Lithium bromide-water vapour is another absorption refrigeration system.

Consider the following statements in respect of a vapour-absorption refrigeration cycle: 1. The absorption refrigeration cycle is generally used when waste heat is a available from an existing source or when free energy like solar energy is to be used. 2. There are no moving parts in the absorption refrigeration plant except a small liquid pump. 3 the value of the coefficient of performance is nearly the same in both vapour-absorption and vapour-compression refrigeration plants. Which of the above statements are correct?

A

1, 2 and 3

B

1 and 2 only

C

1 and 3 only

D

2 and 3 only

Consider the following statements regarding vapour absorption systems in the field of refrigeration: 1. In ammonia-water absorption system, ammonia is the refrigerant. 2. In water-lithium bromide system, water is the refrigerant. 3. Ammonia-water absorption reaction is endothermic. 4. The amount of ammonia absorbed by water is inversely proportional to the temperature of ammonia. Which of the above statements are correct?

A

1, 2 and 3

B

1, 3 and 4

C

1, 2 and 4

D

2, 3 and 4

Lithium forms a BCC lattice with an edge length of 350 pm. The experimental density of lithium is 0.53 g cm-3. What is the percentage of missing lithium atoms? (Atomic mass of Lithium = 7 amu)

A

97.7%

B

95.4%

C

4.6%

D

2.3%

In lithium bromide absorption refrigeration system it is not necessary to keep the refrigeration temperature above 0°C.

A

False

B

True

When water – Lithium Bromide is used in a vapour absorption refrigeration system, then

A

they together act as refrigerant.

B

water is the refrigerant.

C

lithium bromide is refrigerant.

D

None of these

Consider the following statements and choose the correct answer:
1. A direct proportionality exists between vapour pressure and the concentration of water vapour in the atmosphere
2. Relative humidity is an expression of the ratio of the actual vapour pressure of the atmosphere when saturated at the same temperature
3. A rise or fall in temperature with no change in vapour pressure will cause a drop or rise, respectively, in relative humidity
4. A rise or fall in vapour pressure with no change in temperature will be accompanied by a rise or fall, respectively, in relative humidity

A

1, 2, 3 and 4 are true

B

Only 3 and 4 are true

C

Only 2 and 4 are true

D

Only 1, 2 and 3 are true

In a vapour absorption refrigeration system, the compressor of the vapour compression system is replaced by

A

Liquid pump

B

Generator

C

Absorber and generator

D

Absorber, generator and liquid pump

In order to prepare Lithium nitride, air is passed gently over a reactor. Suppose that Nitrogen diffuse to a length 5cm before getting reacted with Lithium. Nitrogen reacts with lithium quickly so that partial pressure of Nitrogen at that point is 0. Reactor is a cylinder of length 10cm and diameter 2cm. Assume air to be a mixture of Nitrogen and Oxygen only. The temperature is 298K and total pressure 1atm. Diffusivity of N2 in O2 is 2*10-5m2/s. Calculate the Molar flux (mol/m2.s) of N2 at a distance of 2.5cm from the top with respect to an observer moving with twice the mass average velocity a direction towards the liquid surface. (R=8.205*10-5m3atmK-1mol-1). Assume z=0 at the top of the reactor.

A

4.242*10-4

B

4.242*10-5

C

4.242*10-3

D

4.242*10-2

Absorption refrigeration uses _______ mechanical power input as compared to vapour compression refrigeration.

A

greater

B

the same

C

the same working fluid as

D

negligible

In a lithium bromide absorption refrigeration system

A

Lithium bromide is used as a refrigerant and water as an absorbent

B

Water is used as a refrigerant and lithium bromide as an absorbent

C

Ammonia is used as a refrigerant and lithium bromide as an absorbent

D

None of the above

Lithium bromide-water vapour is another absorption refrigeration system.

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