24 June 2014

Assessment of Variable Capacity Rooftop Heat Pump

Recently, variable capacity rooftop heat pumps have been introduced into the
commercial space conditioning market. Variable capacity technology enables heat pumps to operate more efficiently and with greater flexibility. The performance of a variable capacity
rooftop heat pump was examined as a dedicated outdoor air system (DOAS) within a laboratory setting. The variable capacity DOAS was outfitted with an enthalpy wheel and modulating hot gas reheat. The variable capacity DOAS was setup to supply a constant volume of relatively neutral air and was examined in both low temperature and high humidity conditions. The results of laboratory testing provide power consumption characteristics for
system operation and demonstrate the ability of the variable capacity rooftop heat pump to adjust capacity output in both heating and cooling-reheating mode. The laboratory tested DOAS was evaluated for two climates in the Southeast United States, which commonly house commercial packaged equipment using electric resistance heating. Analysis was conducted to compare the power consumption between the laboratory tested DOAS and alternative systems using electric resistance heat.