Liquid Heat Transfer Research Articles

Influence of Laminar and Turbulent Flows on Heat Transfer in Liquid-Cooled Plate at Different Fin Arrangements

This paper describes CFD investigation of flow and heat transfer in liquid cool plate of a lithium-ion battery. The work aims to compare the cooling performance of an LCP at different fin arrangement for both laminar and turbulence conditions. Prior to the extensive simulation works, the prediction of surface and liquid temperature is first compared made by conducting an experiment using one of the fin arrangement. Good agreement was obtained indicating the ability of the current model to simulate the flow and heat transfer of similar domain at different fin arrangement. The results indicated that the behaviour of the flow and heat transfer is different at laminar and turbulence conditions. The louvered find arrangement showed superior performance in terms of the enhancement of heat transfer. A combination of optimum configurations for fin arrangement and flow condition has enabled excellence overall heat transfer performance of the system.

3rd All-Russian Scientific Conference Thermophysics and Physical Hydrodynamics with the School for Young Scientists

D M Markovich and S V GolovinThe origins of the Conference start from 1970 in the Soviet Union, Novosibirsk. It was organized by Kutateladze Institute of Thermophysics SB RAS. The name of the conference was «Actual problems of thermophysics and physical hydrodynamics». The conference has been organized under this name up to 2015. The conference chairs were academicians V.E. Nakoryakov, S. V. Alekseenko and corresponding member of RAS D. M. Marckovich. Peer reviewed proceedings of the conference have been published in the format of printed books. In 2016 the conference is reorganized in a new format with a shorter name: «Thermophysics and physical hydrodynamics».The conference takes place in Yalta, a beautiful city in Crimea on the bank of the Black Sea. Lavrentev Institute of hydrodynamics and the National committee on heat and mass transfer are among other conference organizers besides Kutateladze Institute of thermophysics. The present Conference covers the following topics: heat transfer and hydrodynamics in single phase flows, hydrodynamics and heat and mass transfer in multiphase flows, phase transitions, reacting flow dynamics, detonation processes, numerical methods in thermophysics and physical hydrodynamics, techniques of thermophysics and hydrodynamics experiment, thermophysical properties of substances and new materials, heat transfer and hydrodynamics on micro- and nanoscales, electrophysical phenomena in gaseous and liquid media, heat transfer and hydrodynamics in industrial processes and environment protection.There are more than 200 participants. The proceedings contain 156 papers grouped by topic. The scientific committee appreciates the enormous work of the editorial board and reviewers in the preparation of this volume. We would like to express our sincere thanks to all authors for their research contributions, and also to organizers of the conference for their valuable spadework.List of Photos and Sponsor acknowledgements are available in this PDF

Time-dependent structural breakdown of microencapsulated phase change materials suspensions

Microencapsulated phase change materials (MPCM) suspensions are multi-phase heat transfer fluids which exploit the latent heat of phase change materials. The effect of MPCM on the rheological properties of suspensions of microcapsules in glycerol were investigated to explore the suitability of the suspensions as a pumpable heat transfer fluid. Three different rheological models were utilized to characterize the time-dependent structural breakdown of the suspensions, and the second-order structural kinetic model was found to give a better fit to the experimental data than the Weltman and Figoni-Shoemaker models. The MPCM form agglomerates, which are disrupted by shear forces. The breakdown of the agglomerated structures was most pronounced at high shear rates where the microcapsules are subjected to stronger disruptive forces. More agglomerates are present at higher concentrations, which causes a stronger breakdown of the agglomerated structures when the concentration is raised. The time-dependent structural breakdown of MPCM suspensions plays an important role for improving the efficiency of heat transfer liquids based on such materials.GRAPHICAL ABSTRACT

Heat dissipation analysis of double-layer battery pack under coupling heat transfer of air, liquid, and solid

Heat dissipation analysis of double-layer battery pack under coupling heat transfer of air, liquid, and solid

Group analysis of variable coefficients heat and mass transfer equations with power nonlinearity of thermal diffusivity

The paper presents symmetry analysis of three-dimensional equations of heat and mass transfer in a binary liquid. The system contains three unknown functions related to physical properties of liquid. Supposing thermal diffusivity to be depended on temperature with respect to power law, diffusion and thermal diffusion coefficients are found using of classical Lie symmetry approach. It is shown that the solution of the group classification problem consists of two parts. We obtain different results if we take into account that diffusion coefficient either has the same form as the thermal diffusivity coefficient or it depends on temperature and concentration essentially. Some reductions of the governing equations are constructed with the help of the obtained transformations of dependent and independent variables. New exact solutions of the reduced equations have been found in several cases.

