspirat în raport fix cu cantitatea de combustibil injectată. Agregatul cu unde de presiune elimină neajunsurile turbosuflantei, în ceea ce priveşte aportul de aer la turaţii scăzute, acest fapt observându-se în articol. Simularea a fost făcută folosind soft-ul AVL Boost, versiune 2010.

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The development of internal combus-tion engines – spark ignition and compression ignition engines - is not

decelerating in the last period, but contrarily, there can be observed an intensified activity in all appending domains. Other propulsion vari-ants, such as Stirling-, Wankel-, Damp-Engines or Gas-Turbines or, furthermore, the electric motors – considered as systems together with the modules for electric energy storage on board - have no real chances to replace the piston en-gines. The potential of the piston engines, re-garding especially the further reduction of the fuel consumption can be synthesized in the fol-lowing points:

SI ENGINE:

The introduction of direct injection within the diesel engines in the year 1989 provoked a steep fall of the fuel consumption, in the range of 15-20%, what determined an accentuated difference to the SI engines in terms of consumption, up to 35%. In the last years the fuel direct injection has been successfully introduced also in SI en-gines, determining a consumption reduction as well, in this case in a range of approximately 7%, depending on the swept volume. SI engines with direct injection which have been introduced in series production till now are characterized by the mixture formation within the combustion chamber with the support of the inducted air flow or with the support of the chamber form, especially of the piston surface form. Beginning with the year 2006 new concepts have been in-troduced in series production – where the main role in mixture formation is played by the fuel spray jet through multiple holes injectors at in-jection pressures which are higher than 200 bar. The fuel consumption decreases in this case in comparison with SI engines with fuel injection into intake ducts with approximately 20%. A split direct injection within every cycle leads to stable combustion. On this way the handicap to CI engines in terms of fuel consumption is reduced to approximately 10%. At part load there is no more difference between SI and CI engines regarding the fuel consumption. Other measures supporting the process of consump-tion reduction are the following:. variable valve control in terms of course and opening duration – ensuring a consumption reduction in the range of 8-12%. However, the production costs increase in the case of me-chanical control devices with approximately 10%. The electromechanical control devices are not competitive till now, whereas the electro-hydraulic systems are being now introduced in series production.. the impulse charging, by means of electromag-netic valves shows the same effect on the reduc-tion of fuel consumption like the variable valve control. Concomitantly, the better cylinder fill-ing with air when using impulse charging makes not more necessary a variation of the length

of intake ducts with the speed. This concept is now in an advanced development stage, but not yet in series production. . . deactivation of the process in a number of cylinders in multicylin-der engines – leading to a remarkable decrease of the fuel consumption, up to 20% at part load. . start motors mounted on the crankshaft - lead-ing to a consumption reduction in the range of 10-15%.. variable piston stroke – ensuring a consump-tion reduction of 8-20% at part load. Different solutions of this type are developed at the pres-ent.. two spark plugs per cylinder and double, se-quential ignition – reducing the fuel consump-tion up to 5%.. ignition systems at high frequency or ignition systems with plasma jet reduces the carbon di-oxide emission with 10%.. the combination of variable compression ratio with supercharging has a potential to reduce the fuel consumption up to 30%.. downsizing by reducing the number of cyl-inders - for example from 6 to 4 or from 4 to 3, in combination with super-/turbocharging, achieving mean effective pressures in the range of 25 bar, lead to a decrease of fuel consumption up to 25%. For such applications, a two stage charging is recommendable. . supercharging with small turbochargers can improve the fuel consumption in the range of 15%.. reduction of friction losses: in the last 20 years a decrease of approximately 25% has been achieved. However, there is still a consider-able potential. An engine without friction losses would have a 20% higher thermal efficiency. On this way noticeable improvements are possible. The utilization of rolling bearings instead of fric-tion bearings, in relationship with new methods of surface treatment of the rolling pins has also a good potential.. the engine cooling at high temperature of the coolant, combined with a thermal management leads to a fuel economy in the range of 5-10%.. the cooling of exhaust gas by integrating the exhaust ducts in the cylinder head reduces the duration of engine heating after start; on the other hand, the enrichment of the fuel/air mix-

The Future of the Piston Engines

Dr. Ing. h. c. Richard van Basshuysen

Prof. Dr.-Ing. Fred Schäfer

Dr. Richard van Basshuysen is the engineer who introduced, as a world premiere, the direct injection in the diesel engine for automobiles, in his function as R&D responsible at AUDI between 1988-1990, after a brilliant career at NSU and AUDI. After 1990, Dr. van Basshuysen acted for 20 years as editor and coordinator of two automotive engineering magazines – ATZ (Automobiltechnische Zeitschrift) and MTZ (Motortechnische Zeitschrift). His indefatigable activity as an author and editor has as a benefic result for us numerous technical books which are true references in this domain: Internal Combustion Engines, Engines Lexicon, Engines with Direct Injection. The most recent apparition in the Springer Vieweg Edition is the handbook Internal Combustion Engines, 6. edition, with 1200 pages, 1793 figures, 1300 references – elaborated together with 120 co-authors, which are well known specialists from the European automotive industry and from Universities. The following article presents the quintessence of this work.

Prof.Dr.-Ing.habil.Prof.E.h.Dr.h.c. Cornel Stan

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ture -which is necessary for cooling the combus-tion chamber at high load – can be reduced as well. Another advantage of the high temperature coolant is a faster heating of the passenger cabin, which means an economy of energy.. the structure optimization of fuels and lubri-cants has a potential of consumption reduction in the range of 5-10%.. the hybridization: micro-hybridization using start-stop devices, with a potential of consump-tion reduction of 4%; partial hybridization with approximately 10%; full-hybridization with 14%. . the utilization of exhaust gas energy within thermoelectric generators and in Rankine cycles – the obtained electric energy being stored in battery – has a potential to reduce the fuel con-sumption in the range of 6%. Such systems will be introduced in series production in the next 3-5 years. . the supercharging by using mechanical com-pressors presents some advantages in compari-son with the turbocharging in terms of reaction time; but this solution is disadvantageous in terms of fuel consumption and should be avoid-ed in the future.. HCCI – homogeneous Charge Compression Ignition – has a potential to reduce the fuel con-sumption in the range of 15%. switching off the engine during free rolling of the vehicle (gliding) can lead to a double roll-ing distance, thus to a fuel economy of approxi-mately 10%.Combining the mentioned measures conse-quently and reasonable the specific fuel con-sumption can be reduced up to 40%. This goal is achievable in the next 10-15 years. Additionally, the improvement of gear boxes can contribute to the reduction of fuel consumption in the range of 15%.

