Search

The efficiency and working performance of the motor and controller system in micro-electric vehicles depends mainly on its thermal performance, which is contingent upon effective and active cooling. The working temperature of the motor and controller may be too high during operation, which properly causes motor power reduction or motor breakdowns. Therefore, it is crucial to design a good cooling channel for better cooling the integrated motor and controller system. This work proposes an integrated cooling channel of motor and controller, and the fluid-solid coupling analysis is applied for analyzing the velocity, pressure distributions of the cooling channel, and temperature distributions of motor solid components. Meanwhile, the collaborative optimization method based on the multi-island genetic algorithm (MIGA) is used to attain optimal design parameters of the integrated cooling channel of the motor and controller for obtaining a better cooling channel design with lower flow resistance and lower winding temperatures. Results show that the original cooling channel's flow resistance and maximum winding temperature are 31.87 kPa and 120.04°C, respectively. The flow resistance and winding temperature are pretty significant. After optimization, the local vortex flow and zero velocity area in optimal cooling channel design are improved, the coolant flow velocity becomes more uniform, and the flow resistance is significantly reduced. The flow resistance and maximum winding temperature of the optimal cooling channel design are 12.5 kPa and 116.76°C, respectively, which are decreased compared with the original cooling channel structure, with a decrease of 39.4% and 2.7%, respectively. The research findings in this work can provide theoretical reference for solid components temperature evaluation of motor and give valuable data to cooling performance evaluation and optimization of integrated cooling channel for motor and controller system. [ABSTRACT FROM AUTHOR]

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]

The existing grape drying technology and equipment often have problems such as poor hygiene conditions, high drying costs, and large drug residues. Therefore, the market urgently needs grape drying equipment with low energy consumption, high efficiency, and a green-clean processing process. To solve the above problems, a piece of integrated drying equipment combining the two technologies of air impingement blanching and air impingement drying for multi-layer grape material drying is designed. The dried product quality is directly affected by the airflow field distribution. Therefore, obtaining good airflow distribution and airflow velocity uniformity in the drying chamber via parametric studies is essential to ensure uniform drying of products. Since parametric and optimization investigations by physical experiments are usually expensive and time-consuming, computational fluid dynamics (CFD) being a flexible and less expensive tool can be employed to perform such studies. In the current work, the airflow velocity distribution and uniformity of the drying material room are analyzed by Ansys Fluent software. The airflow velocity non-uniformity coefficient is used to evaluate airflow uniformity. Results show that the original design has poor uniformity and needs to be optimized. The influence of air inlet chamber deflection device and material truck airflow baffles on the flow field of the material drying room is investigated to improve the uniformity of airflow distribution. Considering drying efficiency and uniformity, drying material room structure with the addition of deflection device design with the structural parameters of L = 50 mm and θ = 76°, airflow baffle design with the structural parameters of h = 0 mm, θ2 = 20° is chosen as the final optimized design. After optimization, the velocity of airflow between material layers has improved overall, and the maximum difference of average airflow velocity between material layers has been reduced from 0.73 m/s to 0.69 m/s, improving the drying uniformity of dried materials. In comparison to other drying equipment, the current integrated drying equipment combing air impingement blanching and drying has the advantages of being efficient and energy-saving, suitable for large-scale drying of grapes with better drying quality. The current results could guide the drying equipment design for grapes and develop the grape drying industry with high-dried quality. [ABSTRACT FROM AUTHOR]