A versatile one-dimensional numerical model for packed-bed heat storage systems

Abstract Thanks to their versatility and their relatively low cost, packed-bed sensible heat storage systems are promising for various applications like in concentrated solar power plants, adiabatic compressed energy storage and pumped thermal energy storage. A versatile one-dimensional numerical model able to describe many packed-bed configurations is developed and presented. This model is able to treat liquid and gaseous heat transfer fluids, and packed bed with a monomodal or a bimodal particle size repartion, i.e. consisting of a mixture of large and small solid particles (such as rocks and sand). This configuration is commonly encountered in the literature due to the advantages it procures. The model is compared and validated with specific experimental data and results from the literature covering wide ranges of configurations and operating conditions: several heat transfer fluids (molten salts, thermal oil, air), solid materials (rocks, sand, ceramics), fluid velocities, temperature levels and packed bed configurations are successfully tested. This shows the versatility of the developed model. The influence of the fluid velocity on heat losses, thermal diffusion and fluid/solid heat exchange are analysed. It enables to determine the optimal velocity which maximizes the performance of the storage system.

Simulation of casting process: case study on the gating and feeding design for outlet diaphragms of iron ore ball mill

In this paper, the sand casting process was evaluated using ProCAST simulating software and practical experience for manufacturing of the high chromium stainless steel outlet diaphragms used in iron ore ball mill. In the simulation practice, the effects of feeding and gating designs on the liquid flow, heat transfer and solidification phenomenon were evaluated to minimize the liquid surface turbulence during filling of the mold cavity and the shrinkage porosity formation during the liquid solidification in the mold. The effects of different gating ratios and number of feeders were numerically studied using different indicators in the software such as linear velocity, niyama criteria, fraction solid and shrinkage porosity. Further, the optimal design obtained by simulating process was empirically examined. The simulation results showed that the 1:3:4 gating ratio is the proper gating system that it obtains an unpressurized fluid flow without any surface turbulent of the liquid steel in the filling step. In addition, the simulation of solidification phenomenon was indicated that four feeders are required to eliminate of the shrinkage porosities. The empirical casting examination shown the optimal design by the simulation is proper for manufacturing of the steel part without critical defects.

Lattice Boltzmann simulation of electro-hydro-dynamic (EHD) natural convection heat transfer in horizontal cylindrical annuli

The natural convection heat transfer in a dielectric liquid confined in horizontal cylindrical annuli and enhanced by imposing a direct current electric field is numerically investigated using a unified lattice Boltzmann method. This augmentation of heat transfer is attributed to the flow motion induced by the Coulomb force due to the electric field exerting on free charges injected from the inner cylinder. Both concentric and eccentric configurations are considered. It is found that there exists a threshold of the electric driving parameter T, above which the heat transfer enhancement due to the electric effect becomes significant for concentric cases. For eccentric configuration, this change becomes relatively gentle. In addition, the influence of the eccentricity on heat transfer enhancement is also studied.

Exploration of Chemical Reaction Effects on Entropy Generation in Heat and Mass Transfer of Magneto-Jeffery Liquid

