Experimental Study On Fresh Peanut Hot Air Drying

Peanut is one of the most important oil crops in China.According to statistics,in 2015 China's peanut acreage reached 4.62 million hectares and peanut production reached 16.44 million tons.However,if the peanuts are not dry in time after harvest,then it is easy to produce corruption.In most parts of China,people still use the field of natural drying peanuts.The method has the advantages of low drying efficiency,high labor intensity and great dependence on the weather.In this paper,fresh wet peanuts are used as experimental raw material to carry out research on peanut hot air drying process.The aim of this paper is to provide theoretical basis for peanut hot air drying process and equipment development.The main results of this paper are as follows:The initial water content of the tested peanut was 47.91%by analyzing the test sample.In the experiment of peanut drying characteristics,the peanut drying characteristic curve was drawn and the change rule of peanut drying rate was observed.The results showed that the drying process of peanut was the process of slowing down.The decay stage can be divided into three different drying rate deceleration stages,and the drying characteristics of peanut are determined by the different drying characteristics of peanut and peanut shell.In the study of peanut thin layer dry test model,the peanut drying test was carried out under different wind temperature and wind speed.The regression analysis of peanut moisture ratio data and selected three models showed that the matching of Page model was better and the regression effect is remarkable.The model formula under the experimental conditions is obtained.The results show that the predicted value and the experimental value of the model are well fitted.In the single factor experiment of peanut hot air drying parameters,the influence of dry parameters such as hot air temperature,hot air wind speed and material thickness on peanut precipitation rate was analyzed,and the drying curve was drawn.The sensory quality of the tested materials was evaluated.The results showed that the time of peanut drying to safe storage water content decreased with the increase of hot air temperature and hot air wind speed and increased with the increase of layer thickness When the hot air temperature is 58? and 64?,the sensory properties of peanut are obviously changed.In the study of peanut hot air drying optimization process,by using L9(34)orthogonal test design method,using the time and energy consumption required to dry to a safe storage water content(10%or less)as evaluation index,the experiment was carried out to study the main factors influencing the dry air drying of peanut,then to optimize the design,find the best combination of parameters.The optimum process parameters are as follows:the hot air temperature is 46?,the fan frequency is 35Hz and the thickness of the material layer is 30cm.The test results are consistent with the results obtained by the orthogonal test.The results of adding tempering process of peanut hot air drying process and continuous hot air drying process shows that drying rate is slow but not zero at tempering process.This shows that the tempering process is also a drying process.In the early stages of drying,the drying rate after tempering process is higher than the drying rate of the same time period in the continuous drying process.In the late stages of drying,the drying rate of the two processes is not much different,so it can achieve the purpose of saving energy.