Numerical Simulation And Characteristic Analysis Of Flow Field In Heat Pump Drying Chamber

Drying is the main method and means of processing agricultural products.At present,the drying systems commonly used in the market have many types and different specifications,and there is a lack of pertinence in the function of the drying equipment.The structure of the drying box is single,the internal flow field is poorly uniform,and the materials placed in different positions are drying.However,the required drying time varies greatly.In order to improve the uniformity of the flow field in the drying box and make the material heated by the hot air more uniform during the drying process,this article aims at the physical drying system constructed,and the flow field of the drying box structure under the actual stacking mode of loading dry materials is developed.Analysis of flow characteristics,analysis of key parameters such as different drying structures,wind speed,pressure,turbulence intensity,and verification based on experimental test results.An optimization scheme for drying box design is proposed.The main research contents and conclusions are as follows:(1)According to the actual situation of the dried materials,a heat pump drying oven is designed.In order to explore the operation and performance of the drying oven,the no-load and load experiments were carried out on the drying system.The experimental results show that the temperature in the drying oven can reach the set temperature of 55?,and in the drying process,the drying oven is different There is a difference in temperature at the location,and the maximum difference reaches 3?,and the time required to complete the drying of the same material may differ by several hours.(2)The simulation-related hydrodynamic control equations are introduced,and the mathematical and physical models of the drying oven based on the actual material drying conditions are established.The actual dimensions of the actual drying oven are 370 × 290 × 210 cm in length × width × height.Experimental research has established mathematical and physical models,and through experimental verification,it is determined that the error between the simulation results and the experimental results is within 10%.(3)The air inlet of the drying box is set in the middle of the wall surface,and the air inlet and outlet methods of one side inlet air and the opposite side return air can improve the uniformity of the gas flow field in the drying oven.Through the analysis of the simulation results,when the wind speed of the air inlet is set to 5m / s,the pressure difference at different positions in the drying box is the smallest,which is most suitable for the drying experiment.Under the condition that the inlet air volume of the drying oven is determined,a comprehensive simulation analysis is carried out on the cross section of the air inlet and the inlet air speed.Four different working conditions were set,and a comparison revealed that under the condition of an air outlet area of 0.96m2 and a wind speed of 3.0m / s,the turbulence intensity on the research surface selected in the drying chamber was low,and the distribution of turbulence was uniform.In addition,there were also corners Turbulent distribution,so in the actual drying process,the flow field distribution inside the drying box will be more uniform.(4)An analysis of the uniformity of the flow field due to structural changes in the drying cabinet was carried out.By adding a wind deflector at a suitable position in the drying oven,the drying oven is divided into a drying area and a return air area,and the size of the wind deflector is compared and analyzed to obtain the optimal wind deflector position and size.The width of the wind deflector is set to 180 cm,and it is 140 cm away from the right wall.At the same time,by reducing the area of dry materials,the efficiency of hot air utilization can be effectively improved.By adding a diversion fan in the drying box,the uniformity of the flow field can be effectively increased,so that the pressure gradient in the middle of the drying box is prone to the area.Under the action of the fan,the internal pressure difference is reduced,which can effectively enter the drying After entering the drying box,the hot air in the box is directly blown to the opposite side by the action of the guide fan.