300+ [UPDATED] Air Conditioning And Refrigeration Interview Questions and Answers

Q1. What Is Wet Bulb Depression?

Wet bulb depression is the difference between dry bulb temperature and wet bulb temperature.

Q2. Why Rate Of Condensation Is Higher On A Polished Surface Compared To Rusty Surface?

Polished surface promotes drop wise condensation and does not wet the surface.

Q3. Define Co-efficient Of Performance?

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 .

Q4. What Is Air Conditioners?

Air Conditioner continuously draws the air from the space to be cooled & cools it by the principle of refrigeration and discharge it back to the same indoor space that need to be cooled.

Q5. What Is Refrigeration?

Refrigeration is the process of continuously cooling or extraction of heat from the atmosphere or surroundings with the help of external work.

Q6. What Is The Capacity Of One Tonne Machine In Mks System?

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

Q7. What Is Mechanical Refrigeration ?

Producing cold by machine.

Q8. How Much Resistance Is Offered To Heat Flow By Dropwise Condensation?


Q9. Classify The Different Refrigeration Systems?

It may be of the following three types:

  1. Vapor Compression Refrigeration System
  2. Vapor absorption Refrigeration System 
  3. Air Refrigeration Systems

Q10. What Is One Tonne Of Refrigeration ?

One Tonne of Refrigeration me 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 .

Q11. What Will Be The Relative Humidity At Saturation Point?

Relative humidity = 100 %

Q12. Difference Between The Refrigeration And Heat Pump?

Refrigerators ejects heat with work input. But heat pumps gives heat with work input.

Refrigerator contains the heat pump, it pumps the heat out so that your system remains cold.

Q13. Explain The Principle Of Refrigeration?

The operation is according to the second law of thermodynamics – Heat can be made to flow from cold body to hot body with the help of external source.

Q14. Which Unit Produces Cooling Effect In The Refrigeration System ?

The evaporator

Q15. Define Relative Humidity?

Relative humidity is the ratio between the actual moisture content of the air compared with the moisture content of the air required for saturation at the same temperature.

Q16. What Is Sensible Heat Ratio (shr)?

The Sensible Heat Ratio (SHR) express the ratio between the sensible heat load and the total heat load.

Q17. What Are The Basic Units Of Mechanical Refrigeration Systems?

Refrigeration system has 4 basic units

  1. An Evaporator – The cooling Unit
  2. A pump or Compressor
  3. A Condenser – The heat disposer
  4. A liquid mixing device – Expion valve or cylinder or capillary tube

Q18. What Is Relative Cop ?

It is the ratio of actual COP and Theoretical COP

Q19. What Is The Unit Of Refrigeration?

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 ”