168) The total pressure exerted by the mixture of air and water vapour is equal to the sum of pressures which each constituent would exert, if it occupied the same space by itself. This statement is called

169) The expansion valve in a refrigerator controls the flow of refrigerant.

170) The relative humidity lines on a psychrometric chart are

171) The C.O.P. of a heat pump working on a reversed Carnot cycle is

172) A vapour absorption refrigeration system