CFD Analysis Of Environment Of Edible Mushroom House And Optimization Of Ventilation Structure

Edible mushroom cultivation mushroom house can create environmental conditions suitable for the growth of edible mushrooms,which can meet the different needs of environmental conditions at different growth stages.With the development of large-scale production and industrialization,the structure of mushroom houses for edible mushrooms has gradually become larger,resulting in an increase in the uneven distribution of environmental factors and the accumulation of heat in some locations,which places higher requirements on ventilation components and control systems.This paper uses CFD technology to analyze the environmental conditions in the edible mushroom house,optimize the ventilation structure configuration,improve the structure of the mushroom house,improve the air flow and the uniformity of temperature distribution,and provide a good development environment for the growth of edible mushrooms.This article takes the straw mushroom cultivation room of a company in Zhenjiang as the research object,analyzes its internal environment distribution,establishes a CFD model,and conducts environmental measurement tests and edible fungus growth activity measurement tests,and performs CFD simulation and verification to further improve the structure of the mushroom.The main research contents are:(1)Established a CFD model of the mushroom house environment.By analyzing the movement characteristics of the fluid in the mushroom house,selecting the corresponding control equations,Realizable k-? turbulence model and wall function method,a numerical model suitable for CFD analysis of the internal environment of the mushroom house is constructed.(2)Carry out the environmental distribution measurement test under the production status of the mushroom house,analyze the environment of the mushroom house,and obtain the temperature distribution and change law in the mushroom house.The test results of the large and small mushroom houses show that the temperature in the production of small and medium mushroom houses has been changing;the culture material is the main heat source,the highest temperature is 32.5 ?,and the temperature between the culture material layers is slightly lower 30-32 ?;The minimum temperature in the indoor aisle is 29?31?,and the temperature at the bottom of the mushroom house is generally 29?31? lower.The temperature change and distribution in the large mushroom house are similar.In order to obtain the parameters required for CFD analysis,a straw mushroom respiration test was carried out to calculate the respiration heat,and the energy balance model of the mushroom house was used to verify it.The difference between the two estimation methods was 10%.The water content of the culture material was measured to be 22.67%,and the specific heat capacity was calculated to be 1.125 MJ/(m3·?)and the thermal conductivity was 0.135 W/(m·?).The measured parameters are used for subsequent CFD modeling and analysis of the mushroom house environment.(3)Analyze the airflow distribution and temperature changes in the mushroom house,and conduct CFD unsteady simulation of the mushroom house environment.The results show that the ventilation mode of the mushroom house is a turbulent jet.Among them,there is a turbulent jet stream in the small mushroom house,which affects the uniform distribution of the air flow in the mushroom house.Layer up and down.The maximum absolute error between the simulation results and the test data is 0.4?,which is in good agreement.(4)Study the optimization plan of mushroom house ventilation.In the study of the optimization of ventilation in a small mushroom house,keep the total air inlet flow of the mushroom house unchanged,change the diameter of the air supply hole,and analyze the effect of the air velocity of the air supply outlet on the airflow speed between the cultivation racks in the mushroom house.The results show that the smaller the diameter of the air supply hole,the higher the outlet wind speed.The higher the average wind speed between the layers of the culture material in the mushroom house,the worse the speed uniformity.The better outlet wind speed is about 15m/s.Furthermore,the influence of different return air inlet heights on the temperature distribution is further analyzed.The results show that the temperature uniformity obtained by the return air inlet at the upper part is the best.For the large mushroom house structure,three ventilation schemes were analyzed.The results show that the single air supply pipe can still be used for large mushroom house structures.In the case of double air supply pipes,when the airflow flows downwards against the wall,there is a temperature gradient distribution.By increasing the height of the bottom culture material to 0.4m,and setting the return air outlet and the air outlet on the upper layer,the uneven temperature distribution in the mushroom house can be reduced;When the airflow is attached to the culture rack and flows downward,the air supply duct is 0.40 m away from the wall surface and 0.15 m away from the culture rack,and a relatively uniform temperature distribution can be obtained.