Heat engines convert heat or thermal energy into useful work, often shaft power that can be used to turn wheels for transportation or generators to produce electricity. In one sense, refrigerators and heat pumps do the reverse by using electricity, or work, to remove and supply thermal energy. To assess the performance of heat engines we can define their thermal efficiency as the desired output divided by the required input.
Download the full PDF article at the bottom of the page to find out more about the ideal performance of these machines. Also, for anyone interested in a little extra information, you can also find a link to an video on how heat pumps work.
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