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In order to obtain the optimal technological parameters of lettuce vacuum osmotic dehydration, the effects of osmotic temperature, slice thickness, sucrose concentration, and vacuum degree on the vacuum osmotic dehydration were explored. The lettuce water loss rate and solid gain rate decreased with the increase of slice thickness and vacuum degree, and increased with the increase of sucrose concentration and osmotic temperature. Response surface methodology was applied to analyze the influence of the four influential factors on the evaluated parameters and the optimization of lettuce vacuum osmotic dehydration was studied. The results indicated that, within the experimental scope, the optimized technological parameters of lettuce vacuum osmotic dehydration are the temperature of 28°C, the slice thickness of 2 mm, sucrose concentration of 47%, the vacuum degree of 22 kPa, and the water loss rate and solid gain rate are 72.16% and 11.82%, respectively.

High-quality baijiu yeast – modified Sporidiobolus johnsonii A (MSJA) suffers from the problem of weak vitality, thus failing to combine high efficiency and high survival rate drying. Therefore, in this study, we firstly designed a real-time sampling experiment of MSJA spray drying process, and based on this, we established a New CFD model (N-CFD model) that can accurately simulate the variation of the spray drying process of microorganisms such as MSJA. Then, a new spray drying air inlet mechanism of "high-temperature cyclone in the center L-type guide plate + medium-temperature laminar flow in the peripheral holes and slots" was invented. Finally, the parametric scanning simulation was carried out to optimize the flow angle θ of the L-type guide plate using the N-CFD model. The results show that, firstly, the N-CFD model can accurately simulate the temperature distribution (P1 = 0.05) and the motion of drying particles in the drying tower. Secondly, the optimized new air inlet mechanism with the L-type guide plate flow angle θ = 47° can even out the temperature and particle distribution in the drying tower, which meets the "two-stage theory of spray drying." Finally, under the premise of ensuring the drying efficiency, the survival rate of MSJA spray drying was increased from 42.6% to 82.24%, which achieved the objectives of low sticking wall, high efficiency and high survival rate of spray drying MSJA. [ABSTRACT FROM AUTHOR]

In order to reduce temperature rise of motor coils and controller IGBT, improve heat dissipation performance of the cooling channel for motors and controllers, and ensure that the cooling channel has low flow resistance, this paper takes the cooling channel structure of the driving system of a micro electric vehicle and a motor integrated with a controller as the research objects, and establishes a fluid-structure coupling analysis model of motors and controllers through CFD method. The internal velocity field, flow resistance characteristics, motor winding temperature field and IGBT temperature field under the original structure of the cooling channel are analyzed. The collaborative optimization method is used to intelligently optimize the structural parameters of the cooling channel for the motor and the controller, and seek the cooling channel structure with low flow resistance and efficient cooling performance. The results show that the original structure of the cooling channel has local vortexes and ffow dead zones, the ffow resistance of the cooling channel t is 31.87 kPa, and the maximum temperature of the motor winding is 120.04 °C. Under the condition of meeting the goal of an optimization of manufacturing process and ffow resistance, a structure with the most significant improvement of winding temperature rise is selected as the final optimization result. After optimization, local vortexes and flow dead zones of the cooling channel are improved, the flow is smoother, and the ffow velocity is more uniform. The flow resistance decreases significantly, and the ffow resistance decreases by about 12.5 kPa or 39.4% compared with the original model. The maximum temperature at the winding end of the optimized motor reduces by 3.28 °C or 2.7%. The research results can provide a theoretical reference for the design and improvement of the cooling structure of motors and controllers for new energy vehicles. [ABSTRACT FROM AUTHOR]

To evaluate the rationality of the cooling system design for a four cylinder engine, computational fluid dynamics method was used to analyze the engine cooling system from layout design, system flowrate determination, flow field of the cooling system and engine temperature field. The optimization design of adding a throttling notch to the cylinder block water jacket was proposed to solve the problem of significant differences in coolant flow velocity in the cylinder block water jacket. The results show that the coolant flow velocity uniformity in cylinder block water jacket is significantly improved, and the wall temperature of each cylinder liner can be reduced by 1~3 °C. The thermal balance test results at an engine speed of 12 000 r/min show that the maximum difference in cylinder temperature is about 4 °C. The oil temperature is about 129 °C, which is controllable (less than 140 °C), indicating that the cooling system of the four cylinder engine is designed reasonably to ensure uniform cooling of each cylinder and oil cooling. [ABSTRACT FROM AUTHOR]