| The cold storage is an important facility of the cold storage system.The reasonable distribution of airflow in the cold storage has an important impact on the quality of the stored goods.Computational fluid dynamics has unique advantages in studying the flow field of the cold storage,and can effectively predict and optimize the flow field distribution of the cold storage.This article first uses numerical calculation methods to simulate the air distribution in the small experimental cold storage,and verifies the reliability of the simulation through experiments;then uses the verified numerical calculation method to simulate the research of the small station rice cold storage,analyzes the direct blowing of the fan,The influence of constant cross-section air duct and variable cross-section air duct on the flow field;finally,the indirect cooling phase temperature library is used as the research object to simulate different sub-library structures,wall emissivity,and heat source convection field and temperature field in the cargo The purpose of this project is to provide a certain reference for cold storage design and optimization.The main research content and conclusions of this topic are as follows:(1)Taking the small experimental cold storage as the research object,using the standard k-ε model and SIMPLE algorithm to simulate the unsteady flow field and temperature field in the cold storage,and studying different air supply speeds(3m/s,4m/s,5m/s)on the influence of air distribution in the empty warehouse,the accuracy of the numerical calculation model is verified through experiments.The research results show that the air flow in the cold storage is distributed in a circular shape.When the air supply speed is 4m/s,the air distribution in the storage is relatively regular,and the temperature unevenness coefficient is the smallest.The temperature unevenness coefficient of the cold storage increases with the increase of operating time.During the unsteady cooling process,the relative error between the measured temperature and the simulated temperature is within 5%.(2)Taking the Xiaozhan rice cold storage as the research object,the distribution of the flow field under three forms of direct air supply by the fan,air supply by variable crosssection duct and air supply by uniform cross-section air duct was simulated,and the air supply of goods to the fan was studied.And the influence of the internal flow field in the supply air of the variable cross-section air duct.The research results show that when the fan is used for direct air supply,the flow field in the empty storage is similar to that of the small experimental cold storage;when the uniform cross-section air duct is used for air supply,the flow velocity of the air outlet on the side of the air duct is quite different,and the flow field inside the empty storage is unevenly distributed;The internal pressure and velocity distribution of the variable cross-section air duct is basically even,the air outlets on the side of the air duct have similar flow rates,and the flow field in the warehouse is evenly distributed;when the fan is used for air supply,the airflow velocity on both sides and bottom of the cargo is larger,and the area between the cargo The airflow velocity of the cargo is small,so the distance between the cargo should be appropriately increased to improve;when the variable cross-section air duct is used for air supply,the airflow organization between the cargoes is evenly distributed,and a uniformly entangled airflow is formed near the surfaces of the cargo,while still maintaining a partial back shape flow.(3)Study the influence of the structure of the plane sub-library and the corrugated surface sub-library on the interlayer flow field and temperature field of the phase temperature library.The results show that the airflow from the air cooler is offset when flowing in the interlayer,and the airflow organization on both sides of the fan is not distributed.The average temperature of the corrugated surface sub-library is 0.17 ℃,and the average temperature of the flat surface sub-library is 0.21 ℃.The comprehensive heat transfer effect of the corrugated surface sub-library is better than that of the flat sub-library;the airflow distribution is more uniform after adding the diversion channel on the upper side of the interlayer,Turning the corners of the cold storage door into a circular arc structure can improve the local eddy current,and the average temperature of the corrugated surface sublibrary after optimization is 0.14 ℃.When the cargo is stored in the plane sub-library,as the wall emissivity decreases,the radiant heat transfer decreases;with the increase of the internal heat source,the cargo temperature rises,and the temperature unevenness coefficient becomes larger.The gas velocity around the cargo is 0.01～0.025 m/s,the absolute temperature difference in the phase temperature storage is 10 times smaller than that of the Xiaozhan rice cold storage;the functional expression of the cargo temperature on the wall emissivity and the internal heat source is fitted,and the storage temperature of some fruits and vegetables is predicted. |
PDF Full Text Request