Numerical Modeling of Heat and Mass Transfer in a Low-Temperature Heat Pipe

A mathematical model of heat and mass transfer in a low-temperature heat pipe has been formulated. Numerical modeling of the problem of heat and mass transfer has been carried out. The distributions of the velocities, the pressure, and the temperatures in the heat pipe have been obtained. The results can be employed in analyzing the efficiency and power of low-temperature heat pipes.     

Heat and Mass Transfer in Anisotropic Bodies

This review is aimed, on the one hand, at attracting the researchers' attention to the problems associated with heat transfer in anisotropic bodies and, on the other hand, at analyzing the scanty experience in investigating the heat transfer in anisotropic bodies that has been accumulated over the last 30 years. We treat conjugate heat transfer between boundary layers and anisotropic bodies, and heat transfer under conditions of simultaneous reciprocal influence of anisotropic thermal conductivity and anisotropic filtration upon film cooling of bodies with anisotropic properties. New effects are revealed during simulation of conjugate heat transfer; the law of nonlinear filtration in anisotropic bodies is identified; and the effect of individual components and of the orientation of the principal axes of thermal conductivity and penetrability tensors on stationary temperature fields and on the distribution of components of the filtration rate is investigated. The results of analytical investigation of heat transfer in anisotropic bodies enables one, under conditions of lack of adequate information, to exactly simulate nonstationary temperature in simplest anisotropic bodies, which may be used as test results. A number of recommendations are formulated for implementation of heat shielding of anisotropic bodies under conditions of their aerogasdynamic heating.     

Nonstationary Heat and Mass Transfer in Molecular Gases

The analytical solution of the problem on a nonstationary heat source in a diatomic gas has been given. The characteristics of the temperature and sound waves excited by it have been obtained. The distribution of the pressure, temperature, and concentration of the gas molecules has been considered.     

湿膜加湿器热质交换过程分析

湿膜加湿器是利用直接蒸发加湿的工作原理,对空气进行加湿,只消耗风机和循环水泵的电耗,具有结构简单和节省能源的优点。本文根据热质交换理论对湿膜加湿的传质过程进行了理论分析,建立了湿膜加湿器的传热、传质微分方程,得出影响加湿量的主要因素,并讨论了它们的影响趋势。     

Modeling of Heat Transfer and Solidification of Composite Roll

Modeling of heat transfer and solidification of composite roll was established and used to predict the thermal history and solidification process of roll during spray forming. Evolution of temperature field of the preform and cooling rate in the growing deposit during spray deposition and post-deposition were numerically simulated.     

Heat and Mass Transfer Measurements for Tray-Fermented Fungal Products

In this study, heat and mass transfer in static tray fermentation, which is widely used in solid-state fermentation (SSF) to produce fungal products, such as enzymes or koji, is investigated. Specifically, kinetic models of transport phenomena in the whole-tray chamber are emphasized. The effects of temperature, moisture, and humidity on microbial growth in large-scale static tray fermentation are essential to scale-up SSF and achieve uniform fermentation. In addition, heat and mass transfer of static tray fermentation of Trichoderma fungi with two tray setups??traditional linen coverings and stacks in a temperature?Chumidity chamber is examined. In both these setups, the following factors of fermentation were measured: air velocity, air temperature, illumination, pH, carbon dioxide (CO₂) concentration, and substrate temperature, and the effects of bed height, moisture of substrate, and relative humidity of air are studied. A thin (1 cm) bed at 28 °C and 95 % relative humidity is found to be optimum. Furthermore, mixing was essential for achieving uniform fermentation of Trichoderma fungi. This study has important applications in large-scale static tray fermentation of fungi.     

Mathematical Modeling of Heat and Mass Transfer in Evaporation of a Substance from a Porous Body in Vacuum

A problem of the Stefan type which describes heat and mass transfer in a porous body with the double phase transition liquid–ice–vapor has been formulated and solved.     

Hybrid Approach to Modeling the Process of Convective Radiative Heat and Mass Transfer in Closed Differentially Heated Cavities

Journal of Engineering Physics and Thermophysics - A hybrid model has been developed for the analysis of the process of combined mass and heat transfer in closed rectangular cavities under the...     

Influence of Heat and Mass Transfer on Wood Impregnation Kinetics

We have further developed the nonstationary mathematical model of twophase filtration in an anisotropic porous medium — wood — by a fluid, taking into account the temperature dependence of its viscosity. The results of the calculations of the temperature and kinetics of wood impregnation under the action of vacuum and excess pressure for the problem of internal and external heat transfer are presented. The process of preservative impregnation of woodworks with a wateroil emulsion for various degrees of filling of the autoclave, including the maximum one, has been simulated.     

Action of Vibrations on Heat and Mass Transfer in Boiling

The state of the art of the works known in the literature and concerned with the influence of vibrations of structures of plants and artificially initiated vibrations in working liquids on the processes involving boiling is analyzed. The authors discuss theoretical and experimental results on the influence of frequencies and amplitudes on the internal characteristics of boiling, namely, the initiation of a vapor phase, the superheat in boiling, the growth and separation of vapor bubbles and the frequency of their occurrence, the density of nucleation sites, and also on the value of the heat fluxes and on the heattransfer coefficient. Application of vibrational actions for intensification of heat and masstransfer processes is shown to be promising.     

Multi-scale Numerical Modeling of Radial Heat Transfer in Grooved Heat Pipe Evaporators

It is well known that small-scale effects near contact lines have a crucial importance on the radial heat transfer within a grooved heat pipe evaporator. This paper studies this problem using a multi-scale model which is composed of two parts, macroscopic and microscopic. At the macroscopic scale, we solve the heat conduction problem for the solid and the liquid phases, using a finite-element method. In order to avoid the classical singularity problem at the contact line, in addition to taking the solid thermal conductivity into account, we do not impose the saturation temperature but a mixed condition along the interface. The coupling with the microscopic scales is achieved using a correlation for the apparent contact angle, obtained from a lubrication-type theory developed for the contact line region, and taking into account the variation of the saturation temperature with the disjoining pressure and with the meniscus curvature. Our results show a strong influence of this apparent contact angle on the heat transfer within the heat pipe, for two different geometries and as a function of the heat flux.     

Similarity of Heat‐ and Mass‐Transfer Processes in Drying

The possibility of the existence of a hydrodynamically invariant relation between individual parameters of the process of convective drying is studied. The presence of a relation of this kind is a consequence of the similarity of processes that is typical of regular modes of heat and mass transfer.     

板式蒸发式冷凝器传热传质的数值模拟

根据能量守恒和质量守恒定律,对板式蒸发式冷凝器中制冷剂、冷却水与空气之间的传热传质过程,建立了热质交换过程的二维数学模型,由此分析板式蒸发式冷凝器中冷却水温度、空气温度和空气含湿量等参数的分布规律,以及空气流速、干湿球温度、冷却水喷淋密度和冷凝温度对板式蒸发式冷凝器热流密度的影响,并将模拟结果通过实验进行了验证,两者之间的误差在10%以内。研究表明:板式蒸发式冷凝器的热流密度随进口空气流速的增加而增大,随湿球温度的升高而减小,几乎不受进口空气干球温度的影响;热流密度随着冷却水喷淋密度的增加逐渐增大,但增大至一定量后不再对热流密度有明显影响;冷凝温度越高,其热流密度越大。上述结论对板式蒸发式冷凝器的优化设计具有指导意义。