Test: Vapour Compression Systems, Refrigerants - 2 - Mechanical Engineering MCQ

For a heat pump working on vapour compression cycle, enthalpy values of the working fluid at the end of heat addition process, at the end of compression process, at the end of heat rejection process, and at the end of isenthalpic expansion process are 195 kJ/kg, 210 kJ/kg, and 90 kJ/kg respectively. The mass flow rate is 0.5 kg/s. Then the heating capacity of heat pump is, nearly

In a vapour compression plant, if certain temperature differences are to be maintained in the evaporator and condenser in order to obtain the necessary heat transfer, then the evaporator saturation temperature must be:

In milk chilling plants, the usual secondary refrigerant is:

A single-stage vapour compression refrigeration system cannot be used to produce ultralow temperatures because

The vapour compression refrigeration cycle is an inherently irreversible cycle, because

Consider the following statements pertaining to a vapour compression type refrigerator:

1.The condenser rejects heat to the surroundings from the refrigerant.  

2.The evaporator absorbs heat from the surroundings to be cooled.  

3.Both the condenser and evaporator are heat exchangers with refrigerant as a common medium.  

4.The amount of heat exchanged in condenser and evaporator are equal under steady conditions.  

Which of the above statements are correct? 

The correct sequence of vapour compression (VC), vapour absorption (VA) and steam ejector (SE) refrigeration cycles in increasing order of the COP is:

The leakage in a Freon-based refrigeration system can be detected by using a/an 

Consider the following statements:

High condenser pressure in a refrigeration system can occur because 

1. The water flow rate is lower than the desired value.  

2. Non-condensable gases are present in the system  

3. Of accumulation of lubricating oil in condenser  

4. Of low charge of refrigerant in the system. 

Of these statements: 

In system A vapour are superheated by 10°C in the evaporator while in system B vapour are superheated by 10°C in a liquid vapour regenerative heat exchanger, other conditions being the same. Then 

Selection of a refrigerant for a vapour – compression system depends on which among the following?

Oil separator is NOT required in refrigeration system if:

Consider the following statements:

Moisture should be removed from refrigerants to avoid  

1. Compressor seal failure

2. Freezing at the expansion valve  

3. Restriction to refrigerant flow

4. Corrosion of steel parts  

Of these statements:  

ssertion (A): R-22 is used as a refrigerant in all refrigerators.  

Reason (R):  R-22 is non-toxic and non-inflammable. 

Match List-I with List-II and select the correct answer using the codes given below the lists:

Assertion (A): Freon-12 is odourless and its leakage cannot be easily detected. However, it is preferred in comfort air-conditioning.

Reason (R): It is almost impossible for Freon-12 leakage to attain a fatal concentration. 

Match List-I with List-II and select the correct answer using the codes given below the lists:

The color of the flame of halide torch, in a case of leakage of Freon refrigerant, will change to:

What is an azeotrope? 

The leaks in a refrigeration system freon are detected by:

Match List-I (Chemical formula of refrigerant) with List-II (Numerical Designation) and select the correct answer using the codes given below the lists:

Match List-I (Refrigerant) with List-II (Designation) and select the correct answer using the codes given below the lists:

Theoretical vapour compression refrigeration cycle is represented on a T-s diagram as

Match List-I (T-s diagram) with List-II (P-h diagrams) of vapour compression refrigeration cycles and select the correct answer using the codes given below the lists:

Replacing a water-cooled condenser with an air-cooled one in a vapour compression refrigeration system with constant evaporator pressure results in

The power required for the compressor in kw is 

A good refrigerant should have