Because of the time and expense involved in building and testing prototype heat pumps, mathematical models of heat pumps have been developed. These models and experimental work show that refrigerant movement and/or migration during start-up, shut-down and frosting-defrosting is an important parameter. Little information is known about this movement. Therefore, good experimental data of mass flow rate into and out of each component of the heat pump during these transient time are needed. Unfortunately, no mass flow meter exists that can currently measure two-phase flow rates.

This paper describes the system designed, the major problem encountered, and gives some preliminary results of a system to continuously measure the change in refrigerant mass in the evaporator, condenser, accumulator and compressor of a heat pump during both start-up and shut-down conditions. With these measurements, knowing the total charge in the system and measuring with a conventional flow meter the mass rate of flow leaving the compressor, the mass rate of flow entering and leaving each component (including liquid lines) can be determined.

The results are compared with that of Tanaka, et al., 1982 and Mulroy and Didion, 1983.

A system was designed and built. that accurately measured the change in weight of all components except the accumulator. With some modifications it can also be made to measure this change in weight.

Units: I-P