what is the differnece between carnot cycle and Stirling cycle?
what cycle does car engine use?
what happens to the energy during he constant volume processesin the
Stirling cycle
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The Carnot cycle is an idealized cycle for a heat engine. According to most conventional thought it represents the greatest efficiency possible with a heat engine. Carnot efficiency is defined in the following way (T(hot)-T(cold))/(T(hot))x100 = efficiency. No real heat engine can match or exceed Carnot efficiency. Carnot efficiency is theoretical.
The idealized Stirling cycle has a similar (but not identical) PV diagram. Since a Stirling machine is reversible it's theoretical efficiency could match Carnot efficiency.
As a practical matter neither of these ideals can exist in a power producing machine. A real Stirling cycle will have rounded corners to it's PV diagram and indeed can be an excellent real machine of very great usefulness.
Unless your car is a diesel it probably uses an Otto cycle engine. Every different kind of machine will have a place where it excels. Stirling machines, excel at silence, multi fuel ability (including sunshine), and effectiveness in some situations where no other machine in the world can extract any power from that heat source. For example try running a gasoline engine on the heat from your warm hand. [smile]
Unless you drive to work every day on a moped you will probably agree that there are times when efficiency (as measured by miles per gallon) is not the most important thing. The same is true of Stirling engines. Sure a Honda generator is efficient when running on gasoline, but try to run it on a pile of wood and it's a useless hunk of metal. Stirling engines need to be built that do not compete head to head with gasoline engines. For example a small wood fired generator would be very useful in places where gasoline is either very expensive or very inconvenient.
The idealized Stirling cycle has a similar (but not identical) PV diagram. Since a Stirling machine is reversible it's theoretical efficiency could match Carnot efficiency.
As a practical matter neither of these ideals can exist in a power producing machine. A real Stirling cycle will have rounded corners to it's PV diagram and indeed can be an excellent real machine of very great usefulness.
Unless your car is a diesel it probably uses an Otto cycle engine. Every different kind of machine will have a place where it excels. Stirling machines, excel at silence, multi fuel ability (including sunshine), and effectiveness in some situations where no other machine in the world can extract any power from that heat source. For example try running a gasoline engine on the heat from your warm hand. [smile]
Unless you drive to work every day on a moped you will probably agree that there are times when efficiency (as measured by miles per gallon) is not the most important thing. The same is true of Stirling engines. Sure a Honda generator is efficient when running on gasoline, but try to run it on a pile of wood and it's a useless hunk of metal. Stirling engines need to be built that do not compete head to head with gasoline engines. For example a small wood fired generator would be very useful in places where gasoline is either very expensive or very inconvenient.