unit 3 quiz Flashcards
the ___ is another positive displacement compressor and is used for larger air conditioning and refrigeration applications
screw compressor
the 4 major components of a vapor compression refrigeration system are the compressor, condenser, evaporator, and ___
meter device
the amount of heat a refrigerant contains with -40 degree F as the 0 heat content reference point is called ___
enthalpy
from a performance standpoint, a substitute for r-12 is ___
r-134a
the ___ is referred to as a kinetic displacement compressor
centrifugal
the refrigerant vapor picks up additional heat as it flows from the evaporator to the compressor. the heat is picked up from the ___
suction line
whats the purpose of the metering device
meters the liquid into the evaporator
when the refrigerant leaves the metering device, it is not 100% liquid. why
refrigerant passes as 100% liquid but start to turn into 75% liquid and 25% vapor because as it starts to feed into the evaporator, ambient temp raises the refrigerants temp
good ventilation is important when working around refrigeration equipment because modern refrigerants ___
a. are toxic and can poison you
b. have an unpleasant odor
c. are heavier than air and may displace the oxygen around you
d. both a and c
c. are heavier than air and may displace the oxygen around you
the ___ relationship correlates the vapor pressure and the boiling point of water and is the basis for controlling the cooling systems temperature
a. boiling/pressure
b. temperature/pressure
c. boiling/vapor
d. temperature/vapor
b. temperature/pressure
which of the following refrigerants has the lowest boiling temperatures at atmospheric pressure
a. r-502
b. r-22
c. r-134a
d. r-12
a. r-502
the compressor in a refrigeration system ___
a. raises the boiling point of the refrigerant
b. pumps the refrigerant throughout the system
c. both a and b
d. none of the above
b. pumps the refrigerant throughout the system
a ton of refrigeration is equal to ___
a. 288,000 btu/24hr
b. 12,000 btu/min
c. 1 ton of ice
d. 144 btu/hr
a. 288,000 btu/24hr
the law requires technicians to recover refrigerant from all refrigeration systems so that they ___
a. will not be released into the atmosphere
b. may be used again
c. may be reclaimed for future use
d. all of the above
d. all of the above
refrigeration can be described as ___
a. the process of introducing heat to a location where it is not wanted
b. the process of removing heat from a place where it is not wanted to a place where it makes little or no difference
c. the process of making products cold
d. none of the above
b. the process of removing heat from a place where it is not wanted to a place where it makes little or no difference
the temperature inside the refrigerator fresh food section should be about ___
a. 25 degrees F
b. 30 degrees F
c. 35 degrees F
d. 40 degrees F
c. 35 degrees F
the evaporator in a refrigeration system ___
a. compress the refrigerant vapor
b. condenses the refrigerant
c. reduces the boiling point of the refrigerant
d. absorbs heat from the product to be cooled
d. absorbs heat from the product to be cooled
high temperature refrigeration is that produced by ___
a. heat from a furnace
b. the vegetable cooling system of a refrigerator
c. the freezer section of a refrigerator
d. an air conditioning system
d. an air conditioning system
reciprocating compressors have ___
a. a piston and cylinder
b. a rotor to compress the refrigerant
c. two scrolls that mesh together
d. a large fan compressor component
a. a piston and cylinder
what happens when room temperature soda is poured into a glass of ice
a. the ice melts because it is giving up the “cold” to the soda
b. the ice melts because the soda is colder than the ice
c. the ice melts because it is absorbing heat from the soda
d. the ice gets colder
c. the ice melts because it is absorbing heat from the soda
the condenser ___
a. adds superheat to the refrigerant
b. rejects the heat from the refrigerant
c. controls the refrigerant flow throughout the system
d. all of the above
b. rejects the heat from the refrigerant
when a refrigerant enters the compressor, it is a ___ and when it leaves the compressor, it is a ___
a. high pressure superheated vapor, low pressure superheated vapor
b. low pressure low temperature subcooled liquid, high pressure high temperature superheat vapor
c. low pressure low temperature superheated vapor, high pressure high temperature superheated vapor
d. low pressure low temperature superheated vapor, low pressure low temperature subcooled vapor
c. low pressure low temperature superheated vapor, high pressure high temperature superheated vapor
the ___ are used to change the vapor to a liquid and the liquid form back into a vapor the refrigeration
a. condenser and compressor
b. compressor and expansion device
c. expansion device and evaporator
d. condenser and evaporator
d. condenser and evaporator
ice melts in iceboxes because___
a. heat enters when the door is opened
b. heat flows through the insulated walls
c. heat enters when warm food is placed in the icebox
d. all of the above
d. all of the above