Abstract In many chemical engineering processes, a chemical reaction between a foreign mass and the fluid does occur. These processes find relevance in polymer production, oxidation of solid materials, ceramics or glassware manufacturing, tubular reactors, food processing, and synthesis of ceramic materials. Therefore, an exploration of homogeneous first-order chemical reaction effects on heat and mass transfer along with entropy analysis of Jeffrey liquid flow towards a stretched isothermal porous sheet is performed. Fluid is conducting electrically in the company of transverse magnetic field. Variations in heat and mass transfer mechanisms are accounted in the presence of viscous dissipation, heat source/sink and cross-diffusion aspects. The partial differential equations system governing the heat transfer of Jeffery liquid is reformed to the ordinary differential system through relevant transformations. Numerical solutions based on Runge-Kutta shooting method are obtained for the subsequent nonlinear problem. A parametric exploration is conducted to reveal the tendency of the solutions. The present study reveals that the Lorentz force due to magnetism can be used as a key parameter to control the flow fields. Entropy number is larger for higher values of Deborah and Brinkman numbers. It is also established that the concentration species field and its layer thickness of the Jeffery liquid decreases for a stronger chemical reaction aspect. To comprehend the legitimacy of numerical results a comparison with the existing results is made in this exploration and alleged an admirable agreement.

The role of convection in gas and liquid phases at droplet evaporation

The article presents the measuring results of droplet velocity and temperature fields using non-contact optical methods: Particle Image Velocity (PIV), Planar Laser Induced Fluorescence (PLIF) and Thermal imager. The novelty of the work is that the influence of free convection in gas and liquid is investigated experimentally and theoretically and that the key criteria affecting heat and mass transfer are determined. The analysis of experimental data has shown that in the initial period of water drop evaporation, the predominant role in the heat exchange is played by the thermal Marangoni convection. However, for an aqueous salt solution, in spite of the strong influence of the surfactant, the dominant role passes to the solutal Marangoni convection (MaC). In the first seconds after the drop falling, convection and heat transfer in liquid are maximal. Under such conditions it is important to realize an accurate numerical simulation to assess the degree of wall cooling and calculate the non-stationary evaporation. When simulating heat transfer, it is incorrect to neglect free convection in gas or liquid due to their strong nonlinear influence on each other. The heat exchange in the drop is extremely conservative to convection in the liquid (the Peclet number Pe = 100 and the Nusselt number Nu = 4).

Multiphysics modeling of water transport in high-intensity lignite drying process on pore scale

ABSTRACTThe understanding of the moisture transfer process in the pore network is quite important to improve the lignite drying efficiency. Scanning electronic microscopy image was used for construction of pore topology closely approximating the true topology of the real lignite for the heat and mass transfer processes on pore scale by COMSOL simulation. Considering the gas‒liquid phase coexistence of water, “Laminar Two-Phase Flow, Phase Field” module and “Liquid Heat Transfer” module were used. The pore size had significant effects on the flow velocity and the larger pores acted as the main pathway for the moisture transport, therefore affected the maximum drying rate. On the other hand, the connection of pores and the throats distribution in the pathway also had a significant effect on the flow velocity, and the moisture between the throats was hard to transfer as a flow, maybe by vapor diffusion. In high-intensity lignite drying process, the moisture vaporization quickly when heated up and vapor pressure was beneficial to keep the pore size and ensure the smooth of moisture flow pathway, thus improving the efficiency of the drying process.

Experimental comparison of longitudinal and annular fins using PCM for Thermal energy storage

This work deals with comparative study of longitudinal and annular fin using PCM in a thermal energy storage unit experimentally and numerically. The TSU under analysis Consists of paraffin wax as PCM with melting Temperature of 55°C to 60°C. Liquid heat transfer fluid passes between the tubes to charge and discharge the storage unit. Thermal storage tank is connected to the experimental setup which consists of hot and cold-water tanks and experiment is carried our initially charging and discharging by Longitudinal fin process by passing heat transfer fluid similarly the charging and discharging by Annular Fin process by passing heat transfer. The experimental results show that usage of Longitudinal fin and Annular fin for charging and discharging has different heat transfer rate. Even efficiency is increased around 6% for the longitudinal finned heat exchanger than the Annular finned heat exchanger.

