“Dual Combustion Engine”

Presented To:

Sir Qazi Shehzad

Presented by: Jawaria Bint Faheem (12063122-008)

Areeba Malik (12063122-050)

Areeba Asif (12063122-070)

Hina Usman (12063122-077)

Beenish Hafeez (12063122-085)

Engine???

• A Machine Designed To Convert Energy Into Useful Mechanical Motion.

• Thermal Energy Raises Temperature And Pressure Of Gases Within Engine, And Gas Expands Against Mechanical Mechanisms Of Engine.

History• Oil Engine 1888.

• Ackroyd Staurt (Automatic Ignition).

• Rudolf Diesel Used This Principle And Developed Basis Of Dual Combustion Engine.

Dual Combustion Engine

• It is an internal combustion four

stroke engine.

• “Dual” Because Combustion Takes

Place In Two Parts First At Constant

Pressure And Second At Constant

Volume.

• This makes it better than diesel

engine’s cycle.

Dual Combustion Cycle

• Also Known As The Limited Pressure Or Mixed Cycle, Seiliger Cycle Or Sabathe Cycle.

• Thermal Cycle That Is A Combination Of The Otto Cycle And The Diesel Cycle.

Characteristics • It is a four stroke

engine.

• Improved and modern

form of old Diesel

engine’s cycles.

• Its one stroke is divided

into two parts allowing

it to carry out more

work..

• Have increased

efficiency.

Parts Of Engine

Stroke

• Each Cycle Of Piston Consists Of Two Opposite Motions:

There Is A Motion In One Direction, And Then A Motion Back In The Opposite Direction. Each Of These Is Called A Stroke

• Stroke Is The Action Of A Piston Travelling The Full Length Of Its Locomotive Cylinder Or Engine Cylinder In One Direction.

Indicator Diagram

Sequence of Operations

The dual cycle consists of following operations:

• Adiabatic compression

• Addition of heat at constant volume.

• Addition of heat at constant pressure.

• Adiabatic expansion.

• Rejection of heat at constant volume.

Explanation

1)Adiabatic Compression:

Adiabatically compressed air, it turned hot. Fuel injection starts before the point of maximum compression.(ignition phase)

2) Constant Volume Phase:

After a short delay the fuel warms up to the air temperature causing a sudden rise in pressure.

Continued …

3) Constant Pressure Phase:

Further Injection Keeps The Fuel Burning As

Volume Increases

4) Adiabatic Expansion:

After Cut Off, Hot Air Expands Isentropically.

5)Constant Volume (End Stroke):

Exhaust Valve Opens Producing A Sudden

Drop In Pressure Getting Heat Out.

Efficiency

• Engine efficiency of

thermal engines is the

relationship between the

total energy contained in

the fuel, and the amount

of energy used to

perform useful work.

Expression For Efficiency

• From first law of thermodynamics

Q = ∆U + WAnd..

• ∆W = Q1 – Q2

• The efficiency of engine is defined as ƞ = Output / input

Continued..

• The efficiency of engine is defined as useful work done to the heat provided.

Where,

• Q1 is the heat absorbed

• Q1 – Q2 is work done.

Efficiency of dual combustion engine

The analysis of cycle is as follows:

The heat is supplied In two stages. hence

Qin = mcp(T4 – T3) + mcv(T3 – T2)

The heat rejected is

Qout = mcv(T5 – T1)

Simplification

The thermal efficiency may b found as follows:

ƞ = 1 – Qout/ Qin

= 1 – mcv(T5 – T1)/ mcv(T3 -T2)+mcp(T4 –T3)

=1 – (T5 – T1)/ (T3 – T2) +ϒ(T4 – T3)

Simplification Of Formulae• The formula can be further developed to

show that:

η = 1-(kβγ -1)/[(k-1) +γk(β-1)]rvγ-1

• rv is the VOLUME COMPRESSION RATIO.

• rv = V1/V2

• β is the CUT OFF RATIO.

• β = V4/V3

• k is the ratio p3/p2.

• If k=1 then it becomes Otto cycle’s

efficiency.

“Applications”

Dual combustion engines are most commonly used for mobile propulsion in vehicles and portable machinery.

In mobile equipment, dual combustion is advantageous since it can provide high power-to-weight ratios.

“Automobiles”

• Generally using fossil fuel(mainly petroleum), these engines have appeared in transport in almost all vehicles (automobiles, trucks, motorcycles, boats, and in a wide variety of aircraft and locomotives).

Generators/Aircrafts• Very high power-to-weight ratios are

required, dual combustion engines appear in the form of gas turbines. These applications include jet aircraft, helicopters, large ships and electric generators.

“Future Energy Use”

There is a role for Dual Combustion engines for future energy use, because

– Dual combustion engine has high power to weigh ratio.

– Relatively low cost.

– Flexible fuel use.

– Established manufacturing investment.

References Text books:

By Mcconkey And Rajput.

Web sources:

• www.marineinfo.com

• www.freestudy.co.uk

• http://www.brighthubengineering.com/

• en.wikipedia.org\

• www.wartsila.com

Research Pappers:

• Gas Power Cycles Prof. U.S.P. Shet ,and Prof. J.M

. Mallikarjuna

• Performance Analysis of a Dual Cycle Engine by

Ebrahimi