Moxibustion and laser irradiation are perceived to achieve satisfactory therapeutic effects by inducing photothermal effects on biological tissue. Understanding the photon transport and heat transfer process is an effective way to reveal their underlying mechanism. The temperature distribution of in-vitro tissue under gentle moxibustion and 808 nm laser irradiation were measured experimentally. Photon

Transpiration cooling with liquid phase change has proven great potential as an efficient heat dissipation approach in the cases with extreme high heat flux or tiny coolant availability. Water is widely used as the coolant due to the high specific heat and latent heat of phase change. However, the freezing point of water is relatively high while the boiling point is relatively low, resulting in a narrow

In view of the ever-increasing thermal load being placed on gas turbine blade endwalls, there is an urgent need to develop advanced endwall thermal management techniques. This paper proposes a non-axisymmetric endwall contouring method based on two parameterized control curves. The method is then applied to a blade endwall with an upstream purge flow. The effects of contoured endwalls with different

Droplet solidification is governed by classical Stefan problems which have been commonly treated as a single-phase problem by the majority of the studies in the literature. This approach, however, is unable to capture the initial temperature and the start of freezing time correctly. The treatment of two-phase Stefan problem in spherical coordinates is limited. No known exact solution exists, albeit

The aim of this work is to present results obtained through a multi-physics solver used to numerically determine the thermal behaviour of a phase change material both for solidification and melting processes. Particular attention is addressed to the right implementation of PCM properties, which are not constant with respect to the considered phase. Thus, the energy equation is specifically rewritten

Compact cross-flow three-fluid heat exchanger with plain rectangular fins is experimentally investigated for both thermal and hydraulic efficacy under steady-state condition. The elaborative investigation is conducted for all the four viable flow arrangements of cross-flow configuration which comprises the effect of Colburn factor and effectiveness ratio of central and adjacent fluids, and friction

The theoretical analysis of the field synergy is tried to apply to desiccant coated heat exchangers (DCHEs) to clarify its coupled heat and moisture transfer characteristics and the way to enhance the characteristics. In this paper, the heat and moisture transfer model of DFHE is established and verified by comparison with experimental data. Three field synergy angles between temperature gradient,

Detailed computational analysis has been carried out to study the flow and heat transfer features in a latticework structure under various flow configurations. The three flow configurations include the radial flow configuration (RFC), the cross flow configuration (CFC) and the turning flow configuration (TFC). The numerical approach is validated both qualitatively and quantitatively by the comparisons

Conjugate heat transfer of liquid-gas fin and tube heat exchangers is widely used in industry. However, heat transfer characteristics of such system is difficult to predict as the limiting heat rate can be from either side. This paper aims to quantify the conjugate heat transfer performance of fin and tube heat exchangers via mathematical modeling. Three-dimensional conjugate fluid flow and heat transfer

The present study aims at the experimental and numerical investigations of the Paraffin wax-based mini-channels for the performance enhancement of seven high heat-generating IC chips under the natural convection heat transfer mode. Two mini-channels (left and right) are fabricated at the periphery of the substrate board and are filled with the Paraffin wax. The IC chips are placed adjacent to these

With the continued improvement in integration and power density of electronic devices, it is difficult to simultaneously achieve excellent temperature uniformity and cooling performance with the increasing heat flux of electronic component. Herein, a multi-jet impinging system with trapezoidal fins and secondary channels, which can be used to efficiently cool the electronic component, is proposed.

A numerical investigation is performed to study the serrated trenched-hole film cooling performance on the convex and the concave surfaces, with the use of a plenum coolant-fed mode. In current study, the relevant curvature of curved surface is varied as 2r1/d = 30, 60 and 90 at the convex side, 2r2/d = 90, 120 and 180 at the concave side. In addition, three coolant injection angles (such as θ = 30°

Large eddy simulation is used to study the effect of partial blockage on the film cooling characteristics of cylindrical and fan-shaped holes at the blowing ratio of M=0.5. The results show that severe blockage (H/D=0.75) resulted in a decrease of about 97% and 27% in the laterally-averaged film cooling effectiveness of cylindrical and fan-shaped holes. Slight blockage (H/D<0.5) improved the cooling

In this paper, the electro-thermo convection (ETC) of a perfectly insulted liquid induced by two energized and heated circular cylinders in a cold square cavity is numerically discussed. The abundant flow motion phenomenen are comprehensive results of the buoyancy force and Coulomb force. A newly developed unified lattice Boltzmann (LB) model for flow field, electric potential, charge density and temperature

