基于Matlab的转筒干燥器中干燥物料含水率的优化方法

结合转筒干燥器干燥工艺的特点,分析了计算机模拟优化的方法与步骤,并选用Matlab优化,达到一定的工艺要求,进一步为今后的生产提供了科学依据.     

转筒内物料滞留时间的研究

建立了颗粒物料在转筒干燥器内运动的数学模型,推导出了滞留时间的计算公式,用VB语言编制了计算程序.仿真结果与实验结果吻合良好,该仿真程序对此类问题的研究具有参考价值.     

基于三维实体模型的玉米颗粒真空干燥数值模拟

针对真空干燥时单体玉米颗粒内部的传热传质过程,开展基于三维实体模型的模拟研究。使用高精度CT扫描玉米颗粒,图像经MIMICS、ANSYS处理,建立实体模型。以傅里叶传热方程、菲克扩散方程作为控制方程,当量辐射传热和表面水分蒸发传质作为边界条件,使用COMSOL软件完成模拟。模拟结果显示干燥过程中颗粒内部为传质控制过程,提高辐射板温度和真空度均能加快干燥,但真空度高于5.5 kPa后效果不明显,玉米初始含水量增大和初始温度降低,会增加总的干燥时间和能耗。     

贝克利数对圆管流道交变流动传热的影响分析

从可压缩黏性流体的一般控制方程出发,通过数值模拟,研究管内可压缩层流交变流动传热现象,重点关注贝克利数对于传热的影响.采用离散傅立叶级数的形式表征管内交变流动传热特性,研究表明采用五阶级数拟合值与原始数据的相对误差可小于10%.给出了贝克利数为2和300时,一个周期内交变流动传热过程的计算结果,并进行了对比分析.根据模...     

喷动—气流干燥器的数值模拟

为了开发新型的喷动－气流干燥装置，本文建立了它的数学模型，并在微机上对各操作参数及其对性能的影响进行了数值模拟。大量的计算结果从理论上证明，该型干燥器能显著改善单纯气流干燥器的操作性能，故具有潜在的应用前景。     

HEAP-30型氢气干燥器的开发与应用

以环保型制冷剂R134a作制冷工质,采用强化传热技术、在线湿度监测与控制技术等,研制开发出一种用于氢冷发电机的HEAP-30型氢气干燥器.文中介绍了该型干燥器的工作原理、技术特点、性能指标和现场实际应用情况.研究指出;HEAP-30型氢气干燥器能确保发电机内的氢气绝对湿度在额定压力下,长期稳定于1～2g/m3,露点控制在-12～-8℃之间,干燥指标达到国家及部颁标准,并且具有环保、高效、去湿能力大、连续运行稳定、安全可靠等特点,是国内氢冷发电机组氢气干燥的理想设备.     

热管在热泵干燥器中应用的研究

依据质量平衡和能量平衡规律,建立了带热管回热器的热泵干燥器数学模型,该模型由热管,干燥室,蒸发器,压缩机和冷凝器五大模块组成,利用此模型对系统的性能参数及运行规律进行了模拟研究。同时,对模拟所得到的部分结果做了实验验证。     

固体循环气流干燥器湿含量分布的研究

本文研究了固体返料气流干燥器的停留时间分布,干燥时间分布及湿含量分布,建立了湿含量分布密度函数,并就七水硫酸亚铁的干燥进行了模拟计算,结果表明：循环比的大小对产品的湿含量分布具有重要影响。     

冷却干燥通风过程中粮仓内热湿耦合传递的数值模拟

基于多孔介质传热传质的理论,建立了一种冷却干燥通风过程中粮仓内热湿耦合传递的数学模型。借助数值模拟的方法,对冷却干燥通风过程中粮仓内温度和水分的变化进行了模拟研究,得到了冷却干燥通风过程中粮堆内部热量传递和水分迁移的基本规律。     

地源热泵U型埋管土壤温度场数值模拟

结合相关文献给出原始地温计算式,针对垂直U型埋管换热器建立瞬态传热模型,采用控制容积法对方程进行离散,对换热器周围土壤温度场进行数值模拟.对模拟结果进行分析获得地下埋管换热器的传热特性与土壤温度变化规律,并通过实验数据验证模拟结果的正确性.     

