Heat Transfer, Refrigeration and Air Conditioning Questions

• The ratio of actual heat transfer to the maximum possible heat transfer is known as heat exchanger effectiveness.
• The unit of overall coefficient of heat transfer is
• The mass of water vapour present in 1 kg of dry air, is called humidity ratio.
• The refrigerant widely used in domestic refrigerators is
• R-12 is generally preferred over R-22 in deep freezers since
• An infinite parallel planes with emissivities e1 and e2, the interchange factor for radiation from surface 1 to surface 2 is given by
• Hydrogen is used in electrolux refrigeration system so as to __________ the rate of evaporation of the liquid ammonia passing through the evaporator.
• Which of the following statement is correct?
• The cooling system used for supersonic aircrafts and rockets is
• The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure, is called
• The space between the two walls of a thermos flask is evacuated because vacuum is a __________ conductor of heat.
• R-11 has the highest critical point temperature.
• The reciprocating refrigerant compressors are very suitable for
• The relative coefficient of performance is equal to
• In a pressure enthalpy chart, the space between the saturated liquid line and saturated vapour line, represents sub-cooled liquid region.
• Air refrigerator works on
• Most thermostatic expansion valves are set for a superheat of
• The boiling point of carbon dioxide is
• The desirable property of a refrigerant is
• The humidification process, on the psychrometric chart is shown by