Refrigeration systems with minimized refrigerant charge: System design and performance

Abstract

Independently of the choice of refrigerant, environmental and/or safety issues can be minimized by reducing leakage and the amount of refrigerant charge in heat pump or refrigeration systems, preferably both. In the investigation reported here, a laboratory test rig was built, simulating a water-to-water heat pump with a heating capacity of 5 kW. The system was designed to minimize the charge of refrigerant mainly by use of minichannel aluminium heat exchangers and a compact system design. It was shown that the system could be run with 200 g of propane at typical domestic heat pump operating conditions without reduction in the heating coefficient of performance (COP₁) compared with a traditional design. Additional charge reduction is possible by selecting proper compressor lubrication oils or by employing a compressor simply using less lubrication oil.