Thermodynamics

Chapter 11REFRIGERATION CYCLESAmajor application area of thermodynamics is refrigeration,which is the transfer of heat from a lower temperatureregion to a higher temperature one. Devices thatproduce refrigeration are called refrigerators, and the cycles onwhich they operate are called refrigeration cycles. The mostfrequently used refrigeration cycle is the vapor-compressionrefrigeration cycle in which the refrigerant is vaporized andcondensed alternately and is compressed in the vapor phase.Another well-known refrigeration cycle is the gas refrigerationcycle in which the refrigerant remains in the gaseous phasethroughout. Other refrigeration cycles discussed in this chapterare cascade refrigeration, where more than one refrigerationcycle is used; absorption refrigeration, where the refrigerant isdissolved in a liquid before it is compressed; and, as a Topic ofSpecial Interest, thermoelectric refrigeration, where refrigerationis produced by the passage of electric current through twodissimilar materials.ObjectivesThe objectives of Chapter 11 are to:• Introduce the concepts of refrigerators and heat pumps andthe measure of their performance.• Analyze the ideal vapor-compression refrigeration cycle.• Analyze the actual vapor-compression refrigeration cycle.• Review the factors involved in selecting the right refrigerantfor an application.• Discuss the operation of refrigeration and heat pumpsystems.• Evaluate the performance of innovative vapor-compressionrefrigeration systems.• Analyze gas refrigeration systems.• Introduce the concepts of absorption-refrigeration systems.• Review the concepts of thermoelectric power generationand refrigeration.| 607