245) A device used for transfering heat from one fluid to another is called heat exchanger.

246) The coefficient of performance (C.O.P.) of a refrigerator working as a heat pump is given by

247) The temperature below which a gas is always liquified, is known as critical temperature.

248) A Bell Coleman refrigerator working on dense air system as compared to open air system, for the same range of temperature, results in higher coefficient of performance.

249) The ratio of surface convection resistance to the internal conduction resistance is known as