Applied Thermodynamics

Binary Vapour Cyclefor

IC Engine Waste Heat

TEAM MEMBERS

• G. Arun Prasaad 09M104• S. Dinesh Surya Kumar 09M107• I . Sanjay 09M130• R. Vetrivel 09M150• S. Vignesh 09M152• S. Vigneysh Prabu 09M154

Synopsis

• Earlier model• Revised model• Thermo-couple performance• Coolant and Exhaust lines• Air Conditioner lines• Net Thermal Efficiency• Cooling / Heating Effect• Advantages• Disadvantages• References

Thermo-couple Performance.

Coolant and Exhaust lines

Heat absorbed by the coolant at Engine at constant pressure.

Qac = m’c Cp (T2-T1);Heat content of the exhaust

Qe = m’eCp(T2e-Tct);Temperature difference at the thermocouple

∆T= T2e – Ta;

Coolant and Exhaust lines

By Reverse Peltier effect, η heQe = пh I (ke*∆T);

By Seebeck effectV= α (ke*∆T) + 0.5β (ke*∆T)^2;

From these relations, it is possible to find the electrical energy generated by the relation

Ptc=V I≈ η heQe;

Coolant and Exhaust lines

Force produced by the exhaust gases on the blades of the turbo-charger

Fe = m’se* Ve (for linear blade)Power developed by turbo charger

Pt= ηo*(2 п N Fe*rb)/60Heat lost in the radiator by coolant

Qlcr = m’c Cp (kc * T2 – T3)

Coolant and Exhaust lines

An assumption is made that the coolant attains its original state at the end of the cycle.Also, the work developed for the pump is obtained from the crankshaft through combustion energy.Therefore, coolant cycle efficiency is given by

ηc = output/input =(Qlcr)/(Qac) * 100%

= (1- (Qlce)/(Qac)) * 100%Also, the COP of the cycle is given by

COPc = (Wout)/(Win) =(Qlcr)/(Wpump) =(Qlcr)/(kcrk*Wcrk) COPc =(Qlcr)/(ηcom*kcrk*Qcom)

Coolant and Exhaust lines

The exhaust line efficiency is given byηe = output/input =( (Pt+ΣPtc)/Qe ) * 100 %

Assuming that Qe and Qac are nearly equal and individually equal to 35% of the total combustion energy produced and also, the initially utilised combustion energy is 20 %, the total combustion energy utilised is

Qu = Qu1+ Qlcr + Pt+ΣPtc ; = ηcom1Qcom1+ ηe Qe + ηc Qac

Qu = (0.2+ 0.35 ηe + 0.35 ηc ) Qcom1

Air Conditioner line

Heat absorbed by the refrigerant in the vehicle cabin(Evaporator)

Qarc=m’r Cp(Tcab-Trbe)Heat absorbed by the refrigerant in the re-heater (Radiator)

Qarr=m’rCp(Trbr-Trar)Qarr= ηex Qlcr

Total heat absorbed by the refrigerant isQar= Qarr+Qarc

Air Conditioner line

Heat lost by the refrigerant at condenserQlrc=m’r*Cv*(Trbc-Trac)

Temperature difference at the thermocouple∆T= Tcondenser – Ta

By the same relation as above, the thermoelectric power is given by

Ptc≈ η hcondQlrc

Heat lost by the refrigerant at expansion valveQlrx=m’r*Cv*(Trbx-Trax)

Air Conditioner line

Assuming that the refrigerant reaches its original state in the cycle, the thermal efficiency is given by ηr = output/input

ηr = (Qarc + ΣPtc)/(Qar)*100 %The COP of the air conditioning circuit is

COPa.c =(Qarc)/(Wcomp) COPa.c =(Qarc)/( Σ ke *ηe *Qe + Wadd +Pt)

Net Thermal Efficiency

The ultimate thermal efficiency of the system is

ηu= (Pt+ΣPtc - Wcomp ± Qarc)/(Qac ± Qarc + Wadd)

Cooling/Heating Effect

Time taken for ∆T K rise or fall in temperature in the cabin, at constant mass transfer rate prevailing between the surroundings and the vehicle cabin is given by

t=(mair*Cp* ∆T)/(m’a*Cp* ∆T2 ±Qes)

Advantages

• More energy savings.• Can act as both air heater and air cooler.• The energy is stored as electricity and also

an air conditioning effect is provided.• Chances for Cascading operations.• Electrical energy stored has several usages.• Sufficient energy, when generated, can be

used to replace some devices like alternator.

Disadvantages

• Space cost and design constrains are more.• ECM module programming becomes complex.• Weight increases.• Some design features are to be included in the vehicle while

fixing this setup.• Multiple heat exchange units reduce Sub-cycle and overall

efficiency.• Refrigerant selection is tedious and must have a wide working

range with optimum specific heat capacity.• Humidity control unit is needed.• Selective optimum temperature differences are needed to

extract maximum power from the thermo-couple.

References

• Automotive Air-Conditioning - Boyce H. Dwiggins –Delmar Publications

• Thermal Science Data Book – B T Nijaguna. TMG HILL• Thermal Engineering – R. Rudramoorthy. TMG HILL• Automotive Mechanics – William H Crouse and Donald L Anglin

(SIE) TMG HILL.• NPTEL files – Thermodynamics-IIT MADRAS.• Engineering Thermodynamics – P. Chattopadhyay. Oxford

University Press.• Thermodynamics – Cengel and Bones.• TEPC journals• Internet.

Thank You...!