Airflow velocity uniformity in material drying room used in steam blanching and hot-air vacuum drying equipment is crucial for obtaining a good drying quality of fruits and vegetables. To analyze the airflow velocity uniformity and give the optimization design for improving the airflow uniformity, CFD method is used for the flow field analysis of material drying room and the velocity non-uniformity coefficient is used as the evaluation indicator for the velocity uniformity. Results show that the airflow velocity distribution in the material drying room at the original inlet airflow distribution chamber is relatively uneven and the airflow velocity non-uniformity coefficient in drying area is 34 %. For reducing the airflow velocity non-uniformity, the airflow velocity distribution of three structural modification directions with 12 designs in total are analyzed and compared. The minimum airflow velocity non-uniformity coefficient for adding a spoiler model, reducing the closed end width and adding nozzle baffles are 17.1 %, 30.2 %, 10.4 %, respectively. Through comparison, adding the nozzle baffle with a width of 11 mm at the rear end of each nozzle outlet is considered as the optimal designs to conduct the experimental validation. Experimental validation results shows the the relative error between the simulated value and the measured value is within 10 %, proving that the CFD prediction results is reliable and the research results can give a theoretical reference for the designers to evaluate and optimize the structure of inlet airflow distribution chamber for improving the airflow uniformity in drying area. [ABSTRACT FROM AUTHOR]

Aiming at improving the cooling of motor annular water jacket, the effects of different water jacket designs and pump rotation speed and epoxy resin filling on the flow field characteristics and motor temperature distribution were studied. Results show that uneven flow distribution leads to high temperature of motor coil and large temperature gradient. The optimized water jacket has better flow, uniform flow distribution of long and short paths, higher utilization rate of coolant, and the coil temperature is 2 °C lower than that of original model. On the basis of optimized water jacket, when epoxy resin filling methodology and pump rotation speed increased to 5000 r/min are applied, the coil temperature can be reduced by 16 °C compared with the original model. From the cooling performance optimization results in current case, the improvement order from the smallest to the biggest is the optimization of motor water jacket flow field, optimization of motor water jacket system flow rate, and the epoxy resin filling. To meet the cooling demands of motor, the comprehensive effects from the aspects of reducing coolant system resistance, increasing pump speed, epoxy resin filling and other effective technologies are ought to be considered for all case studies. [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]

The comprehensive performance evaluation procedure and overall performance evaluation indices for the four cylinder engine cooling systems are proposed in this work and the four cylinder engine cooling system with two different flow patterns are investigated. Coolant velocity distributions of nose bridge area sections of cylinder head water jacket and plane section of cylinder block water jacket in series flow pattern cooling system meet the coolant flow velocity requirements of 1.5 m/s in high-temperature area. Coolant velocity distributions of water jacket in parallel flow pattern cooling system is relatively lower and not meet the velocity requirements of 1.5 m/s. Through the improvement of pump performance, the system coolant flowrate in parallel flow pattern cooling system can be increased to 90 L/min. After velocity uniformity improvement of water jacket, the coolant velocity distributions in parallel flow cooling system become more uniform. Coolant velocity and heat transfer coefficient of high temperature area both meet the design requirements of coolant velocity 1.5 m/s and heat transfer coefficients of 5000 W/(m2·K). The cooling performance for the engine with parallel flow pattern cooling system is significantly improved and meets the cooling design requirements. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) is a vital endogenous gaseous transmitter molecule involved in the regulation of various physiological and pathological processes in living biosystems. In order to investigate the biological function of CO, many technologies have been developed to monitor the level of endogenous CO in biosystems. Among them, the fluorescence detection technology based on the fluorescent probe has the advantages of high sensitivity, excellent selectivity, simple operation, especially non-invasive damage to biological samples, and the possibility of real-time in situ detection, etc., which is considered to be one of the most effective and applicable detection techniques. Therefore, in the last few years, a lot of work has been carried out on the design, synthesis and in vivo fluorescence imaging studies of CO fluorescent probes. Furthermore, using fluorescent probes to detect the changes in CO concentrations in living cells and tissues as well as in organisms has been one of the hot research topics in recent years. However, it is still a challenge to rationally design CO fluorescent probe with excellent optical performance, structural stability, low background interference, good biocompatibility, and excellent water solubility. Therefore, this review focuses on the research progress of CO fluorescent probes in the detection mechanism and biological applications in recent years. However, this popular and leading topic has rarely been summarized comprehensively to date. Thus, the research progress of CO fluorescent probes in recent years is reviewed in terms of their design concept, detection mechanism, and their biological applications. In addition, the relationship between the structure and performance of the probes was also discussed. More significantly, we hope that more excellent optical properties fluorescent probes for gaseous transmitter molecule CO detection and imaging will overcome the current problems of high biotoxicity and limited water solubility in future. [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]

