Design And Experiment Of A Walnut Cracking And Separating Integrated Device

The walnut(Juglans regia L.)is one of the oldest cultivated fruit species in the world.The kernels have excellent nutritional and therapeutic value,which is attributable to their high content of unsaturated fatty acids and abundance of amino acids and minerals.In post-harvest and processing,compared to other operations(e.g.,peeling,cleaning,drying,storing,etc.),walnut cracking and shell-kernel separation are not only an important link in primary processing but also the premise and guarantee of further processing,which will directly affect the quality and added value of the products.However,the existing processing methods of walnut cracking and shell-kernel separation universally suffer from kernel damage,incomplete shell cracking,incomplete separation,and entrapment loss,which seriously restrict the development of walnut processing industry.The reason is that most scholars focus on the research and development and design of a single processing process,ignoring the fact that walnut cracking and shell-kernel separation are a continuous and inseparable processing system.Therefore,the research and development of continuous equipment for walnut cracking and shell-kernel separation are an urgent problem to be solved.The key lies in the effective combination of multiple process devices and the clear effect of operation parameters on the performance.It not only provides guidance for the design of walnut cracking and separating integrated machine,but also provides theoretical reference for the research of other agricultural materials cracking and shell-kernel separation integrated.To this purpose,this study attempts to design a walnut cracking and separating integrated machine.The research is divided into three parts:(1)The design of a walnut cracking and separating integrated machine.First,the classification drum was designed to achieve different sizes of walnut cracking,and the speed of the classifying drum was determined to be 20–25 r/min according to the particle flow characteristics of walnuts in the classifying drum.Second,the roller-plate cracking device was designed to achieve the cracking effect of crushed shell-intact kernels,and the cracking gap and cracking angle were determined to be 24-33 mm and 0-1.36° according to the kinematic characteristics of walnuts in the gap of the roller-plate.Again,the two-stage separation duct was designed to improve the accuracy of walnut shell-kernel separation,and the air speed range of the twostage fans was determined to be 18.35–21.82 m/s for the first stage and 12.71–15.76 m/s for the second stage based on the suspension velocity of each component material.The CFD simulation simulated the effect of the separation bend pipe radius structure on the uniformity of the flow field.In addition,a star-shaped feeding roller and a cyclone separator were designed.Finally,the conveying device is designed to realize the equipment of the whole machine.(2)Optimization of operation parameters of key components of the walnut cracker.First,the parameters were optimized using RSM-CCD to establish the regression models of the test factors(cracking gap(CP),cracking angle(CA),and roller speed(RS))and the test indicators(walnut cracking rate(WCR),whole kernel rate(WKR),specific energy consumption(Es),and productive efficiency(Pe)).Second,processing data and ANOVA were performed using Design-Expert software,and the main and secondary factors affecting the WCR,WKR,Es,and Pe were determined by the factor contribution method.In addition,the interaction of the two factors was analyzed using the response surface methodology,and the regression model was optimized according to the importance of the optimization objective using MATLAB software.The results show that the optimal parameter combination is a cracking distance of 29 mm,a cracking angle of 0.55°,and a roller speed of 107 r/min.The verification test of the walnut cracking is carried out under the optimal parameter combination.The walnut cracking rate is 95.24%,the whole kernel rate is 89.80%,the specific energy consumption is 1.92 kJ/kg,and the productive efficiency is 385.58 kg/h.Finally,the adaptability test was carried out to examine the adaptability of the best operating parameters to different varieties of walnut cracking.The variety adaptability test showed that the walnut cracking device with a shell thickness less than 1.2mm and a gap between the shell and kernel greater than 1.6 mm has a better walnut cracking effect,such as the ‘Wen 185’,‘Xinwen 179’,and ‘Zha 343’ varieties.(3)Optimization of operation parameters of key components of the walnut shell-kernel separator.First,the RSM-CCD is implemented to model the design variables(inclination of the deflector plate Ⅰ IDP1,inclination of the deflector plate Ⅱ IDP2,wind speed of fan Ⅰ WSF1,and wind speed of fan Ⅱ WSF2)on the objective functions(impurity rate IR and loss rate LR).Second,the reliability of the regression model was tested by ANOVA.The main and secondary factors affecting the impurity rate(IR)and loss rate(LR)were obtained by the factor contribution method.In addition,the interaction effects of the design variable on the objective function were analyzed using the response surface methodology(RSM).Finally,the NSGA-Ⅱ algorithm was used to optimize the response surface model to obtain the Pareto front,and the optimal Pareto solution was obtained by using TOPSIS: the inclination angle of wind plate Ⅰ was 40.2°,the inclination angle of wind plate Ⅱ was 32.9°,the wind speed of fan Ⅰ was 20 m/s,the wind speed of fan Ⅱ was 14 m/s,and the walnut shell kernel separation test was carried out under the optimal parameter combination.The impurity rate is 5.41%,and the loss rate is 7.32%.