Heating performance of a VRF heat pump system incorporating double vapor injection in scroll compressor

Abstract

Heat pumps with a vapor injection cycle are currently used to compensate for heating capacity degradation at lower outdoor temperatures. A double vapor injection system with a scroll compressor was developed in order to enhance the vapor injection technique. The heating performance of the variable refrigerant flow heat pump systems employing non-vapor injection, single vapor injection, and double vapor injection was experimentally investigated. At the compressor frequencies of 90, 110, and 150 Hz, the heating capacities of the double vapor injection system were improved by 8.9, 12.1, and 18.9%, respectively, compared to those of the single-vapor injection system; and the coefficient of performances (COPs) were improved by 5.8, 8.6, and 9.8%, respectively. The double vapor injection system appeared to be superior to the single vapor injection system in terms of heating capacity and COP.