CI ENGINE

The potential to reduce the fuel consumption in compression ignition engines is smaller than for spark ignition engines, because of the applica-tion of direct injection, which has already pro-voked a reduction of fuel consumption in the range of 15-20%. However, some measures with potential are no-ticeable:. the variable valve control in terms of course and opening duration is also reasonable for CI engines but the potential of consumption reduc-tion is smaller, achieving some 5-10%, because at part load it is not necessary to throttle the

intake air flow.. the impulse charging, by means of electro-magnetic valves has a potential of consumption reduction up to 20%. The geometrical compres-sion ratio can be lower in this case, the charging being more advantageous.. the deactivation of the process in a number of cylinders in multicylinder engines is also advan-tageous in the case of CI engines but the effect in terms of consumption reduction is lower than at SI engines. On the other hand, the uniformity of the crankshaft rotation is impaired.. start motors mounted on the crankshaft lead to similar effects as in SI engines . variable compression ratio makes no sense for CI engines.. the friction losses in CI engines cost some 26% efficiency, having more importance as in Si en-gines.. downsizing has similar effects in both SI and CI engines. In recent development projects for CI engines have been achieved maximal cylinder pressures up to 200 bars for car engines and up to 250-300 bar for trucks engines. The use of turbo-charges with electric motor activation facilitates the start of such engines.. the two stage charging (twin turbocharging) has been introduced in series production of CI en-gines in the year 2004, demonstrating a fuel con-sumption improvement in the range of 20-25%.. the fuel injectors with variable flow cross sec-tion (vario-injectors), depending on the load, lead to a reduction of fuel consumption in the range of 5%. On the other hand, the vario-injectors are benefic for the improvement of additional performances, such as the dramati-cally decrease of the pollutant emission and of the noise, with the concomitant increase of the torque. This concept is not in series application till now because of the high costs. A compensa-tory measure consists on the increase of injec-tion pressure up to 2500-3000 bar. Such systems will be introduced in series production between 2013-2015.. the engine cooling at high temperature of the coolant, combined with a thermal management leads to a fuel economy in the range of 5-10%.. the further improvement of the thermody-namic cycle can have a contribution to the fuel consumption reduction in the range of 5%.. the water injection provokes a diminishing of NOx and soot emissions and facilitates the re-duction of fuel consumption.. the utilization of exhaust gas energy after tur-bocharger, a reduction of consumption in the range of 5% appears as possible.

. the hybridization using CI engines leads to the lowest fuel consumption. However, at this time the costs are higher than integrating SI engines – nevertheless the car manufacturers are inten-sively implicated in the development of this concept. . the structure optimization of fuels and lubri-cants has a similar potential of consumption as in the case of SI engines.. Replacing aluminum pistons with steel pistons both weight and friction diminish, facilitating the reduction of fuel consumption in the range of 2-5%.

FINAL REMARKS

Despite the fact that the values mentioned in this work are approximated, it can be deducted that the specific fuel consumption of SI and CI engines will be comparable in the future. The CI engines will keep advantages of some 10-15% in terms of consumption but their production costs will remain 1.5 to 2 times higher. On the other hand, the reduction of fuel con-sumption of both SI and CI engines will be remarkable, ensuring their domination in the competition with the fuel cells. In this context must be also considered the price of the fuel cells which is at the present 15-20 times higher as the price of piston engines. Regarding the pollutant emission there is practically no more difference between piston engines and fuel cells.. the convergence of Si and CI engines in the future is more and more evident – testimonies being the development projects of Daimler (Diesotto) and Volkswagen (CCS- Combined Combustion System).The author of this study means that there is a further improvement potential, which was not explored till now, consisting in the increase of oxygen concentration during the combustion process. This goal is achievable by reducing of nitrogen concentration in the aspirated air, by fuels with higher oxygen concentration or by water injection.All these reserves will ensure a long life of the piston engines as propulsion systems for auto-mobiles.

REFERENCES:

Richard van Basshuysen/Fred Schaefer: Motoare cu Ardere Internă – noţiuni fundamentale, componente, sisteme, perspective, ediţia a 6-a (în limba germană), Vieweg-Springer, 2012, ISBN 978-3-8348-1549-1.

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ABSTRACTThis paper presents a study of the car acceleration. The vehicle has an on-board computer that enables the acquisition of data which is fed from the already incorporated transducers. Some acceleration features are highlighted.

Acceleration is one form of determining a vehicle’s performances. Theoretical study of the acceleration process is aiming to determine the calculus methodology for time and covered space by the vehicle until reaching the speed of 100 km/h; with these parameters, acceleration performances of various similar cars may be compared. [1; 3] Experimental study of acceleration allows the setting of performances in certain movement and driving conditions; thus the dynamic performances and real efficiency performances may be set. [2]In the paper herein a comparative study of acceleration is performed. The tests were carried out with a Logan Laureate vehicle that is equipped with an on-board computer. To this purpose 50 acceleration tests were selected and an additional 50 normal tests which are further on called non-acceleration tests. These later test describe a normal regular vehicle movement; speed variation character for the two cases is seen in figure 1, where also the maximum values overhaul are being presented. We have to underline that in classical, theoretical study, the vehicle’s acceleration is being studied having the engine performing on its exterior characteristic, in full throttle in order to estimate

maximum performances [1; 3]. In practical situations, the engine operates in partial loads [2]. Indeed, as we can see from figure 2a, the engine operates in 44% of situations at level or

high loads and within 50–95% (different from full loads) approximately equal as the non-acceleration tests from figure 2b. As we can see from figure 2, engine load is appreciated by the

Experimantal Study of the Car Acceleration Equipped

with On-Board ComputerIng. Marian-Eduard Rădules-cu A.P., auto technical expert, Bucharest e-mail: [email protected]

Drd. ing. George BivolMinistry of National Defense, Buchareste-mail: [email protected]

Prof.dr.ing. Ion CopaeMilitary Technical Academy, Bucharest e-mail: [email protected]

Fig. 1. Vehicle speed

Fig. 2. Throttle’s position (engine load)

Fig. 3. Engine speed

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throttle’s angular position x , as a percentage compared to its maximum opening position. In the literature engine load is also appreciated through the intake air pressure pa. The graphs from figure 2 also highlight that in the case of acceleration the null value for the engine load is achieved only during gear changing. Added to that figure 2 also presents a discreet representation of parameters (as data is), and also a continuous representation (as usually is done), the latter having the disadvantage that

it generates values that do not pertain the real data. Discrete representation of data allow for data set prominence where most are concentrated as we can see from figure 3 for engine speed n. As we can see form figure 3a, in the case of acceleration 90% of the values are situated within 3000-4800 rev/min; similarly from figure 3b we can see that the non-acceleration tests 67% of the values are within 2000–3000 range, meaning below the value range as the case of acceleration tests.

