Heat Pump on-off Capacity Control and Defrost Performance Tests Using Demand and Time-Temperature Defrost Controls

摘要

Two heat pumps were tested at several on-off cycles to determine performance at part load conditions. Also, the heat pumps were tested at full capacity under frost buildup conditions with both time-temperature and demand deforst controls. The objectives were to develop correlations for use in seasonal performance models. For on-off cycling, it was found that COP as a fraction of steady state COP could be predicted with power law relationships involving capacity as a fraction of steady state capacity. Frost buildup occurred in a two step process, with initial gradual frost buildup to a transition point followed by rapid frost buildup until a defrost cycle was initiated. Heat capacities under frost buildup conditions were predicted as a function of outdoor air temperature and difference between specific humidity of the outtdoor air and specific humidity of saturated air at outdoor coil temperatures. (ERA citation 06:030826)