Numerical investigation on Metal Foam Pin-Fin Heat Sink (MFPFHS) has been conducted and compared to the traditional Solid Pin-Fin Heat Sink (SPFHS). For investigating turbulent convection heat transfer and friction factor characteristics in the MPFHS, the 3D steady continuity, momentum, and energy equations are discretized using the finite volume approach. The key parameters investigated here are;

Numerical studies are performed to investigate the condensation behavior of single and multiple bubbles in subcooled boiling flow. An open-source code is developed to model the dynamic behavior of the bubbles in real-time. The Newtonian flow is considered and relative equations are solved employing a coupled Level Set (LS) and Volume of Fluid (VOF) method known as CLSVOF model according to the Pressure

In this paper, the saturated pool boiling heat transfer from a heated circular surface is investigated numerically based on the popular lattice Boltzmann phase-change method. The crucial interfacial phenomena, including the bubble growth, departure, coalescence, and rising under different wall superheats, wettabilities, and heater sizes are studied, and the corresponding heat transfer characteristics

The interaction between the natural ambient winds found in the atmospheric boundary layer (ABL) and buoyant flames is crucial in broad applications in the scientific and engineering fields. Unlike the buoyancy-driven pool fires in still air that have been studied extensively, the complexity of physics changes significantly in wind presence. This study aims at analysing the characteristics of boundary-layer

Recent studies have demonstrated that the simple cylindrical hole with backward injection, where the jets are injected reverse to the mainstream flow direction, outperforms its forward-injected counterpart at relative high blowing ratios. Meanwhile, trench is known to be of high cooling effectiveness with forward injection at high blowing ratios. Few studies addressed the combination of the two setups

The influence of the braided structure on the film cooling performance over a ceramic matrix composite plate was numerically and experimentally investigated. The model based on the effective thermal conductivity and the model based on the internal micro braided structures were both built to demonstrate the effects of the braided structure on the cooling performance. Firstly, the experiment of the film

The two-phase flow and heat transfer characteristics of a free liquid jet impinging on a heated rotating disk are investigated by the CFD method. Numerical simulations are conducted over a range of rotational Reynolds numbers, jet Reynolds numbers, jet temperatures, nozzle diameter to disk spacing ratios, and disk to nozzle diameter ratios. The results show that the local Nusselt number increases first

In this work we show that laser-spot step-heating thermography allows measuring the thermal diffusivity of solids accurately. It consists in illuminating the sample surface with a continuous-wave focused laser spot and recording the time evolution of the surface temperature with an infrared camera. The inherent noise associated to time domain measurements is reduced by applying a very simple image

The temperature of light-emitting diode (LED) light bulbs must be managed to maintain their performance and increase their lifespan, and the design and application of an appropriate LED heat sink are particularly important for temperature management. This study investigated the heat-dissipation performance of a heat sink with perforated fins on a cylindrical base. To improve the heat-dissipation performance

The submerged jet impingement boiling is one of the most effective heat transfer methods in dissipating both transient and steady concentrated heat loads. However, studies on the submerged jet impingement boiling still lack experimental data, especially for the heat transfer characteristics of the onset of nucleate boiling (ONB). Therefore, an experimental study of a submerged circular jet impinging

In the present study, the flow pattern, boiling heat transfer, and pressure drop of R1234yf are experimentally studied inside a plain tube with an inner diameter of 8.3 mm, the outer diameter of 9.52 mm, and the length of 670 mm, in seven different inclination angles from −90° (downward vertical flow) to +90° (upward vertical flow). The experiments are conducted at four mass velocities of 80, 160,

The optimal shape of a Plate-Pin-Fin Heat Sink with Perforations and Splitters (PPFHS-PS) is designed in this work using the software package CFD-ACE+ and the Levenberg-Marquardt method (LMM) to determine the maximum thermal performance factor η under a fixed fin volume constraint. In the present work, the implementations of perforations and splitters on a pin fin are examined, and the diameter of

A methodology for obtaining analytical solutions for the extended Graetz problem including the effects of axial conduction, viscous dissipation heating, and additional volumetric heating effects in an infinite domain has been developed. The domain extends infinitely in the directions parallel to the flow, being divided into a preparation upstream region, in which the walls are either thermally insulated

