Multi-indicator Optimization Of The Uniformity And Thermal Environment In High Rack Cold Store

Cold storage is a crucial element in the cold chain for preserving the quality of fruits and vegetables.Temperature non-uniformity resulting from changes in the store space temperature may lead to water loss and weight loss,which can negatively impact product quality.Researchers aim to address this issue by developing appropriate air supply methods that ensure temperature uniformity while saving energy.However,the applicability of the uniform temperature field approach to the more complex airflow environment in high rack cold stores used in cold chain logistics transport remains uncertain.Therefore,this study aims to establish and analyse a model of a high rack cold store with a full load of fruits to investigate the distribution characteristics of velocity and temperature fields under different air supply modes.In this research,a high rack cold store model filled with fruits was established based on a certain cold storage facility.A three-dimensional coupled mathematical solution model of gas flow and heat transfer between the cold air fans,the goods,and the air environment inside the cold storage was developed using fluid dynamics theory.The model was analyzed and validated for mesh independence.The distribution characteristics of the velocity and temperature fields in the cold store under different air supply modes,including horizontal blowing,vertical blowing,and attached air supply,were investigated.Additionally,the effects of twelve different air supply angles and twelve fixed and variable air supply speeds of four rows of fans on the airflow distribution,temperature uniformity,and energy efficiency in the high rack cold store were analyzed using a multi-indicator optimization method to find the most suitable air supply mode.The results show that the commonly used horizontal blowing air supply mode can cause respiratory heat accumulation in the lower part of the goods and result in a high-temperature area（288.5 K）.The use of wall-mounted fans for vertical blowing and the two middle rows of fans for horizontal blowing can significantly reduce the temperature in the cold storage and improve uniformity.When the fans are blowing at-90°/270°,the temperature field in the cold storage is more uniform,and it is recommended to avoid the-75°/255°fan angle.The shelf position has a significant impact on temperature uniformity and energy utilization,and the best results were achieved with an air outlet diameter of 350 mm and an outflow velocity of 12.7 m·s^-1.The final placement of goods should be close to the inner wall to ensure sufficient convective heat exchange area during cooling and minimize the disturbance to other goods’temperature in the cold storage.The purpose of this research paper is to present an airflow improvement scheme that can effectively enhance the temperature uniformity of goods in the cold store while improving energy efficiency.The study employs a multi-indicator parameter optimization approach to investigate the uniformity of the cold store environment under different conditions.The findings offer valuable theoretical guidance for improving the uniformity of the airflow organization and temperature field in the high rack cold store,as well as optimizing the thermal environment to enhance efficiency.