Airflow And Heat Transfer Characteristics In A Cold Storage For Fruits And Vegetables Based On Fiber Air Dispersion System

When China is about to achieve a well-off society in an all-round way,people’s pursuit of a better quality of life becomes more prominent,which greatly promotes the vigorous development of China’s cold chain logistics.As an indispensable part of the cold chain logistics industry,fruit and vegetable cold storage plays an important role in ensuring that seasonal fruit and vegetable products can be supplied to consumers throughout the year.The distribution of the flow field in the fruit and vegetable cold storage has a great impact on the storage environment of fruits and vegetables,and plays a decisive role in the storage quality of fruits and vegetables.A reasonable air supply method can not only effectively improve the airflow organization form in the cold room,and improve the uniformity of the storage environment,but also reduce the cooling time after the fruits and vegetables are stored in the cold room to achieve the purpose of ensuring the storage quality of fruits and vegetables.Fiber air dispersion system is a terminal device made of fiber fabric with air distribution and transmission functions.It has the characteristics of uniform air supply,anti-condensation,easy installation,clean and environmental protection.This paper takes an apple cold storage room in Xi’an as the research object,and uses numerical simulation technology to study the flow field characteristics of the apple cold storage under the air distribution mode of the fiber air distribution system.The main research contents in this article are:Based on the design parameters of the actual refrigerator and the selection manual of the fiber air duct,a three-dimensional coupled mathematical solution model of gas flow and heat transfer in the air cooler(plus fiber air distribution system)-cargo-air environment in the cold room is established through the flow heat transfer theory.The effects of ejection-permeation ratio and supply air temperature on the flow field distribution and cooling time in the cold room were studied,and compared with the traditional cool air blower to obtain a more suitable air supply method.In this paper,the air distribution characteristics of the fiber air distribution system are studied under different ejection-permeation ratio and air temperature.The results showed that: Compared with the pure ejection condition,the air supply mode combined with permeation can meet the storage air velocity requirements of the cold room.The temperature storage environment of cold storage will be better when ejection is the main and permeation as a secondary.The velocity distribution and temperature gradient of the cargo area in the cold room are similar under different supply air temperatures,but there is a linear relationship between the air supply temperature and the ambient temperature of the cold room.The study on the cooling law of the air supply mode in the fiber air distribution system under different ejection-permeation ratio and air supply temperature shows that: The cooling rate is faster and the temperature uniformity in the cargo area is higher when ejection is the main and permeation as a secondary.With the decrease of the ejection-permeation ratio,the cooling time under the five conditions is 58 h,50h,76 h,88h,and 94 h.With the increase of the supply air temperature,the cooling time under the three conditions is 5h,20 h,and 72 h,the cooling time showed a four-fold increase when the air zone is equally cooled to 1℃.The distribution of the flow field and the cooling time in the cold storage which with the fiber duct air supply mode and the direct cooling fan air supply mode are compared under the condition of the same air volume and air temperature.The results showed that: compared with the direct air supplied by the cooling fan,the speed uniformity of the air zone in the fiber duct air supply mode increased by up to 23%,and the average temperature in the cargo zone decreased by up to 0.29℃ compared with the direct air supplied by the cooling fan.The cooling time required by the fiber duct air supply mode when the temperature in the cargo area reaches 1℃ is 39% lower than that of the direct air supply by the cooling fan.This paper studies the air distribution characteristics and cooling time in the cold storage under the air supply of the fiber air dispersion system to verify the superiority of its application in the cold storage,which has theoretical guiding significance for the design and operation management of the cold storage of the fiber air distribution system.