This set of Solar Energy Multiple Choice Questions & Answers (MCQs) focuses on “Solar Refrigeration and Air-Conditioning Systems – 1”.
1. Which of the following are types of photovoltaic refrigeration?
a) Vapour compression refrigeration and thermoelectric refrigeration
b) Vapour compression refrigeration and vapour jet refrigeration
c) Photovoltaics and concentrated solar power systems
d) Rankine cycle and vapour jet refrigeration
View Answer
Explanation: Vapour compression refrigeration and thermoelectric refrigeration are types of photovoltaic refrigeration. Photovoltaic is used to perform solar refrigeration. Like Rankine Cycle and concentrated power systems, it is not a type of refrigeration.
2. What is a solar powered refrigerator?
a) A refrigerator that is directly sourced by electricity
b) A refrigerator that is sourced by solar energy
c) A refrigerator that is sourced by wind and sun
d) A refrigerator that is sourced by biomass and sun
View Answer
Explanation: A solar powered refrigerator is a refrigerator that is sourced by solar energy. Photovoltaics or solar thermal energy is used to convert solar energy into a usable form (electricity) for refrigeration.
3. What is refrigeration?
a) A process where is work is done is to add heat from one system to another
b) A process where heat is used by the system to do work
c) A process where work is done to move heat from one system to another
d) A process where work is done to add cold air into the system
View Answer
Explanation: Refrigeration is a process in which work is done to (re)move heat from one system and add it to another. This results in temperature decrement in the system from which heat was (re)moved.
4. What are the types of popular refrigeration systems?
a) Vapour compression and vapour adsorption
b) Vapour adsorption and vapour absorption
c) Vapour compression and liquid compression
d) Vapour compression and vapour absorption
View Answer
Explanation: Refrigeration systems are broadly classified into vapour compression (VCR) and vapour absorption systems (VAR). Liquids are not compressed in refrigerating systems.
5. Vapour compression refrigeration systems use ______ energy to perform compression.
a) mechanical
b) thermal
c) gravitational
d) nuclear
View Answer
Explanation: Vapour compression refrigeration systems use mechanical energy. The electrical energy is converted into mechanical energy to perform the process of compression.
6. What type of energy does vapour absorption refrigeration system use?
a) mechanical
b) thermal
c) nuclear
d) electrodynamic
View Answer
Explanation: Vapour absorption refrigeration systems use thermal energy. The electrical energy is converted into thermal energy to perform the process of absorption.
7. Which of the following refrigeration systems are used in air-conditioning systems?
a) Vapour absorption
b) Vapour jet
c) Vapour compression
d) Liquid adsorption
View Answer
Explanation: Vapour absorption refrigeration systems are used in air-conditioning systems. It is also used in domestic and commercial refrigerators, large-scaled warehouses for storing food items by freezing.
8. Which of the following best describes the process of vapour compression refrigeration?
a) Warm air → compressor → condenser → expansion valve → evaporator → colder air
b) Evaporator → compressor → condenser → expansion valve → evaporator → colder air
c) Warm air → compressor → expansion valve → evaporator → colder air
d) Warm air → evaporator → compressor → condenser → expansion valve → evaporator → colder air
View Answer
Explanation: In vapour compression refrigerator, warm air is first evaporated and then passed into a compressor. This compresses the vapour which is then passed through a condenser to obtain a liquid. The liquid is expanded through an expansion valve to form a combination of liquid and vapour which is then passed through an evaporator to obtain cold air.
9. What does a refrigerant do in a vapour compression refrigeration system?
a) Removes heat from one system and empties it into another system
b) Adds heat to the system
c) Absorbs heat continuously
d) Converts thermal energy into electrical energy
View Answer
Explanation: A refrigerant in a vapour compression refrigeration system removes heat from one system and empties it into another system. It is a circulating liquid that basically performs operation of “refrigeration”.
10. Which of the following is an example of a refrigerant?
a) Platinum
b) CFCs
c) Argon
d) Nitrogen
View Answer
Explanation: CFCs are common examples of refrigerants. Freons like R-11, R-12, R-21, R-22 and R-502 are also used. Platinum, Argon and Nitrogen are not used as refrigerants.
11. How does a photovoltaic refrigeration system work?
a) By converting sun’s thermal energy into electricity which is used to drive a motor coupled to a compressor
b) By converting sun’s thermal energy into electricity which is used to drive an AC motor coupled to a compressor of a vapour compression system
c) By converting sunlight into DC current to drive a DC motor which is coupled to a compressor of a vapour compression system
d) By converting sunlight into DC current which is used to drive an AC motor coupled to a compressor of a vapour compression system
View Answer
Explanation: A photovoltaic refrigeration system works by converting sunlight into DC current. This DC current drives a DC motor which is coupled to a compressor of a vapour compression system.
12. It is important to ensure that _______ characteristics of motor matches that of PV array.
a) mechanical
b) thermal
c) insulating
d) electrical
View Answer
Explanation: It is important to ensure that electrical characteristics of motor matches that of PV array. This is to ensure that the power delivered by the PV array sufficient to drive the motor which in turn drives the system.
13. How does the compression process between vapour compression and vapour absorption systems differ?
a) Vapour compression uses mechanical compression while vapour absorption uses thermal compression
b) Vapour compression and vapour absorption use thermal compression
c) Vapour compression and vapour absorption use thermal compression
d) Vapour compression uses electrical compression while vapour absorption uses mechanical compression
View Answer
Explanation: The compression processes differ in the compression technique and energy conversions. Vapour compression uses mechanical compression while vapour absorption uses thermal compression.
14. Solar thermal energy is used to perform vapour absorption refrigeration.
a) True
b) False
View Answer
Explanation: Solar thermal energy is used to perform vapour absorption refrigeration. Since vapour absorption refrigeration uses thermal compression, the thermal energy is directly used to extract heat from the working fluid.
15. Freon is a trade for a family of haloalkane refrigerants.
a) True
b) False
View Answer
Explanation: Freon is a trade for a family of haloalkane refrigerants manufactured by DuPont. Haloalkanes are derivatives of alkanes containing one or more halogens like chlorine, fluorine, etc.
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