Biomass Pyrolysis-solar Collector Hybrid Heating System Development And Testing

Shaanxi Province is a typical northern cold area.In winter,the heating energy consumption of cold residential buildings accounts for large proportion among the total energy consumption.In rural areas,there are a frequent lack of central heating facilities,and the wide use of bulk coal often causes heavy fog in the Guanzhong area of Shaanxi Province in winter.Shaanxi Province is rich in solar energy resources and biomass resources,and it can supply a better pathway for cleaner heating as well as the efficient use of solar energy and biomass.Based on pyrolysis technology and solar technology,this paper studies and develops a biomass pyrolysis-solar heat-coupled heating system that is easy to promote in Guanzhong,Shaanxi,in order to solve the problems of low pyrolysis efficiency,unstable solar heat supply and heat supply in winter,which provides a theoretical basis for future application in building heating.The main research contents and results obtained in this paper are as follows:The laboratory of the Western Observation and Test Station was selected as the heating test object.The average heat load of the building that needs to be heated during the heating season was 3.12 kW,and the maximum daily heat load was calculated to be 137 kWh.After determining the heating load range,the parameters of the system were finalized to determine the heat exchange area of the flue gas heat exchanger was 0.373 m²;the diameter of the wood gas ejector was 12 mm;the area of the solar collector was 3.36 m²;the selection of the radiator It is 600 mm×60 mm×26;the heads of the circulating water pump on the heating side and the collecting side are 10 m and 6 m respectively;and the system operation strategy is designed to obtain the whole of the biomass pyrolysis-solar heat collecting coupling heating system.System design and subsystem structure shape and parameter design.Through the TRNSYS software,the solar subsystem is carefully simulated and verified.In January,the solar collector can provide a total time of daily independent heating for 1.42 h on average.A mathematical model of the heat output of the biomass subsystem is established.With the boundary parameters obtained by preliminary experiment,it is found that the biomass subsystem can provide an average heat energy of 8.54 kWh per hour,and the biomass subsystem can run 9 hours per day to meet the heating demand of the building throughout the day,and the volume of the circulating water tank is determined to be 1,200 L.The system’s thermal performance evaluation model is established,meanwhile the thermal efficiency,enthalpy efficiency and primary energy saving rate are calculated and analyzed.During the four-day heating test,the average indoor temperature was 19.12℃,which was higher than the designed indoor temperature of 18℃,which achieved the require of system design.The complete thermodynamic evaluation of the system was carried out and the results showed that the heating system has good thermodynamic performance in the heating season in local area,and the system’s thermal efficiency is 71.62%.The exergy is calculated to be 43.29%and the primary energy saving rate is 92.07%.Through the sensitivity analysis,it can be found that the primary energy efficiency of the system is negatively correlated with light intensity,while the thermal performance is positively correlated with ambient temperature.The life cycle cost of the system is 13184.19 yuan/year,with a simple recovery period of 5.87 years.Compared to the coal-based heating system,this system can reduce the CO₂ emission by 336.83 kg（equals to 86.6%）per day during the heating season.Moreover,compared with the small air source heat pump-assisted solar heating system,the proposed heating system is both economically and environmentally sustainable in its current form.