Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Seasonal Performance Evaluation Procedures for Domestic Electric Driven Heat Pump's and Air Conditioner's



David Didion


Virtually all of the residential and commercial heat pumps available in today's market operateDT on the same fundamental principles as do, that of the vapor compression cycle. Also, virtually all of these systems use fluorocarbon compounds as a working fluid and have a constant speed positive displacement compressor with leaf spring valves. This concept has been continuously developed throughout this century and has served society well; however, it contains a couple of inherent limitations which cause any particular design to perform somewhat less than ideally. The first and most significant of these limitations is due to the fact that a refrigerant's density is proportional to its pressure. Therefore, when the evaporator temperature is required to be decreased, the saturation pressure must also be decreased with a corresponding reduction in the circulating refrigerant suction density, causing a loss in system capacity. This capacity loss is accented by the use of constant speed piston compressors whose valves operate on a differential pressure between the interior cylinder conditions and either the suction or discharge line pressures. If either the condenser or evaporator temperature conditions increase or decrease, respectively, less valve open time will exist per stroke and thus less refrigerant will be pumped; leading to an additional loss in capacity. This capacity reduction is particularly significant in the heat pump heating application for residences since it occurs simultaneously with an increase in building transmission (and thus heat pump) load. Of course, this overall decrease in refrigerant aass flow rate which causes the decrease in capacity also causes a decrease in compressor work. However, since the pressure difference or lift has increased the worle per unit mass of refrigerant has increased and thus the compressor work never decreases as such as the capacity, resulting in a net decrease in heat pump efficiency or coefficient of perforuance (COP).
Proceedings Title
Japanese Association of Refrigeration 1988 Annual Meeting
Conference Dates
March 1, 1988
Conference Location


heat pumps, air conditioning, performance evaluation, vapor compression, refrigerants, equations, temperature, standards


Didion, D. (1988), Seasonal Performance Evaluation Procedures for Domestic Electric Driven Heat Pump's and Air Conditioner's, Japanese Association of Refrigeration 1988 Annual Meeting, Tokyo, , [online], (Accessed June 12, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created March 1, 1988, Updated February 19, 2017