Achieving an optimal cooling of the generator unit is indispensable for high working performance. In this work, computational fluid dynamics analysis on the flow field of the conventional type and silent type of the S688CCS series generator unit is conducted, and design optimization of the generator unit with poor cooling is studied based on flow field analysis results. Flow field simulation results indicate that the total cooling air quantity of the silent type generator unit is lower than that of the conventional type generator unit, and the cooling air quantity of the radiator is also lower than that of the conventional type generator unit, which is not conductive for the cooling of the silent type generator unit. The flow field optimization is achieved by adopting the single variable control method to improve the structure of the fan cover, silent components for silence, adjacent structure, and air inlet grille. The corresponding structure optimization scheme is put forward. After optimization, the air quantity for the cooling radiator of the silent type generator unit is 44.33% higher than that of its original structure, and the total cooling air quantity is higher than that of the conventional type generator unit. The research results in this work can provide a theoretical basis for the design of the cooling air flow path of generator units for achieving an optimal cooling performance. [ABSTRACT FROM AUTHOR]

Achieving an optimal cooling of the generator unit is indispensable for high working performance. In this work, computational fluid dynamics analysis on the flow field of the conventional type and silent type of the S688CCS series generator unit is conducted, and design optimization of the generator unit with poor cooling is studied based on flow field analysis results. Flow field simulation results indicate that the total cooling air quantity of the silent type generator unit is lower than that of the conventional type generator unit, and the cooling air quantity of the radiator is also lower than that of the conventional type generator unit, which is not conductive for the cooling of the silent type generator unit. The flow field optimization is achieved by adopting the single variable control method to improve the structure of the fan cover, silent components for silence, adjacent structure, and air inlet grille. The corresponding structure optimization scheme is put forward. After optimization, the air quantity for the cooling radiator of the silent type generator unit is 44.33% higher than that of its original structure, and the total cooling air quantity is higher than that of the conventional type generator unit. The research results in this work can provide a theoretical basis for the design of the cooling air flow path of generator units for achieving an optimal cooling performance. [ABSTRACT FROM AUTHOR]

In current research, the hydraulic performance prediction and optimization of an engine cooling water pump was conducted by computational fluid dynamic (CFD) analysis. Through CFD simulation, the pump head, shaft power and efficiency for the original pump at volume flow rate 25 L/min and impeller rotating speed 4231 r/min were 3.87 m, 66.7 W and 23.09% respectively. For improving hydraulic performance, an optimization study was carried out. After optimization, four potential optimized designs were put forward. The efficiency of the optimized design No.1 for engine cooling water pump was nearly 6% higher than that of the original pump model; and the head of the optimized design No.2 for engine cooling water pump was 9% higher than that of the original pump model. Under the condition of maintaining the pump head and considering comprehensive improvement effect, the optimized design No.3 was considered as the best design and selected as the test case for validating the optimum design. The hydraulic performance predictions for this optimum engine cooling water pump agreed well with experimental data at design condition with relative discrepancies of 2.9% and 5.5% for the pump head and pump efficiency, respectively. It proved that performance prediction calculation model and the automatic optimization model were effective. This research work can provide theoretical basis for the design, development and optimization of engine cooling water pump. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) is one of the important gaseous signalling molecules, which plays key roles in various critical biological processes. In this work, we report a novel two-photon near-infrared (TP-NIR) fluorescent probe (MNIR-H2S) for the sensing of mitochondrial H2S in living cells, tissues, zebrafish and nude mice. Using a xanthene dye as a TP-excitation (810 nm) NIR-emission (668 nm) fluorophore, a well-known H2S response moiety with a robust intramolecular charger transfer (ICT) effect can quickly respond to H2S and effectively quench the fluorescence intensity, and an oxonium cation structure serves as a mitochondria-targeting site. Notably, MNIR-H2S displays high sensitivity, high selectivity, low cytotoxicity, powerful mitochondrial localization ability, deep tissue penetration, and a very minimal imaging background. Biological imaging results show the biological application of MNIR-H2S as a robust new tool for use in H2S imaging in biological systems. [ABSTRACT FROM AUTHOR]