Highlighting ranges where most experimental data are concentrated may also be observed in the parameters’ bivariable dependence graph. To this purpose an example is being presented in figure 4, where the dependence from the engine speed and its torque is presented; the graphs also gives the external characteristic of the engine (B representing maximum torque) with its power Pe and torque Me. As we can see from figure 4a, a great majority of torque values in the case of acceleration are found in the right side of maximum torque (in the area of high power output, area A). In exchange in the case of non-acceleration (regular movement), most values for the engine torque are in the left side of maximum torque (at lower power outputs).The graphs from figure 1a and 3a also highlight the fact that in the case of an electronically controlled vehicle it is difficult to notice the moments of time where gears are shifted if the vehicle’s speed is targeted (figure 1a), but we need to analyze the engine’s speed (figure 3a) The main cause is of course the rapidity with which the gears are shifted, without double clutching, with almost instantaneous shifting from one speed to another; the mentioned aspect is also revealed in figure 5 where the shifting duration are shown for one acceleration test. The graph from figure 5 highlights the moments of time needed for gear shifting, marked on the graph I–V, as well as the acceleration time td=36,7 s on which a speed of 120 km/h (point P) is reached. The two targeted forms of movement also have other particularities as we can see from figure 6 where engine hourly fuel consumption is presented Ch. As we can see from figure 6a, in the case of acceleration we clearly can distinguish fuel consumptions through gears I–V, which is not the case for non-acceleration tests (figure 6b). The graphs also highlight the fact that as the vehicle speed V increases so does the fuel consumption. In order to better accentuate the nature of the process and their evolution tendencies a discreet representation of data was used. From figure 7 we can deduct a functional dependence between the acceleration pedal position p and engine speed n; area A from the graph allows for setting the delay between the moment the acceleration pedal is engaged and the moment the engine speed starts to vary. Besides, this graph allows for setting of times on which the driver acted upon the acceleration pedal in order to change gears. In order to analyze the energetic efficiency of the acceleration, figure 8 presents engine

Fig. 4. Engine speed and torque dependence

Fig. 5. Time moments needed for shifting gears in the case of acceleration test.

Fig. 6. Hourly fuel consumption and vehicle speed dependence

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torque Me depending on its speed n for various values of actual specific fuel consumption ce. In fact this represents the well known spatial static characteristic of engine ce=f(n, Me), but transposed in 2D having izo-consumption curves where ce=const. (a so called complex characteristic). Based on this characteristic we get the classical economic pole, A dot on the graphic where ce=240,5 g/(kWh). Likewise, the graph also presents another spatial static engine characteristic that of he=f(n, Me), also transposed into 2D having curves of constant engine efficiency he=const.; based on this the well known energetic pole is achieved, dot C where he=30.23%. The graph also presents the engine’s external characteristic Me=f(n), on full load (for x=100%), dot B being specific for maximum engine torque; we can see the energetic pole C is situated on the external characteristic. As we can see from figure 8, the experimental values specific for acceleration are closer to the economic pole A and to the energetic pole C than the case of the non-acceleration tests data; therefore, the engine is more efficient in case of acceleration.We also need to mention that the experimental values specific for acceleration are situated closer to the economical pole A, fuel consumptions being greater than those recorded in the case of non-acceleration tests, as we can see in figure 9 where the average values of hourly fuel consumption Ch and the fuel consumption registered for 100 covered kilometers are presented C100. This has two causes: first of all in the case of acceleration tests, the recorded engine power is higher

Fig.7. Acceleration pedal position and engine speed, an acceleration test

Fig. 8. Engine complex static characteristics

Fig. 9. Average values for fuel consumption registered during tests

18


(see fig.4); secondly from figure 8 we can see that the experimental data specific for non-acceleration tests are closer to D area, where specific consumptions are lower even than the classical A economical pole. In other words, in this second case the consumption values are shrunk without having another economical pole (a minimum value) other that A dot. The graphs from figure 9, which indicates a higher fuel consumption in the case of the acceleration tests (the graphs from the left side), show an even more diverse fuel consumption for the non-acceleration tests (the graphs from the right side). Higher fuel consumption values in the case of acceleration tests ensures higher vehicle speeds

as we can see from figure 10, where average values and maximum values are presented for each test and overall. Comparing the upper graphs with the lower graphs we can see that in the case of the acceleration tests we achieved an average value for the vehicle speed which is 51.1% higher than the case of the non-acceleration test-runs and a maximum value which is 21.6% higher. From figure 11a we can see that I the case of acceleration tests the aerodynamic resistances are most important (engulfing 51.75% of all resistance forces), and figure 11b shows that in the case of a normal vehicle movement (non-acceleration tests), the rolling resistances are most important (36.88% of the total), but not as

accentuated, the three components being closer together in their importance (approximately 1 third each).Similarly we can perform acceleration study following other issues like parameter functional dependence establishment or the influence of certain factors onto the acceleration it’s self.