A novel twisted annulus between two counter-twisted oval tubes is proposed for a double-tube heat exchanger. The oval tubes of the annuli have same twist pitch, but twist with opposite twisting directions. The thermohydraulic performance of the annuli with different aspect ratios and twist ratios is numerically presented. The results indicate that strong secondary flow is generated in the twisted annulus

In the present work, we report heat transfer during the unidirectional laminar flow of ferrofluids in a parallel plate channel in the presence of a homogeneously applied magnetic field perpendicular to the flow direction. We have considered generalized Couette flow which results from the combination of shear stress, due to the relative motion between the parallel plates, and applied pressure gradient

The heat transfer and pressure drop performance of magnetic nanofluids (MNFs) under different alternating magnetic fields were investigated experimentally. The results showed that the effect of alternating magnetic field on local heat transfer coefficient is better than that of unidirectional and non-magnetic fields along flow direction. The local heat transfer coefficient in the rear of the flow channel

The numerical simulation of the horizontal solidification of pure tin under natural convection and under forced convection induced by Electromagnetic Stirring (EMS) is presented and compared with experimental results obtained by the ‘AFRODITE’ benchmark setup, described in several previous publications [6–10]. The experiment consists in solidifying a rectangular ingot (100 × 10 × 60 mm) using two lateral

The combination of a microchannel and a circular synthetic jet has been proven as a promising cooling technology for microelectronic devices. However, the flow control and heat transfer characteristics of a circular synthetic jet in a microchannel are still not clear. This work numerically investigates the interaction between a circular synthetic jet and a cross flow in a microchannel using an in-house

In this study, a three-dimensional model involving heat transfer and melt flow is established to study the influence of the focus position and incident beam angle on the molten pool behavior in electron beam welding of aluminum alloy. The effects of gravity, surface tension and recoil pressure are considered during the simulation process. The formation process of a dynamic keyhole is also investigated

A novel curve tube design called Triple Tube Heat Exchanger was investigated to identify the thermofluidic characteristics in the current paper. This research analysis comprises of both computational fluid dynamics and experimental results. A three-dimensional computational fluid dynamics model was developed using Ansys R19.1 (fluent) research package, and the k-epsilon model is used to realize the

During the design stages of a new geothermal heat exchanger special care is devoted to the peak heating and cooling demands of the building. These lead to extreme temperatures in the heat carrying liquid that may cause unwanted material damages in the installation. The short duration of these peak demands, of a few days at most, require the inclusion of the thermal inertia of the heat carrying liquid

Convective energy transport can be found in various engineering and nature systems. From practical point of view this transport phenomenon within engineering cabinets can be progressed in the presence of temperature modulation. In this research, the transient natural convective heat transference of a temperature-dependent viscosity liquid inside an inclined cube in the presence of time-dependent temperature

Convection is the main reason for surface roughness in both polymeric and non-polymeric films obtained by the drying process (solvent evaporation). It is important to find the origin to control this phenomenon which leads to the creation of a variety of surface patterns that are formed on the polystyrene/methyl ethyl ketone solution in various thicknesses and concentrations. In this research, the convection

Solar assisted thermal energy storage systems have gained potential over last few years. The present study investigates the melting behaviour of PCM in an enclosure under two different boundary conditions representing outlet temperature pattern of a solar collector and is compared with results of a baseline case with isothermal heating. Output temperature of a coaxial evacuated tube for two typical

Thermal stabilization is crucial in directional solidification since the required melt concentration for the following directional growth is obtained through it. In the thermal stabilization stage, a mushy zone where the microstructure changes as thermals stabilization proceeds is formed. The melt concentration difference in liquid droplets in it can lead to diffusion-determined remelting/resolidification

In this study, the thermal insulation properties of nonwoven samples embedded with silica aerogel are examined. Finite element based simulations are performed using COMSOL Multiphysics and ANSYS software in order to predict the thermal performance of samples with different aerogel content. Comparison is made between samples with aerogel as insulating material with stagnant air as surrounding fluid

This paper describes a new method for measuring both the thermal conductivity and thermal diffusivity for solid materials, referred to as the new plane source (NPS) method. This method is quite similar to the Extended dynamic plane source (EDPS) method; however, the essential difference is the location of the temperature measurement. The NPS measures the temperature of the specimen at both the heat

Lubricant filling into a closed fluid domain of a transmission component has always been a challenge, for it is limited by a number of factors, like structural characteristics of a transmission component, load characteristics, and oil temperature of during an operation. This paper proposes a lubricant volume optimization model that takes into account the effect of temperature and heat, with an electronically

