Gas is compressed reversibly at the constant temperature T H. Process 4-3: Reversible Isothermal Expansion (T L=constant)ĭuring this process, heat is absorbed. Gas expands slowly until the temperature drops from T H to T L. The engine is perfect insulated so that no heat is lost and absorbed. Process 1-4: Reversible Adiabatic Expansion Process 2-1: Reversible Isothermal Compression (T H=constant)ĭuring this process, heat is rejected. Gas is compressed slowly until the temperature rises from T L to T H. Process 3-2: Reversible Adiabatic Compression The process undergoes in direction 3-2-1-4-3 The reversed Carnot cycle also consists of two isentropic and two isothermal processes. And we know from the 1 st law of thermodynamics, the required work can be determined in W rev=- Q H – Q L. In this case a work input in the amount of W rev is required to achieve this process. We see from the model, heat Q L is absorbed from the low-temperature reservoir (T L=constant) and heat Q H is rejected to a high-temperature reservoir (T H=constant). Unlike the Carnot heat engine, the Carnot refrigeration cycle undergoes a process with opposite direction. Furthermore, the initial cost of a heat pump is greater than that of many furnaces, so that a heat pump must last longer for its cost to be recovered.Download the script: The Reversed Carnot Cycle Heat transfer occurs from a cold reservoir\boldsymbolis usually supplied by electrical energy that costs more per joule than heat transfer by burning fuels like natural gas. We say backward, rather than reverse, because except for Carnot engines, all heat engines, though they can be run backward, cannot truly be reversed. Heat pumps, air conditioners, and refrigerators utilize heat transfer from cold to hot. Most people don’t realize they are also sharing their homes with a heat pump. Almost every home contains a refrigerator. Calculate a heat pump’s coefficient of performance.įigure 1.Explain the differences between heat pumps and refrigerators.Demonstrate how a heat pump works to warm an interior space.Describe the use of heat engines in heat pumps and refrigerators.
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