Experimental study on the performance of an inverter heat pump with a bypass orifice

An economical, fixed geometry, bypass orifice was invented to control more precisely the refrigerant flow in an inverter heat pump system. Flow characteristics of the bypass orifice were investigated as a function of orifice geometry and operating conditions. Experimental results of bypass orifices were compared with those of capillary tubes. The bypass orifice showed the best flow trend as a function of frequency: the flow slope of the bypass orifice with respect to frequency was the highest among the orifice, capillary, and bypass orifice. The performance of an inverter heat pump with a bypass orifice and then a capillary tube was measured with a variation of frequency in the psychrometric calorimeter. It was observed that the performance of the inverter heat pump was enhanced with the application of the bypass orifice in the system instead of a capillary tube. The improvement of COP in an inverter heat pump with a bypass orifice versus the capillary tube was prevalent at the low frequency region.