A microchannel flow is considered and the influence of the micro-post arrays and air trapped on velocity and temperature increase of the working fluid is examined experimentally and numerically incorporating 3-D simulations. The channel bottom plate is considered to be smooth and hydrophilic, which moves with a constant velocity, while channel top wall is stationary and it has staggered arrangement

In this study, a thermal energy storage system is modeled as an axisymmetric ventilated cavity partially filled with a porous medium that is subject to turbulent flow. Local thermal non-equilibrium is considered to analyze the heat transport and the turbulent k−ε model is used to account for the high inlet flow velocities. Finite volume method is employed for discretization of the equations that are

Composite materials have been widely used across industry sectors. However, they are characterized by a variability of thermal conductivity with the architecture and manufacturing processes. Hence, thermal transfer in composite materials requires an improved fundamental understanding. From numerical purposes, the Finite Element Method (FEM) seems a robust method to study heat transfer in composite

In this investigation, the cooling characteristics of mini-channel heat sink with the water-based nano-phase change material emulsions are examined experimentally. The n-eicosane nanoparticles and the pure water are considered as the as the phase change material and base fluid, respectively. The fluid flow and convection heat transfer in the mini channel heat sink are studied at different parameter

Rib turbulators are widely applied in internal cooling channels of gas turbine blades to improve cooling performance. In this study, heat transfer and friction factor were investigated in internal cooling channels with V-shaped, X-shaped, and cutback X-shaped ribs. Infrared thermography was used to measure heat transfer distribution on the ribbed surface, and the Reynolds number ranged from 10 000

This work is focused on exploring the flow and heat transfer capabilities for slotted and axisymmetric cavity configurations for synthetic impinging jets; the jet is enclosed between two isothermal parallel plates, impinging into the top hot plate. Numerical simulations using the Arbitrary Lagrangian-Eulerian formulation of the Navier-Stokes equations are performed for Reynolds numbers of 50, 300 and

Solid-liquid phase change thermal diode (SL-PCTD) is potential for thermal rectification, however the unsustainable thermal rectification ratio of the SL-PCTD hampers its practical application, demanding a reasonably compatible design. Herein, a SL-PCTD composed of calcium chloride hexahydrate (CaCl2·6H2O) and paraffin wax is investigated, where the supercooling effect of CaCl2·6H2O plays a significant

This study focuses on an experimental and numerical heat transfer investigation of an impingement jet array with a concave target plate that resembles a turbine blade's leading edge. The array consists of nine circular jets with a diameter of Djet and the target plate has a curvature radius of R=Djet. The target plate also features film cooling holes in a staggered configuration so that each jet is

An experimental investigation in mini channel heat sink has been performed to assess the thermal-hydraulic behavior of composite dispersed hybrid nanofluid. Reduced graphene oxide-Zinc oxide (rGO-ZnO) nanocomposite particles have been synthesized and dispersed in water to prepare hybrid nanofluid with 0.01% volume concentration. Effects of different Reynolds number (50–600), volumetric flow rate (0

This study develops a tube element method for thermal performance analysis of fin-and-tube heat exchangers operating with airflow nonuniformity. Experimental investigations have been performed on two fin-and-tube heat exchangers to validate the proposed tube element method. The heat exchanger tubes are discretized into a finite number of tube elements. These tube elements are observed as distinctive

This article presents a study of the thermal constriction resistance developed in a semi-infinite medium subjected to a circular heat source with mixed boundary conditions. The problem is considered axisymmetric and stationary. Two cases of mixed boundary conditions are considered. The contact area can be subjected to a non-uniform axisymmetric heat flux density while the remainder of the surface is

New heating technologies are constantly being developed worldwide, specially the electrical ones that take advantage of renewable energy. In this paper, the Basic Cell of Energy Transference (BCET) is proposed as an innovative fluid heater, carrying a microwave-fed heat transfer plate for thermal contact. A fully-dimensional thermo-fluid analysis was implemented and validated to determine the key design

The thermal performance of a latent heat energy storage system utilising tightly fitted, thermally bonded and non-bonded metal inserts as a heat transfer enhancement material has been investigated. Two methods were used for this purpose. Firstly, a numerical study using volume averaging method was performed and secondly, an analytical study using scale analysis to obtain the theoretical prediction

