Research On Traditional Ways Of Heating And Indoor Thermal Environment In Rural Areas In North China

The improvements or innovations of the traditional Chinese kang are crucial for converting or renewing heating technologies in the future for the rural houses in north China. Various kinds of heating methods and their thermal processes of the traditional rural houses in north China are described in this paper, based on amount of existing theories, field investigations and thermal environment tests. The thermal process of the most typical house with the traditional kang in the heating period is systematically studied in this paper.According to the thermodynamics equilibrium theory, a common mathematical model of dynamic thermal process, which stands for the indoor thermal environment of the room with the kang, is founded through the analysis of dynamic thermal equilibrium of indoor air temperatures and temperatures of inside and outside surfaces.This model is dispersed and solved by using reaction coefficient. A simplified mathematical model of the room is put forward, only taking into account the radiation heat transfer between the surfaces of the kang and the other interior surfaces, while ignoring the reciprocal radiation heat transfer between all other interior surfaces; a simplified mathematical model of the kang is also put forward, while ignoring the radiation reciprocal heat transfer between surfaces inside the kang. With two models connected, the hourly values of indoor air temperature and surface temperature are brought forward in the case of different burning mode of the kang.Methods are given to calculate heat gain from solar and long-wave radiation of the house with the kang, and the methods to make sure the values of heat transfer coefficient of internal and external surface are also studied. The comfort value range of the indoor air temperatures is confirmed, in the condition of given comfortable kang surface temperatures and standard outdoor temperatures, according to the relationship of subjective comfortable temperature of human, indoor air temperature and MRT. On this basis, the value range of heat transfer coefficient of each interior surface is given, with accounting outdoor temperatures fluctuating, due to the particularity of the room that the high temperature heat source is on one side. It comes to a conclusion that the percentage of the radiation heat transfer of the kang surface is about 70%, based on the ratio of radiation heat transfer coefficient and convective heat transfer coefficient on its surface.A main program of the calculation and a subroutine for solving the reaction coefficient is given by using MATLAB. It is proved that the aforementioned mathematical model can accurately present the actual working of the houses with the kang during the heating period. Finally, measures are proposed to improve the winter indoor thermal environment of the house with the kang, via comparing the data obtained by changing input parameters of the model with the actual test data.