914 ENGINEERING THERMODYNAMICS
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- Dielectric strength of refrigerants is an important property in hermetrically sealed com-
pressor units. - Leakage of ammonia can be detected by halide torch method.
Of these statements :
(a) 1, 2 and 4 are correct (b) 2 and 4 are correct
(c) 1, 2 and 4 are correct (d) 1 and 3 are correct. - The most commonly used method for the design of duct size is the
(a) velocity reduction method (b) equal friction method
(c) static regain method (d) dual or double method. - The refrigerant used for absorption refrigerators working on heat from solar collectors is a
mixture of water and
(a) carbon dioxide (b) sulphur dioxide
(c) lithium bromide (d) freon 12. - During the adiabatic cooling of moist air
(a) DBT remains constant (b) specific humidity remains constant
(c) relative humidity remains constant (d) WBT remains constant. - When a stream of moist air is passed over a cold and dry cooling coil such that no condensa-
tion takes place, then the air stream will get cooled along the line of
(a) constant wet bulb temperature (b) constant dew point temperature
(c) constant relative humidity (d) constant enthalpy. - For large tonnage (more than 200 tons) air-conditioning applications, which one of the
following types of compressors is recommended?
(a) Reciprocating (b) Rotating
(c) Centrifugal (d) Screw. - In a cooling tower, “approach” is the temperature difference between the
(a) hot inlet water and cold outlet water (b) hot inlet water and WBT
(c) cold outlet water and WBT (d) DBT and WBT. - When the discharge pressure is too high in a refrigeration system, high pressure control is
installed to
(a) stop the cooling fan (b) stop the water circulating pump
(c) regulate the flow of cooling water (d) stop the compressor. - A refrigerating machine working on reversed Carnot cycle takes out 2 kW per minute of
heat from the system while working between temperature limits of 300 K and 200 K. C.O.P.
and Power consumed by the cycle will be respectively
(a) 1 and 1 kW (b) 1 and 2 kW
(c) 2 and 1 kW (c) 2 and 2 kW. - Consider the following statements :
In the case of a vapour compression machine, if the condensing temperature of the refriger-
ant is closer to the critical temperature, then there will be - excessive power consumption 2. high compression
- large volume flow.
Of these statements :
(a) 1, 2 and 3 are correct (b) 1 and 2 are correct
(c) 2 and 3 are correct (d) 1 and 3 are correct.