Direct experimental measurement for partitioning of wall heat flux during subcooled flow boiling: Effect of bubble areas of influence factor

Heat transfer models in liquid-vapor two-phase flow with wall boiling rely on the wall heat flux partitioning to quantify heat transfer to liquid and vapor separately. Several wall heat flux partitioning models have been proposed over the years based on variety of heat transfer mechanisms, but the three basic mechanisms that form the core of these models are liquid convection, surface quenching and evaporation heat transfer. A key parameter commonly used to determine the relative contribution made by each mechanism is area fraction of influence of bubble which is determined by multiplying maximum bubble projected area fraction with bubble area of influence factor (K). In classic wall heat flux partitioning models, K accounts for the area within which heat is transferred to liquid that moves in towards the heated wall as bubbles lift-off. The value of K has been a subject of controversy over the years with no unanimous conclusion among researchers. Therefore, in this paper, advanced diagnostic approach involving the combination of infrared thermometry and total reflection principle was employed to experimentally study nucleate flow boiling. Rigorous data analyses was performed to partition the wall heat flux into the aforementioned three basic heat transfer mechanisms using different values of K. All three heat transfer mechanisms were significantly sensitive to varying values of K, but setting K = 0.5 with percentage uncertainties of −60%/+50% closely predicted the experimental measurements. In addition, overlapping area of influence due to merging bubbles was observed to be significant in the model at high heat flux condition and must be discounted to get the true bubble area of influence. A correction method for the overlapping area of influence was therefore proposed to enhance accuracy of the predictive model.

Condensation heat transfer and pressure drop of refrigerants HFO-1234yf and HFC-134a in small circular tube

HFO-1234yf has similar thermodynamic properties to HFC-134a but much lower GWP value. It is expected as a good candidate to replace the refrigerant HFC-134a in the near future. However, only very few papers have been published in the past years regarding to the flow condensation heat transfer performance of this new refrigerant. This study provides an experimental analysis of flow condensation heat transfer and pressure drops of refrigerants HFO-1234yf and HFC-134a in a small circular tube. The test results show that both pressure drop and condensation heat transfer performance depend on the fluid properties, flow conditions and flow patterns. The major controlling properties on pressure drops and heat transfer coefficients is strongly depending on their two-phase flow pattern at various flow conditions. At the lowest mass velocity, gravity is the major force that dominates the heat transfer mechanism and the flow pattern is slug. Higher liquid viscosity retarded the condensate flow but higher liquid conductivity provided better heat transfer through the liquid film. Both liquid viscosity and conductivity are the important controlling properties. While mass velocity and vapor quality increased, the effect of shear force increased and the flow pattern transferred to annular. Liquid thermal conductivity became the major controlling property at high vapor qualities. But at low vapor qualities, gravity is still important and therefore liquid viscosity is one the major controlling parameter. At the highest mass velocity conditions, gravity effect is negligible even though at very low vapor quality condition. Shear force dominated the condensation heat transfer mechanism and liquid conductivity is the most important controlling property. It can be concluded that the flow condensation heat transfer performance is strongly depending on the two-phase flow patterns at various flow conditions.

Temperature fluctuations accompanying MHD heat transfer of liquid metal downflow in a pipe

The present paper describes the experimental investigation of liquid metal mixed convection characteristics in a vertical pipe affected by strong transverse magnetic field. The influence of thermo-gravitational convection in non-isothermal flows of liquid metal affected by magnetic field is significant. Under certain conditions and configurations of the magnetohydrodynamic (MHD) heat transfer, thermo-gravitational convection, can cause low-frequency temperature fluctuations with abnormally high intensity. The RK-3 loop (HEattransfer Liquid Metal Experimental Facility (HELMEF)) has been designed and put into operation for heat transfer and hydrodynamics investigations during previously unstudied ratios of flow parameters such as Reynolds, Hartman, Grashof numbers, wherein temperature, velocity and their statistical characteristics are measured. New experimental data were obtained and processed by reconstruction of temperature fields and fields of temperature fluctuation characteristics. Modes with low frequency fluctuation of temperature have been studied using new experimental facility and compared to previous results. The boundaries where low frequency temperature fluctuations decay in a strong magnetic field have been found and studied for the first time.

Effects of solid-liquid intermolecular interactions on liquid flow and heat transfer in microtubes

This paper investigates the laminar flow and heat transfer characteristics of liquid in microtubes by considering the solid-liquid intermolecular interactions. We propose an apparent viscosity model of liquid from the wetting theory and the Hamaker theory to account for the interface effect. The numerical simulation considering this model is conducted to study the flow and heat transfer characteristics of liquid in microtubes. Simulation results indicate that the flow and heat transfer characteristics such as velocity distribution, pressure drop, flow friction and heat transfer coefficient deviate from the predictions of the conventional theory. The deviation increases as the hydrophilicity or hydrophobicity increases, and decreases as the diameter of the microtube increases.

