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Influence of Thermal and Solutal Marangoni Effects on Free Surface Deformation in an Open Rectangular Cavity

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Journal of Thermal Science 2017年第3期26卷 255-262页

作者： ZHOU Xiaoming huai xiulan Institute of Engineering Thermophysics Chinese Academy of Sciences

Steady thermo-solutocapillary convection in a rectangular cavity with deformable free surface under microgravity condition is numerically studied, where level set method is employed to capture the free surface deformation. Both the temperature and solute concentration gradients are applied horizontally. The computational results show that, as the thermal to solutal Marangoni number ratio varies between-10 and-1(namely,-10 ≤ R_σ <-1), the flow field exists one anti-clockwise rotating convective cell driven by thermocapillary convection, and the free surface bulges out near the left end wall and bulges in near the right end wall. As-1 < R_σ < 0, the flow field exists one clockwise rotating convective cell driven by solutocapillary convection, and the free surface bulges out near the right end wall and bulges in near the left end wall. As R_σ =-1, the flow field consists of one clockwise and one anti-clockwise rotating convective cells, and the free surface bulges in at the central point and bulges out near the left and right end walls.

关键词： thermo-solutocapillary convection rectangular cavity free surface level set method

Heat Transfer and Entropy Generation Analysis of an Intermediate Heat Exchanger in ADS

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Journal of Thermal Science 2018年第2期27卷 175-183页

作者： WANG Yongwei huai xiulan Institute of Engineering Thermophysics Chinese Academy of Sciences

The intermediate heat exchanger for enhancement heat transfer is the important equipment in the usage of nuclear energy. In the present work, heat transfer and entropy generation of an intermediate heat exchanger(IHX) in the accelerator driven subcritical system(ADS) are investigated experimentally. The variation of entropy generation number with performance parameters of the IHX is analyzed, and effects of inlet conditions of the IHX on entropy generation number and heat transfer are discussed. Compared with the results at two working conditions of the constant mass flow rates of liquid lead-bismuth eutectic(LBE) and helium gas, the total pumping power all tends to reduce with the decreasing entropy generation number, but the variations of the effectiveness, number of transfer units and thermal capacity rate ratio are inconsistent, and need to analyze respectively. With the increasing inlet mass flow rate or LBE inlet temperature, the entropy generation number increases and the heat transfer is enhanced, while the opposite trend occurs with the increasing helium gas inlet temperature. The further study is necessary for obtaining the optimized operation parameters of the IHX to minimize entropy generation and enhance heat transfer.

关键词： heat transfer entropy generation intermediate heat exchanger thermodynamic ADS

An experimental study of temperature and moisture content of wet porous materials under short-pulsed laser heating

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Journal of University of Science and Technology Beijing 2005年第5期12卷 476-480页

作者： Renxi Jin xiulan huai Nuclear Power Teaching Unit Naval Submarine Academy Shandong 266071 China Institute of Engineering Thermophysics Chinese Academy of Science Beijing 100080 China

The measurements of temperature and moisture content of a wet porous material were accomplished on the micro-seconds scale. The temperature wave was observed when the wet porous material was heated by short-pulsed laser with high power. It firstly revealed that the moisture content of wet porous material rapidly rises twice in one laser irradiation. The influences of laser parameters, the thickness and initial moisture content of the wet porous material on its temperature and moisture content were investigated.

关键词： porous material transient measurement temperature moisture content short-pulsed laser

High Temperature Catalytic Hydrogenation of Acetone over Raney Ni for Chemical Heat Pump

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Journal of Thermal Science 2014年第1期23卷 85-90页

作者： DUAN Yanjun XU Min huai xiulan Institute of Engineering Thermophysics Chinese Academy of Sciences University of Chinese Academy of Sciences

Exothermic hydrogenation reaction of acetone is an important part of an IAH-CHP, and the performance of IAH-CHP is affected directly by this reaction. This paper studies the influence of space velocity, temperature, hydrogen flow rate and pressure on conversion and selectivity experimentally. The byproducts are analyzed and classified into three types: hydrogenation product, cracking products and condensation products. Both the conversion and selectivity of this reaction have the same trend with the change of space velocity, temperature and hydrogen flow rate, and has the opposite trend with the change of pressure. As the space velocity increases, the conversion curve is a gradual decline parabola but the selectivity curve is close to a straight line. Hydrogen flow rate has a more obvious influence on conversion than temperature, whereas on selectivity the situation is opposite. High pressure increases the conversion of acetone to all products, but the increment of byproducts is more than that of isopropanol, so the selectivity decreases as pressure increases.

关键词： Chemical heat pump Raney Ni Hydrogenation Acetone Conversion Selectivity

Visualization of Film Wavelike Characteristics and Measurement of Film Thickness in Spray Cooling

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Journal of Thermal Science 2013年第2期22卷 186-195页

作者： Yan Hou Yujia Tao xiulan huai Institute of Engineering Thermophysics Chinese Academy of Sciences University of the Chinese Academy of Sciences

An experimental investigation was performed to study the heat transfer in an eight-nozzle spray cooling system with de-ionized water as the working fluid. Visualization of the liquid-solid contact area and the flow near the heated surface was made using a microscopic lens system in conjunction with an advanced high-speed camera. The film thickness and film wavelike characteristics under liquid volume flow rates ranged from 2.78×10 -6 m 3 /s to 1.39×10 -5 m 3 /s and surface temperatures between 22℃ and 78.2℃ were examined respectively. The development process of the liquid film on the heated surface was observed. The local mean film thickness, the film wavelike characteristics and the behavior of the bubbles appeared in the liquid film were captured using an image processing technique. It is discovered that there exists a climax of local mean film thickness during the starting process of spray cooling. When the liquid film reaches the dynamic stable state, the dimensionless mean film thickness decreases with the increase of the liquid volume flow rate, and increases with the increase of surface temperature generally. Besides, the volume flow rate has a more significant impact on the wavelength and amplitude of the liquid film compared to the surface temperature.

