ORC for waste heat recovery in cars

[RAMAKRISHNA N]

hi there...to all the enthusiastic people of thermodynamics/thermal engineering. I am working on a project to recover the exhaust heat of a car,for which i require a great amount of guidelines from ur side.firstly,I am not sure as to how much of heat is wasted through the exhaust. Do u think i can use a primitive method which uses a water jacket(small dia pipe encircling atleast half the portion of the exhaust pipe)and find the mass flow rate and temp rise .I am not sure about the accuracy. Could u suggest some other method to measure the amount of heat rejected through exhaust.
Secondly,do u think the exhaust heat is simply sufficient to run a compressor of the cars airconditioning system.


regards

ram

 

[brewnog]

Heat rejected to exhaust is found out by measuring fuel mass flow into the engine, air mass flow into the engine, exhaust temperature and ambient temperature. Just do a simple heat balance.

I doubt the heat you are able to recover would be sufficient to run air conditioning; you need air con just as much while the engine is idling.

 

[RAMAKRISHNA N]

Is there any other way in which we can use the exhaust heat other than turbocharging?
I feel the thermal efficiency of the engine can be increased to an greater extent by converting the heat from the exhaust into useful work.

 

[Topher925]

BMW is working on a steam recovery system. I'm a little skeptical about it though.

http://www.autoweek.com/apps/pbcs.dll/article?AID=/20060217/FREE/60213002/1024/LATESTNEWS

There is a lot of energy to be recovered but its not in a very usable forum. The hardware required to extract that energy will probably be so heavy and robust it would be more efficient and cheaper to just not have a recovery system at all.

 

[brewnog]

Is there any other way in which we can use the exhaust heat other than turbocharging?
I feel the thermal efficiency of the engine can be increased to an greater extent by converting the heat from the exhaust into useful work.

Sure, you could pass water through it and you'd have some warm water which you could clean your windows with. Or you could put a thermopile on it and power the LCD panel for the stereo. Or you could put a turbine in it, and use this to drive a compressor...

 

[FredGarvin]

About the only thing, and I am sure this has been tried, is to use it to heat the incoming fuel. On our engines it's a good thing, but we don't run gasoline. I can't imagine anything really useful you could do with it.