CHAPTER 5 Refrigerators and Heat Pumps Perpetual motion machines

FIGURE 5-25 Basic components of a refrigeration system and typical operating conditions. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5-6

FIGURE 5-26 The objective of a refrigerator is to remove Q L from the cooled space. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5-7 COP R = Q L /W in Not really an efficiency because it is usually greater than 1

FIGURE 5-27 The objective of a heat pump is to supply heat Q H into the warmer space. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5-8 Like a refrigerator in your window with the door open outside. COP HP = Q H /W in Usually in the area of 2 – 3. COP HP = COP R + 1

Air Conditioners Essentially refrigerators. Often use Energy Efficiency Rating, EER –Btu’s of heat removed/W-h EER = 3.412COP R.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5-9 FIGURE 5-33 Proof that the violation of the Kelvin-Planck statement leads to the violation of the Clausius statement.

Perpetual-Motion Machines Of the first kind – PMM1 –Violate the first law (create energy). Of the second kind – PMM2 –Violate the second law.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display FIGURE 5-34 A perpetual-motion machine that violates the first law of thermodynamics (PMM1). For PMM2 see page 264