旋转圆盘式干燥机的设计

采用基于移动加热板的颗粒热传递模型,根据实际干燥过程分段计算大型旋转圆盘式干燥机的传热系数,介绍了采用有限元分析和简化力学模型的旋转圆盘干燥机转子的强度计算模型,其应用结果与干燥机的实际运行情况基本相符。     

物料与窑壁间歇接触对回转窑传热过程的强化效应

根据回转窑内物料颗粒的运动特点，推导了颗粒团在贴壁运动过程中的非稳态导热系数及界面处的接触传热系数，进而得出了物料与封盖窑壁间的换热系数；结合已有研究成果，建立了回转窑的传热数学模型。计算表明，未考虑物料与窑壁间歇接触对回转窑传热过程的强化效应时，物料温度偏低；温度越高，强化效应对物料温度的影响越大；考虑物料与窑壁间歇接触对回转窑传热过程的强化效应，有利于提高回转窑煅烧熟料的质量和热效率。     

Experimental Study of Heat Transfer Performance of Polysilicon Slurry Drying Process

In recent years, the growth of the solar energy photovoltaic industry has greatly promoted the development of polysilicon. However, there has been little research into the slurry by-products of polysilicon production. In this paper the thermal performance of polysilicon slurry was studied in an industrial drying process with a twin-screw horizontal intermittent dryer. By dividing the drying process into several subunits, the parameters of each unit could be regarded as constant in that period. The time-dependent changes in parameters including temperature, specific heat and evaporation enthalpy were plotted. An equation for the change in the heat transfer coefficient over time was calculated based on heat transfer equations. The concept of a distribution coefficient was introduced to reflect the influence of stirring on the heat transfer area. The distribution coefficient ranged from 1.2 to 1.7 and was obtained with the fluid simulation software FLUENT, which simplified the calculation of heat transfer area during the drying process. These experimental data can be used to guide the study of polysilicon slurry drying and optimize the design of dryers for industrial processes.     

高温熟料非稳态非热平衡渗流换热模型

回转窑卸入篦冷机的高温水泥熟料为红热半透明的多孔介质,其复杂的气固换热机理给篦冷机的工艺改进带来较大难度。针对这一问题,将高温红热颗粒等效为光学厚介质,推导了一种高温熟料颗粒间传导与辐射综合换热系数,基于渗流力学与传热学理论,建立了考虑高温熟料颗粒间热辐射效应的水泥熟料非稳态非热平衡渗流换热模型。通过对所建模型进行求解,得到了料层内熟料温度与气体温度的分布规律,比较了不同区域冷却速率的差异,获得了辐射传热因素对料层温度分布的影响。     

Wave heat transfer in anisotropic space with nonlinear characteristics

An analytical solution to the problem of heat transfer in anisotropic space, the thermal-conductivity tensor components of which depend on temperature, has been obtained for the first time. Heat transfer is initiated by a pulsed point thermal-energy source. It is found that the heat transfer is of the wave type with a finite propagation rate of the thermal-wave front, although the heat conduction equation is of a parabolic type. Cases of different power-law temperature dependences of the thermal-conductivity tensor components have been investigated. It has been shown that the thermal-wave fronts have the shape of ellipsoids (in space) or ellipses (in plane). The results can be used to analyze the heat exchange in composites under laser irradiation.     

