Quote:
Originally Posted by ChazInMT
Ya know a few weeks ago we went around about the variable valve timing, that essentially is a variable displacement method.
But....at the end of the day....all we are trying to cut out of the equation is the pumping losses, which on their worst day are costing us 4% efficiency. I came away thinking the variable valve timing was a pretty good solution.
60% of the energy losses in the engine are due to thermal losses. What can we do to even get 1/3 of that back? Pretty much double our mileage if you could.
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Uh wait where are you getting 60% from?
Pumping losses aren't a big deal at the end of the day like you say, but friction is! Friction eats away several times more energy than pumping. When that's considered, the actual heat cycle itself isn't doing too bad at maybe 50% efficiency. Could be bumped up to 60% with higher expansion ratio and multiple ignition points or something, but cooling losses are hard to solve when the engine is car sized and material constraints (and those emissions regulations) limit the temperatures we can burn fuel at. A second stage heat recovery solution (TEG, steam turbine, etc.) can get some of it back but the economics isn't super great.