Study On Thermal Performance And Improvement Of Kang System Based On The Utilization Of Burning Cave

Recently, the energy consumption of goods is 177 million tce in rural house in China and accounts for 26.1% of the total energy consumption. In addition, the heating energy consumption of rural house has reached 315.5 million tce which is 1.93 times than the urban house. Therefore, the energy situation in rural areas in China is not optimistic. The heating method in winter in rural areas is always kang, heating wall and burning cave and the heat resource of these methods is the abundant biomass materials such as straws, corncobs and so on in rural areas. However, these heating methods exist some problems such as the low heat energy utilization rate, the poor indoor air quality, the low surface temperature of kang at night and the local overheating. Meanwhile, the burning cave heating weakens the people’s lifestyle on kang. In order to solve these problems, the investigation was developed in rural areas based on the heat utilization of burning cave and the study line was formed based on meeting the people’s lifestyle and thermal comfort.Firstly, the thermal performance of burning cave system was studied based on the experimental and theoretical methods. The results showed that the floor temperature was uniform and ranged from 21℃～29.3℃ and the indoor temperature meet the thermal comfort which is 12℃～16℃. The thermal efficiency of burning cave was 37.9%. At the same time, the stability of thermal environment in the burning cave room was analyzed from the angle of quantification.The results showed that the indoor and outdoor temperature fluctuation ratio of burning cave was 0.21 which was less than the kang and the integrated temperature fluctuation of burning cave was 3.03℃ which was less than the kang. In a word, the burning cave room was more stable than the kang room by quantification. In addition, some existing problems of traditional burning cave heating were proposed.Secondly, the stove combined with kang system based on burning cave coupled with stove was proposed by the skillful craftsman according to the existing problems of traditional burning cave heating. The characteristics of the heat source and the thermal performance of kang body were analyzed by experimental and theoretical analysis in different conditions. The results showed that the kang surface temperature of the stove combined with kang system based on burning cave coupled with stove can maintain above 25℃ in the evening. Furthermore, the heat stability of the stove combined with kang system based on burning cave coupled with stove was superior than the traditional stove combined with kang 78.1% of the kang heating dissipation, which was greater than the stove kang not using the burning cave, can meet the room heating load. Thus, the stove combined with kang system based on burning cave coupled with stove can improve the kang surface temperature effectively. However, the local overheating of the kang surface appeared and the new system cannot satisfy the continuous heating.Finally, the burning cave-coil-kang coupling heating system which can achieve the gradient utilization of energy and improve the thermal comfort of kang surface was proposed based on the existing problems of the traditional burning cave and the stove combined with kang system based on burning cave coupled with stove. Then the burning cave-coil-kang coupling heating system was designed and established through the regularity of human physiological which is warm feet and cold head. Through the experimental and theoretical analysis, the coupling heating system achieve the gradient utilization of energy and 75.2%of the supply water temperature entering into the kang body meet the stipulation of the floor radiant heating which ranges from 35 ℃-50 ℃.The appropriate supply water temperature made the kang surface temperature keep above 24 ℃ and the highest temperature was 33℃ which illustrated that the local overheating didn’t appeared. In addition, the highest comprehensive thermal efficiency was 51.34% which increased by 10.72% compared with the traditional burning cave system.Starting from the thermal performance analysis of the traditional burning cave heating system, the study combined with the northern rural people’s lifestyle makes full use of the characteristic resources in rural areas and gradually put forward the heating system which can improve the thermal utilization efficiency and thermal comfort of kang surface.