Study And Design Of Waterless Washing Nozzle For Fresh Apricot

Apricot is one of the main characteristic fruit and vegetable varieties in Xinjiang.It is loved by people because of its rich nutrition and medicinal value.Usually fresh apricot is transported into the market after picking.However,due to the lack of rain and sand-dust weather in Xinjiang,there are a large number of dust particles on surface of apricot which seriously affect the external quality of fresh apricot.At present,water washing is the main method for fruit washing.But the fresh apricot after water washing is easy to cause the damaged of wax layer of apricot surface,and it greatly increased the rate of qualitative change during the transportation and storage.And then it will produce the enormous economic losses to fruit growers and fruit sellers.In this paper,in order to solve the washing problem of dust on the fresh apricot surface,waterless washing scheme for fresh apricot was put forward before sending to the market.In other words,high-pressure air jet was used to wash the fresh apricot.It not only save valuable fresh water resources but reduce the risk of two pollution of fresh apricot.The nozzle was the key component in the waterless washing device.It is very important to select the better nozzle structure to improve the working efficiency of the device.In this research,the CFD technology was used to simulate and analyze different internal and external flow field of nozzle,and better washing nozzle of the four nozzles was determined.A waterless washing nozzle test platform of fresh apricot was built,and the experiments were done.The test results were consistent with the simulation results,which verify the correctness of the simulation results.The main research works are as follows:1.The types of fruit washing nozzles were inquired and investigated.Considering the material properties of fresh apricot,nozzle inlet diameter was designed as 6 mm and nozzle length was designed as 20 mm uniformly.The inlet and outlet of nozzle was cylindrical hole.2.The internal and external flow fields of four nozzles with different structures were simulated and analyzed based on CFD technology.The results showed that the working section of fresh apricot was a circular section with a diameter of 60 mm,and it was 280 mm which far from the nozzle outlet.The column cone nozzle was better nozzle of the four nozzles which average velocity of the working section was 24.12 m/s,followed by column nozzle,fan nozzle and column fan nozzle.3.According to the test requirements,test platform of nozzle was set up which included pneumatic system,control system,conveying mechanism and executing mechanism.In order to verify the reliability of the simulation results,pressure-sensing test and waterless washing effect test were carried out based on the nozzle test platform.The waterless washing rate was calculated by image processing technology.Total pressure area of column cone nozzle was the maximum in the four nozzles which was 142 mm2.The stress distribution areas which greater than 0.14 MPa of the column cone nozzle was 27 mm2 which was the maximum of the four nozzles.In addition,the average waterless washing rate of the column cone nozzle was 93.55%,which was the highest of the four nozzles.Moreover,the experiments verified that the results of the numerical simulation were correct.4.According to the research of four kinds of nozzles,the shell nosing angle was an important factor of the nozzle performance.In order to determine the better shell nosing angle of column cone nozzle,the CFD technology was used in this paper.Research showed that the flow field flow velocity increased with the angle.The inlet velocity of the nozzle was set as 80 m/s.The airflow velocity of the working section was more than the maximum velocity which fresh apricot epidermis could bear when the shell nosing angle was 30°.The average velocity of work section was 32.35 m/s when the shell nosing angle was 15°,and its non-uniformity coefficient of velocity was the smallest at this time.Thus the better shell nosing angle of the column cone nozzle was 15°.5.The results in this study could provide a reference for follow-up engineering and technical personnel in future research and in the optimization of the waterless washing nozzle.