Design Of Differential Pressure Pre-cooling Experimental Platform For Fruits And Vegetables

Temperature is an important environmental factor that affects the quality of fruits and vegetables and post-harvest preservation and precooling technology can effectively control the ambient temperature.After the fruits and vegetables were picked,it is the key link to take precooling measures to remove the field heat of fruits and vegetables in time to ensure the smooth circulation of cold chain.In-depth research on pre-cooling related technologies can not only effectively ensure the development of high-level and high-quality fruit and vegetable production in our country,enhance the international status of our country's agricultural production,but also effectively increase the income of the majority of farmers and ensure the quality of life of the people.Differential pressure pre-cooling is an effective and universal pre-cooling method.It is widely used in fruits and vegetables at home and abroad because of its reasonable use of storage capacity,high cooling efficiency(3 to 4 hours to complete),uniform cooling,and suitable for all kinds of fruits and vegetables Pre-cooling industry.More importantly,compared with other pre-cooling methods,differential pressure pre-cooling can reduce the condensation of the product surface caused by water loss,thereby maximizing the preservation of fruit and vegetable quality.At present,there is still a lack of research on differential pressure pre-cooling in China,such as insufficient equipment and poor pre-cooling conditions,which makes it impossible for a considerable part of China to complete the pre-cooling work of agricultural products.The development of pre-cooling equipment is imminent.According to the needs of the research group,based on the analysis of the related technologies of differential pressure pre-cooling,this paper builds a set of experimental platform for differential pressure pre-cooling of fruits and vegetables.The main research content of the paper includes the following parts:1.Summarized and analyzed several mainstream pre-cooling methods,and introduced in detail the working principle,main structural composition and research status of differential pressure pre-cooling devices at home and abroad,which led to the main research content.2.Combined with the working principle of differential pressure pre-cooling,use computer fluid mechanics(CFD)to numerically simulate the size and internal structure of the box of the differential pressure pre-cooling experimental platform to ensure that the air enters the packaging box in a laminar flow uniformly.Whether the air flow is more moderate is used as an index to evaluate the pros and cons,and finally the box size of the platform is determined to be 4.6×0.5×0.9m,and the internal structure is designed with curved arcs on the left and right sides of the box.3.According to the best pre-cooling conditions of differential pressure pre-cooling experiment(wind speed range 0.5 ~ 3m/s,temperature range 0 ~ 5?,humidity range 80% ~ 90%),based on the theoretical calculation with reference to relevant parameters,combined Actually,the main instrument and equipment required for the experimental platform were selected and designed.The final fan is an axial fan model ADT315 produced by Lundeng Fan Technology(Tianjin)Co.,Ltd.,with an air volume of 2500m3/h,a static pressure of 200 Pa,and a power of 370W;the frequency converter is selected from the specifications produced by Beijing Tongsen Technology Co.,Ltd.0.75 KW,380V frequency converter,the frequency range is 0~50Hz;the humidifier uses the ultrasonic humidifier model HS-05-3,the humidification capacity is 3kg/h.4.Conducted performance tests on the main influencing factors(temperature,humidity and wind speed)that affect the effect of differential pressure pre-cooling.Among them,the refrigeration unit can be reduced to the experimental temperature of 2? in only 15.86 min at room temperature of 26?;humidification The device can raise the humidity in the box to 85% within 9.3 minutes;the differential pressure fan can quickly reach the set value of the wind speed after starting,and its speed range is 0~9m/s,and the error is controlled within ±2.5%,both It can meet the experimental requirements of actual differential pressure pre-cooling.