| With the acceleration of urbanization in China,space heating has become an indispensable part of people’s daily life during the cold season,especially in rural areas where local economic development is slow and per capita disposable income is low,comfortable,safe,economical and environmentally friendly heating methods have become the general demands of rural residents.However,the current heating methods in rural areas have high pollution and low energy utilization efficiency.Rural areas are rich in biomass resources,and using it for heating has good environmental and economic benefits.But the current development and utilization of biomass resources is not perfect,and there are still some problems in various biomass resource heating methods.This study proposes a heating system used biomass briquette fuel as primary energy input.The system uses low-temperature flue gas as a heat source and conducts space heating through a flue gas radiator.Taking the flue gas type heating radiator which is the most important equipment of the heating system as the object,two types of radiators,baffle-type and hole-type,are proposed.The ANSYS Fluent simulation software is used to simulate the steady-state heat transfer,and the two types of heat dissipation are analyzed.The influence of the structural parameters and operating parameters of the radiator on the heat dissipation performance was studied.And the reliability of the numerical model is verified by experiments.The specific research results are as follows:(1)For the proposed baffle-type structure,the reduction of the baffle spacing and the increase of the width of the baffle-type radiator can increase the heat dissipation of the radiator,however,at the same time lead to a sharp increase in the flow resistance.Taking the comprehensive evaluation index h/Δp as the standard,the structural parameters of the baffle-type radiator have the best performance when the baffle width is 65 mm and the baffle spacing is 100 mm;the reduction of the baffle spacing and width can improve the temperature uniformity of the side surface.The change of the baffle structure parameters can adjust the area occupied by the high temperature area.(2)For the proposed hole-type structure,the increase of the hole diameter of the hole-type radiator and the decrease of the hole spacing and the increase of the offset distance can increase the heat dissipation of the radiator,while the flow resistance remains at lower level.The surface temperature uniformity of the hole-type radiator is poor,but at the same time,there are fewer high temperature and dangerous areas.Taking the evaluation index h/Δp as the standard,the structural parameters of the holetype radiator adopt the optimal performance when the hole diameter is 70 mm,the hole spacing is 100 mm,and the offset distance is 5mm under this condition;(3)For the two proposed structures,increasing the flue gas inlet temperature and inlet flow rate can significantly increase the heat dissipation of the flue gas radiator,which varies in the range of 42.6～51.1%.When the flow rate increases,the utilization rate of the flue gas by the radiator would decrease.However,the increase of the inlet flow rate will also lead to an increase in the flow resistance.The flow resistance of the baffle-type radiator varies in the range of 7.5～39.1Pa.Compared with the baffle-type radiator,the flow resistance of the hole-type radiator is smaller,which varies in the range of 3.7～16.2Pa;increasing the inlet flow rate can improve the temperature uniformity of the radiator surface and the average temperature of the side surface,but it will increase the proportion of the high temperature area of the radiator.Increasing the inlet temperature will reduce the surface temperature uniformity,while increasing the average temperature of the side surface and the proportion of high temperature and hazardous areas of the radiator.(4)By building an experimental platform for the flue gas heating system for testing,the deviation of the average temperature of the side surface,the temperature of the flue gas outlet and the heat dissipation are 5.5%,4.3% and 7.2% respectively.Within the error range,the reliability of the numerical model is verified.Based on the economic and resource characteristics of rural areas,this research provides a solution for heating in economically backward rural areas,which scientifically and rationally utilizes abundant biomass resources in rural areas,and opens up new ideas for research and application of residential heating equipment and systems in rural areas in China. |