With the development of high-performance electronic equipment, pool boiling heat transfer has attracted great attentions because of its great heat dissipation capability. Although the physical properties of surface like thermal conductivity and wettability could have important influence on pool boiling, their effect has not been systematically studied. In this work, the copper, nickel and copper-nickel

Numerical simulation is performed to evaluate the privilege of inserting stationary or rotating twisted tape inside a tube as a heat transfer enhancement technique. The main emphasis of this work is placed on understanding the effect of pitch distance on the hydrothermal performance of such a system. The obtained results are validated with published experimental findings. The results of numerical study

Condensation heat and mass transfer characteristics of low GWP zeotropic refrigerant mixtures R1234yf/R32 (mass fractions of 0.52:0.48 and 0.77:0.23, respectively) inside a horizontal smooth tube (inner diameter 4 mm) were studied experimentally. Moreover, a non-equilibrium film heat and mass transfer model was also developed by considering the mass transfer resistance on the vapor and the liquid side

In this study, the effect of the variable radiative absorption coeeficient in a two-dimensional closed cavity containing an electrical conductor fluid under a uniform magnetic field on the heat transfer and the fluid flow is investigated. The governing equations for the laminar flow and the boundary conditions are solved numerically using the finite volume method. The dependence of the velocity and

The thermal performance, embodied energy, and environmental CO2 emissions are evaluated experimentally for MWCNT/water nanofluid flow in a double pipe U-bend heat exchanger. The experiments were conducted at different Reynolds number (3500–12000) and particle volume concentrations (0.05%–0.3%). The thermal conductivity and viscosity are augmented by 15.27% and 9.15% at a temperature of 70 °C with respect

The prediction of turbulent heat transfer at a reasonable computational cost is a topical issue in computational fluid dynamics. This study addresses the numerical simulation of heat transfer from a circular cylinder in a cross-flow. Simulations were performed at a low sub-critical Reynolds number (Re = 3900) using the Partially-Averaged Navier-Stokes (PANS). Seven ratios of unresolved to total turbulent

The objective of the present work is to measure the local heat transfer coefficient for an unconfined slot air jet impinging on a metal foamed flat plate having different pore densities using a thin metal foil technique. The enhancement of the heat transfer caused by the metal foamed flat plate in comparison with a smooth flat plate is measured. The experiments are performed for the Reynolds number

The considerable increase of the heat flux and chips density on the phased array antenna has brought great challenges to the thermal management. The objective of the work is to explore an effective scheme to achieve ideal uniform temperature distribution and lower maximum temperature with the condition of non-uniform heat flux. Taking into account of the high efficiency of microchannel heat sink and

Hotspot cooling is a significant problem in the thermal management of electronic devices. With device dimension scaling down, the dissipation space becomes more and more confined making hotspot cooling challenged. However, effective solutions are limited. In this study, the feasibility of hotspot cooling by ionic wind in confined space is justified. It is demonstrated that the hotspot in a confined

The cocoon with a unique hierarchy not only provides a space in which the pupa to adult metamorphosis occurs, but also protects the pupa from weather, predators and parasitoids. In this paper, scanning electron microscope (SEM) is adopted to elucidate the basic geometric properties of the cocoon and silk morphology. Tussah cocoon has a special geometric structure, and its silk fibers have shaped morphology

The effect of relative position of two rows of film holes on film cooling performance was experimentally and numerically investigated on each side (suction side and pressure side) of rotating blade leading edge. The film cooling performance was measured by pressure sensitive paint and phase-locked techniques. The numerical simulation was also employed to improve the understanding of flow filed. The

In this paper, we consider the flow and heat transfer behaviour of turbulent upward and downward flows of supercritical n-decane, in order to reveal the features of heat transfer deterioration (HTD) that would be expected in relevant active regenerative cooling systems for scramjet engines. Specific focus is placed on key velocity-field features that appear in these flows. Following the validation

This paper investigates the effect of two-phase mixing of gas and liquid in a top-blowing mixing tank on the uniformity of temperature distribution, using hot heat transfer oil and air as the working medium. Results show that temperature difference is the main factor influencing the temperature field uniformity in the mixing tank, and the uniformity of the temperature distribution increases with the

Porous fins due to high extended heat transfer surface are widely used in different engineering devices including heat exchangers, solar collectors, and chemical reactors. Location of these fins within the working area can be very manifold. Therefore, the present research deals with computational analysis of complicated porous fin influence on nanofluid flow and heat transfer within the heated/cooled

