Republic of Iraq Northern Technical University Equipments ...

Republic of Iraq

Ministry of Higher Education & Scientific Research

Northern Technical University

Technical Institute /Kirkuk

Equipments & Machineries Dep./ Branch of Ref. & Air Conditioning

A Research Submitted to

((Equipments & Machineries Dep./ Branch of Ref. & Air Conditioning))

Prepared by

Ibrahim Najmaldeen Mahmood Jalal Ali Asgher

Ahmed Bahir Mohammed Ibrahim Ahmed Mohammed

George Odisho Bawith

Supervised by

2018 1439

بسم الله الرحمه الرحم

رب أوزعى أن أشكر وعمتك ﴿

وعلى والدي الت أوعمت عل

وأن أعمل صالحا ترضاي

برحمتك ف عبادك وأدخلى

﴾ الصالحه

عظمال اللهصدق

(19)الات سورة الىمل

إليي لا يطيب الميل إلا بشكرك ولا يطيب النيار إلا بطاعتك ..

.. ولا تطيب المحظات إلا بذكرك

ولا تطيب الآخرة إلا بعفوك ..

ولا تطيب الجنة إلا برؤيتك ..

اذا كان الاىداء يعبر ولو بجزء من الوفاء فالاىداء إلى

.. من بمغ الرسالة وأدى الأمانة .. ونصح الأمة .. إلى نبي الرحمة ونور العالمين

الشموع التي تنير لنا دروب الحياة ..الى الوالدين الحبيبين

اخواننا و اخواتنا الذين يؤازرونا ويدعموننا..الى

اضاف لنا تقدما في الحياة ..ق الى كل صدي

الى اساتذتنا و مربونا ..

لموصول الى ىذه المرحمة ناالــــــى من ميدوا الطريق امام

..نا واجتياد نالكم ثمرة جيد نيدي

لباحثون ا

كن عالما .. فإن لم تستطع فكن متعمما ، فإن لم تستطع فأحب العمماء ،فإن لم"

تستطع فلا تبغضيم"

