Performance And Applied Research Of Hybrid Solar Collector Applied To The Rural House In Northern China

The space heating of the rural buildings in northern China consumed a large amount of energy and resulted in severe environment pollution. Solar air heating system and solar water heater can efficiently resolve the problem of space heating and domestic hot water. But the current systematic solutions design the two systems separately or don’t take the load matching into account. So the system annual utilization is very low, and economics and user acceptance of the system is not high. In the paper, we proposed the most reasonable solar thermal solution for north countryside, which is intended to develop a air-water hybrid solar collector to heat air for heating in the heating season and heat water to provide domestic hot water in non-heating seasons. We researched the practicability of this solution through the relevant theoretical, experiment and demonstration study. The contributions of the paper are as follows:Firstly, Based on load analysis, we proposed the design principle of air-water hybrid solar collector applied to the rural house in northern china, And then a air-water hybrid solar collector was designed. A series of steady-state tests based on ASHRAE Standard was conducted. The results indicated that the maximal thermal efficiency reached 65.06% in water heating, and varied from 51.48% to 55.91% in air heating, the pressure drop of the collector was 37~134 Pa. The collector has a good application prospect.Secondly, Theoretical models for air-water hybrid solar collector in air and water heating were established respectively, by which we conducted systematic optimized calculation on the thermal performance of the collector. Results showed that the economic thickness of fins and insulation material is 30~50 mm and 0.3~0.5 mm, respectively, and the economic circulating flowrate of hot water and air is 100~200 L/h and 80~120 m3/h, respectively.Thirdly, We built a air-water hybrid solar collector system demonstration project, and the operation effect of different seasons were measured. Results indicated that the indoor temperature was10~15℃ and the average system efficiency varied from 31% to 35% in heating season. The thermal efficiency of solar water system varied from 49.6% to 58.2% in non-heating seasons. The solar system can proviod enough hot water and meet the need of space heating. For the house which has space heating demand all-day, we equiped the solar system with a low temperature air-source heat pump as the auxiliary heating source.The average COP of heat pump was about 2.5 and the indoor temperature could be set according to user’s demands during the operating phase of heat pump. The solar fraction varied from 20% to 37% during the test.