Research On The Solar Active-passive Combined Heating Modes Of Farmhouses In Cold Regions

Currently,rural houses in the cold northern regions of China are generally faced with high heating energy consumption,poor indoor thermal environment and high carbon emissions.Solar heating systems with low operating costs and low environmental pollution have great potential to be used for winter heating in northern agricultural houses.However,traditional solar heating systems usually focus on passive or active solar heating,but there is a lack of research on the mode and compatibility of the two combined heating systems.Therefore,it is of great practical significance and engineering value to design a combined solar passive and active heating system that is compatible with the characteristics of agricultural houses in northern China and to study the matching operation mode of the two.Based on the heating characteristics and mechanism of passive and active solar energy,this paper proposes an active-passive combined heating system and operation mode for agricultural houses in the cold regions of northern China,and takes a farmhouse in Tianjin as a case study for its passive solar energy renovation and active construction.The passive heating control strategy based on zero-state response is proposed by constructing a natural ventilation heat exchange model between the sun room and the room.The experimental test results on a typical day show that the average indoor daytime temperature can be raised to 21.69℃under the conditions of outdoor temperature of-5.0℃～2.5℃.The simulation results of this passive heating strategy using TRNSYS show that the average daytime indoor temperature is 17.75°C during the heating season of 2020-2021,and the time when the indoor temperature can be maintained above 14°C accounts for 73.33%of the total daytime hours.The results of the experimental studies on the combined solar active-passive heating system with complete solar heating,combined solar and electric auxiliary heating,and combined solar and nighttime heat storage operation modes show that the indoor temperature can be raised above 15℃in each operation mode,and the operation energy consumption in the heating process is low,with the average operation unit price of 0.003 Yuan/m~2d in the complete solar heating mode and 0.003 Yuan/(m~2·d)in the combined solar and electric heating mode.The average unit cost of heating in the fully solar heating mode is 0.003 Yuan/(m~2·d),the average unit cost of heating in the combined solar and electric heating mode is 0.30 Yuan/(m~2·d),and the average unit cost of heating in the combined solar and night storage mode is 0.09 Yuan/(m~2·d).This shows that the combined solar active and passive heating mode can effectively improve the indoor thermal environment and reduce the cost of heating in winter,which is suitable for the promotion and application in rural buildings in the cold areas of northern China.