Stirling Engine to harness energy lost as heat from combustion engine

[yhelothar]

I was just reading about the stirling engine. It looks like a very efficient way of turning heat energy to mechanical energy. Given that a large fraction of the energy put into combustion engines are lost as heat, wouldn't it make sense to instead of just dissipate that heat via radiators, this heat can be harnessed to make more energy with the stirling engine?

I assume this has probably been tried before but doesn't work well? If so, why not?

 

[imagoon]

Already been worked on by MIT:

http://dspace.mit.edu/bitstream/handle/1721.1/32832/60689109.pdf?sequence=1

They only improved by 7%. I believe the extra parts (and weight) then reduced the efficiency of the gas engine to the point where it became a cost:benefit issue. There is real world issues such as inefficiency of heat moving through the materials to the hot side of the Stirling for example. The 7% they showed was a "perfect" system, ie no losses, no friction etc.

 

[PsiStar]

I have often thought about modeling the Stirling engine in something like SolidWorks with heat transfer, mechanical dynamics & all that. That would require more addons than I can currently justify ... but it would be a fun project.