Fig. 10. Vehicle speed average and maximum values for each test

BIBLIOGRAFIE

[1] Andreescu C. Dinamica autovehiculelor pe roţi, vol.1.Editura Politehnica Press, Bucureşti, 2010[2] Copae I., Lespezeanu I., Cazacu C. Dinamica autovehiculelor. Editura ERICOM, Bucureşti, 2006[3] Gillespie D. T. Fundamentals of Vehicle Dynamics. SAE Inc., S.U.A, 1992

Fig. 11. Percentage average values for progression resistance in the case of each test

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ABSTRACTThe increasing complexity of the powertrains dedicated to the road vehicles by the introduction of hybrid systems that integrate internal combus-tion engines in sophisticated mechano-electric equipment, re-draw the attention to the problem of wear and reliability. In such systems, the ICEs are conceived to be operated in new types of re-gimes as start-stop regimes, where the share of partial loads is much more significant. In the pres-ent paper, it is proposed a new approach based on thermodynamic modeling that allows a holistic modeling of degradation phenomena associated to the wearing of engine components and of the related thermomechanical processes.1. INTRODUCTIONThe global trends in demographic evolution and the transitions within the automotive markets lead to forecasts estimating that the global auto-motive fleet will exceed 2 billion vehicles in the next two decades [1], that is introducing signifi-cant pressure on the environment and implicitly on the requirements for the reduction of GHG emissions. From a technology perspective the above mentioned pressures led to the introduc-tion of hybrid vehicles which integrate in the vehicle powertrain systems internal combustion engines with reversible electric motors and start-stop automatic control systems.According to several studies published in the lit-erature the start-stop functioning regimes could allow the reduction of the fuel consumptions up to 10% and reduction of CO2 emissions up to 20%. Such performances are usually evaluated using standard cycles as the European City and Intercity Cycles.

Several studies have emphasized the fact that new technologies, besides of the benefits in terms of improvement of efficiency and the reduction of the environmental impact, are characterized by the introduction of several unknowns in terms of tribological processes and lubrication aspects at the contact between the moving surfaces at the level of ICE components[2][3]. 1. Thermodynamic modeling using the concept of exergyIn the modern theory of thermodynamics every process in nature is following the conservation laws: For closed systems:

(1)

Where: S1,S2 – the values of the entropy of the system in the initial and final states

– entropy transferred over the boundary fSgen – generated entropy as an effect of the process irreversibility. For open systems:

(2)

Where: Svc – the entropy associated to the sub-stance from the control volume

– exchange of entropy corresponding to the heat fluxes exchanged over the boundary;

– exchange of entropy corre-

sponding to the mass flows in and out over the boundary;

– entropy generation rate.Exergy is defined as the maximum theoretic work that could be obtained if a system evolves until the thermodynamic equilibrium state with the envi-ronment only by the means of processes of inter-action of the system with the environment.Given an open system at an initial state s=s(p,T), and given the „environment” as a reservoir of sub-stance/energy that is in contact with the system and having the capacity to takeover mass and en-ergy flows much more higher than those of the system. The maximum work that could be ob-tained by the evolution of the system, taking into consideration only the processes in which the sys-tem interacts with the environment is calculated with the following formula:

(3)

Where: e – exergy per mass unit;h – enthalpy per mass unit;s – entropy per mass unit;0 – index corresponding to the equilibrium with the environment. In the case of systems integrating several com-ponents between which there are chemical reactions and exchange of kinetic and po-tential energy, the exergy of a single compo-

The Analysis of the Wear Processes per Cycleusing the Thermodynamic Modelingof the Internal Combustion Engines

T. MamutFaculty of Power Engineering, “Politehnica” University of Bucharest, E-mail: [email protected];

A. Badea Faculty of Power Engineering, “Politehnica” University of Bucharest,E-mail: [email protected]

E. MamutFaculty of Mechanical Engineering, “Ovidius” University of Constanta, E-mail: [email protected]

Fig. 1. The concepts of thermodynamic system and process

Fig. 2. Process decompositionin sub-processes

Fig. 3. Exergy accumulation over the entire value chain

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nent is calculated with the following formula: (4)

Where: – Gibbs free energy per unit mass;Rk – gas constant for the component k;ck, ck,0 – concentrations for component k and con-centration at the equilibrium state;Wj – mean velocity for the component j;g – local gravity;zj, zj,0 – spatial coordinates at the initial and at equi-librium state with the environment using a refer-ence level.The use of exergy balance equations can be done by the definition of the reference balance contour centered on a system or on a process. In certain sit-uations centering on system or on process of the balance contour might be the same thing because in a certain system there are located the evolution of the certain processes but also there are very of-ten situations while in an engine there are several processes that take place, either sequential or in parallel. In figure 1 there are shown the concepts of exergy loss and exergy destruction for both cases as system or process.The exergy loss represent a property that char-acterizes a specific flow of mass outflowing from the system, and has not a certain purpose (i.e. the exhaust gases from an ICE). The destructed exergy represents a term in the balance equation for which there is not a physical association with a certain mass flow or energy flow. It is a term used to „close“ the balance equation. The exergy

destruction is connected to the generated entropy term and the equivalent physical phenomenol-ogy consisting on structural changes or material degradation both at system level or process level, is usually considered beyond the subject area of thermodynamics. For the system represented in Figure 1 a, the bal-ance equation shall take the following form:

(5)For figure 1 b, the equation is taking the following shape:

(6)In order to develop an engineering approach based on exergy modeling it has been proposed the concept of „cumulated exergy content“ (CEC). This property could be defined both at the level of process and at the level of system or structure. As could be observed in Figure 2, in the case of a complex process it can be decomposed in sub-processes so that for each of them there are derived inputs and outputs according to the con-tribution of each sub-process on the entire pro-cess. By normalizing the exergy flows exchanged between the sub-processes in respect to the mass flow unit, it is possible to highlight the exergetic efficiency at the level of each sub-process and in this way to allow the identification of „loss cen-ters“ in order to identify solutions for improving the efficiency.In the case of a system or a manufacturing value chain of the system, starting from raw materials until the final system, it is considered that each processing phase consists in exergy consump-tion associated to the used mechanical work and the state of the system that is passing through each processing phase could be defined with a property that measures the cumulated net exergy consumed in each phase. The final system will be characterized by consumed exergy cumulated from the raw material state of the components, to the finale state of the system.As it can be observed in the Figure 3,

(7)Where: CEC1, CEC2 – cumulated exergy con-tent for associated systems;E1,E2,E3,E4,E5,E6,E7,E9,E11,E12,E13 – consumed ex-ergies in different phases of manufacturing;E8, E10 – lost exergies in different phases of manu-facturing;EdE, EdPP, EdF – terms related to the destroyed ex-ergy. For a given system obtained by the manufactur-ing and assembling of n components, the value of the cumulated exergy content (CEC) is calculated with the following formula:

(8)

