Conventional heat pumps use the vapor compression refrigeration cycle. In a certain application, the condensing temperature is t1 and the evaporation temperature t2. After the condenser, the liquid is subcooled and has the temperature tb = t1 - 10 °C. Before the compressor, the temperature of the vapor is td = t2 + 5 °C. The mass flow rate of the circulating refrigerant is ?̇ . The refrigerant is R22 (table) a) Determine the condensing pressure, the evaporation pressure, and the vapor quality at the inlet of the evaporator. b) Calculate the temperature after the compressor, the heating coefficient of performance, and the heat given off by the condenser if the compressor is isentropic, i.e. ηC = 1. c) Calculate the temperature after the compressor, the heating coefficient of performance, and the heat given off by the condenser if the compressor has the efficiency of ηC = 0.75 d) Calculate the Carnot efficiency ηCt, defined as the cooling coefficient of performance according to the conditions in task c) divided by the Carnot cooling coefficient of performance. Additional data: ?̇ = 0.07 kg/s t1 = 40 °C t2 = -10 °C
Conventional heat pumps use the vapor compression refrigeration cycle. In a certain application, the condensing temperature is t1 and the evaporation temperature t2. After the condenser, the liquid is subcooled and has the temperature tb = t1 - 10 °C. Before the compressor, the temperature of the vapor is td = t2 + 5 °C. The mass flow rate of the circulating refrigerant is ?̇ . The refrigerant is R22 (table) a) Determine the condensing pressure, the evaporation pressure, and the vapor quality at the inlet of the evaporator. b) Calculate the temperature after the compressor, the heating coefficient of performance, and the heat given off by the condenser if the compressor is isentropic, i.e. ηC = 1. c) Calculate the temperature after the compressor, the heating coefficient of performance, and the heat given off by the condenser if the compressor has the efficiency of ηC = 0.75 d) Calculate the Carnot efficiency ηCt, defined as the cooling coefficient of performance according to the conditions in task c) divided by the Carnot cooling coefficient of performance. Additional data: ?̇ = 0.07 kg/s t1 = 40 °C t2 = -10 °C
Refrigeration and Air Conditioning Technology (MindTap Course List)
8th Edition
ISBN:9781305578296
Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson
Publisher:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson
Chapter22: Condensers
Section: Chapter Questions
Problem 7RQ: When a standard-efficiency air-cooled condenser is used, the condensing refrigerant will normally be...
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Conventional heat pumps use the vapor compression refrigeration cycle. In a certain application, the
condensing temperature is t1 and the evaporation temperature t2. After the condenser, the liquid is
subcooled and has the temperature tb = t1 - 10 °C. Before the compressor, the temperature of the vapor
is td = t2 + 5 °C. The mass flow rate of the circulating refrigerant is ?̇ . The refrigerant is R22 (table)
a) Determine the condensing pressure, the evaporation pressure, and the vapor quality at the inlet
of the evaporator.
b) Calculate the temperature after the compressor, the heating coefficient of performance, and the
heat given off by the condenser if the compressor is isentropic, i.e. ηC = 1.
c) Calculate the temperature after the compressor, the heating coefficient of performance, and the
heat given off by the condenser if the compressor has the efficiency of ηC = 0.75
d) Calculate the Carnot efficiency ηCt, defined as the cooling coefficient of performance
according to the conditions in task c) divided by the Carnot cooling coefficient of performance.
Additional data:
?̇ = 0.07 kg/s
t1 = 40 °C
t2 = -10 °C
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