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Lecture Companion site to accompany thermodynamics: An engineering approach (7/e): Chapter 11 - Yunus Çengel, Michael A. Boles

Chapter 11 - Refrigeration cycles. This chapter introduce the concepts of refrigerators and heat pumps and the measure of their performance, evaluate the maximum possible coefficient of performance for refrigerators and heat pumps based on the reversed Carnot cycle, analyze the ideal vapor-compression refrigeration cycle,. | Chapter 11 Refrigeration Cycles Study Guide in PowerPoint to accompany Thermodynamics: An Engineering Approach, 7th edition by Yunus A. Çengel and Michael A. Boles The vapor compression refrigeration cycle is a common method for transferring heat from a low temperature to a high temperature. The above figure shows the objectives of refrigerators and heat pumps. The purpose of a refrigerator is the removal of heat, called the cooling load, from a low-temperature medium. The purpose of a heat pump is the transfer of heat to a high-temperature medium, called the heating load. When we are interested in the heat energy removed from a low-temperature space, the device is called a refrigerator. When we are interested in the heat energy supplied to the high-temperature space, the device is called a heat pump. In general, the term heat pump is used to describe the cycle as heat energy is removed from the low-temperature space and rejected to the high-temperature space. . | Chapter 11 Refrigeration Cycles Study Guide in PowerPoint to accompany Thermodynamics: An Engineering Approach, 7th edition by Yunus A. Çengel and Michael A. Boles The vapor compression refrigeration cycle is a common method for transferring heat from a low temperature to a high temperature. The above figure shows the objectives of refrigerators and heat pumps. The purpose of a refrigerator is the removal of heat, called the cooling load, from a low-temperature medium. The purpose of a heat pump is the transfer of heat to a high-temperature medium, called the heating load. When we are interested in the heat energy removed from a low-temperature space, the device is called a refrigerator. When we are interested in the heat energy supplied to the high-temperature space, the device is called a heat pump. In general, the term heat pump is used to describe the cycle as heat energy is removed from the low-temperature space and rejected to the high-temperature space. The performance of refrigerators and heat pumps is expressed in terms of coefficient of performance (COP), defined as Both COPR and COPHP can be larger than 1. Under the same operating conditions, the COPs are related by Can you show this to be true? Refrigerators, air conditioners, and heat pumps are rated with a SEER number or seasonal adjusted energy efficiency ratio. The SEER is defined as the Btu/hr of heat transferred per watt of work energy input. The Btu is the British thermal unit and is equivalent to 778 ft-lbf of work (1 W = 3.4122 Btu/hr). An EER of 10 yields a COP of 2.9. Refrigeration systems are also rated in terms of tons of refrigeration. One ton of refrigeration is equivalent to 12,000 Btu/hr or 211 kJ/min. How did the term “ton of cooling” originate? For more information and animations illustrating this topic visit the Animation Library developed by Professor S. Bhattacharjee, San Diego State University, at this link. .