The aim of this study is to present an inverse thermomechanical methodology to identify thermal boundary conditions and the thermal expansion coefficient from experimental deformation measurements. By means of an analytical approach, we establish a thermoelastic mechanical transfer function between the temperature of a heated surface and the mechanical deformation of a solid at a given abscissa far

Experimental study and sensitivity analysis on the heat transfer and pressure drop of a shell and helically coiled tube heat exchanger (SHCTHE) are carried out. The inclination angle (ɵ) is varied from the horizontal direction (0°) to vertical direction (90°) by a step of 10° and the coil Dean number (Dec) is varied from 1540 to 3860. The results indicate that the effectiveness of SHCTHE (ε) at the

The paper analyses a novel model of unsteady convective heat transfer in a nanofluid layer on a flat vertical surface subject to instantaneous (abrupt) onset of film boiling. It occurs if heat flux suddenly switched on exceeds the critical heat flux necessary to bring a nanofluid to film boiling regime. The usual system of equations of fluid flow and convective heat transfer is supplemented by an equation

To reveal the impact mechanism of water droplet diameter distribution in the rain zone on the cooling capacity and water-splashing noise for natural draft wet cooling towers (NDWCTs), a 3 D numerical model of thermal performance and a theoretical calculation model of water-splashing noise were established and validated, respectively. Using these two models, the influences of different diameter distributions

The complex pore structures are of great significance to gas transport and heat transfer in shale gas reservoirs, but an accurate prediction of permeability and thermal conductivity is a challenge to a porous medium with the complex geometry and distribution of pore networks. This study investigates the permeability and thermal conductivity of shale matrix with a bundle of tortuous fractal tree-like

Efficient and targeted cooling of small discrete heat sources located in a confined gap, such as a microslit, is challenging. In this study, we demonstrate by using electrospray technique, the charged droplets can be effectively transported within a microslit – consisting of a top substrate and a bottom substrate – and subsequently deposited on the heated spots located within it; up to approximately

Heat flux (HF) distribution around the receiver tube of parabolic trough collectors (PTC) has a crucial effect on their outlet temperature (To) and thermal efficiency (ηth). Since its receiver tube is as a heat exchanger, the higher amounts of ηthcan be achieved by changing the geometry of the receiver tube. In previous researches, the geometrical variations were made in the internal geometry of the

In this paper, effect of the heaters' clearance on mixed convective cooling performance in a discretely heated horizontal duct is examined. Tests are carried out for a constant value of the modified Grashof number (GrDh*=1.15×107), and for Reynolds numbers (ReDh) between 792 and 3,962. In the analysis, surface to surface radiation and wall conduction are coupled with convective heat transfer. Experiments

Since experimental studies in the field of nanofluid pool boiling requires costly and time-consuming tests, numerical methods such as artificial neural networks with higher predictability and nonlinear features are suitable for prediction and modeling of problem parameters. In this paper, 180 pool boiling laboratory data of Fe3O4/water nanofluid are employed as datasets used for network training to

Combustion within porous inert media is an effective way in order to obtain high radiant outputs for a large range of power densities, while simultaneously reducing pollutant emissions. Due to the complex interactions between the different heat transfer modes involved, the parameters that influence the heat transfer process hold much potential in terms of optimization of the porous radiant burner performance

In this work, nucleation site interaction and nucleate boiling heat transfer are studied on a hybrid rough surface, a surface with multiple cavities and a pillar on sides of each cavity, using a two-dimensional pseudopotential phase-change lattice Boltzmann method (LBM). To elucidate the effects of incorporation of pillars, the results of the hybrid rough surface are compared with a simple rough surface

Generally, using heat transfer enhancement techniques in heat exchangers always accompanies frictional pressure drop amplification; entropy generation analysis is a suitable technique to investigate the heat transfer and pressure drop together. In this study, the effects of tube's geometrical parameters and flow conditions on entropy generation during two-phase boiling flow of R134a refrigerant in

We study the melting process of phase change materials (PCM) inside a shell-and-tube heat exchanger with punched-fin and slit-fin numerically based on the enthalpy-porosity model in the present paper. The phase change material used is paraffin wax. A comparison of the liquid fraction, the total melting time, and the average temperature was performed to assess the improvement of the melting processes

The heat transfer characteristics in a rectangular channel under rotating conditions with impingement jet and film holes was studied. The key features of the geometry are multiple impingement jets and film holes in the leading edge model. The jet Reynolds number (Rej), jet rotation number (Roj) and buoyancy number (Buo) varied from 5000 to 10,000, from 0 to 0.24, and from 0 to 0.57, respectively. Four