Quote:
Originally Posted by NeilBlanchard
This may make the engine a little more efficient, but at the thermal efficiency level -- why isn't an internal combustion engine as efficient (or even close to the same efficiency) of an electric motor? I'm talking quantum leaps here. Streamlining cranks ain't going to be enough.
It has to be the connecting rod / crankshaft that are causing the greatest loss within the engine, or the long 3 strokes of coasting, or something basic, that is keeping ICE's from being 50-60-70-80-90% efficient, right? Why aren't they that efficient? Gasoline / diesel is a wonderfully compact fuel, right? Why can't we get a lot more work out of burning it?
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No, the greatest loss is the chemical conversion of energy to mechanical energy at the shaft. Electric motors have a fundamentally different energy conversion physics.
If you want to know the hard and fast limits on chemical engines, look no further than thermodynamics and the Stirling engine if you intend to do a chemical to mechanical energy conversion.
You can potentially improve energy conversion of a fuel by using a fuel cell, but then you will be directly competing with electric batteries for energy delivery and density.
I think we will be improving on current designs only marginally until electrics overtake the market. Materials with higher temperature tolerance offer higher thermal efficiency potential -- ceramics have yet to make much impact though. All of these radical engine designs offer only small improvements in frictional or pumping losses, while having serious flaws in longevity or manufacturability. Call me a nay-sayer, but I think the future is bright for renewable fuels for the short term and electric for the long term.