In this experimental and numerical investigation, the use of circular cross sectioned ring-type flow turbulators was considered as a method to increase local heat transfer coefficients in annular heat transfer passages. Experimental data was obtained for cases with and without ring turbulators within a horizontal annular test section using water for average Reynolds numbers ranging from 2000 to 7500

Transverse buoyant jet-induced mixed convection inside a large thermal cycling chamber with perforated plates is investigated experimentally and numerically. The mean temperature distribution and temperature fluctuation are obtained experimentally under cooling and heating conditions. The numerical simulation is conducted by solving the Reynolds-averaged Navier-Stokes (RANS) equations using the low-Re

This study aims to enhance the localized energy of the plasma arc to meet the requirement of thick metal plate welding. To achieve this, a novel hybrid heat source by coaxial arranging the laser and plasma arc was proposed, named laser-enhanced plasma arc (LPA). This special torch combines the two kind sources by a tubular tungsten electrode which the laser passes through, use laser to heat localized

Particle reinforced materials are widely used in many areas, including energy storage, energy saving, thermal protection, and thermal management. These applications tend to require an accurate foreknowledge of the effective thermal conductivity of these materials. Although there exist many different effective thermal conductivity models for this kind of materials, a general and accurate model for the

This work presents a hybrid analytical/numerical approach for transient heat conduction through composite hollow cylinder structures applied for Plug and Abandonment (P&A). The Distribution Transfer Function Method (DTFM) is a mathematical framework able to solve both nonhomogeneous boundary conditions and a nonlinear partial differential equation with spatial-temporal source term, presenting good

With the development of heat engines, in some fields the heat wall suffers from dynamic heat flux, thus some cooling control techniques are needed to meet this dynamic cooling requirement. The traditional stationary vortex generators have not met the cooling demand in these cooling fields with dynamic heat flux. Existing studies have shown that the capacity of convective heat transfer depends on the

This paper investigated ceiling temperature profile induced by double pool fires in a tunnel. A series of small-scale experiments and fire dynamics numerical simulations have been carried out with different fire sizes and fire spacing. The results showed that the longitudinal ceiling temperature distribution falls into exponential decays, and the experimental data is higher than Delichatsios's model

Recently, the particular energy separation of the vortex tube was thought to be caused by the energy transferred from the inner core stream to the outer periphery stream through the precessing vortex core, and the precessing frequency is a remarkable signal released by the vortex core. To study the basic distribution of the precessing frequency and the relationship between the frequency and energy

The experimental investigations are designed to study ignition behaviors of ethanol and heptane pool by adjacent fires. Four quartz glass pools with diameters of 74, 114, 150 and 200 mm are used. The multiple of pool diameter is selected as a criterion to characterize critical ignition distance with different pool diameters. The influences of pool diameter and interval distance on critical ignition

Designing an accurate and efficient heat protection system for the area around the high-temperature stagnation point on supersonic aircraft is still an important topic of research. In the present study, a three-dimensional high thermal conductivity carbon/carbon (C/C) composite thermal protection system embedded with L-shaped carbon fiber bundles for directional heat transfer is proposed as a high-efficiency

Thermal contact conductance (TCC) is a key parameter, which influences the reliability of various cryogenic systems. The accurate estimation of TCC is a basic requirement for the optimal design of cryogen-free conduction cooling systems. The lack of reliable TCC results for bare demountable aluminium contacts in the sub-ambient temperature range (50–300 K) prompted us to undertake the systematic experimental

The Distribution of Ratios of Energy Scattered by the medium Or Reflected by the boundary surface (DRESOR) method based on the Monte Carlo method is an important new approach to solve the radiative transfer equation accurately and efficiently. This method has been applied extensively for the detection and analysis of the furnace flame temperature. However, the discrete method, the number of direct

Although the microstructure of matrix has a significant impact on coal thermal–hydrological–mechanical interaction, this effect has not been included in the permeability analysis of the coal bed methane (CBM) extraction. Previous studies have typically investigated the relationship between coal porosity and permeability through classical cubic permeability model, neglecting the contribution of the

