Experiment And Numerical Simulation Of Hot Air Drying Of Mushroom

In order to solve the problems of high energy consumption and low simulation accuracy of hot air drying system in mushroom drying,a new mathematical model was proposed based on the mechanism of heat and moisture transfer of mushrooms.Its numerical simulation is realized by UDF in ANSYS fluent.The results of this study will contribute to the design of more efficient convection hot air drying equipment,which can improve the drying process of mushrooms,while shortening the drying time and reducing energy consumption.It provides reference for the research and development of hot air drying technology.The main research contents of this paper are as follows:Firstly,the resistance coefficient,porosity,equilibrium water content and other parameters of mushroom which as porous medium were determined through experiments.Secondly,the convection drying process of single mushroom is simulated.It involves building mathematical models,physical models,and writing UDF programs for them.In this paper,the air supply temperature of 45℃ is taken as an example.The simulation results show that the water transfer and temperature transfer in the mushroom are similar,and the external change occurs first,while the internal change lags behind.Therefore,internal mass transfer resistance is the dominant factor affecting water transfer resistance of mushrooms,and external mass transfer resistance is the second.It shows that according to the law summarized in the experiment,the mushroom still has a strong adaptability when the external convective conditions change greatly.In order to explore the change rule of dry base moisture content of mushroom,the drying experiment of mushroom was carried out under different air supply temperatures.The experimental data were regressed according to 9 drying kinetics models,and the drying kinetics model with the highest matching degree was obtained as Hii model.Finally,the mathematical model and physical model were established and UDF program was written to simulate the convection drying process inside the mushroom drying box.Then the simulation results are compared with the experimental results to verify the accuracy of the simulation.On this basis,the optimized simulation experiment of convection drying was carried out to explore the influence of different air supply forms on drying time and energy consumption.The results show that using periodic reverse air supply and introducing fresh air can effectively shorten the drying time and achieve energy saving and consumption reduction.Air supply temperature of 55℃,wind speed of 0.6m/s,fresh air ratio of 30% and 55℃,0.6m/s,reverse air supply cycle of 2h can effectively shorten the drying time.These conclusions can provide some basis for the design of mushroom drying technology.