This set of Refrigeration Multiple Choice Questions & Answers (MCQs) focuses on “Condensers – Cooling Towers”.
1. Which of the following cooling towers possess maximum heat transfer from air to water?
a) Natural Draft
b) Mechanical Draft
c) Natural and Mechanical Draft
d) Atmospheric Draft
View Answer
Explanation: Natural Draft is where air circulates naturally without any external force, and the atmospheric draft is a type of natural draft. So, the mechanical draft is the type of cooling tower which gives the maximum heat transfer due to usage of fans for the circulation. More the force more heat can be transferred.
2. How is the performance of the cooling tower indicated?
a) Wet-bulb temperature
b) Dry bulb temperature
c) Approach
d) Range
View Answer
Explanation: Approach can be defined as the temperature difference between water leaving the cooling tower and ambient wet-bulb temperature. If the approach is low, then the performance is good and vice-versa. This approach value denotes how close the cooling tower gets the water to the wet-bulb temperature of the ambient or surrounding air.
3. What is the difference between the temperature of entering and leaving water in the cooling tower?
a) Wet-bulb temperature
b) Dry bulb temperature
c) Approach
d) Range
View Answer
Explanation: Range can be defined as the difference between entering water temperature and leaving water temperature. This is also an indicator of the performance of cooling tower but for the effective performance, a better indicator, i.e., the approach is used.
4. What is the formula for the effectiveness of cooling tower from the following?
a) Range / (Range + Approach)
b) Approach / (Range + Approach)
c) Range / Approach
d) Approach / Range
View Answer
Explanation: Approach can be defined as the temperature difference between water leaving the cooling tower and ambient wet-bulb temperature. The range can be defined as the difference between entering water temperature and leaving water temperature.
Hence, the effectiveness can be given as,
Effectiveness = Range / (Range + Approach).
5. A cooling tower brings water temperature to _________
a) WBT
b) DBT
c) DPT
d) Ambient WBT
View Answer
Explanation: Approach can be defined as the temperature difference between water leaving the cooling tower and ambient wet-bulb temperature. If the approach is low, then the performance is good and vice-versa. This approach value denotes how close the cooling tower gets the water to the wet-bulb temperature of the ambient or surrounding air. So, cooling tower brings the water temperature to ambient wet bulb temperature for the operation.
6. What is the correct representation of range from the following?
a) Range = Cooling tower water outlet temperature – Wet bulb temperature
b) Range = Cooling tower water inlet temperature – Wet bulb temperature
c) Range = Cooling tower water outlet temperature – Dry bulb temperature
d) Range = Heat load in kcal per hour / Water circulation in liters per hour
View Answer
Explanation: Range can be defined as the difference between entering water temperature and leaving water temperature. It is also defined as the heat load per water circulation. As in the given options, the first three are incorrect as one of them represents approach so correct representation is,
Range = Heat load in kcal per hour / Water circulation in liters per hour
Range = Cooling tower water inlet temperature – Cooling tower water outlet temperature.
7. What is L / G in terms of the cooling tower?
a) Length / Girth
b) Length / Gradient
c) Air mass flow rate / Water flow rate
d) Water flow rate / Air mass flow rate
View Answer
Explanation: The L / G is called a liquid-gas ratio. It is defined as the ratio of water flow rate to the air mass flow rate in the cooling tower. This L / G ratio affects the effectiveness of the cooling tower.
8. Mechanical draft cooling tower size is ________ the size of the natural draft cooling tower.
a) smaller than
b) larger than
c) equal to the
d) very much larger than
View Answer
Explanation: The mechanical draft cooling towers are smaller in size than that of the natural draft cooling towers with the same capacity due to the fact that a large volume of forced air increases the cooling capacity.
9. The cooling capacity of mechanical draft cooling towers cannot be varied.
a) False
b) True
View Answer
Explanation: The main advantage of mechanical draft cooling towers is cooling capacity can be controlled. This can be achieved by controlling the amount of forced air entering the cooling tower.
10. Mechanical Draft cooling towers do not depend on atmospheric air.
a) True
b) False
View Answer
Explanation: One of the advantages of mechanical draft cooling towers is that they do not depend upon the atmospheric air. Fans do the operation. Due to the fact of independence, this type of cooling towers can be even installed inside the building.
Sanfoundry Global Education & Learning Series – Refrigeration & Air Conditioning.
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