If ouside air is to be conditioned from 60% relative humidity and 40 °C dry bulb temperature to 50% relative humidity and 24 °C dry bulb temperature, which psychromatic process would be required?

Consider the following statements: 1. The relative humidity of air does not change with temperature as long as specific humidity remains constant. 2. Dew-point temperature is the temperature at which condensation begins when air is cooled at constant volume. 3. Saturated air passing over a water surface does not cause change of air temperature. 4. For saturated air, dry-bulb, wet-bulb and dew-point temperatures are identical. Which of the above statements are correct?

A

1 and 2

B

2 and 3

C

1 and 4

D

3 and 4

The wet bulb temperature is lower in dry air than in wet air at the same temperature. A dry bulb thermometer registers a higher temperature than a wet bulb thermometer except at __________ percent relative humidity.

A

0

B

100

C

50

D

None of these

It is desired to condition the outside air from 70% relative humidity and 45°C dry bulb temperature to 50% relative humidity and 25°C dry bulb temperature (room condition). The practical arrangement will be

A

Dehumidification

B

Cooling and humidification

C

Cooling and dehumidification

D

Dehumidification and pure sensible cooling

The bypass factor (B. P. F.) in case of sensible heating of air is (Where td₁ = Dry bulb temperature of air entering the heating coil, td₂ = Dry bulb temperature of air leaving the heating coil, and td₃ = Dry bulb temperature of heating coil)

A

(td₂ - td₃)/(td₃ - td₁)

B

(td₃ - td₂)/(td₃ - td₁)

C

(td₃ - td₁)/(td₂ - td₃)

D

(td₃ - td₁)/(td₃ - td₂)

The bypass factor, in case of sensible cooling of air, is given by (where td₁ = Dry bulb temperature of air entering the cooling coil, td₂ = Dry bulb temperature of air leaving the cooling coil, and td₃ = Dry bulb temperature of the cooling coil)

A

(td₁ -td₃)/( td₂ -td₃)

B

(td₂ -td₃)/( td₁ -td₃)

C

(td₃ -td₁)/( td₂ -td₃)

D

(td₃ -td₂)/( td₁ -td₃)

The bypass factor (B.P.F.) in case of sensible heating of air is (Where td₁ = Dry bulb temperature of air entering the heating coil, td₂ = Dry bulb temperature of air leaving the heating coil and td₃ = Dry bulb temperature of heating coil)

A

$$\frac{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}$$

B

$$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_2}}}{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}$$

C

$$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}$$

D

$$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_2}}}$$

The bypass factor, in case of sensible cooling of air, is given by (where td₁ = Dry bulb temperature of air entering the cooling coil, td₂ = Dry bulb temperature of air leaving the cooling coil and td₃ = Dry bulb temperature of the cooling coil)

A

$$\frac{{{\text{t}}{{\text{d}}_1} - {\text{t}}{{\text{d}}_3}}}{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}$$

B

$$\frac{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}{{{\text{t}}{{\text{d}}_1} - {\text{t}}{{\text{d}}_3}}}$$

C

$$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}$$

D

$$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_2}}}{{{\text{t}}{{\text{d}}_1} - {\text{t}}{{\text{d}}_3}}}$$

When unsaturated air is adiabatically saturated, which of the following properties decrease? 1. Dry bulb temperature 2. Wet bulb temperature 3. Relative Humidity 4. Specific Humidity

A

1 only

B

1 and 2 only

C

2 and 3 only

D

3 and 4 only

Humidity chart is useful for the solution of problems concerning condensation, vaporisation and air conditioning. At a given dry bulb temperature, value of humidity obtained from the humidity chart directly, is in terms of __________ humidity.

A

Molal

B

Relative

C

Percentage

D

None of these

In the following question, sentences of a paragraph have been jumbled and labelled as A, B, C and D. You are required to rearrange the jumbled sentences of the paragraph and mark your response accordingly by selecting the correct option. A: Air conditioning is the process of removing heat and moisture from the interior of an occupied space to improve the comfort of occupants. Air conditioning can be used in both domestic and commercial environments. B: Electric refrigerant-based AC units range from small units that can cool a small bedroom, which can be carried by a single adult, to massive units installed on the roof of office towers that can cool an entire building. C: Air conditioners often use a fan to distribute the conditioned air to an enclosed space such as a building or a car to improve thermal comfort and indoor air quality. D: This process is most commonly used to achieve a more comfortable interior environment, typically for humans and other animals.

A

ADCB

B

ACDB

C

ABDC

D

ABCD

If ouside air is to be conditioned from 60% relative humidity and 40 °C dry bulb temperature to 50% relative humidity and 24 °C dry bulb temperature, which psychromatic process would be required?

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