Performance analysis of periodic heat transfer process of energy-storage heat exchangers

Analyses the periodic heat transfer processes in HVAC system, including those in the floor with phase change materials, night ventilation, buried pipe heat exchanger. The periodic heat transfer process can be regarded as non-simultaneous heat transfer process between equivalent cold source and heat source, and the media such as floor and soil play the role of heat storage and indirect heat transfer. Proposes analysis method of the heat resistance for the whole heat transfer process, and considers that the amount of heat exchange is determined by the heat resistance of three parts, i.e., the heat absorption process from hot fluid to media surface, the heat release process from media surface to cold fluid, and heat conduction process within the media. Gives the proportions of the three part resistances in these processes including the daytime-heat-absorption and the nighttime-heat-release of floor，the ventilation cool storage in the nighttime, and yearly heat transfer of the buried pipe, and analyses the factors restricting thermal storage performance, which is helpful for the design and optimization of the energy-storage heat exchange system.