Development and Verification of a Linear-fit Mixed System Rating Method for Unitary Two-speed and Variable-speed Air Conditioners

A linear-fit method of rating residential-type air conditioning systems was evaluated based on performance predictions and laboratory testing of one two-speed matched system and two mixed systems (matched two-speed condensing unit, matched indoor coil blower, and two mixed coil blowers). The individual evaporators and the condensing unit were separately tested using water heated/cooled condensing/evaporating units at standard air conditions over a range of evaporator refrigerant saturation temperatures, evaporator superheats, and liquid refrigerant temperatures. Capacity predictions were within ±1.0 % of the tested values for the mixed systems, and the EER predictions were within ±1.5 % of the measured EERs. The methods used for system rating on the two-speed system can also be applied to a variable-speed system.