In this study, a modified Pinto-Espinoza (P-E) magnetization model that has a wider range of applications is proposed based on the conventional magnetization model. This model uses the relative reference frame conversion method to determine the magnetization force experienced by ferromagnetic particles when magnetic fields are applied in any direction. The accuracy of the improved P-E magnetization model is confirmed on the basis of this, and a coupled simulation environment between the discrete element method (DEM) and the finite volume method (FVM) is constructed. Simulated is the motion of ferromagnetic particles under various magnetic field directions and magnetic induction intensities. The particle distribution, particle velocity vector, and particle total energy change were all investigated. It is inferred that the chain formation direction of ferromagnetic particles in the magnetic field is consistent with the magnetic field direction, and they attract each other along the magnetic field direction and repel each other along the vertical magnetic field direction. Changing the intensity of the magnetic induction can effectively ease the particle delamination phenomenon. The faster the chain formation speed increases with increasing magnetic induction intensity, the shorter the time necessary to attain a stable condition.

聚光太阳能发电技术提供了一种可再生能源转换系统,其中接收器是聚光太阳能发电系统的关键部分.文中利用DDPM-DEM模型对双腔式流化床接收器内的稠密颗粒流动和传热过程进行数值模拟,模型中考虑了颗粒的流动、碰撞和传热作用.基于欧拉-拉格朗日方法对太阳能流化床颗粒接收器中的气固两相流动进行建模,辐射源相和接收器内辐射场的相互作用通过DO模型描述.得出稠密颗粒内循环流动可以增强接收器内颗粒与气体之间的热传递效果,同时接收器内的温度分布也更加的均匀,颗粒温度和气体温度都得到很大提高,分别达到1400 K和1200 K.

In order to improve the separation efficiency of the large scale industrial cyclone separation filter, a new cyclone separator is designed which combines the principle of inertia separation and centrifugal separation. Based on the theory of particle dynamics, a two fluid model is established, which is used to numerically simulate the gassolid flow characteristics in the cyclone separator. The variation law of fluid velocity, particle trajectory and other parameters is analyzed. The results show that the separation efficiency of the new cyclone separator is improved compared with the traditional cyclone separator.

As a new type of combustion device, circulating fluidized bed has overcame many disadvantages of coal fired industrial boilers. It has improved combustion efficiency and reduced pollutants.The heat transfer characteristics related to fluidized bed are expensive and are subject to environmental conditions.The FLUENT17.0 software is used as a platform for numerical simulation to solve.Numerical simulations are based on experiments by Tong Zhao et al. A simplified two-dimensional structure of circulating fluidized bed is applied to simulate the internal flow process and combustion process, and the heat transfer problem of fluidized bed is further studied. Based on the heat transfer model, the influence of the bed temperature and radiation heat transfer on the total heat transfer coefficient is researched.After theoretical calculation, the three distribution laws of heat flux density along the height direction of reactor are found, which provides reference for optimization reference.

Nanofluids have attracted more and more concerns own their excellent heat transfer performance in comparison with conventional fluids. In this paper, a reverse non equilibrium molecular dynamics method is presented to analyze the enhanced thermal properties of CuAr nanofluids. It is found that the thermal conductivity of CuAr nanofluids is sensitive to particle size and volume fraction. Meanwhile, the micro-mechanism of the enhancement of thermal conductivity of CuAr nanofluids is analyzed. The results reveal that the nanofluids have some similar microstructure characteristics as crystals. The nanoparticles are more likely to adsorb liquid molecules influenced by the solid-liquid interactions.

Compared with conventional fluids such as water and ethylene glycol, the excellent heat transfer effect of nanofluids has made it one of the hotspots of research in the past decade. In this paper, the heat conduction enhancement mechanism of nanofluids is simulated by a reverse non equilibrium molecular dynamics method. The heat flux density and thermal conductivity of nanofluids change with the addition of Cu nanoparticles in Ar, and the volume fraction of nanoparticles changes the energy transfer process in nanofluids to a certain extent. Furthermore, the microscopic mechanism of the enhancement of thermal conductivity of nanofluids is analyzed. It was found that the addition of nanoparticles made the microstructure of nanofluids similar to that of crystals. Under the condition of smaller particle size, the effect of temperature gradient on the fluid is obvious.