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Common methods of drying have three ways: radiation, conduction and convection. Convective drying has been widely used due to its simple equipment and wide application range. The parameters that can be optimized are temperature, wind speed and humidity, but the temperature has an upper limit in each drying stage. Exceeding the upper limit will destroy the quality of agricultural products. It’s not conducive to sufficient heat exchange between wind and material if exceeding the optimum air volume. The humidity is unrestricted for most of the drying period. Low humidity can increase the drying rate and, so humidity is an ideal adjustment parameter. Wheel dehumidification is a common mode in solid dehumidification. However, the traditional wheel dehumidifier has problems such as high energy consumption and unreasonable structure, while heat pump has limited deep dehumidification capacity, but the energy saving effect. In view of the above problems, in this paper, we proposed a model of wheel dehumidifying and for the problems of high energy consumption and unsuitable for drying of agricultural products based on traditional structure of wheel dehumidifying, the optimization design of the dehumidifying structure and the dehumidification system was carried out. Firstly, a conversion mechanism was set up to solve the problem of reasonable conversion between fresh air and circulating air to realize energy-saving drying. Secondly, the surface cooler was replaced by an evaporator and a condenser was set up to recycle the energy. The heat released from the condenser was used to heat dry the inlet air or to regenerate the dehumidification wheel. In order to test and improve the performance of the wheel and heat pump combined dryer, in this paper, we took the sliced Pleurotus eryngii as the research object, and aimed to reduce the color difference of the Pleurotus eryngii, specific power consumption and improve the rehydration, using Box-Benhnken. In the central combined experimental design theory, we carried out three-factor and three-level response surface tests on three factors that affected the drying quality and energy consumption, such as regeneration temperature, dry temperature and conversion point relative humidity. Data analysis was carried out and the response surface mathematical model was established. The four-dimensional renderings was used to analyze the influence mechanism of the above three indicators on the changes of the three test factors. The results showed that the R2 was near to 1and the test factors had a great influence on the drying quality and energy consumption. The order of importance of each factor to rehydration was dry temperature > regeneration temperature > conversion point relative humidity, the order of importance to aberration was regeneration temperature > conversion point relative humidity > drying temperature, the important influence order on SPC was dry temperature > regeneration temperature > conversion point relative humidity. The lower regeneration temperature resulted in the lower drying temperature, the higher rehydration ratio, and the lower relative humidity of the converse. The lower drying temperature, the smaller the relative humidity of the conversion point, and the lower chromatic aberration, and vice versa. The regeneration temperature, the drying temperature and the conversion point relative humidity to SPC showed a trend of low first and then high. When the regeneration temperature was 87 °C, the drying temperature is 50 °C, and the relative humidity of the conversion point was 45%. The rehydration ratio of Pleurotus eryngii was 4.028, the color difference was 22.89, SPC was 2633 kJ/kg, and the error between the predicted and absolute value was less than 6%. This study explored the critical dehumidification mechanism based on enthalpy point and improved the wheel dehumidification structure, and formulated the optimum dehumidification drying process of Pleurotus eryngii. The results can provide the basis for the design of wheel dehumidification and HPD combined dryer and the optimization of drying process. [ABSTRACT FROM AUTHOR]

Pleurotus ostreatus has been one of the most widely cultivated and the largest edible fungi in China. Global production has been growing rapidly, due to simple cultivation, low cost, quick effect, high yield, and short cycle. According to the statistics of the China Edible Mushroom Association, the output of Pleurotus ostreatus in 2020 was 6.8647 million tons, accounting for 17.45% of the total output of edible fungi, indicating the third-largest cultivar in China. However, there is still a great challenge on the efficiency and stability in the current production of oyster mushroom cobs combined with the induction, sterilization, and fermentation of Pleurotus ostreatus cultivation material and the central-hole inoculation. Taking a corncob particle as the Pleurotus ostreatus fermentation material, this study aims to develop a strain charging and inoculating machine, particularly for the higher efficiency of single machine operation, high stability, and full automation. Three devices were mainly composed of a charger, a