Design and experimental tests of a rotary active magnetic regenerator prototype

A rotary active magnetic regenerator (AMR) prototype with efficiency and compact design as focus points has been designed and built. The main objective is to demonstrate improved efficiency for rotary devices by reducing heat leaks from the environment and parasitic mechanical work losses while optimizing the utilization of the magnetized volume. Heat transfer calculations combined with 1D AMR modeling have revealed the necessity for an insulating air gap between magnet and regenerator when designing for high efficiency. 2D finite difference AMR modeling capturing the interplay between heat transfer fluid flow and an inhomogenous time-varying magnetic field in the individual regenerator beds has been used in the design process. For one operating point a COP of 3.1 at a temperature span of 10.2 K and a cooling power of 103 W were measured. Major issues limiting the performance have been identified and improvements are outlined for future work.     

Performance improvement of air source heat pump using gas-injected rotary compressor through port on blade

Gas injection has been a crucial technology to avoid the serious degradation of air source heat pumps in low ambient temperature. A novel injection structure on the blade for rotary compressors has been put forward in previous research to overcome the drawback of traditional injection structures. Based on a verified numerical model, the thermodynamic performance of an air source heat pump with the new gas-injected rotary compressor is investigated. The results indicate that, compared to the air source heat pump with the regular single-stage rotary compressor, the proposed injection structure can enhance heating capacity and COP of the air source heat pump by 23.1–28.2% and 4.5–8.1%, respectively.     

Preliminary survey on the mechanisms of the wave-like behaviors of heat transfer in living tissues

The mechanism of the wave like behaviors of heat transfer in living tissues were studied through introducing a new concept of multi-mode energy coupling. A phenomenological thermal wave model of bioheat transfer was obtained. A new conceptual equation was proposed to correlate the heat flux with the temperature gradient, thus the intriguing high magnitude of the characteristic time in living tissues was better understood. A hypothesis was proposed for further testing the current theory. Numerical calculations were performed to study the temperature transients in the skin stratified as three layers with different thermal parameters. Deviations between the thermal wave model of bio-heat transfer and the Pennes' equation were studied for several typical transient bio-heat processes and the possible practical implications were discussed. A simple temperature criterion has been established to determine when the thermal wave propagation dominates the principal heat transfer process.     

Coupled thermo-hydraulic modelling of pavement under frost

Frost action is a major factor causing deteriorations of pavements in cold regions. The resultant temperature and moisture redistributions play an important role in determining the mechanical responses of pavement. This paper develops a multi-physical model to analyse the coupled thermo-hydraulic field under pavements, especially those in the unsaturated base and subgrade. This model integrates the Fourier's laws for heat transfer, Richards' equation for fluid transfer and poroelastic constitutive relationships. Various coupled parameters were utilised to transfer information between field variables. Additional relationships, such as the similarity between drying and freezing processes and the Clapeyron equation for ice–water balance, were incorporated to allow for the effects of frost action. The coupled nonlinear partial differential equation system was solved on a multi-physical platform. Two instrumented pavement sections (one asphalt pavement and one concrete pavement) were used to validate the results of the model simulations. The simulation results match reasonably well with the field-monitored data.     

Additional boundary conditions in unsteady-state heat conduction problems

Using some additional sought function and boundary conditions, a precise analytical solution of the heat conduction problem for an infinite plate was obtained using the integral heat balance method with symmetric first-order boundary conditions. The additional sought function represents the variation of temperature with time at the center of a plate and, due to an infinite heat propagation velocity described with a parabolic heat conduction equation, changes immediately after application of a first-order boundary condition. Hence, the range of its time and temperature variation completely incorporates the ranges of unsteadystate process times and temperature changes. The additional boundary conditions are such that their fulfilment is equivalent the fulfilment of a differential equation at boundary points. It has been shown that the fulfilment of an equation at boundary points leads to its fulfilment inside the region. The consideration of an additional sought function in the integral heat balance method provide a possibility to confine the solution of an equation in partial derivatives to the integration of an ordinary differential equation, so this method can be applied to the solution of equations, which do not admit the separation of variables (nonlinear, with variable physical properties of a medium, etc.).