关键词： Spray cooling Visualization Film thickness measurement Film wavelike characteristics

Exergy analysis and performance enhancement of isopropanol-acetone-hydrogen chemical heat pump

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Frontiers in Energy 2017年第4期11卷 510-515页

作者： Min XU Jun CAI xiulan huai Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China

Exergy loss analysis was conducted to identify the irreversibility in each component of the isopropanol- acetone-hydrogen chemical heat pump （IAH-CHP）. The results indicate that the highest irreversibility on a system basis occurs in the distillation column. Moreover, the effect of operating parameters on thermodynamic performances of the IAH-CHP was studied and the optimal conditions were obtained. Finally, the potential methods to reduce the irreversibility of the IAH-CHP system were investigated. It is found that reactive distillation is apromising alternative. The enthalpy and exergy efficiency of the IAH-CHP with reactive distillation increases by 24.1% and 23.2%, respectively.

关键词： waste heat reuse chemical heat pump exergyanalysis isopropanol

Collection efficiency in a three-dimensional randomly arranged dual-layer granular bed filter

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Particuology 2020年第2期18卷 88-94页

作者： Junlin Chen Xunfeng Li xiulan huai Jingzhi Zhou Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The dual-layer granular bed filter packed with randomly arranged granules was simulated to study the effects of bed depth of the lower layer of fine granules and the inlet gas velocity on the collection *** computational results show that the collection efficiency is much better from this granular bed than a single-layer granular bed,especially for particle diameters of 1-10μ*** inlet gas velocity has less effect on the grade collection efficiency of the dual-layer granular bed than of the single-layer granular *** dual-layer granular bed provides a high collection efficiency and low pressure *** relationship between the grade collection efficiency and the Stokes number(St)based on the inlet gas velocity is *** St is below a threshold,the grade collection efficiency remains stable;if St is in value above threshold,the grade collection efficiency increases linearly with lg(St).As the bed depth of the lower layer of fine granules increases,the threshold for St shifts forward.

关键词： Dual-layer granular bed filter Pressure drop Grade collection efficiency Stokes number

Interaction of Two Cavitation Bubbles in a Tube and its Effects on Heat Transfer

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Journal of Thermal Science 2017年第1期26卷 66-72页

作者： LIU Bin CAI Jun TAO Yuequn huai xiulan Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China University of the Chinese Academy of Sciences Beijing 100080 China

When two cavitation bubbles exist in a confined space, the interaction between the bubbles significantly affects the characteristics of bubble dynamic behaviors. In this paper, a three-dimensional(3D) model is established to study the growth and collapse of two cavitation bubbles in a heated tube and its effects on heat transfer. The liquid and gas phases throughout the calculation domain are solved by a set of Navier-Stokes equations. It is assumed that the gas inside the bubble is compressible vapor, and the surrounding liquid is incompressible water. The mass transfer between two phases is ignored. The calculated bubble profiles were compared to the available experimental data, and a good agreement has been achieved. Then, the relationship among the bubble motion, flow field and pressure distributions was analyzed. On this basis, the effects of bubble interaction on the heat transfer between the wall surface and sounding liquid were discussed. It is found that heat transfer in the centre wall region is enhanced owing to the vortex flow and micro-jet induced by the bubble contraction and collapse. In contrast, the highest surface temperature appears in the surrounding region, which is mainly attributed to the thermal resistance induced by the bubble. The present study is helpful to understand the heat transfer phenomenon with cavitation in the liquid.

关键词： Cavitation, Interaction effects, Bubble dynamics, Heat transfer

Simulation of Heat Transfer with the Growth and Collapse of a Cavitation Bubble Near the Heated Wall

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Journal of Thermal Science 2013年第4期22卷 352-358页

作者： Bin Liu Jun Cai Fengchao Li xiulan huai Institute of Engineering Thermophysics Chinese Academy of Sciences University of Chinese Academy of Sciences

The growth and collapse behaviors of a single cavitation bubble near a heated wail and its effect on the heat transfer are numerically investigated. The present study is designed to reveal the mechanism of cavitation enhanced heat transfer from a microscopic perspective. In the simulation, the time-dependent Navier-Stokes equations are solved in an axisymmetric two-dimensional domain. The volume of fluid （VOF） method is employed to track the liquid-gas interface. It is assumed that the gas inside the bubble is compressible vapor, and the sur- rounding liquid is incompressible water. Mass transfer between two phases is ignored. The eaiculated bubble pro-files were compared to the available experimental data, and a good agreement was obtained. Then, the relationship among bubble motion, flow field and surface heat transfer coefficient was analyzed. On this basis, the effects of such factors as the initial distance between the bubble and the wall, the initial vapor pressure and the initial bubble nucleus size on the heat transfer enhancement are discussed. The present study is helpful to understand the heat transfer phenomenon in presence of cavitation bubble in liquid.

关键词： cavitation bubble bubble growth bubble collapse heat transfer enhancement