Where: – cumulated exergy con-tent for the entire system;

– consumed exergies for the manufacturing of the component i;

– exergy losses in the manufacturing process of component i;

– destoryed exergies in the manufactur-ing process of component i.By transposing in terms of exergy both the ener-gy conversion process that takes place in a given system and the structure of the components of the system enable a development of a unified ap-proach that can be useful in the optimization of the engineering systems.There are several approaches presented in the lit-erature regarding the scientific background of the optimization methodologies. Some of them are summarized in reference [4].In the engineering practice there were validated and extended two directions as the Constructal Theory and the Exergoeconomic Theory.The constructal theory was proposed in 1996 by professor A. Bejan based on a methodology for optimizing the flow geometries of fluids through heat exchangers based on the principle of mini-mizing the generated entropy in the flow process, which is equivalent with minimizing the destruct-ed energy. The optimization principle also called the constructal law, as it was formulated in 1996, has the following definition: „For a finite-size sys-tem to persist in time (to live), it must evolve in such a way that it provides easier access to the im-posed currents that flow through it”. Later, this law was generalized for a wide class of processes, from flow processes, heat transfer, transportation, urban planning, demographic evolution, resource plan-ning etc. The developed methodology consists in a hierarchical approach of the design of structures by the aggregation of optimized elements named „constructs”. The optimization at each hierarchical level is done based on the principle of minimizing the generated entropy in the flow process.The limits of the constructal theory are deter-mined by the flow regimes putting usually an em-phasis on optimal geometries at the laminar flows because in laminar flows the generated entropy is minimal. The second limitation consists on the fact that the developed methodologies are centered only on the relation of geometries to the minimal gener-ated entropy processes. The effort to manufacture

Fig. 4. The relation between the normalized wear rate and normalized flow of entropy.

Fig. 5. The heat dissipation process in the friction area

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those geometries and the resources as materials involved are not taken into consideration.The Exergoeconomic theory consists in principle in transposing both the processes and the struc-tures in terms of exergy and in the second phase the conversion of terms in exergy into costs. The conversion into costs is made based on the statisti-cal evaluations of the equivalence between exergy and the different reference hard currencies for a certain level of technology, of the price of raw ma-terials and of the energy resources.The method is robust and has been tested for a wide range of systems. The main limitations of this approach consist of the market fluctuations and the uneven evolution of the process of differ-ent raw materials. At the same time the exergo-economic approach doesn’t take into account the physical degradation of the components of a sys-tem during its operation and of the depreciation of its performances due to wear. Such aspects are considered in the form of additional costs which

might be arbitrary. 2. THE MODELING OF THE WEARING PROCESSES BASED ON THE ENTROPY GENERATION CONCEPTThe notion of entropy generation opened over decades a wide scientific debate. If we take strictly the wording of the II law of thermodynamics, the generated entropy is just a simple term conven-tionally adopted (mathematically) in order to transform the inequality from equation (9) in a entropy balance equation (as equation 1) without a physical meaning.

(9)

On the other side, many scientists have revealed the fact that in the dissipative processes, the gen-erated entropy is connected to structural changes. The main observations came from material sci-ences where there exist a substantial literature in which the entropy generation is associated with the accumulation of defaults and degradation phenomena in different types of structures like viscoelastic materials, amorphous or crystalline structures [4]. In the last two decades a spectacular development has been done in the area of tribology where there wore synthesized empirical observations and de-fined several laws that are relating the phenomena that occurs in the friction processes with the ac-cumulation of generated entropy. Thus, following detailed scientific experiments on

the processes that take place in the contact patch between moving bodies there wore proposed ini-tial hypotheses on the use of generated entropy as a reference property for the degradation phe-nomena. In reference [5] there are presented the results of an analysis, based on an impressive vol-ume of experimental data, of the relation between the friction coefficient and entropy. As it can be observed in figure 4, the evolution of the wearing coefficient defined based on the Archard model has a thermodynamic determination consist-ing on the entropy flow. It should be mentioned that in reference [5], the proposed formulation is based on entropy flow and not on entropy gen-eration. In the following references [6][7][8][9][10] the dependence between wearing coefficient and entropy has been reformulated following an emphasis on generated entropy. Thus, by reducing the friction process strictly to dissipative phenom-enon with the propagation of heat as it is present-ed in the sketch from figure 5, the work dissipated by friction is leading to a gradient of temperature and implicitly to the transfer of heat Q through the balance contour associated to the friction area. If we shall refer to equation (1), it includes the term referring to the dissipated work by friction and the term referring to generated entropy shall be as small as the heat transfer shall be much more intensive and this aspect is accordingly with the results obtained by decades of empirical obser-vations on wearing processes. The complexity of the phenomenology associated to the wearing process in the contact patch has been studied in detail in reference [8] and are synthesized in table 1. At present, intensive research activities are car-ried out and there are explored several theoretical approaches starting from quantum mechanics, thermodynamics of irreversible processes and fractal theory in order to develop detailed models and rigorous scientific backgrounds. For the pur-pose of the present study we could mention the fact that based on extended research it has been formulated „degradation – generated entropy theorem” [8]. According to this theorem, consid-ering a number of n dissipative processes charac-terized by energies where

are generalized coordinates associated to each process and for a property that is characterizing degradation, , being a monotone and positive function, depending on pi energies,

the degradation rate , is a linearfunction depending on the components of the

generated entropy in dissipative pro-

Process Entropy change

Adhesion, where is surface energy, A area

Plastic deformation, where is the work per volume, V volume

Fracture , where where Ni are numbers of molecules and μi are chemical potential for reactants and products

Phase transition where H is enthalpy

Chemical reaction , where Ni are numbers of molecules and μi are chemical potential for reactants and products

