Micro heat pump system with thermal storage for domestic appliances
The application of heat pump systems in domestic appliances offers significant energy savings compared to the use of electric heating elements. Required cooling or dehumidification can provide the heat source for the heat pump. Peculiarities of small-scale domestic applications are the strong variability in both operating conditions and load, combined with a large temperature lift between cooling and heating demand. To tackle these challenges, a refrigerant cycle consisting of a low-temperature reservoir (e.g. ice storage or cold water reservoir), a high-temperature reservoir (e.g. hot water storage) and an air/refrigerant heat exchanger with a thermal storage at an intermediate temperature level is investigated. Heat can be shifted between these three storage tanks at different temperature levels by means of a heat pump system. In addition, heat can be extracted from or transferred to the ambient air using the air/refrigerant heat exchanger. The heat pump system utilizes the natural refrigerant R600a and a hermetic reciprocating compressor. In the scope of this paper, a possible refrigerant circuit is presented. Experimental investigations of a smallscale water/water heat pump with a hermetic reciprocating compressor form the basis for the further investigation of the proposed system supported by simulation models.