This set of Refrigeration Multiple Choice Questions & Answers (MCQs) focuses on “Types of Refrigerant Compressors”.
1. Where is the reciprocating compressor mostly suitable?
a) Small displacements and low condensing pressures
b) Small displacements and high condensing pressures
c) Large displacements and low condensing pressures
d) Large displacements and high condensing pressures
View Answer
Explanation: Reciprocating compressor is the type of compressor in which vapour refrigerant is compressed by the back and forth motion of the piston. As per the construction of piston and cylinder and for better performance as per the flow of refrigerant it is very suitable for small displacements and high condensing pressures to give the optimum refrigeration.
2. Where is the centrifugal compressor mostly suitable?
a) Small displacements and low condensing pressures
b) Small displacements and high condensing pressures
c) Large displacements and low condensing pressures
d) Large displacements and high condensing pressures
View Answer
Explanation: Centrifugal compressor is the type of compressor in which in the simplest form consists of an impeller to which a number of curved vanes are fitted symmetrically. As per the construction, the impeller rotates in an airtight volute casing with inlet and outlet points, and for better performance as per the flow of refrigerant, it is very suitable for larger displacements and low condensing pressures to give the optimum refrigeration.
3. The main advantage of centrifugal compressors is surging.
a) False
b) True
View Answer
Explanation: When refrigeration load decreases due to the reversal flow of refrigerant from compressor to the evaporator and causes stress conditions in the compressor, this phenomenon is called surging which occurs in these types of compressors and is one of the disadvantages.
4. What is the required condenser and evaporator pressure ratio for reciprocating compressors?
a) > 1.5 bar
b) < 1.5 bar
c) 1 bar
d) > 3.5 bar
View Answer
Explanation: Reciprocating compressor is the type of compressor in which vapour refrigerant is compressed by the back and forth motion of the piston. For optimum operation and effective results, the ratio of condenser and evaporator pressure should be greater than 3.5 bar.
5. What is the required condenser and evaporator pressure ratio for rotary compressors?
a) > 1.5 bar
b) < 1.5 bar
c) 1 bar
d) > 3.5 bar
View Answer
Explanation: Rotary compressor is the type of compressor in which vapour refrigerant is compressed by the movement of blades and have positive displacement. For optimum operation and effective results, the ratio of condenser and evaporator pressure should be greater than 1.5 bar.
6. What is the required condenser and evaporator pressure ratio for centrifugal compressors?
a) > 1.5 bar
b) < 1.5 bar
c) 1 bar
d) > 3.5 bar
View Answer
Explanation: Centrifugal compressor is the type of compressor in which in the simplest form consists of an impeller to which a number of curved vanes are fitted symmetrically. For optimum operation and effective results, the ratio of condenser and evaporator pressure should be less than 1.5 bar.
7. Which of the following is the condition to use two compressors in the refrigeration system?
a) The desired temperature is 3°C
b) The desired temperature is -3°C
c) The desired temperature is -50°C
d) The desired temperature is -5°C
View Answer
Explanation: So as to get very low temperature, the compressor has to do more work. So, for the given conditions if the desired temperature is -50°C then use of two compressors is advised.
8. Centrifugal compressors are used to handle _______ volume of refrigerant.
a) small
b) medium
c) large
d) very large
View Answer
Explanation: Centrifugal compressors do not have parts like valves, pistons, etc. just impeller and casing. Centrifugal compressor has negligible clearance volume due to the construction and hence has large volumetric efficiency. Compressor runs at higher speeds and handles a large volume of vapour refrigerant.
9. Reciprocating compressors are used to handle _______ volume of refrigerant.
a) small
b) medium
c) large
d) very large
View Answer
Explanation: Reciprocating compressors have parts like valves, pistons, and cylinders and have larger clearance volume than other compressors to get smooth operation. Due to the presence of more parts and relatively higher clearance volume, it can handle a small volume of vapour refrigerant.
10. Centrifugal compressors are more stable than reciprocating in terms of operation.
a) False
b) True
View Answer
Explanation: Centrifugal compressors do not have parts like valves, pistons, etc. just impeller and casing. Due to fewer parts operating at the same time, there are no unbalanced masses hence compressor operates with lesser vibrations and remains quiet too. Hence, Centrifugal compressors are more stable than reciprocating in terms of operation.
Sanfoundry Global Education & Learning Series – Refrigeration & Air Conditioning.
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