Spin flash drying equipment is widely used in chemical, food and other fields. Drying process consumes large amounts of energy and reduction in operating cost will be extremely beneficial for the industry. Therefore, in order to improve the efficiency of spin flash dryer. A three-dimensional CFD model of the drying process was established by computational fluid dynamics, and the flow field characteristics and heat transfer mechanism of the drying process were obtained. We studied the specific effects of different parameters on the drying process, and verified the results with calcium carbonate as raw material. The experimental results are basically consistent with the simulation results. The velocity, temperature and pressure in the drying chamber near the wall are greater than those in the central region, which generally decrease with height. The speed of the cutter set has a large effect on the tangential and radial velocity, but the influence on the pressure drop is not significant. Meanwhile the temperature and velocity of inlet air have a greater impact on distribution of flow field and material drying, the variable structure improves the stability of the drying process. [ABSTRACT FROM AUTHOR]

In order to meet the needs of customers and take advantage of the customer's innovative resources, companies open up their design activities of products to customers. In contrast to the traditional product innovation, the primary characteristic of open innovation is the participation of a large number of autonomous individuals across organisational boundaries, and there is not a central authority. Hence, it is necessary to study the dynamic mechanism for obtaining a good decision. This paper first studies the evolution of individual interaction based on game theory and then studies the dynamic characteristics of large-scale interaction. According to the results of simulation, it is concluded that the opinions are convergent under various communication conditions, and he convergent velocity distribution of the product solution with payoffs as the independent variable is obtained. A case study is used to deeply understand the participant behaviour based on the game theory and verify the conclusion of dynamic analysis in this paper. [ABSTRACT FROM AUTHOR]

Aiming at the problem of multilayer physical structure for the skeleton of porous media, a multiscale and multilayer structural model of heat and mass transfer processes for drying of grain packing porous media was established by applying the pore network method and multiscale theory. An experimental study on rice drying was conducted in order to validate this model. The simulation and experimental results indicated that the established model could explain the mechanical properties of rice drying well. The rate of heat transfer was faster than the rate of mass transfer and there was a higher moisture gradient inside the rice grain. The diffusion coefficient of rice embryo played an important role in the drying process, and whose effect on drying was larger than the diffusion coefficient of rice hull and chaff. The moisture was imprisoned effectively inside the rice when the diffusion coefficient of rice embryo was very small. [ABSTRACT FROM AUTHOR]

In order to obtain the optimized technological parameters of hot air-vacuum combined drying of lettuce, the effects of hot air temperature, intermediate conversion moisture content, slice thickness and vacuum degree (four influence factors) on lettuce drying were explored. The drying time and rehydration ratio of lettuce were the experimental indices, and the relationships between the experimental indices and the influence factors were analyzed by using the response surface methodology. The regression mathematical models were established. The optimized technological parameters of hot air and vacuum combined drying are 50C hot air temperature, 40% intermediate conversion moisture content (w.b.), 20 kPa vacuum degree and 5 mm slice thickness. Practical Applications Combined drying is widely used in food, which is considered as an effective method to achieve energy conservation and shelf life. The objective of this paper was using response surface methodology to obtain optimized hot air vacuum drying parameters for lettuce. The significance of this research can improve the drying efficiency, provide a reference for other fruits and vegetables' drying process optimization and provide a technical basis for the drying of lettuce and the designing of related equipment. [ABSTRACT FROM AUTHOR]