Experimental and Scale Analysis of a Solid/Liquid Phase Change Thermal Energy Storage System

ABSTRACTA detailed experimental study has been carried out to evaluate the heat transfer performance of a solid/liquid phase-change thermal energy storage system. The phase-change material, 99% pure eicosane with a melting temperature of 36.5°C, was contained in a vertically oriented test cylinder that was cooled or heated at its outside boundary, resulting in radially inward freezing or melting, respectively. Detailed quantitative time-dependent temperature distributions and melt-front motion and shape data were obtained. In the freezing case study, a mathematical model was developed based on a one-dimensional analysis, which considered heat conduction as the only mode of heat transfer. In the melting case study, a heat transfer scale analysis was used to help interpret the data and development of heat transfer correlations. In the melting scale analysis, conduction heat transfer in the solid and natural convection heat transfer in liquid were considered. Comparison of experimental data with scale analysis predictions of the solid-liquid interface position and temperature distribution was performed. The analytical results agreed, in the worst case, within 10% of the experimental results in both melting and freezing cases. In the case of melting, scale analysis results agreed within 5% (after initial superheat disappeared in 50 minutes) with experimental results, and experimental results confirm the existence of four melting regions.

A numerical modeling for the steady-state performance of a micro heat pipe using thin liquid film theory

A numerical analysis on heat and mass transfer in a micro heat pipe was performed in this work. Mass, energy, and momentum equations were applied to vapor and liquid phases under steady-state operation in the numerical model. As a result, the trends in mass flow, pressure distribution, and temperature distribution for the working fluid circulating inside the micro heat pipe were obtained for vapor and liquid, respectively. In particular, the vapor-liquid interface shape obtained with a thin liquid film through augmented Young-Laplace equation and areas for heat and mass transfer of liquid and vapor from the vapor-liquid interface thickness were predicted. These areas were applied to solution on the governing equations for vapor and liquid. The numerical model was validated by experimental results. The errors between the experimental and numerical results for the average temperature difference of the evaporator and condenser were found to be less than 1 °C. The errors for thermal resistance had maximum and minimum values of 15.2% and 3.8%, respectively.

Simultaneous investigation of MHD and convective phenomena on time-dependent flow of Carreau nanofluid with variable properties: Dual solutions

In countless applications, there is a thoughtful necessity for augmenting the poor thermal conductivity of conventional liquids to improve effectual heat transfer liquids. Nanofluids are fluids interruptions of nanoparticles and broad scrutiny have been presented on nanoliquid solicitations in heat transfer progressions. The intention of this exertion is to scrutinize the dual nature solutions of unsteady magnetite Carreau nanofluid influenced by porous stretching/shrinking surface. The phenomena of heat and mass transfer have been established in the manifestation of combined convective conditions with heat sink/source and variable thermal conductivity. By utilizing compatible conversions to rehabilitate the structure of nonlinear partial differential equations (PDEs) into nonlinear ordinary differential equations (ODEs) which were then elucidated numerically via bvp4c. Under the impact of diverse somatic parameters the graphical depiction of all the probable dual solutions of velocity, temperature, concentration, skin-friction coefficient, local Nusselt and Sherwood numbers are scrutinized. These outcomes specify that the liquid velocity display similar tendency for both upper and lower solutions and decline for unsteadiness parameter, while it enhance for Weissenberg number.

Separating the Heat from the Gap

Increasing the conversion efficiency of incident solar energy to electricity is a key goal in the solar R&D community. In this issue of Joule , a conceptual hybrid photovoltaic/thermal (PV/T) receiver design is reported by the research groups of Evelyn Wang and Gang Chen. High exergetic efficiency is achieved by absorbing below-bandgap and excessively high-energy photons as thermal energy, while allowing photons at the PV's bandgap to pass through to the underlying cell.