22562 Power Engineering and Refrigeration External Oral / Viva Practice Questions with Answers
1. 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.
2. What is Mechanical
Refrigeration ?
Ans : Producing cold by machine.
3. 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 .
4. 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
5. Which Unit Produces Cooling
Effect in the refrigeration system ?
Ans : The evaporator
6. 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 ” .
7. 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 .
8. 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” .
9. 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 .
10. What is Relative COP ?
Ans : It is the ratio of actual
COP and Theoretical COP .
11. What is the basic difference
between air conditioning and refrigeration ?
Answer : Refrigeration solely
deals with cooling . One of the major applications of the air conditioning is
cooling but it also involves the artificial tampering of the natural
conditions. In air conditioning the cooling is coupled with heating. It also
takes care of circulation of the air, purity of the cooled air and also
humidity of the controlled space. Refrigeration and air conditioning are
interrelated.
12. What are applications of the
refrigeration ?
Answer: Ice making, Preservation
and transportation of the perishables, Industrial Purposes, Air conditioning.
13. Show the classification of
air-conditioning systems .
Answer : air-conditioning systems
are classified on the basis of 3 major points
a. Major functions : It
involves 1. comfort air condition systems and 2. Industrial Air
conditioning
b. Season of the year : 1. Winter
air-conditioning 2. Summer air-conditioning 3. Year round
air-conditioning
c. Equipment arrangement : 1.
Unitary Systems 2. Central Systems
14. What are applications of
air-conditioning systems ?
Answer : Air conditioning
application involves human comfort. Summer air conditioning is very popular in
offices and large industries.
15. Which Unit Produces Cooling
Effect in the refrigeration system ?
The evaporator
16. 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 ” .
17. What is One Tonne of
Refrigeration ?
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 .
18. Describe Refrigeration system
with Reversed Rankin Cycle . Draw T-S and P-h Diagram of the cycle with
Sub-cooling and Super-heating. .
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.