Air-Conditioning Questions and Answers – Psychrometry – Thermodynamic Wet Bulb Temperature

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This set of Air-Conditioning Multiple Choice Questions & Answers (MCQs) focuses on “Psychrometry – Thermodynamic Wet Bulb Temperature”.

1. What is the alternate name for thermodynamic wet-bulb temperature?
a) Isobaric WBT
b) Isobaric Saturation Temperature
c) Adiabatic WBT
d) Adiabatic Saturation Temperature
View Answer

Answer: d
Explanation: The thermodynamic wet-bulb temperature is also known as adiabatic saturation temperature due to the process involved in it.
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2. What is the temperature at which air can be brought to saturation state adiabatically?
a) Thermodynamic WBT
b) Thermodynamic DBT
c) Thermodynamic DPT
d) DPT
View Answer

Answer: a
Explanation: The temperature at which air can be brought to saturation state adiabatically is called a thermodynamic wet-bulb temperature or adiabatic saturation temperature.

3. Which of the following is carried out to obtain saturation state at the thermodynamic WBT?
a) Condensation
b) Evaporation
c) Compression
d) Expansion
View Answer

Answer: b
Explanation: The temperature at which air can be brought to saturation state adiabatically is called a thermodynamic wet-bulb temperature or adiabatic saturation temperature. This state is achieved by evaporation of water into the flowing air.
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4. Which of the following is the major equipment in the simplest form is used to do saturation of air?
a) Chamber
b) Vessel
c) Insulated Chamber
d) Pipe
View Answer

Answer: c
Explanation: The equipment used for saturation of the air in the simplest form is an insulated chamber containing an optimum amount of water.

5. The arrangement for extra-water to flow into the chamber from its top is called as ___________
a) chamber ingot
b) chamber gate
c) make-up gate
d) make-up water
View Answer

Answer: d
Explanation: The equipment used for saturation of the air in the simplest form is an insulated chamber containing an optimum amount of water. In order to get more water into the chamber, an arrangement is provided, which is called make-up water.
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6. What is the ratio of humidity ratio of entering and discharging air?
a) W2 / W1 = (hs2 – hfw) + ha2 – ha1 / (hs1 – hfw)
b) W1 / W2 = (hs1 – hfw) + ha2 – ha1 / (hs2 – hfw)
c) W1 / W2 = (hs2 – hfw) + ha2 – ha1 / (hs1 – hfw)
d) W1 / W2 = (hs2 – hfw) + ha1 – ha2 / (hs1 – hfw)
View Answer

Answer: c
Explanation: Balancing enthalpies, h1 – W1 hfw = h2 – W2 hfw
As, h1 = ha1 + W1 hs1 and h2 = ha2 + W2 hs2
So, by putting values we get,
W1 / W2 = (hs2 – hfw) + ha2 – ha1 / (hs1 – hfw).

7. The term (h2 – W2 hfw) is known as_________
a) sigma term
b) sigma heat
c) heat factor
d) heat term
View Answer

Answer: b
Explanation: The term (h2 – W2 hfw) is known as sigma heat, and this term remains constant during the adiabatic process.

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8. If h1 = 32 kJ/kg, h2 = 41 kJ/kg, hfw = 49 kJ/kg, W1 = 0.0109 kg/kg of dry air and W2 = 0.0297 kg/kg of dry air then what is the value of sigma heat?
a) 41.0865
b) 39.5447
c) 38.9013
d) 45.8775
View Answer

Answer: b
Explanation: Sigma heat = (h2 – W2 hfw)
So, putting values in the formula,
Sigma heat = [41 – (49 x 0.0297)] = 39.5447.

9. Evaporation from water to flowing air is carried out adiabatically.
a) False
b) True
View Answer

Answer: b
Explanation: The temperature at which air can be brought to saturation state adiabatically is called a thermodynamic wet-bulb temperature or adiabatic saturation temperature. This state is achieved by evaporation of water into the flowing air.
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10. Make-up water is used to keep the water level constant.
a) True
b) False
View Answer

Answer: a
Explanation: In order to get more water into the chamber, an arrangement is provided, which is called make-up water. This water is added from the top to keep the water level constant and keep the energy transfer at an optimum pace.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter