Evaluation of an economizersolution for a heat pump

Sammanfattning: This thesis evaluates the performance of a heat pump intended to be used as an economizer. The idea is to use the heat from still hot refrigerant after the condenser in a larger heat pump, running on propane, as the heat source for the economizer pump. So, at the same time as this increases the subcooling for the larger pump, the necessary heat is provided to the smaller heat pump. Though, in this report only the small pump was considered.  Components for the pump were already decided upon, and when the components were all available the layout of the pump was planned. One of the main interests for the project was to maintain the refrigerant charge as small as possible, since it is using the flammable refrigerant isobutane. Also, the measurement points and devices were decided upon, what, where and how the desired values should be obtained. When the heat pump was laid out and the rest of the test facility was constructed test were run in order to evaluate the performance of the heat pump. For the tests water was used as both heat sink and source, even though the future heat source will be propane. The tests included different combinations of three parameters; evaporating temperature, water temperature at the condenser outlet and compressor speed. The results show that the heat pump is overall well-functioning and the coefficient of performance is relatively high for the operating conditions studied. As expected, the heating capacity increases with the increased speed of the compressor. Heating capacity, cooling capacity and COP all three increases with an increased evaporating temperature while maintaining the water temperature from the condenser constant. The COP values are considered quite high, the economizer could be economically beneficial though more economic evaluation must be made.