DOE EERE Research Reports

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 increasaed with increasing source-water temperature and flow rate. In the cooling mode, the capacity and COP decreased iwth 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 calculations, 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_D ranged from 0.196 to 0.137 for heating and 0.131 to 0.161 for cooling. The net 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 results 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.