Which of the following is not a function of the compressor in a refrigeration system?
Select one:
a. To raise the pressure of the refrigerant.
b. To
... [Show More] draw low temperature refrigerant out of the evaporator.
c. To draw low pressure refrigerant out of the evaporator.
d. To lower the temperature of the refrigerant.
e. To maintain sufficiently low pressure in the evaporator. - ✔✔ d
Which of the following is not true?
Select one:
a. On a semi-hermetic compressor, the end plates can be moved for servicing
b. Compressors may raise the temperature of the refrigerant
c. Larger compressors are equipped with the eccentric type crankshaft
d. Compressor bearings are usually from sleeve and shell type
e. It is possible that liquid refrigerant enters the compressor - ✔✔ c
In a rotating vane design rotary compressor, a good seal is maintained between the vanes and the cylinder by
Select one:
a. high pressure refrigerant vapour
b. low pressure suction
c. the eccentric rotor size
d. the oil
e. centrifugal force - ✔✔ e
In a reciprocating compressor, the volume of compressed air per hour is 64.75 m3/hr. lf the volumetric efficiency of the compressor is 80%, what is the actual volume compressed?
Select one:
a. 51.8 m3/hr
b. 60.9 m3/hr
c. 46.5 m3/hr
d. 65.6 m3/hr
e. 68.3 m3/hr - ✔✔ a
In the condenser:
Select one:
a. The heat in the refrigerant lost in the evaporator must be restored.
b. Latent heat must be restored to the refrigerant.
c. The surrounding medium must be hotter than the refrigerant.
d. The condensing medium absorbs heat from the refrigerant.
e. The time to cool a product is condensed. - ✔✔ d
It is not correct that:
Select one:
a. The evaporator temperature and pressure are directly related
b. Temperature of the cooling medium for the condenser has reverse effect on the temperature of the condenser
c. The discharge pressure of the compressor is equal to the upstream pressure of the expansion valve
d. The head pressure and temperature are directly related
e. Condenser pressure is always more than the evaporator pressure - ✔✔ b
In an indirect refrigeration system, how can we be ascertain that the circulating chilled water won't freeze up
Select one:
a. By keeping the discharge pressure of compressor higher than its suction pressure
b. By making sure that the evaporator temperature does not sink below 0ºC
c. By keeping the temperature of chilled water at 5ºC
d. By controlling the regulating valve at the evaporator
e. By controlling the temperature of evaporator and condenser of the refrigeration system - ✔✔ c
Which of the following are principal parts in a closed cycle compression refrigeration system?
1- Absorber
2- Evaporator
3- Compressor
4- Condenser
Select one:
a. 2, 3, 4
b. 1, 2
c. 3
d. 1, 2, 4
e. 1, 2, 3 - ✔✔ a
Which of the following statements about compression refrigeration system pressures is false?
Select one:
a. The discharge pressure of the condenser is equal to the upstream pressure of the expansion valve
b. Condenser pressure is always more that the evaporator pressure
c. The head pressure and temperature are directly related
d. Temperature of the cooling medium for the condenser has reverse effect on the temperature of the condenser
e. The evaporator temperature and pressure are directly related - ✔✔ d
Centrifugal refrigeration compressors:
Select one:
a. Must be the hermetic type
b. Are of the positive displacement type only
c. Must be staged to achieve the required pressure
d. Must have water jackets
e. Are used with ammonia systems only - ✔✔ c
The primary difference between direct and indirect refrigeration systems is the:
Select one:
a. Type of refrigerant
b. Location of the medium being cooled
c. Type of heat transfer medium
d. Evaporator pressure
e. Compressor location - ✔✔ b
The three main classifications of refrigeration compressors are:
1. Reciprocating
2. Axial
3. Centrifugal
4. Rotary
5. Turbo
Select one:
a. 1, 3, 5
b. 2, 3, 4
c. 1, 2, 3
d. 1, 3, 4
e. 3, 4, 5 - ✔✔ d
If a cooled medium had an evaporation temperature of 2°C, the evaporation temperature of the liquid refrigerant should be approximately:
Select one:
a. 6°C to 8°C
b. 1°C
c. 2°C
d. -8°C to -3°C
e. 0°C - ✔✔ d
Rotary compressors have several different designs, some of which are:
1. Stationary blade
2. Rotary lobe
3. Helical rotor
4. Rotating blade
5. Reciprocating piston
Select one:
a. 1, 3, 5
b. 1, 3, 4
c. 2, 3, 4, 5
d. 1, 2, 3, 4
e. 3, 4, 5 - ✔✔ d
The type of brine used for skating and hockey rink refrigeration systems is usually:
Select one:
a. Calcium chloride
b. Calcium carbide
c. Calcium nitrate
d. Sodium chloride
e. Calcium sulphate - ✔✔ a
For a direct expansion system which of the following statements is true?
Select one:
a. Water cooled by the chiller evaporation coils is used to refrigerate at temperature below 0°C.
b. For large systems calcium chloride brine is cooled by the evaporator then pumped to the area being refrigerated.
c. The evaporator can be located in air circulating ducts communicating with the material or space being refrigerated
d. A direct expansion system is not the same type of system as the direct refrigeration system
e. The evaporator in this system is never in direct contact with the material or space being refrigerated. - ✔✔ c [Show Less]