بعد رحمة بحث و جيد و اجتياد تكممت بإنجاز ىذا البحث ، نحمد الله عز وجل

عمينا فيو العمي القدير ، كما لا يسعنا إلا أن نخص بأسمى انعمياعمى نعمو التي

..ير للأستاذةعبارات الشكر و التقد

كما نتقدم بالشكر الجزيل لكل من أسيم في تقديم يد العون لإنجاز ىذا

..البحث، و نخص بالذكر أستاذتنا الكرام الذين أشرفوا عمى تكوين دفعة

الله العمي القدير ان يجزي الجميع خير الجزاء نسال

يحبو ويرضاه انو سميع مجيب .. وان يوفقيم لما

لباحثون ا

Description Symbols

Coefficient of Performance C.O.P

Pressure P

Enthalpy h

Heat of condenser Qc

Heat of evaporator Qe

Temperature T

Saturated temperature Tsat

Percentage mixing ratio by weight wt

Work of evaporator We

Ozone depletion OD

Global warming GW

Page Item

Chapter One/Introduction

1 1-1 Introduction

1 1-2 Ozone layer

1 1-3 Global Warming

2 1-4 Phase Equilibrium Diagram of Binary Mixture

3 1-5 The Aim of This Work

Chapter Two/Refrigerant Mixtures

4 2-1 Introduction

4 2-2 Background - Refrigerant Mixtures

4 2-3 Refrigerant Criteria

5 2-4 Alternative Refrigerants

7 2-5 Classification of Refrigerants

8 2-6 Azeotropic/Zeotropic Refrigerants

8 2-6-1 Azeotropic Mixtures

9 2-6-2 Non-Azeotropic/Zeotropic Mixtures

11 2-7 Oils

11 2-8 Refrigeration Oil

Chapter Three/Refrigerants Properties

13 3-1 Introduction

13 3-2 Azeotropic Refrigerants

13 3-3 Zeotropic Refrigerants

13 3-4 Saturated Properties Tables for Mixtures

14 3-4-1 For Azeotropic Refrigerants

17 3-4-2 For Zeotropic Refrigerants

21 3-5 Pressure – Enthalpy (P-h) Charts for Mixtures

21 3-5-1 For Azeotropic Refrigerants

24 3-5-2 For Zeotropic Refrigerants

Chapter Four/Conclusion and Recommendation

28 4-1 conclusion

29 4-2 Recommendation

References

30 References

Chapter One

Introduction

1-1 Introduction:-

Many of evolutions and modifications have been carried out compressive

cooling systems since beginning until the present time. Most of studies

focused on the mechanisms and methods of developing those systems, in

terms of performance (C.O.P). And the key factor was energy consuming

and their results, then the focus in researches and studies switched to other

fields which was concentrated on two main hubs, which are, the first is to

maintain a healthy environment by avoiding all harmful gasses accompanied

from engine combustion and air- conditioning refrigerants which have a

great impact on global warming and Ozone depletion, and second, is to

accommodate a natural alternatives instead of classical energy for long

term.

1-2 Ozone layer:-

The ozone layer or ozone shield is a region of Earth's stratosphere that

absorbs most of the Sun ultraviolet radiation. It contains high concentrations

of ozone (O3) in relation to other parts of the atmosphere, although still

small in relation to other gases in the stratosphere. Where Refrigerants

containing chlorine or bromine contribute to the breakdown of the ozone

layer.

1-3 Global Warming:-

There is an average increase in earth surface temperature with the increase

of the environmental harmful gases emission such as carbon dioxide

https://en.wikipedia.org/wiki/Earth

https://en.wikipedia.org/wiki/Stratosphere

https://en.wikipedia.org/wiki/Sun

https://en.wikipedia.org/wiki/Ultraviolet

https://en.wikipedia.org/wiki/Ozone

,Methane and other existed gases in the atmosphere . those gases called

greenhouse gases because they contribute in increasing the earth

temperature, this phenomenon is called the Global warming, and the average

of increasing temperature in the air where noticed in the middle of 20th

century as it continues to rise. Whereas the earth temperature was increased

0.74 ± 0.18° C over the last century. Where this increase in temperature

negatively affect the industrial revolution and the advancement of

technology which become one of the risks that surround the earth

environment and must be taken into consideration [1].

1-4 Phase Equilibrium Diagram of Binary Mixture:-

Phase equilibriums of binary mixtures are represented on phase diagrams.

Figure (1-1) depicts a phase diagram for a binary mixture system at constant

pressure. The dew point line represents the dew point temperatures of all the

possible mixture compositions, where Tdew is defined as the temperature at

which a superheated vapor mixture will first begin to condense upon

cooling. The bubble point line represents the bubble point temperatures of

all the possible mixture compositions, where Tbub is defined as the

temperature at which a sub-cooled mixture will first begin to evaporate upon

heating. The composition of one of the components, in this case the

component with the lowest boiling point, is depicted on the lower axis,

where the equilibrium vapor composition Y is that which corresponds to the

liquid composition X at the same temperature. It can be seen from the figure

mentioned above that the saturation temperature of one pure component is

on the left vertical axis while that of the other component is on the right

vertical axis [2].

Figure (1-1) Phase equilibrium diagram at constant pressure for a binary

mixture [2].

1-5 The Aim of This Work:-

The aim of this work is, to identify the blend refrigerant compression

cooling system, which is consists of two or more refrigerant gases and

knowing the proportion of each gas exist in the mixture and studying the

differences in their properties and behavior, as well as comparing them with

compression refrigeration pure gases which consist of one pure refrigerant

gas.

Chapter Two

Refrigerant Mixtures

2-1 Introduction:-

This chapter studies the properties of substances used as working fluids in

compression cycles, and discusses the classification of refrigerants.

