Engineering :: Refrigeration and Air conditioning

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In a mechanical refrigeration system the highest temperature of refrigerant occurs

A.	Between condenser and evaporator	B.	In evaporator
C.	Before expansion valve	D.	Before expansion valve
E.	Between compressor and condenser

As warm air cools, its

A.	Relative humidity increases	B.	Relative humidity decreases
C.	Capacity to hold moisture increases	D.	There is no effect on moisture holding capacity
E.	Dew point occurs

When the air temperature reaches the point where relative humidity is 100% the air is saturated because it cannot hold any more moisture. This temperature is called

A.	Freezing point	B.	Partial freezing point
C.	Dew point	D.	Dew point of water vapour
E.	Dew point of air

Defrosting of evaporators is done because

A.	Frosting is undersirable	B.	Frosting increases refrigerating effect
C.	Frosting retards heat flow	D.	Frosting obstructs flow of refrigerant
E.	Frosting may cause damage to equipment

The chemical formula for Freon-12 is

A.	CHCIF2	B.	CH3CL
C.	CCI2F2	D.	CCIF3
E.	CCIF2CF3

Of the following chemicals the liquid having the greatest cooling effect on an individual is

A.	Water	B.	Brine
C.	Ether	D.	Water containing ammonium hydroxide
E.	Alcohol

In a refrigeration cycle the heat is rejected by refrigerant at

A.	Evaporator	B.	Condenser
C.	Expansion valve	D.	Compressor
E.	All of the above

The flow of the refrigerant in a refrigeration cycle is controlled by

A.	Compressor	B.	Condenser
C.	Evaporator	D.	Expansion valve
E.	Copper tubing

Sub-cooling is

A.	Cooling a part of liquid	B.	Differential cooling of a liquid
C.	Removing latent heat from a gas	D.	Removing sensible heat from a liquid
E.	Cooling a liquid below 0?C.

10.

An increase in the movement of the molecules within a solid, liquid or gas corresponds to

A.	A drop in temperature	B.	No change in temperature
C.	Latent heat addition/removal	D.	A rise in temperature
E.	None of the above