Design And Experimental Study Of Waste Heat Drying Grain Device For Internal Combustion Engine Of Combine Harvester

With the continuous improvement of domestic agricultural mechanization,combine harvester shows a trend of gradual growth.However,only a small part of energy is converted into mechanical work during operation,and nearly 70%of heat is lost through waste gas and coolant,resulting in fuel waste and environmental pollution.Combined with the shortage and serious mildew of the newly harvested grain in China,this paper puts forward a new idea of using the waste heat of combine harvester internal combustion engine to pre-dry the newly harvested grain.According to the structure of the required heat exchanger and the selection of tube bundle spacing,FLUENT simulation was carried out.Then,combined with the waste heat characteristics of internal combustion engine and grain drying mechanism,a two-stage heat pipe heat exchanger with heat pipe as the main heat exchange component was designed,and the experimental data and simulated data were compared.Combined with the existing heat generation simulation equipment and grain drying equipment,a drying experiment was carried out on wheat grain with imported wind speed,drying time and feed rate as variable factors.The research results are as follows:(1)The numerical simulation results show that the heat transfer efficiency of the cross-row arrangement with 50 mm tube spacing is 10.2%and 4.9%higher than that of the cross-row arrangement with 30 mm tube bundle spacing and 40 mm tube bundle spacing,and 21.5%higher than that of the parallel arrangement.(2)According to the simulation results,a heat pipe heat exchanger with a maximum heat transfer of 1.5 kW and 32 tubes of 265 mm x 365 mm x 1025 mm was designed.The maximum pressure loss in the evaporation section was 61.4 Pa,and the maximum pressure loss in the condensation section was 13.2 Pa.When the available waste heat of the internal combustion engine was 96.2 kW,the maximum heat recovery rate was 43.8%.(3)The experimental results in wheat drying showed that when the inlet air velocity was 0.5 m/s and the feed rate was 0.5 kg/s for 20 minutes,the utilization efficiency of waste heat reached the highest 35.7%,the moisture content of wheat was reduced by 80,and the fuel utilization rate was increased by 14.6%.The measured outlet temperature was about 62 C and the pressure loss was 0.98 Pa.Compared with the simulation results,the relative error of pressure loss was about 10%,and the temperature was increased by 14.6%.The degree error is about 5.2%.