Measured Effect of Air Flow and Refrigerant Charge on a High-Performance Heat Pump

Panel: Residential Buildings: Technologies, Design, Performance Analysis, and Building Industry Trends

Authors:
Erin Kruse, Ecotope, Inc.
Larry Palmiter, Ecotope, Inc.
Paul Francisco, Univeristy of Illinois

Abstract

In recent years there has been increased interest in the impacts of refrigerant charge and indoor coil airflow on heat pump performance in heating mode in the Pacific Northwest. The published literature contains almost no studies of this nature. As a first step to remedy this problem, extensive laboratory measurements were made on three heat pump models at Herrick Laboratories at Purdue University.

The heat pump discussed in this paper was a 3-ton "high performance model" with a rated Seasonal Energy Efficiency Ratio (SEER) of 14.5 and a Heating Seasonal Performance Factor (HSPF) of 9.0. Both heating and cooling mode measurements were made and included capacity, power, airflow, refrigerant mass flow rate, and coefficient of performance. Tests were done at each of three outdoor temperatures in heating mode (17 F, 35 F, and 47 F) and in cooling mode (82 F, 95 F, and 125 F). In both modes tests were done at refrigerant charges and airflows varying independently from approximately 25% above to 25% below the manufacturer's nominal recommended values. In addition, cycling and defrost tests were also performed to allow estimation of the HSPF and SEER. This paper summarizes the results of the laboratory tests and also the HSPF values calculated for six climate zones using ARI Standard 210/240.