ASHRAE Terminology

process whereby a side port in the compressor (usually a screw compressor or multiwheel centrifugal compressor) is used to provide refrigerant subcooling, resulting in an improvement in overall system efficiency.

a variation of solution heat exchangers, used on steam-fired, double-effect machines and on some single-effect, steam-fired machines. Uses the condensed steam to add heat to the solution entering the generator.

number of degrees that a pressurized liquid is cooled lower than its saturated temperature at that pressure.

rate of heat removal by the refrigerant assigned to the condensing unit in a refrigerating system. This is equal to the product of the mass rate of refrigerant flow produced by the condensing unit and the difference in the specific enthalpies of the refrigerant vapor entering the unit at a specified superheat and the refrigerant liquid leaving the unit at a specified subcooling.

the absolute value of the difference between the starting and ending temperatures of a phase-change process by a refrigerant within a component of a refrigerating system, exclusive of any subcooling or superheating. This term usually describes condensation or evaporation of a zeotrope.

quantity of heat removed from a liquid to reduce it from its saturation temperature at saturation pressure to some lower temperature at the same pressure.

rate of heat removal from a fluid flowing through a cooler (air, water, brine, etc.) at stated conditions, the difference in specific enthalpies of the cooling fluid entering and leaving the cooler. In case frosting occurs within the cooler, the latent heat of fusion and the subcooling heat of the ice (frost) must be added in determining the net cooler refrigerating capacity.

heat exchanger, after the condenser, for subcooling the condensed refrigerant.

process of cooling refrigerant below condensing temperature for a given pressure, also, cooling a liquid below its freezing point where it can exist only in a state of unstable equilibrium. See supercooling.

at a defined pressure, the difference between a given liquid temperature and the bubble point temperature.

total refrigerant heat rejection effect less the condensing heat rejection effect.

additional refrigeration effect made available by subcooling the refrigerant liquid in the condenser.