Mixing

where Ni are numbers of molecules and R is the universal gas constant

Heat transfer, where T1 and T2 are temperatures of

the two bodies

Table 1. Entropy variation in various dissipative processes

Fig.6. Off-design Analysis of Operating Systems

22


cesses (where X and J are the generalized forces and fluxes associated to each process). Bi coef-ficients are obtained as partial derivatives of the degradation rate in respect to the generated en-tropy in each process.3. RESULTSThe subject of entropy generation and the rela-tion with the degradation phenomena associated to the non-linearity of the properties of materi-als, friction and the heat transfer that take place at finite differences of temperature has been also presented in reference [4]. In this way it has been demonstrated that by the deformation of different materials it occurs a dissipation phenomenology based on the mechanical hysteresis which leads to equation (2). As a consequence one could claim that the irreversibility of the processes in nature is materialized at the level of structural components of the equipment and installations by the increase of the generated entropy. At the beginning of the last decade in several papers published in the lit-erature it has been proposed the idea of diagnosis of thermo energetic equipment based on exergy analysis [11]. The proposed method consisted on the identification of the functional penalties associated to a specific component or a system in which a certain process takes place by studying the impact on the energy efficiency of the term associ-ated to exergy loss or destructed. The method has been developed integrating heuristic tools and ar-tificial intelligence and it became over the years a classical method of analysis that is completing the set of methods for diagnosis and troubleshooting.By the analysis of the literature it can be observed that there are many results published by different scientist that point on the relation between the in-crease of entropy generation phenomena and the degradation of the system performances. Trying to explain this only in terms of cumulated exergy content might be misleading because the CEC of a new system is never decreasing and if the system is operated like the case of ICE, the CEC is increas-ing, so we shall have a degraded system having a CEC higher than the new one. In order to correct this situation it has been proposed a new property as Exergy Value. The Exergy Value of a function-ing system at a certain moment has been defined as the CEC of a new system that could perform the same functions as the used system [3]. The formula proposed for calculating the exergy value of a functioning system under the impact of degra-dation and/or wearing processes is the following:

(10)

Where:EVR,sys – the exergy value of a func-tioning system;CECF,sys - the cumulated exergy con-tent of the system at the moment of commission-ing;T0 – reference temperature of the environ-ment;tS,i – operation period of component i;

Sgen,i – entropy generation rate during the load of the component i.By the adoption of this new property there is cre-ated a new opportunity for the analysis and opti-mization of equipment during the period of op-eration (off-design). For this purpose it has been drawn the viewgraph of Figure 6On Figure 6 can be distinguished the dependence curves between the generated entropy and the cu-mulated exergy content and respectively between the generated entropy and destructed and lost ex-ergy. As a consequence according to this diagram by investing exergy in a specific equipment (in a repairing process), respectively increasing the CEC of that equipment with several enhancement like better isolations, highly efficient components, and so on, the performance of the equipment is increasing and the generated entropy in the opera-tion of the equipment is decreasing. Over the operation of the system, its components are depreciated and this is leading to a lower ex-ergy value. The diagram of Figure 6 allows the calculation of the total exergy value as the sum of exergy value of the system and the lost and de-structed exergy while the same system is operated (as a measure of its performance) allowing the comparison of different stages of wear and depre-ciation of the system. In this way it is possible to evaluate the need of investment in terms of cu-mulated exergy content that has to be invested in repairing the system.This methodology has been applied to the study of an ICE in Start-Stop regime.As can be observed in figure 7, there were selected the main friction couples, respectively the piston ring-cylinder liner, crankpin-connecting rod bearing and main journals – bearings.In the case of the friction couple piston ring – cyl-inder liner the calculations have been done for a spark ignition engine with the bore of 130 mm and a stroke of 142 mm. Based on the simulations of generated entropy over the cycle it has been

obtained that a single cold start cycle from the wearing point of view is equivalent to 14 cycles of function-ing at the nominal sta-bilized regime [12]. 4. CONCLUSIONSThe paper presents fundamental aspects of thermodynami-cally modeling of thermomechanical systems applied to ICEs.The advantage of the presented method consists on the possibility to quantify the wear accumu-lated on each functioning cycle of the engine us-ing the concept of generated entropy and to define the wearing state of the engine by the use of the generalized concept of exergy.ACKNOWLEDGEMENT: The work has been funded by the Sectorial Ope rational Programme Human Resources De velopment 2007-2013 of the Romanian Ministry of Labour, Family, Social Protection and Elderly through the Financial Agreement POSDRU/107/1.5/S/76813

Fig. 7. Wearing couples in an ICE

REFERNCES:[1] J. Dargay, D. Gately, M. Sommer, Vehicle owners-hip and imcome growth worldwide 1960-2030, Enegy Journal, 28 (2007), 143.[2] N. Fonseca s.a., Influence of Start-Stop system on CO2 emissions of a Diesel vehicle în urban traf-fic, Transportation Research part D: Transport and Environment, 16 (2011), 194-200.[3] J. C. Walker s.a., The influence of Start-Stop transient velocity on the friction and wear behaviour of a hyper-eu-tectic Al-Şi automotive alloy, Wear, online, 2012.[4] A. Bejan, E Mamut, Thermodynamic optimization of complex energy systems, Kluver pub. 1996.[5] Doelling et all, B.P. An experimental study of the correlation between wear and entropy flow în machinery components. J. Appl. Phys. 2000, 88, 2999–3003.[6] M. Nosonovski, Entropy în Tribology: în the Search for Applications, Entropy 2010, 12, 1345-1390.[7] M. Amiri and M. Khonsari, On the Thermodynamics of Friction and Wear – A Review, Entropy 2010, 12, 1021-1049[8] Michael D. Bryant, Entropy and Dissipative Processes of Friction and Wear, FME Transactions (2009) 37, 55-60[9] M.D. Bryant et all, On the thermodinamics of degra-dation, Proc. R. Şoc. A 2008 464.(Degradation – en-tropy generation theorem)[10] H. A. Abdel-aal, Wear and irreversible entropy ge-neration în dry sliding, Anals of University Dunărea de Jos, Galaţi, Fâs. VIII, 2006 ISSN 1221-4590[11] R. Melli, V. Verda, Thermoeconomic Approach to the Diagnosis of EnergySystems, Summer School of Thermodynamics2011, Anzio, Italy[12] T. Mamut, Thermodynamic Modeling of Internal Combustion Engines, Seminar at the Institute for Technical Thermodynamics, University of Rostock, Germany, 2013

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Abstract: The paper presents a study on structural and functional particularities of EGR depollution systems used on compression ignition engines. There are presented in comparison the specific construc-tive elements, the organization method of the depol-lution systems and also the advantages and disad-vantages for each option.

