dual combustion cycle
TRANSCRIPT
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“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)
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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.
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History• Oil Engine 1888.
• Ackroyd Staurt (Automatic Ignition).
• Rudolf Diesel Used This Principle And Developed Basis Of Dual Combustion Engine.
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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.
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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.
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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.
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Parts Of Engine
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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.
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Indicator Diagram
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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.
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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.
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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.
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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.
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Expression For Efficiency
• From first law of thermodynamics
Q = ∆U + WAnd..
• ∆W = Q1 – Q2
• The efficiency of engine is defined as ƞ = Output / input
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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.
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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)
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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)
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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.
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“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.
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“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).
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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.
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“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.
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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
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