Laboratory tests of a residential low-temperature water source heat pump

Abstract

A residential unitary low-temperature water-source heat pump was tested in the laboratory. Tests were performed over a broad range of source-water temperature 45 to 70/sup 0/F (7.2 to 21.1/sup 0/C) and water-flow rates 5 to 30 gpm (3.2 X 10/sup -4/m/sup 3//s to 8.2 X 10/sup -4/m/sup 3//s). The heat pump capacity and coefficient of performance (COP) were found to be linearly related to the source-water temperatures. In the heating mode, the capacity and COP increased with increasing source-water temperature and flow rate. In the cooling mode, the capacity and COP decreased with increasing source-water temperature but increased with increasing water-flow rate. However, when an assumed water-pumping power, for a 150 ft (46 m) total head, was taken into account in the COP calculation, it was found that the net COP for both heating and cooling decreased with increasing water-flow rate. For cyclic operation over the tested source-water temperature range, the coefficient of degradation, C /SUB D/, ranged from 0.196 to 0.137 for heating and from 0.131 to 0.161 for cooling. The effect of inlet air humidity was also studied for cooling mode operation. A sample calculation is included in the paper to demonstrate the application of the test resultsmore » in calculating the annual performance factor (APF). The test results are used to form a data base on the performance of a typical residential, unitary low-temperature water-source heat pump.« less