1. The Domestic Electrolux cannot be used for industrial purposes.
a) True
b) False
Explanation: The Domestic Electrolux cannot be used for industrial purposes as the COP of the system is very low. The whole cycle is carried out entirely by the gravity flow of the refrigerant.
2. Find the COP of the domestic Electrolux system when the heat supplied in the generator (QG) is 1885 KJ/kg and the heat absorbed in the evaporator (Qe) is 1045 KJ/kg.
a) 0.4
b) 0.45
c) 0.55
d) 0.65
Explanation: The COP of the domestic Electrolux system is the ratio of the heat absorbed by the evaporator and the heat supplied by the evaporator.
COP = \(\frac{1045}{1885}\) = 0.554.
3. Which of the refrigerant is used as a refrigerant in Lithium Bromide Absorption Refrigeration system?
a) Ammonia
b) Water
c) Hydrogen
d) Lithium Bromide
Explanation: Water is used as a refrigerant in Lithium Bromide Absorption Refrigeration system whereas lithium bromide, which is highly hydroscopic salt, is used as an absorbent. Lithium Chromate is used a corrosion inhibitor
4. In lithium bromide absorption refrigeration system it is not necessary to keep the refrigeration temperature above 0°C.
a) True
b) False
Explanation: In lithium bromide absorption refrigeration system it is necessary to keep the refrigeration temperature above 0°C as it is the freezing point of water. Water is used as a refrigerant in the system.
5. Find the COP of the lithium bromide absorption system when the heat supplied in the generator (QG) is 1255 KJ/kg and the heat absorbed in the evaporator (Qe) is 955 KJ/kg.
a) 0.66
b) 0.75
c) 0.85
d) 0.76
Explanation: The COP of the lithium bromide absorption refrigeration system is the ratio of the heat absorbed by the evaporator and the heat supplied by the evaporator.
COP = \(\frac{955}{1255}\) = 0.76.
6. Find the relative COP of the system whose maximum COP is 2.0 and the actual COP is 0.8.
a) 0.5
b) 0.4
c) 0.3
d) 0.6
Explanation: The relative COP is the ratio of actual COP and the maximum COP of the system,
Relative COP = (Actual COP) / (Maximum COP)
= \(\frac{0.8}{2.0}\) = 0.4.
7. What is the key difference between a simple VAR and Electrolux refrigerator?
a) Absorber
b) Liquid pump
c) Working mechanism
d) Generator
Explanation: Simple VAR uses a generator to do work as well as a pump to pressurize the liquid to the generator. So, total work done is the summation of work done by a pump and generator. Refrigeration effect is the heat absorbed in the evaporator. But as in the case of Electrolux refrigerator pump is not present. It is the VAR system with no liquid pump; hence, it is the key difference between Simple VAR and Electrolux refrigerator.
8. What is the other name for Electrolux refrigerator?
a) Single-fluid absorption system
b) Two-fluid absorption system
c) Three-fluid absorption system
d) Four-fluid absorption system
Explanation: Electrolux refrigerator uses Ammonia, Hydrogen, and Water to carry out the desired effect. As three fluids are used for the operation, Electrolux refrigerator is also called a Three-fluid absorption system.
9. What is the purpose of using Hydrogen in Electrolux refrigerator?
a) To increase the vapour pressure of ammonia
b) To increase the rate of evaporation
c) To decrease the rate of evaporation
d) To get evaporated by using ammonia
Explanation: Hydrogen is light, non-corrosive, and insoluble in water. Hydrogen being light, used for increasing the rate of evaporation. As lighter the gas, faster is the evaporation process. Hence hydrogen is used on the low-pressure side of the system to allow faster evaporation of ammonia.
10. What is the role of water in the Electrolux refrigerator?
a) Solvent
b) Evaporation rate enhancer
c) Evaporation rate reducer
d) Refrigerant
Explanation: Water is used as a solvent in Electrolux refrigerator due to the nature of readily absorbing the refrigerant i.e., ammonia.