nest, and an inoculation device. The key components of the whole machine were designed, according to the requirements of the charging quality and inoculation amount in the production of bacterial sticks, thereby determining the structural parameters of the charging auger, the socket groove cam, and the inoculation cam. A response surface method was used to optimize the test factors, where the diameter of the auger and the pitch of the auger were the influencing factors, and the charging productivity and density were the response indicators. A regression mathematical model was established for the charging productivity and density. The response value of the rotation speed of the auger was obtained to determine the most significant impact. Furthermore, the inoculum amount of bacteria was measured under different inoculation electromechanical speeds. As such, the inoculum amount was 132.33 g, and the inoculation variation coefficient was 1.19 %, when the inoculation motor speed was 120 r/min, which satisfied the number of bacteria in the center hole of the fermented material. The production requirement was measured to be 242.5 mm less than 5% of the charge and the average inoculation depth of the inoculation unit. Multi-objective optimization of the regression model was carried out to further verify the charging performance of the equipment. The optimal structural parameters of the charging device were obtained as follows: the auger rotation speed of 191.94 r/min, auger diameter 133.22 mm, auger pitch 100.00 mm, while the charging productivity was 723 bags/h, the charging density was 537.27 kg/m³, and the charging mass was 2.42 kg. The optimized all-in-one and stand-alone machine was verified for production. It was found that the charging productivity of the all-in-one machine was 726 bags/h, the charging density was 536.25 kg/m³, the coefficient of variation of the charging quality was 0.82%, and the coefficient of variation of the inoculation amount was 0.92%, the coefficient of variation of the inoculation depth was 1.05%, the mouth of the fungus bag was firm and flat, while the folds were uniform, and the nest has no leaking bags. This key component can fully meet the equipment demand for the mechanized production of oyster mushroom fermentation materials in northern regions. [ABSTRACT FROM AUTHOR]

China is the largest producer and exporter of Lentinus edodes in the world. To improve its market value, twin-screw extrusion and expansion machine has been developed to further process the Lentinus edodes. To resolve the problems of blockage, low prematurity and missing operation parameters of this machine in producing Lentinus edodes pufferent, we presented an improved twin-screw extrusion and expansion machine in this paper to lower puffer ability, improve water absorption and reduce its hardness. The equipment consists of a frame, a mixing device, a feeding device, a tempering device, a heating device, an extruding and bulking device and a rotary cutting device. It is equipped with a cooling system, a lubricating system, a transmission system, a control system and a pressure detection system. Design and determination of the anti-blocking device for the feed mixing device, the pre-maturing and tempering device, and the structural parameters of the twin screw were conducted. In order to investigate the influence of operation parameters on swelling performance of the product, the Box-benhnken combined test method was used to study the working parameters of the double screw extruder. The effects of screw speed, extrusion temperature and water content on the swelling rate, hardness, brittleness and water absorption of the expanded product were analyzed, and the determinants were optimized. The results showed that, based on the level of the significance, 1) factors affecting the expansion rate were ranked in material water content > expansion temperature > screw speed, 2) factors affecting hardness were ranked in material moisture content > screw speed > swelling temperature, 3) factors affecting brittleness were ranked in material moisture content > screw speed, 4) factors affecting water absorption were ranked in material moisture content > swelling temperature > screw speed. The optimal operating parameters were: screw speed 167.23 r/min, swelling temperature 151.68℃, material moisture content 16.83%. Under these conditions, the swelling rate, hardness, brittleness and water absorption of the product were increased by 4.04%, 18.61 N, -8.46 mm/cm2 and 313.86% respectively, compared to the traditional machine. Practical application of the optimized parameters revealed that the error between the optimized productivity and real productivity was less than 4%, with the maximum productivity being 165 kg/h. Compared with the existing equipment in the laboratory at School of Mechanical Engineering in Yangzhou University, the designed machine increased the swelling rate, brittleness, water adsorption and brittleness by 25.00%, 40.55% and 62.35% respectively, while reducing the hardness by 48.21%. Therefore, the design of this machine can provide relatively mature technical equipment for the development of mushroom swelling products. [ABSTRACT FROM AUTHOR]