1. THE MOTIVATION STUDY:Over the time, the demographic and industrial development was made possible by creating an in-frastructure for the transport of goods and people. This thing led to an explosion of the vehicles num-ber equipped with internal combustion engines.Experience has shown that 18% of the total amount of CO2 caused by the anthropogenic activ-ity is due to road traffic. Also, the harmful effect of automobile on the environment and human body have led to the emergence of the exhaust emission legislation which became more and more strictly (Figure 1).Using 3-way catalytic converters for spark ignition engines and the 2-way catalytic converters for die-sel engines allowed a substantial reduction of CO and HC values. Experience has shown, that nitro-gen oxides (NOx) are the most difficult to refute applying both: depollution methods in the genesis or depollution methods based on the exhaust gas aftertreatment. This is why, especially for diesel engines, the nitrogen oxides emission remained a topical issue, which involves another important researches.The generalized method used to reduce nitrogen ox-ides is represented by systems type EGR - Exhaust Gases Recirculation. The first applications with EGR systems were produced in series since 1992.The researches developed until now has shown that the production of nitrogen oxides increases

with temperature and O2 concentration in the combustion chamber. Following this, through EGR systems a part of the exhaust gas is rein-troduced into the cylinder with the effect of de-creasing the global temperature in the combus-tion chamber and reducing oxygen used for the NOx formation.In this context, the synthetic and comparative study of different constructive variants for EGR system is required as needed.2. STUDY ON STRUCTURAL AND FUNCTIONAL PARTICULARITIES OF EGR DEPOLLUTION SYSTEMS The operating principle of EGR systems is shown schematically in Figure 2, and the effect of the exhaust gas recirculation on the NOx con-centration is shown in Figure 3.As we can see, a 5% decrease of O2 concentra-tion using EGR leads to a reduction of the global temperature with 200 K in the combus-tion chamber which results also a decrease of the concentration of nitrogen oxides from 900 ppm to about 350 ppm. So, it is fully justified the efficacy of the depollution method application

with the exhaust gas recirculation using EGR systems.A wide range of constructive solutions have been adopted over time, the most common are shown schematically below:a) Low pressure EGR system (Figure 4):This is the most used type of system. The ex-haust gas is directed to the admission via the EGR valve and by using valve 4 is controlled the amount of the recirculated gas. The main ad-vantages of this option are the simplicity and the quick response. The major disadvantage it is rep-

Study on Structural and Functional Particularitiesof EGR Depollution Systems Used on Diesel Engines

Prof. univ. dr. ing.Florian IVANUniversity of Pitesti, Romania

Dr. ing. Andrei BUŞOI University of Pitesti, Romania

Fig. 1. Fig. 2.

Fig. 3.

Fig. 4. 1 – răcitor EGR; 2 – răcitor aer comprimat – «intercooler» ; 3 – filtru particule; 4 – supapă EGR

24


resented by the conditioning in function of the engine exhaust gas flow.b) High pressure EGR system (Figure 5):At this version the exhaust gas is taken out down-stream of the turbocharger and placed in the ad-mission upstream of the compressor. Due to the low pressure values of the exhaust gas after the par-ticulate filter (3), on the exhaust section is used the exhaust throttle (5). This system has a very slow response, consequence of the large length of the exhaust gas route and a lower reliability of the admission system components caused by the prolonged contact with the exhaust gas. Unlike the classic system, experience has shown some ad-vantages in tasks where gas flow is reduced. There are also reported and improved decreases of fuel consumption.c) Hybrid EGR system with exhaust throttle (figure 6)This system uses both: low pressure EGR and high pressure EGR, trying to reduce the disad-vantages of each solution extending the conveni-ent function range. Thus, at high loads, with suf-ficient gas flow to not reduce the performances of the turbo unit it is used high pressure EGR and for small loads where the gas flow is low, it is used low pressure EGR. In this way the function point of the turbocharger will remain in areas of maxi-mum efficiency. Also, the longer road traversed by the exhaust gas allows a better cooling and an increase of the system efficiency. Experience showed that the solution offers considerable ad-vantages in terms of economy and dynamic.d) EGR system controlled with pressure pulses (fig-ure 7)This function system is based on the fact that in certain points the medium pressure of the exhaust gas has a lower value with a strong pulsating char-acter. As a result, this system uses a check valve whose opening is controlled by pressure peaks. It presents the advantage that this solution allows the exhaust gas recirculation also at low loads. To prevent the reverse flow of the gas it can be used a special valve called Reed, figure 7. e) EGR system with Venturi type (figure 8)The function of this solution is based on the prin-ciple convergent-divergent system, Venturi type. So, a narrowing of section 5 in the inlet of the admission circuit will cause a drop pressure in the input but also an increase of the recycled gas flow rate. In this sense it is facilitated the passage of the gas from the EGR valve to the intake manifold due to increase the speed of the convergent-divergent system (Venturi type). f) EGR system with rotating valves (figure 9)The method consists in compensating the low

Fig. 6. 1 – răcitor EGR; 2 – răcitor aer comprimat – «intercooler»; 3 – filtru particule;

4 – supapă EGR; 5 – volet


4 – supapă EGR; 5 – ajutaj de tip venturi


4 – supapă EGR; 5 – volet

Fig. 7.

25


flow of exhaust gas at low loads using a rotating valve. Experience has shown, that this solution has the disadvantage that increases the pumping losses. In Figure 9 are shown schematically the components of this constructive solution.g) EGR system with electric pomp (figure 10)An alternative to the high-pressure EGR system is to use a pump to ensure the exhaust gas recircu-lation in the admission (Figure 10). This system allows a good management of the amount of EGR even for low operating regimes. The disadvantage of this solution is the necessity of a additional en-ergy to action the pump. The action can be electric

or directly powered by the engine. Electrical train-ing is recommended because it is not dependent on the engine operating conditions. In addition, the electronic control unit software (ECU) can perform the optimum granting of the exhaust gas flow with the regime of the engine, so the solution allows the action of the EGR system in the regime drive by wire.h) EGR system with additional valve powered by the distribution mechanism (figure11)To implement this solution, the distribution sys-tem is equipped with an extra cam that causes the valve lift during the admission process. This thing

facilitates the return in the cylinder of the exhaust gas located in the gate of the valve outlet, a phe-nomenon known as the internal EGR. The disad-vantage of this solution consists in the structural complications imposed by the implementation of the valve lift mechanism in correlation with the admission valve and the engine operating mode.3. CONCLUSIONSThe problem of reducing nitrogen oxides (NOX), is a major concern for the depollution of the en-gines vehicles. Thus, reducing systems of nitrogen oxides using exhaust gas recirculation (EGR) will be in the future an essential solution.This paper summarizes the main types of EGR depollution systems - highlighting the fact that they must respond to a major challenge: the cor-relation of the amount of exhaust gas with the engine operating conditions. The strict control of the amount of the exhaust gas claim com-plexes and constructives solutions and the auto-matic monitoring through the electronic control units (ECU).This thing can be achieved by developing a «strong» software that allows the action of the EGR system in the regime drive by wire.

