Refrigeration Flashcards
In a shell-and-tube type heat exchanger, the most common cause of decreased performance is __________ .
fouling on the seawater side
The degree to which the viscosity of an oil will change with a change in temperature is indicated by the __________ .
viscosity index
The meat box temperature control circuit, as used in the ship service refrigeration system, is an example of __________ .
two position control (ON or OFF)
Which of the gage types listed is shown in the illustration? GS-0114
Simplex Bourdon tube type
Which of the following instruments can be used to measure the rate of air flow? A Thermometer B Anemometer C Psychrometer D Aerometer
B Anemometer
What is the function of a heat interchanger used in a refrigeration system?
A lower the temperature of liquid refrigerant before entering the expansion valve
B reduce the possibility of liquid refrigerant from flooding? back to the compressor
C minimize sweating of the suction line
D All of the above.
D All of the above.
What is the principal purpose of subcooling liquid refrigerant prior to its entering the expansion valve?
increase the refrigeration effect by decreasing the amount of flash gas
The pressure difference between the system cut-in and cut-out pressures of a refrigeration unit low pressure cutout device is known as what?
differential
In a small appliance using HFC-134a you would expect to see the greatest temperature drop across what system component?
condenser
A liquid line to suction line heat interchanger in a refrigeration system using a reciprocating compressor serves what function?
reduce the possibility of liquid refrigerant slugging the compressor
The process of removing moisture from air is known as what?
dehumidification
Vapor barrier seals used in the insulation on refrigerated space boundaries serve what function?
they reduce the possibility of moisture laden warm air from outside the refrigerated space from entering the insulation
A pressure drop in the liquid line of a refrigeration system may cause what condition?
flash gas to form in the liquid line
Subcooling is a method of reducing the temperature of the liquid refrigerant below what temperature or point?
condensing temperature
In a small refrigeration appliance using HFC-134a you would expect to see the greatest temperature drop across which system component?
thermal expansion valve
The low-pressure refrigerant leaves the evaporator of a refrigeration system in what condition?
superheated vapor
Which chemical symbol represents ammonia?
NH3
A compound gauge is used to measure _________.
pressure and vacuum
Under normal conditions, the refrigerant enters the compressor in an operating refrigeration system in what condition and/or state?
superheated vapor
In a refrigeration system, the heat normally producing the flash gas at the thermostatic expansion valve, is obtained by what means?
the portion of liquid refrigerant which does not flash
An increase in the heat load subjected to a refrigeration system will cause what to happen?
the compressor suction pressure to increase
The only means of removing the latent heat of condensation from a refrigerant in the normal refrigeration cycle is by performing what process?
condensing refrigerant in the system condenser
Which of the listed statements describes specific heat?
A The amount of heat required to change the temperature of one pound of a material, one degree Fahrenheit.
B The amount of heat required to change one pound of a solid material to a liquid or vice versa.
C The amount of heat required to change one pound of a liquid material to a vapor or vice versa.
D The amount of heat required to change one pound of solid material to a vapor or vice versa.
A The amount of heat required to change the temperature of one pound of a material, one degree Fahrenheit.
The temperature at which water vapor in the atmosphere begins to condense is called what?
dew point temperature