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The VOF model was employed to simulate the pool boiling under typical engineoperating temperature conditions and was experimentally validated. A trapezoidal raised surface morphology with a hydrophilic-hydrophobic combination was designed, and the heat transfer ability and bubble evolution phenomena on the surface were analyzed. Then the variance contribution of each structural parameter of the trapezoidal raised surface to the average surface temperature rise and the average surface heat transfer was evaluated. Finally, the NSGA-II algorithm was used to optimize the structural design of the designed trapezoidal raised surface with the optimization objectives of minimizing the average temperature rise and maximizing the average heat transfer coefficient. Specifically, compared with the hydrophilic smooth surface, the optimized structure showed an increase in the average heat transfer coefficient by 194.5% and a decrease in the maximum average temperature rise, AT, by 33.9%. [ABSTRACT FROM AUTHOR]

In this study, a high voltage heater system with a size of 310 mm × 210 mm × 60 mm has been numerically studied and experimentally verified to explore the influence of the cavity structure on the flow and heat transfer performance. The response surface model and analysis of variance are used to determine the influence of the length of the mainstream area of the inlet, Lin, the length of the mainstream area of the outlet, Lout, the length of the parallel flow channel, Lch, and the single channel width, W, on the flow heat transfer, and ultimately find the best structural plan. The results show that the structural parameters of the parallel flow channel are significantly more important than those of the mainstream area, with the width and length of the parallel single channel being the primary and secondary structural parameters, respectively. The optimization scheme obtained by the NGSA-II algorithm can simultaneously meet the requirements of heat transfer and flow uniformity. Specifically, compared with the original model, the flow distribution uniformity coefficient, S, and the inlet/outlet pressure drop, Ptotal, decreased by 53.49% and 19.52%, respectively, while the average heat transfer coefficient increased by 28.05%. [ABSTRACT FROM AUTHOR]

In order to investigated the influence on the liquid cooling system cooling effect by changing the structural parameters, single Li-ion battery heat generation model is conducted, and used in following simulation. Subsequently, sixteen models are designed by orthogonal array, and the results are obtained by extremum difference analysis, which can quantify the influence degree, identify major and minor factors, and find the relatively optimum combination. Finally, different channel entrance lay-out is adopted to investigated. With a series of work, the effective of single battery heat generation model is proved by the discharge experiment. The coolant velocity has most evident influence on the Li-ion battery temperature rise, rectangular channel aspect ratio is second one, and the heat conducting plate thickness has the smallest influence. Similarly, for Li-ion battery temperature difference, the effect of heat conducting plate thickness and rectangular channel aspect ratio as the same, both are secondary factor, and coolant velocity is main factor. With different channel entrance lay-out, both the maximum temperatures denote a same upward trend, and better balance temperature distribution is obtained by adopt Case C system which with alternating arrange channel entrance lay-out. [ABSTRACT FROM AUTHOR]

In agricultural equipment, heat exchangers are mainly used for heat exchange and full utilization. Based on the theory of enhanced heat transfer, we establish a reasonable mathematical model and physical model for the multi-degree-of-freedom spiral plate type agricultural machinery heat exchanger, and use the FLUENT numerical simulation software to add the spiral disturbing fluid to the spiral plate heat exchanger flow channel. Numerical simulation and further optimization simulation of the fluid-conducting conditions with poor heat transfer effect were carried out, and an optimal arrangement of two kinds of spiral-shaped turbulent fluids with constant curvature and variable curvature was determined. The heat transfer effect of the fixed-curvature spiral-shaped disturbing fluid is superior. Further optimize the structure of the disturbing fluid. When the diameter of the disturbing fluid increases, the heat transfer can be enhanced; thus, the diameter of the disturbing fluid plays an important role in enhancing the heat transfer effect. [ABSTRACT FROM AUTHOR]

During the operation of turbines, one of the common accidents is due to the structure failure of blades. The contact model with strong non-linearity and time variation makes it difficult to be analyzed. In this paper, firstly, the contact model is described by using fractal theory. Secondly, the new method for the optimization of turbine blade is proposed, which is a kind of structure with local nonlinearity and multi degree of freedom. The method reduces the number of degrees of freedom by forming a new super element, which makes the linear part of turbine blade without repeated calculation in the non-linear iteration process. Therefore, it can shorten the calculation time and reduce the demand for computing resources. Finally, an optimization of the turbine blade is carried out, and the maximum equivalent stress reduces by 13.19%, which proves the effectiveness of the new optimization method. [ABSTRACT FROM AUTHOR]