This is the fourth part of Mechanical Engineering Interview Questions. This fourth part is totally dedicated to viva questions from the chapter Refrigeration & Air-Conditioning. You can have a look at the previous 3 parts here –

• Refrigeration and Air Conditioning Solved Problems 1 
• Mechanical Engineering Interview Questions part 1 (With Answers)
• Mechanical Engineering Interview Questions – part 2
• Mechanical Engineering Interview Questions part – 3
• Mechanical Engineering Interview Questions Part  04 
• Mechanical Engineering Interview Questions Part  05 
• Mechanical Engineering Interview Questions Part  06 
• Mechanical Engineering Interview Questions Part  07 
• Mechanical Engineering Interview Questions Part  08

Refrigeration & Air-conditioning Interview & Viva Questions With Answers

Define Refrigeration – Ans : Refrigeration may be defined as a process of producing cold by extracting heat from a body or space and heat thus removed is rejected to atmosphere or space where it is unobjectionable.

What is Mechanical Refrigeration ? Ans : Producing cold by machine.

Classify the different Refrigeration Systems . 

Ans : It may be of the following three types 1. Vapor Compression Refrigeration System 2. Vapor absorption Refrigeration System  3. Air Refrigeration Systems .

What are the basic Units of Mechanical Refrigeration systems ? 

Ans : Refrigeration system has 4 basic units

a. An Evaporator – The cooling Unit

b. A pump or Compressor

c. A Condenser – The heat disposer

d. A liquid mixing device – Expansion valve or cylinder or capillary tube

Which Unit Produces Cooling Effect in the refrigeration system ?

Ans : The evaporator

What is the Unit of Refrigeration ? 

Ans : As Power Unit of mechanical devices is given by H.P , for electrical equipment the unit of power is kW or MW . In the same way the unit of refrigeration is  ” Tonnes of Refrigeration ” .

What is One Tonne of Refrigeration ? 

Ans: One Tonne of Refrigeration means machine is capable of removing heat from a body equal to the heat absorbed by one tonne of ice when it melts from 0 ° C to 0 ° C Water in 24 hours . Here one tonne is equal to 2000 lb .

What is the capacity of one tonne machine in MKS system ? 

Ans : In MKS system a machine having capacity to produce cooling effect of 50 kcal/minute is known to be a “One Tonne Machine” .

Define Co-efficient of Performance.  Ans : In case of engine the performance is judged the efficiency of the engine. That is – Efficiency = Work Done / Heat Supplied .

And in case of refrigeration the process is first reversed that is we have to supply work to obtain lower temperature  or say for that removal of heat. Thus performance of refrigeration is just reversed . That is – N/W

Where – N = The rate of heat abstracted from the body in given time technically called “Net Refrigeration Effect” and W = Work Done .

Thus COP = Net Refrigeration Effect / Work Done Supplied . This is Called Theoretical COP .

What is Relative COP ? 

Ans : It is the ratio of actual COP and Theoretical COP .

Describe Refrigeration system with Reversed Rankin Cycle . Draw T-S and P-h Diagram of the cycle with Sub-cooling and Super-heating. . 

Ans: Please Follow This Link .  T-S and P-h diagram with subcooling and superheating. 

Stay Tuned more questions from the chapter refrigeration and air-conditioning are coming.