Development of a heat exchanger that can be de-iced for the use in ice stores in solar thermal heat pump systems

摘要

Ice stores can be used to improve the system efficiency of heating installations that combine solar collectors and heat pumps in a serial arrangement. Besides the various advantages of using ice stores as a heat source for the heat pump, a possible disadvantage is that growing ice layers on the heat exchanger's surfaces increase the heat transfer resistance which leads to lower heat pump COPs due to lower temperatures in the heat pump evaporator. To improve the heat transfer across the heat exchangers in the ice storage a periodical de-icing of the heat exchangers is proposed and presented in this paper. A prototype for a heat exchanger that is periodically de-iced with heat was developed. The measurements of an experimental ice storage presented in this paper show a good feasibility of the de-icing and thus a successful regeneration of the heat exchanger's performance. The hydraulic integration of the heat exchangers in a solar thermal heat pump system was designed. A mathematical model of an ice storage with heat exchangers that can be de-iced was developed and validated with data from measurements.