The flame spread over combustible materials is often affected by the fire thermal radiation and convection and the heat exchange with adjacent objects, which are especially complex on melting thermoplastics. This work chooses polyethylene (PE) tubes with a 2-mm thin wall to study the flame-spread behaviors under three heating conditions, (a) hot inner boundary, (b) hot ambient, and (c) external radiation

Gear quality is one of the factors that determine the stability of the wind turbine. Electromagnetic heating is a green and efficient heating method, which has been used to heat wind power gears. Good mechanical properties could be obtained by induction hardening on the surface of wind power gears. And a uniform hardened layer along the tooth profile is needed. In this paper, research on the effect

The tip leakage flow between rotating turbine blades and the stationary turbine casing causes aerodynamic losses and high thermal loads. Numerous novel tip geometries have been proposed for reducing both of these effects, one of them is a shelf squealer tip. The objective of this study is to investigate the aerothermal performance of three squealer blade tip configurations: conventional, vertical shelf

Improving the heat transfer of cooler is favourable to reduce the cold end temperature and dead volume of Stirling engine. In this study, the effect of the implementation of a helical wire to a cooling tube of the reciprocating flow in Stirling engine was investigated numerically. The performance of helical wire with different geometric parameters and under different operating conditions were studied

An experimental investigation has been carried out to study the thermo-hydraulic performance of a solar air heater with staggered multiple C-shape perforated and non-perforated finned absorber plate. The experiments were conducted with a relevant range of flow parameters as Reynolds number from 3000 to 27000 and geometric parameters such as relative pitch to gap ratio from 3.4 to 3.8, relative height

In this paper, the lattice Botlzmann method is used to simulate the coalescence behavior of double bubbles on different wettability walls. For hydrophilic surfaces, the supplementary microlayer can be captured when bubbles coalesce, and there is an obvious heat flux peak. For the hydrophobic surface, there is no supplementary microlayer because the bubbles coalesce at the bottom. It is difficult to

This paper reports the results of our studies on the performance of thin film evaporation, mostly used in the evaporator of an ultra-thin vapor chamber using micropillar arrays. The dry-out heat flux and evaporator surface temperature have been used as the performance metrics. A numerical model has been formulated to solve for the fluid flow and phase change heat transfer considering the capillary

Application of thermocouple sets of various complexity as temperature sensors in porous materials can be accompanied with systematic errors related to the very high differences between the thermal conductivities of thermocouple forming metals and measured samples. Since the higher measurement uncertainties can then make some presumed utilizations of measured temperature fields questionable, this paper

There are industrial applications, such as spherical tanks under very low wind conditions, in which natural convection from spheres at high Rayleigh numbers can be of great importance. Due to different limitations, this problem has been studied either experimentally or numerically for Rayleigh numbers smaller than 1011, approximately. Furthermore, just a few correlating equations are available in scientific

The way of heat exchange in the closed wet cooling tower is through the direct contact between the air in the tower and the process water, so as to achieve the purpose of reducing the temperature of the process water. In order to improve the thermal performance of closed wet cooling tower and solve the problem of low heat transfer efficiency, a new elliptical finned tube of cooling tower is proposed

In the present study, the nucleate pool boiling heat transfer characteristics of water on the hydrophilic and uncoated metal foam covers were experimentally investigated, and were compared with those on hydrophobic metal foam covers to analyze the influence of surface wettability on pool boiling heat transfer on metal foam covers. The experimental conditions cover pore densities of 5–50 PPI (pores

In the current investigation, heat, flow characteristics, and exergy analysis of hybrid and single nanoparticles-based water passing through a triple ribbed tube heat exchanger (TRTHE) under several design and operation parameters are studied. A computational fluid dynamics (CFD) modeling is carried out using ANSYS-FLUENT 19 code while the validation criteria are accomplished with experimental data

We present an original model describing the transient flow boiling crisis of water at high subcooling and atmospheric pressure. We hypothesize that in such conditions, the mechanism of the boiling crisis is the prevention of the bubbles recondensation when a thin fluid layer near the heated wall reaches temperature saturation conditions. To capture this phenomenon, we propose an energy model describing

With the growing demand of higher power density, at the expense of lesser environmental encroachment, use of supercritical carbon dioxide in miniature systems is becoming increasingly lucrative. However, concerned literature, particularly for horizontal geometry under heating condition, is relatively thin. Presently work, therefore, focuses on the numerical characterization of thermalhydraulics of