Numerical study on the performance of a hybrid heating system combining solar Chinese kang and solar air collector applied in cold rural areas

In the present work, a hybrid solar heating system combining solar kang system with solar air heating system for keeping indoor space within thermal comfort level has been investigated. Solar kang system is an improvement of traditional Chinese kang. It use solar power to replace traditional sources of energy and can solve the overheating and air pollution problem of traditional heating methods. Solar air heating system includes two pieces of solar air collectors working like Trombe wall. Main aim of the current research is to study the hybrid combined heating system's thermal characteristic and influences on indoor environment. A mathematical model of the system has been developed and built for simulation. Thermal performance of the system in Qinghai weather condition has been simulated with the weather data of typical year. Influence of the different solar collector areas and operation strategies of the system have been investigated. Heating effects with auxiliary power in cloudy/rainy days of the system are also studied. Results show that the system's operation can raise the indoor air temperature of an 18m2 room about 12°C higher than ambient temperature. Average indoor temperature rises from 6.7°C to 9.7°Cwith whole collector area changes from 8m2 to 12m2.Although solar air heating system can provide more energy for indoor heating, kang system performances better than solar air system on increasing indoor average temperature. Solving overheating problem and adding extra power for cloudy days is essential for system's long-term heating effect. This work outlines the main influence factors and proves the practicability of the hybrid solar heating system which can be applied in cold rural areas.