Experimental performance of a heat pump driven by vapor injection linear compressor

Aiming to improve the performance of the linear compressor, a prototype of a linear compressor with vapor injection has been developed, and a quasi-two-stage compression heat pump with an intermediate heat exchanger has been established. The influence of key parameters on the flow distribution and performance of the injection linear compressor are experimentally investigated. Under the condition of evaporating temperature of -20 degrees C, condensing temperature of 50 degrees C, the heating capacity of 234 W with COP of 2.06 is achieved. Compared with the non-injection mode, the heating COP of the injection mode increases by 28% on average. The heating COP is affected by the combination of injection pressure and supply power frequency, while the injection mass flow rate is independent of the supply power frequency under the given conditions. As the injection pressure rises, the injection mass flow rate increases linearly. However, there is a special characteristic of the free-piston linear compressor which is different from traditional injection compressors. The injection process has a great effect on the suction process, and the suction mass flow rate decreases with the increasing injection pressure.