Mechanical Engineering MCQs

Page No. 139

For proper refrigeration in a cabinet, if the temperature and vapour pressure difference between cabinet and atmosphere is high, then_________________?


abigger cabinet should be used


bsmaller cabinet should be used


cperfectly tight vapour seal should be used


drefrigerant with lower evaporation temperature should be used



The advantage of dry compression is that________________?


ait permits higher speeds to be used


bit permits complete evaporation in the evaporator


cit results in high volumetirc and mechanical efficiency


dall of the above


View Answer all of the above

The suction pipe diameter of refrigerating unit compressor in comparison to delivery side is_________________?


abigger


bsmaller


cequal


dsmaller/bigger depending on capacity


View Answer bigger

Under-cooling in a refrigeration cycle_________________?


aincreases COP


bdecreases COF


cCOP remains unaltered


dother factors decide COP


View Answer increases COP

The coefficient of performance is the ratio of the refrigerant effect to the_________________?


aheat of compression


bwork done by compressor


centhalpy increase in compressor


dall of the above


View Answer all of the above

Vertical lines on pressure-enthalpy chart show constant_______________?


apressure lines


btemperature lines


ctotal heat lines


dentropy lines


View Answer total heat lines

The general rule for rating refrigeration systems (excepting for C02 system) is to approximate following h.p. per ton of refrigeration__________________?


a0.1 to 0.5 h.p. per ton of refrigeration


b0.5 to 0.8 h.p. per ton of refrigeration


c1 to 2 h.p. per ton of refrigeration


d2 to 5 h.p. per ton of refrigeration



Cooling water is required for following equipment in ammonia absorption plant__________________?


acondenser


bevaporator


cabsorber


dcondenser, absorber and separator (rectifier)



The C.O.P. of a refrigeration cycle with lowering of condenser temperature, keeping the evaporator temperature constant, will__________________?


aincrease


bdecrease


cmay increase or decrease depending on the type of refrigerant used


dremain unaffected


View Answer increase

The evolution of heat of solution takes place in ammonia absorption plant when _____________________?


aammonia vapour goes into solution


bammonia vapour is driven out of solution


clithium bromide mixes with ammonia


dweak solution mixes with strong solution



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