Message text written by "Ptegler"
>What energy is 'going in'???
gasoline as a fuel is not 'energy in' . The engine has to 'work'
to burn a fuel
<
The energy in is the chemical energy contained in the fuel. When you
oxidize gasoline you generate heat. How much heat is a function of how
efficient the burining process is. The energy out is torque at the rear
wheels times rotational speed. Efficency of a gasonie engine is mechanical
energy out divided by chemical energy in.
>Like almost EVERY man made machine...
>HEAT is generated. Heat is 'energy output'
Heat is generated by burning fuel. Mechanical work is derived from the
heat by compressing the unburned fuel and air mixture and then
decompressing the heated combustion products. You get a net energy output
because it takes less work to compress the cool air/fuel mixture than you
can extract from decompressing the heated combustion products. This is a
thermodynamic propery called enthalpy. The same principal applies to steam
engines. Compress water, boil it, decompress the steam extract a portion
of the heat energy used to boil the water.
The efficiency of the process is a measure of how much more energy is
extracted from the xpansion process than is used in the compression
process.
(My gosh! I haven't doen this much physics since college)
Dave
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