REFERENCES:[1] Buşoi, A., Contribuţii privind optimizarea unor procese şi sisteme în vederea depoluării chimice a M.A.C. - urilor care echipează autoturismele de cla-sa medie, Teza, Piteşti 2012; [2] Khair, M., Ma-jewski, A., Diesel emissions and their control, SAE, Hardbound, 2006; [3] Klaus Mollenhauer, Helmut Tschoeke, Handbook of Diesel Engines, Berlin 2010; [4] Howard J.B., Longwell J.P., Formation mecha-nisms of PAH and soot in flames – in M, COOKE et coll „Polynuclear Aromatic hydrocarbons: Formation, Metabolism, and measurement”, 7th intern, Symp, 1983; [5] SIMON REIFARTH EGR-Systems for Die-sel Engines, TRITA – MMK 2010; [6] Development of on board diagnostics systems.

Fig. 11.


4 – supapă EGR; 5 – pompă electrică


4 – supapă EGR; 5 – clapetă rotativă

26


University Research

„Contributions to the Comparative Analysis of the Tribological Parameters of the Nip-talcum and Hard Chromate Coatings on Steel” / Contribuţii la analiza comparativă a parametrilor tribologici pentru straturi de depunere nip-talc şi cromare dură pe suport de oţel

Aspects Concerning the Influence of the Combustion Chambers Architecture on the Performance of Internal Combustion Engines and Emissions / Aspecte privind influenţa arhitecturii camerelor de ardere asupra performanţelor motoarelor cu ardere internă şi emisiilor poluante

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Author: Drd. Eng. Popescu Marian-Teodor, e-mail: [email protected] Adviser: Prof. dr. ing. Băilă Neagoe University of Pitesti

The doctoral thesis reflects the current trend of building stronger mecha-nical systems, focusing on the necessity of improving the resistance to friction and wear, diminishing losses and increasing the new performance.There have been identified new processes of increasing the lifetime and the quality of mechanical systems, which can be exposed to extreme so-licitations during functioning at high temperatures, in the partial or total absence of lubricant.Tribological tests of dry friction were performed on samples on which were placed layers of materials resistant to wear, like NiP with or without talcum and hard chrome. Tests were conducted at a temperature of 300°C, with different rotational speeds on ambientale

pawn-disk tribometers,in the laboratories of Ecole Nationale d’Ingénieurs, Tarbes, France. The system used for gathering and processing the results of the tribological research is of recent technology, consisting of a console type HBM Spider 8 connected to a PC. The data acquisition is continu-ous, using informatical product CatmanEasy.Topographies of deposited composite layer surfaces were obtained by interferometry method in whi-te light, using an interferometric optical roughness meter type WYKO Veeco NT 1100. Therefore, minimum 4 sectors have allowed to establi-sh the amount of surface wear and rubbing slope profiles created during testing. After each test, an assessment of the tribological behavior of the deposits has been performed. Therefore, minimum 4 sectors have allowed to establish the amount of surface wear and rubbing slope profiles created during testing. After each test, an assessment of the tribological behavior of the deposits has been performed.

Author: Drd. Eng. Dima D Alexandru Mihai.e. mail: [email protected] Scientific Adviser: Prof. dr. ing. Marin BicaUniversity of Craiova.

The present paper’s aim consists in one of the main research goals of the automotive industry regarding the influence of the combustion chamber ar-chitecture over the performances of the internal combustion engines. This work presents the study conducted on three compression ignited engines and one spark ignited engine, following the pollutant emissions evolution

for different speeds and various load conditions and also the influence over the power performances for which there were designed and constructed two loading stands. The study pointed also over the behavior of the com-pression ignited engines for the case when fueled with different biodiesel blends and also mixed with diesel, regarding the pollutant emissions and power performances in comparison with classic fuel. It was found that the combustion chamber architecture influences in a very important manner the performances and the exhaust gases of an internal combustion engine being a field which can offer new possibilities of deve-lopment for the automotive industry.

Kart Low Cost Project 2013rezultatul cooperării între Université de Bourgogne, ISAT de Nevers

28 May 2013 marked the third edition of the Kart Low Cost project, already known as a competition between different schools in the automotive and transport engineering.As location, the team of Higher Institute of Automotive and Transports in Nevers, France has chosen to organize the competition KLC 2013 on the track F-58 of the Formula 1 Grand Prix circuit, from Magny-Cours.Design and manufacture of high performance karts on a tight budget (2000 euro for thermal project, 3500 euro for electric) is the key point of competition. Karts were built from scratch by students at the University of Pitesti, Romania and their french colleagues at the University of Bourgogne, ISAT Nevers. After qualifying, which was established the order of entry into competition, karts went through sprint tests, maneuverability, durability, design and evaluation of chassis and technological innovati-on.If Kart Low Cost project started in 2011 with only thermal kart component, 2013 marks the second participation of electric karts.Although the track was covered with rain water and put problems to the pilots, students have de-monstrated extraordinary technical capabilities of karts. In this competition we have seen excellent motivation of both participating teams, ISAT and UPIT. Following the results obtained during sport tests and after evaluating each project in terms of design and technological innovation, the students from University of Pitesti won first place in both components of the competition (thermal and electric project).The competition aims at the development of future engineers by developing knowledge of a technical project management, developing the spirit of teamwork by assigning responsibilities, under strict de-adlines and budget constraints.Kart Low Cost project is a result of collaboration between University of Bourgogne, ISAT Nevers, France and University of Pitesti, Romania. The next meeting will be held in Romania, in May, 2014.

More details: [email protected] (ş.l.dr.ing. Cătălin Zaharia, Universitatea din Piteşti)

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Ingineria · 4 Ingineria Automobilului Automotive Engineering: print edition publication, 2006...

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