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**131. The primary function of the compressor in a refrigeration system is to:**
– A. Increase the pressure of the refrigerant
– B. Decrease the pressure of the refrigerant
– C. Change the state of the refrigerant from liquid to vapor
– D. Change the state of the refrigerant from vapor to liquid
**132. Which of the following refrigerants has the lowest ozone depletion potential (ODP)?**
– A. R-12
– B. R-22
– C. R-134a
– D. R-410A
**133. In a refrigeration system, the evaporator functions to:**
– A. Increase the pressure of the refrigerant
– B. Decrease the pressure of the refrigerant
– C. Reject heat to the surroundings
– D. Absorb heat from the surroundings
**134. The coefficient of performance (COP) of a refrigeration system is defined as:**
– A. The ratio of heat rejected to the surroundings to the work input
– B. The ratio of work input to the heat absorbed from the surroundings
– C. The ratio of heat absorbed from the surroundings to the work input
– D. The ratio of heat rejected to the surroundings to the heat absorbed from the surroundings
**135. In a refrigeration cycle, the throttling process occurs at the:**
– A. Condenser
– B. Evaporator
– C. Compressor
– D. Expansion valve
**136. The process of subcooling in a refrigeration cycle involves:**
– A. Cooling the refrigerant below its condensing temperature
– B. Heating the refrigerant above its condensing temperature
– C. Expanding the refrigerant in the expansion valve
– D. Increasing the pressure of the refrigerant in the condenser
**137. The primary function of the expansion valve in a refrigeration system is to:**
– A. Increase the pressure of the refrigerant
– B. Decrease the pressure of the refrigerant
– C. Control the flow rate of the refrigerant into the evaporator
– D. Control the temperature of the refrigerant leaving the condenser
**138. The evaporator fan in a refrigeration system is responsible for:**
– A. Increasing the pressure of the refrigerant
– B. Decreasing the pressure of the refrigerant
– C. Circulating air over the evaporator coils
– D. Circulating refrigerant through the system
**139. Which of the following statements about the Carnot refrigeration cycle is true?**
– A. It operates without any irreversible processes
– B. It has a lower coefficient of performance compared to practical refrigeration cycles
– C. It requires a compressor to operate
– D. It cannot achieve temperatures below the ambient temperature
**140. The condenser in a refrigeration system functions to:**
– A. Increase the pressure of the refrigerant
– B. Decrease the pressure of the refrigerant
– C. Reject heat to the surroundings
– D. Absorb heat from the surroundings