Some of the most common refrigerants are presented, as well as the special

phenomena occurring with the use of zeotropic refrigerant mixtures. Finally,

the use of secondary refrigerants and oil in refrigerant are discussed.

2-2 Background - Refrigerant Mixtures:-

Evaporation or condensation of a pure fluid is isothermal. However, a

mixture with two or more components exhibits non-isothermal phase change

behavior. For example, start and finish of evaporation of a mixture occur at

bubble point and dew point temperature respectively [3].

2-3 Refrigerant Criteria:-

A working fluid in a compression refrigeration system must satisfy a

number of requirements that can be divided into two groups:

1. The refrigerant should not cause any risk of injuries, fire or property

damage in case of leakage.

2. The chemical, physical and thermodynamic properties of the refrigerant

must suit the system and the working conditions at a reasonable cost.

Table (2-1) show refrigerant criteria but at the same time it is not possible

to fulfill all the requirements above at the same time. The most important

criterion is chemical stability within the refrigeration system. All the

other criteria are meaningless if the refrigerant decomposes or reacts with

the materials used in the system.

Table(2-1) The criteria can be specified more precisely as follows [4]:

2-4 Alternative Refrigerants:-

The vast majority of refrigerating systems use the practical reversed

Rankine cycle. Some alternative systems use the Rankine cycle with

refrigerants which restrict their fields of application but many alternative

systems are cycles or methods which are fundamentally different.

Refrigerants are divided into groups according to their chemical

composition. Following the discovery that some of these chemical

compounds may be harmful to the environment, they are being replaced with

more environmentally friendly alternatives (as show in figure 2-1). The

Stable and inert Chemical

*Non-toxic

*Non-flammable

*Benign to the atmosphere , etc Health & safety &

environmental

*Critical point and boiling point temperatures

appropriate for the application

*low vapor heat capacity

*low viscosity

*High thermal conductivity

Thermal

*Satisfactory oil solubility \ miscibility

*High dielectric strength of vapor

*Low freezing point

*Easy leak detection

*Low cost

Other

process is not easy, and although there are alternatives to old refrigerants,

the new ones are usually not flawless.

Figure (2-1) Alternatives to the "old" refrigerants [4].

Table (2-2) Summary table of the different types of refrigerants.

Table (2-3) Summary table of the different types of refrigerants.

Alternative

refrigerants

HCFC

(with chlorine)

pure

e.g.R22 mixtures

R410A

HFC

(no chlorine)

pure

e.g.R134a mixtures

R407C

Hologen free

pure

e.g.Ammonia

propane

mixtures

e.g.proanel

iso-butane

Glide Safety Series Refrigerant A1 Methane series R32

A1 Ethane series R125

A1 Ethane series R134a

A2 Propane series R245ca

R245a

1K A1\A1 Zeotropic mixture

(44%R125\52%R143a\4%R134a) R404A

7K A1\A1 Zeotropic mixture

(23%R32\25%R125\52%R134a) R407C

Azeotropic mixture

(50%R32\50%R125) R410A

Azeotropic mixture

(50%R125\50%R143a) R507A

Azeotropic mixture

(46%R23\54%R116A) R508B

Atoms in the Molecule Meaning Prefix

CL \ F \ C Chlorofluorocarbn CFC

H \ CL \ F \ C Hydrochlorofluorocarbon HCFC

H \ F \ C Hydrofluorocarbon HFC

H \ C Hydrocarbon HC

Table (2-4) Health and safety classification.

CLASS/GROUP Description

A The toxicity of the refrigerant is not identified at

concentrations below 400 ppm volume.

B Evidence of toxicity identified at concentrations below 400

ppm by volume.

1

No flame propagation in air at 18*c and 101kpas> This

group has the least severe restrictions, but the maximum

amount of refrigerant in the system (g-room volume) is

limited. The purpose of this limitation is that if a pip fracture,

the concentration of refrigerant in the room is kept below the

hazardous level.

