Refrigeration and Air Conditioning
When the lower temperature of a refrigerating machine is fixed, then the coefficient of performance can be improved by

Lowering the higher temperature
Raising the higher temperature
Operating the machine at higher speeds
Operating the machine at lower speeds

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Refrigeration and Air Conditioning
Dry bulb temperature is the temperature of air recorded by a thermometer, when

None of the listed here
Its bulb is surrounded by a wet cloth exposed to the air
The moisture present in it begins to condense
It is not affected by the moisture present in the air

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Refrigeration and Air Conditioning
The C.O.P. of an absorption type refrigerator is given by (where T₁ = Temperature at which the working substance receives heat, T₂ = Temperature of cooling water, and T₃ = Evaporator temperature)

[T₃ (T₁ - T₂)]/ [T₁ (T₂ - T₃)]
[T₁ (T₁ - T₂)] / [T₃ (T₂ - T₃)]
[T₃ (T₂ - T₃)] / [T₁ (T₁ - T₂)]
[T₁ (T₂ - T₃)] / [T₃ (T₁ - T₂)]

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Refrigeration and Air Conditioning
In a lithium bromide absorption refrigeration system

Lithium bromide is used as a refrigerant and water as an absorbent
None of these
Water is used as a refrigerant and lithium bromide as an absorbent
Ammonia is used as a refrigerant and lithium bromide as an absorbent

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