Durham School of Architectural Engineering and Construction


Date of this Version



International Refrigeration and Air Conditioning Conference. Paper 918.


Copyright the authors.

International Refrigeration and Air Conditioning Conference at Purdue, July 14-17, 2008


This paper presents a thorough evaluation of a method for determining refrigerant charge that employs low-cost, non-invasive measurements (i.e., surface mounted temperature measurements). The method could be used as part of a protocol for verified service providers (VSPs) in AC diagnostic tune-up or refrigerant charge, air flow (RCA) verification programs. Ultimately, the method could be embedded within a portable virtual refrigerant charge gauge for a technician’s use or permanently installed on the AC unit. The accuracy of the virtual refrigerant charge sensor method is evaluated in this paper using laboratory data for a number of different systems and over a wide range of operating conditions. The systems include residential split systems and light commercial packaged systems employing either fixed capillary tubes, thermostatic expansion valves or electronics expansion valve, and R-22 as the refrigerant. The virtual refrigerant charge sensor is shown to have good performance in terms of accuracy and robustness and has the potential to be easily implemented and installed.