Refrigeration Principles 3 Review
A ton of refrigeration is equal to
288,000 btu/24 hr
As the load on the evaporator increases, the automatic expansion valve will open to allow more refrigerant to enter the evaporator.
False
High temperature refrigeration is that produced by
an air conditioning system
The normal position for a suction service valve during normal operation is
backseated
How does the receiver ensure that only 100% liquid refrigerant enters the liquid line?
by means of a dip tube
contains superheat spring, needle (pin) and seat, superheat spring adjusting gear
cage
The purpose of an externally equalized thermostatic expansion valve is to
compensate for excessive evaporator pressure drop
The pressure in a refrigeration system is changed in the
compressor and expansion device
At what location or locations in a refeigeration system does the saturation pressure correspond to the saturation temperature?
condenser and evaporator
The refeigerant in a refrigeration system changes state in the
condenser and evaporator
used to secure the thermal bulb to the suction line
copper strap
A thermostatic expansion valve controls refrigerant flow to the evaporator based on
evaporator suction line superheat
brings evaporator outlet pressure into the valve
external equalizer port
An automatic expansion valve uses thermal bulb to help control the amount of refrigerant being fed into the evaporator.
false
Balanced port TXV are used to
feed refrigerant at a normal rate with low condenser entering air temperatures
The cross liquid charge bulb at the TXV contains fluid that
has different characteristics from the system fluid
A refrigeration system is operating with a vapor charged thermostatic expansion valve. The thermal bulb is sensing a suction line temperature that is higher than the temperature that allows liquid to be present in the bulb. Any additional increases in the evaporator load will
have no effect on the position of the needle in the seat
When the load on the evaporator increases, the TXV
increases the flow of refrigerant
moves in and out of the seat to modulate refrigerant flow into the evaporator
needle (pin)
The TXV sensing bulb is mounted
on the suction line between compressor and evaporator
contains the diaphragm, valve tag, and thermal bulb
powerhead assembly
The compressor in a refrigeration system
pumps the refrigerant throughout the system
If the power element of a TXV loses its charge, the
refrigerant flow to the coil will stop
Determines the amount of superheat that a valve will maintain
superheat spring
The bourdon tube
tends to straighten out with an increase in vapor pressure
If the thermal bulb assembly develops a leak, what will occur?
the bulb pressure will reduce and the valve will close
A hot pull down is when
the load on the evaporator produces a suction pressure that increases the load on the compressor
Refrigeration can be described as
the process of removing heat from a place where it is not wanted to a place where it makes little or no difference
Senses evaporator outlet temperature
thermal bulb
A capillary tube controls the refrigerant flow into the evaporator.
true
A refrigeration system requiring a "fast pull down" would most likley use a thermostatic expansion valve with a liquid - thermal bulb.
true
A vapor charged thermal bulb assembly responds faster than a liquid charged thermal bulb assembly.
true
An automatic expansion valve works best when the evaporator load is constant.
true
An expansion valve is the pressure reducing device that controls the flow of liquid refrigerant into the evaporator.
true
The discharge gas from the compressor is high pressure, high temperature, superheated vapor.
true
The step motor valve uses a small motor to control the valve's port. which in turn controls evaporator superheat.
true
Holds valve's components together while providing ports to connect system's refeigerant line
valve body
The primary function of an expansion device is to
Produce a reduction in the pressure on the liqiud refeigerant. Regulate the flow of refrigerant into the evaporator. Lower the boiling point of the refrigerant far enough below the temperature of the load to get the needed heat transfer rate.
The purpose of a capillary tube is to
Regulate the refrigerant flow into the evaporator. Lower the pressure of liqiud refrigerant. Lower the boiling point of the refrigerant.
If a thermostatic expansion valve's thermal bulb came lose from the suction line at the outlet of the evaporator, which of the following could result?
The bulb pressure would increase and TXV would open. The superheat in the evaporator would decrease. Liquid refrigerant would flow back to the compressor.
