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Refrigeration
FPE Final Exam
Refrigerants have a large _____ _____ and low _____ ______. | latent heat, boiling point |
Define latent heat. | A quantity of heat added or removed during a phase change. |
The boiling point for a refrigerant can be adjusted by changing ______. | pressure |
The freezing temperature of a refrigerant should be below the _____ temperature. | evaporator |
T or F: The critical temperature for a refrigerant should be sufficiently low. | False |
____ as a refrigerant has a very high latent heat of vaporization. | Ammonia |
What happens in the evaporator of a refrigeration system? | Liquid refrigerant vaporizes to a gaseous state. |
T or F: Refrigerator space decreases the temperature of the surroundings. | True |
What are the two types of evaporators for a refrigeration system? | Direct-expansion, indirect-expansion |
T or F: Direct-expansion evaporators are used when cooling is desired in several locations in a system. | False |
Refrigerant enters the compressor in a ____ state at ____ pressure and temperature. | vapor, low |
The compressor raise the _____ and _____ of the refrigerant. | pressure, temperature |
What are the three types of compressors? | Reciprocating, centrifugal, rotary |
What is the purpose of a condenser in a refrigeration system? | Transfers heat from the refrigerator to another medium. |
What is the purpose of an expansion valve in a refrigeration system? | Controls the flow of liquid refrigerant to the evaporator. |
Define flashing. | When the heat given up by refrigerant is used to convert some liquid into vapor. |
Define cooling load. | The rate of heat energy removed from a given space in order to lower the temperature of that space to a desired level. |
Multi-stage refrigeration systems involve more than one _____. | compressor |
T or F: Multi-stage refrigeration systems cause an decrease in total power requirement. | True |