Efficiency Considerations for Cyclic Processes

Numerous practical energy systems include thermodynamic cycles. The idea of efficiency for cycles is generally based solely on the first law, symbolizing the fractional portion of the heat supplied to a cycle that is transformed into work, and might be verbally defined in the following alternative manners:

• What we get or what we have to pay for
• Useful output or input
• Useful effect or energy that should be purchased
• Quantitative value of desired outcome or quantitative value of inputs employed to generate that outcome.  

Identification of specific energy amounts as output and input gives mount to various definitions for efficiency, leading at times, as in the situation of electrically-driven heat pumps and refrigerators, to values more than 1, and emerging anomalous, as indicated, the case is redeemed by calling the coefficients of performance (COP).