2

Lower flammability limit than group 1, but the toxicity is the

largest hazard. These is also a limit on the amount of

refrigeration in the system, depending the category to which

the room in question belongs.

3

Highly flammability. This group has the most severe

restrictions. Depending on the filling licenses are needed in

some cases. If a refrigerant is not classified, it is considered

as group 3 refrigerant until classification.

2-5 Classification of Refrigerants:-

This section is focused only on the primary refrigerants which can be

classified into thfollowing five main groups:

• halocarbons.

• hydrocarbons.

• inorganic compounds.

• azeotropic mixtures.

• nonazeotropic mixtures.

Figure (2-2) refrigerant classification[1].

2-6 Azeotropic/Zeotropic Refrigerants:-

A refrigerant may be either a pure compound or a mixture (blend) of two

or more refrigerants. Examples of pure refrigerants are R12, R22 and R134a.

Examples of mixtures are R502, R404A and R407C. A mixture can behave

either as a pure refrigerant (azeotropic mixtures), or differently (non-

azeotropic, or zeotropic, mixtures).

2-6-1 Azeotropic Mixtures:-

Although it contains two or more refrigerants, at a certain pressure an

azeotropic mixture evaporates and condenses at a constant temperature.

Because of this, azeotropic mixtures behave like pure refrigerants in all

practical aspects. Figure (2-3a) shows that the temperature is constant in the

liquid-vapor mixture region for a given pressure. For example

1- R500 consist of (R12/R152)(73.8/26.2)wt%

2- R502 consist of (R22/R115)(8.8/51.2)wt%

3- R503 consist of (R23/R13)(40.1/59.9)wt%

2-6-2 Non-Azeotropic/Zeotropic Mixtures:-

Zeotropic mixtures have a gliding evaporation and condensing temperature

[show Figures (2-4) and (2-5)]. When evaporating, the most volatile

component will boil off first and the least volatile component will boil off

last. The opposite happens when gas condenses into liquid. Figure (2-

3b) shows that for a given pressure, the temperature will change in the

liquid-vapor mixture region. This results in a gliding evaporation and

condensing temperature along the heat transfer surface. In practice, the

saturation temperature at the inlet of the evaporator will be lower than at the

outlet. In the condenser, the saturation temperature at the inlet will be higher

than at the outlet.For example

1- R404a consist of (R122/R143/R134a)(44/52/4)wt%

2- R407c consist of (R32/R125/R134a)(23/25/52)wt%

3- R410a consist of (R32/R125)(50/50)wt%

4- R413a consist of (R600a/R218/R134a)(3/9/88)wt%

Figure (2-3)….(a): Pure refrigerant or azeotropic mixture (no glide). (b):

Non-azeotropic (zeotropic) mixture (glide) [5].

Figure (2-4) Condenser and evaporator temperature program, counter-

current flow [5].

Figure (2-5) Condenser and evaporator temperature program, co-current

flow [5].

Zeotropic mixtures have a gliding evaporation and condensing temperature

When evaporating, the most volatile component will boil off first and the

least volatile component will boil off last. The opposite happens when gas

condenses into liquid .change in the liquid-vapor mixture region. This results

in a gliding evaporation and condensing temperature along the heat transfer

surface. In practice, the saturation temperature at the inlet of the evaporator

will be lower than at the outlet. In the condenser, the saturation temperature

at the inlet will be higher than at the outlet [6].

2-7 Oils:-

Oil is normally present in a refrigeration system, and the interaction

between the oil and the refrigerant must be considered. High oil solubility is

used in hermetic compressors, but immiscible oils are normally used when

the working fluid is ammonia.

2-8 Refrigeration Oil:-

The moving parts of a compressor assembly must be lubricated for smooth

operation and prevention of damage. Oil is also used at the seals and gaskets.

