Thermal storage performance analysis on Chinese kangs

Chinese kangs are widely used as a rural home heating system in Northern China by 175 million people. The main features of Chinese kangs include the effective use of thermal mass in kang plate. In this paper, a thermal and airflow model for an elevated kang is developed with a simply consideration of the heat transfer in building envelope. Approximate analytical formulas are derived to identify the critical parameters that affect the levels and fluctuations of kang plate temperature and indoor air temperature. It can be observed that the increase of the plate time constant and the heat source frequency with continuous firings and equally distributing the firings and adding the number of firing with intermittent firings can effectively decrease the fluctuation of kang plate temperature and indoor air temperature. The results of model analytical solutions can serve engineers for design proposals or check analysis to determine the required thermal capacity of kang plate at the early design stage. An example of heat source-based design process is described to determine the thickness of a kang plate and firing distribution.