Experimental And Simulation Study On The Drying Process Of Fungus During Convection Drying Process

With the continuous improvement of people's living standards and the rapid development of science and technology,the demand for fungi is increasing.However,due to the lack of storage,transportation and post-treatment technology,it will lead to rot and deterioration of fungus plants,resulting in huge economic losses.Drying is a common processing method of fungus products.The quality of dry products mainly depends on the drying process of fungus plants.The study on the drying process of fungi mainly includes the change law of water content and temperature with time and the change law of physical parameters and volume with water content,which is the basis of the optimization design of drying equipment and drying process.In this paper,pleurotus eryngii,a common fungus in the market,was taken as the main research object to study the convection drying process of pleurotus eryngii slices.The drying characteristics and rules of pleurotus eryngii slices were studied by means of experimental test and numerical simulation.The main research contents and conclusions of this paper are as follows:(1)In view of the drying characteristics of pleurotus eryngii,the temperature of hot air and the thickness of pleurotus eryngii slices were taken as the main research objects,and the convection drying experiment was conducted on pleurotus eryngii slices.Of apricot bao mushroom drying characteristics of the test data using a variety of thin layer drying mathematical model fitting,the results show that in some hot air heating temperature range,the higher the temperature,the smaller the slice thickness,the shorter the drying time needed for complete,and the hot blast temperature between 50 to 60 ?,dry and complete the required time of up to 100 min,the drying characteristics changed significantly,the drying rate versa;The convective drying process of pleurotus eryngii had no constant drying stage,and the main drying stage was slow drying stage.In addition,the predicted values of the Parabolic model and the two-term model are well consistent with the experimental data of the convective drying characteristics of pleurotus eryngii aureus,with errors within 5%.In addition,the shrinkage deformation of pleurotus eryngii was obvious in the convection drying experiment,which should not be ignored in the study of its drying characteristics and rules.(2)The experimental results showed that the drying characteristics and rules of pleurotus eryngii were not only affected by the external drying conditions,but also by the physical parameters of the material itself.Among them,thermal conductivity,specific heat and shrinkage deformation in the drying process have a great influence on the drying characteristics of pleurotus eryngii.Based on the above reasons,the thermal conductivity and specific heat of pleurotus eryngii in the process of convective drying were experimentally tested by using hotwire method and DSC,and the shrinkage deformation of pleurotus eryngii slices in the direction of length and thickness during the experimental process were experimentally tested.The results showed that the thermal conductivity of pleurotus eryngii slices was affected by temperature and humidity.In the drying process,the higher the moisture content of slices,the higher the temperature,the greater the thermal conductivity.The prediction model of thermal conductivity under different temperatures was established,and the error between theoretical calculation and experimental value was within 6%.The specific heat of pleurotus eryngii slices was mainly affected by water content,and the lower the water content,the smaller the specific heat.In addition,the shrinkage deformation of pleurotus eryngii slices in the diameter direction showed a linear relationship with the change of water content,while the shrinkage deformation in the thickness direction showed a nonlinear relationship with the change of water content.(3)Based on Fick diffusion theory,Fourier heat transfer theory and Luikov theory,a numerical model for the convection drying process of pleurotus eryngii slices was derived,and the coupling law of heat and mass transfer in the convection drying process of pleurotus eryngii slices was numerically simulated.The main physical parameters of pleurotus eryngii slices required for simulation were calculated and obtained by the mathematical model fitted based on the experimental results of pleurotus eryngii slices drying in the second part of this paper.In addition,the nonlinear effect of shrinkage deformation on the drying process of Pleuritus eryngii slices was considered.By comparing the experimental results,the relationship between the drying characteristics,thermal conductivity and shrinkage deformation of pleurotus eryngii slices and water content was analyzed.The results showed that the simulation results of the convection drying process of pleurotus eryngii slices were in good agreement with the experimental data,and the error was less than 8%.In conclusion,the numerical model proposed in this paper can successfully predict the drying process of pleurotus eryngii slices under different drying conditions.