In addition, a small amount of oil is added to the refrigerant in the system to

maintain the thermostatic expansion valve in proper operating condition.

The classification of refrigeration oil is based on three factors such as

viscosity, compatibility with refrigerants, and pour point. R-12 requires oil

with a viscosity rating of about 300 for air-conditioning service; however oil

up to 1000 viscosity rating has been used in some systems.

The refrigerant oil must be compatible with the refrigerant used in the

system, and there must not be any change or separation by chemical

interaction. The temperature at which oil just flows is its pour point. The

properties of good refrigeration oil are low wax content, good thermal and

chemical stability, low viscosity, and a low pour point.

Chapter Three

Refrigerants Properties

3-1 Introduction:-

Refrigerants mixtures as a refrigerant has thermodynamic properties, in

vapor compression refrigeration cycles design must know these properties to

study refrigerant conditions and decide the acceptable design.

A program (REFPROP) were used to accomplished fluids mixing process

(Zeotropic and Azeotropic) and getting properties table and (p-h) schemes

and studying properties behaviour those mixtures [7].

In this work, seven refrigerants- as Examples for both Azeotropic and

Zeotropic types - will be studded and comparing their properties:

3-2 Azeotropic Refrigerants:-

4- R500 consist of (R12/R152)(73.8/26.2)wt%

5- R502 consist of (R22/R115)(8.8/51.2)wt%

6- R503 consist of (R23/R13)(40.1/59.9)wt%

3-3 Zeotropic Refrigerants:-





3-4 Saturated Properties Tables for Mixtures:-

For these tables the range of properties depending on pressure was (1 to 25)

bar by (1 decrement) was shown in following tables (3-1 , 3-2,3-3,3-4,3-5,3-

6 and 3-7).

3-4-1 For Azeotropic Refrigerants:-

1- R500 consist of (R12/R152)(73.8/26.2)wt%

Tables (3-1) saturated properties for R500.

2- R502 consist of (R22/R115)(8.8/51.2)wt%


3- R503 consist of (R32/R125)(50/50)wt%


3-4-2 For Zeotropic Refrigerants:-

1- R404A consist of (R122/R143/R134a)(44/52/4)wt%

Tables (3-4) saturated properties for R404A.

2- R407C consist of (R32/R125)(50/50)wt%

Tables (3-5) saturated properties for R407C.

3- R410A consist of (R32/R125)(50/50)wt%

Tables (3-6) saturated properties for R410A.

Tables (3-7) saturated properties for R413a.

3-5 Pressure – Enthalpy (P-h) Charts for Mixtures:-

For these charts the range of pressure (Y axis) was (1 to 20) bar and of

enthalpy ( X axis) was (100 -600) kJ/Kg shown in following figures [(3-1)

, (3-2),(3-3),(3-4),(3-5),(3-6) and (3-7)].

3-5-1 For Azeotropic Refrigerants:-

1- R500 consist of (R12/R152)(73.8/26.2)wt%

Figure (3-1) saturated properties for R500.

2- R502 consist of (R22/R115)(8.8/51.2)wt%

3- R503 consist of (R23/R13)(40.1/59.9)wt%


3-5-2 For Zeotropic Refrigerants:-

1- R404A consist of (R122/R143/R134a)(44/52/4)wt%

Figure (3-4) saturated properties for R404A.

2- R407C consist of (R32/R125/R134a)(23/25/52)wt%

Figure (3-5) saturated properties for R407C.

3- R410A consist of (R32/R125)(50/50)wt%


Chapter Four

Conclusion and Recommendation

4-1 Conclusion:-

1- Pure refrigerants which have low OD and GW are very limited and

the number of diverse applications of refrigeration is ever increasing.

If a pure refrigerant cannot meet the requirements. But mixture

refrigerant offer the advantage of tailoring the composition to suit

various temperature requirements. It is also possible to control the

properties such as toxicity, flammability, oil miscibility by

manipulating the composition. Hence, they are finding greater use.

2- A refrigerant may be either a pure compound or a mixture (blend) of

two or more refrigerants. Examples of pure refrigerants are R12, R22

and R134a. Examples of mixtures are R502, R404A and R407C. A

mixture can behave either as a pure refrigerant (azeotropic mixtures),

or differently (non-azeotropic, or zeotropic, mixtures).

3- Zeotropic mixture is one whose composition in liquid face differs to

that in vapour phase. Zeotropic refrigerants therefore do not boil at

constant temperature unlike azeotropic refrigerants. For example





4- Azeotropic mixture is a stable mixture of two or several refrigerants

whose vapour and liquid phases retain identical compositions over a

wide range of temperature. For example

7- R500 consist of (R12/R152)(73.8/26.2)wt%

8- R502 consist of (R22/R115)(8.8/51.2)wt%

9- R503 consist of (R23/R13)(40.1/59.9)wt%

5- Different zeotropic mixtures have different temperature glides. For

Ex. zeotropic mixture R152a/R245fa has a higher temperature glide

than R21/R245fa. A larger gap between the boiling points creates a

larger temperature glide between the boiling curve and dew curve at a

given mass fraction. However, with any zeotropic mixture, the

temperature glide decreases when the mass fraction of a component

approaches 1 or 0 (when the mixture is almost separated into its pure

components) because the boiling and dew curves get closer near these

mass fractions.

4-2 Recommendation:-

1- Drawing compression cycle for the fluids (R404a, R413a, R500,

R502, ….) scheme for each fluid and conducting practical calculation,

such as (C.O.P , We , Qe , Qc).

2- Charging refrigeration system by two kinds of blends and study the

differences between them practically.

[1] Thomas F. Stocker, Dahe Qin, Pauline M. Midgley, "Climate Change

2013 The Physical Science Basis", Working Group I Contribution to the

Fifth Assessment Report of the Intergovernmental Panel on Climate Change,

Printed in the United States of America, (2013).

[2] Reinhard Radermacher and Yunho Hwang, "Vapor Compression Heat

Pumps with Refrigerant Mixtures", by Taylor & Francis Group, LLCCRC

Press is an imprint of Taylor & Francis Group, (2005).

[3] Leelananda Rajapaksha, "Zeotropic Refrigerant Mixtures in Vapour

Compression Refrigeration Systems - Issues and Implications" ENGINEER

- Vol. XXXVIII, No. 04, pp. 52-59, (2005).

[4] Ibrahim Dincer, "Energy Solutions to Combat Global Warming",

University of Ontario, Canada (2017).

[5] Xiayan Z., Changfa J., Xiuling Y., "Prediction Method for Evaporation

Heat Transfer of Non-Azeotropic Refrigerant Mixtures Flowing Inside

Internally Grooved Tubes", Applied Thermal Engineering, Vol. 28, Issues

14-15, pp. 1974-1983, (2007).

[6] Ibrahim D. "Refrigeration Systems and Application", John & Wiley,

England (2003).

[7] NIST Standard Reference Database 23, Version 9.0 E.W. Lemon, M.L.

Huber and M.O. Mclinden , Copy right 2010 by U.S. Secretary of commerce

on behalf of the United States of America.

References

جميورية العراق وزارة التعميم العالي والبحث العممي

الجامعة التقنية الشمالية/كركوكالتقني معيدال

فيفرع التبريد والتكيقسم المكائن والمعدات/

بحث مقدم الى

(( ن والمعدات / فرع التبريد والتكييفمكائقسم ال ))

من اعداد

ابراهيم نجم الدين محمود جلال علي اصغر

ابراهيم احمد محمد احمد باهر محمد

جورج عوديشو باوث

باشراف

2018 1439

Republic of Iraq Northern Technical University Equipments ...

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