Nanofluid preparation and its deposition on metallic surfaces are in wide practice due to their enhancement capability in the pool boiling heat transfer. The effect of zirconia nanoparticles coated layer on pool boiling heat transfer has been investigated with de-ionized water. The turbidity, viscosity and stability test are conducted, and confirmed a better dispersion of nanoparticles. The synthesized

The present study involves the use of dip nanocoating, one of the passive techniques by the modification of the heater surface to understand the behavior of pool boiling heat transfer characteristics at atmospheric pressure using deionized water and Graphene- Poly (3,4-ethylenedioxythiophene): Poly (styrenesulfonate) as a working fluid and coating material. The copper specimen is coated with the mentioned

In this study, the cooling and dehumidification performance of a photovoltaic powered thermoelectric air conditioning system is investigated under tropical climate. The system is first investigated under a controlled environment with different flow arrangements of the hot junction cooling air stream. Better temperature reduction was observed when the cross-flow arrangement is used. Besides, it delivered

Thermosyphon based evacuated tube solar collectors have seen exponential growth in the last few decades for domestic hot water applications. The output temperatures of such collectors can be increased by integrating evacuated tube receivers with compound parabolic concentrators (CPCs) to meet many industrial heat loads. This paper presents a new concept of increasing concentration of solar radiation

In humid climates, due to high relative humidity present in the ambient air, traditional air drying system is becoming inefficient for drying the agricultural/food products. On the other hand, there is a scarcity of useful drinking water in many parts of the world. In order to meet the aforementioned requirements, a novel multipurpose liquid desiccant drying/desalination system has been proposed in

Water scarcity is the biggest survival challenge for the current generation, and atmospheric water condensation can be a solution. This paper presents the results of a numerical and experimental evaluation of a novel thermoelectric air duct dehumidifier system (TE-ADD) installed on a test chamber. The subject system, made of twenty-four thermoelectric modules along with heat sinks and fans, was used

Metal-organic frameworks (MOFs) are emerging as potential adsorbents for adsorption based systems intended for various applications. Aluminum fumarate is one of the promising MOFs for being used as an adsorbent for water-based adsorption heat pumps. Though there have been a lot of studies regarding water adsorption characterization of aluminum fumarate, there is hardly any literature addressing the

Thermal energy storage has a potential future to store renewable energy. Thermochemical energy storage (TCES) is the most promising and possesses more advantages over sensible and latent heat thermal storage systems such as higher energy storage density and ambient temperature storage. The major concern at this time for TCES is to find the material or combination of materials which can be thermally

Countermeasures for global warming have been promoted internationally. Heat pump cycles that utilise refrigerants with high global warming potential values are required to adopt the next generation refrigerants to conform to the revised Montreal Protocol. Refrigerants R410A is commonly used in the room air conditioners while it has been substituted with HFC32 in Japan; yet their global warming potential

As the use of semiconductors in industrial site increases, research on ultra-low refrigerators is required to increase the life and quality of the semiconductors. While various types of refrigerators exist, Joule–Thomson refrigeration with the mixed refrigerant is preferred because of its compactness and stability. The performance of Joule–Thomson refrigeration with mixed refrigerants is based on the

The urge to replace hydrofluorocarbons which possess high global warming potentials has taken center stage in the air conditioning industry due to both international and local policies such as the Kigali Amendment and Japan’s revised Fluorinated Gas law. This has prompted the exploration of novel refrigerants as well as their mixtures to create high performance environmentally friendly alternatives

Experimental study on using nanofluid in a cross-flow minichannel heat exchanger (MICHX) to investigate its transient behavior was completed. Step changes of temperature and flow rate in the hot liquid were applied and the dynamic performance of the heat exchanger was analyzed. Results of nanofluid were compared to water and demonstrate an enhancement of 19% in heat transfer when using 2.5 wt% concentration

The effect of non-uniform magnetic field on forced convection heat transfer of ferrofluids in flattened tubes has been investigated numerically using two-phase mixture model. The equilibrium magnetization for the ferrofluids is considered, and the linear relationship of magnetization with applied magnetic field intensity is assumed to relax. The main goal of the current research is to study the effect

Advances in manufacturing technologies and the recent explosion of materials and methods for creating additively manufactured devices has opened new avenues for novel heat sink designs that can be optimized for flow and conduction considerations. This review paper highlights many of the recent successes and challenges associated with the utilization of “3 D printed” heat sinks for applications in electronics

The thermal efficiency of the modified Trombe-wall system proposed in this work is improved compared to its conventional version thanks to the adjunction of a porous material to the absorber wall. Thermal measurements were made in a wide Rayleigh number range, with high values reaching 4.52 × 109. The ratio between the matrix’s thermal conductivity of the porous material and that of the air varies

The systematic experimental investigation of the viscosity of more than 30 different nanofluids was carried out. The investigated nanofluids were prepared based on distilled water, ethylene glycol and engine oil containing nanoparticles Al2O3, TiO2, ZrO2, CuO, Fe2O3, and Fe3O4, as well as nanodiamonds. The nanoparticle volume concentration ranged from 0.25 to 8%. The size of nanoparticles varied from

The swirling flow is used to increase mixing and decrease nitrogen oxide emission in the combustor. Meanwhile, the swirling incoming flow has a significant effect on both aerodynamic and heat transfer characteristics of the downstream first-stage turbine. This paper conducts a numerical investigation on the influences of the inlet swirl core on the film cooling performance of a leading-edge model.

The heat and mass transfer characteristics of a micropolar nanofluid-filled cubic cavity are investigated with different types of nanoparticles (Al2O3, TiO2, Cu and Ag). Pure water is assumed as the base fluid. The governing equations are simplified by means of vorticity-vector potential formulation and subsequently solved numerically using the finite volume method. The influences of relevant parameters

The non-Fourier dual-phase-lag heat model has been solved as a well-known accurate bioheat model to compute the temperature distribution in a three-dimensional multilayered skin of the human finger including the embedded vessels. A novel conjugate solver over the platform of OpenFOAM codes has been developed. Three types of vessels that are representor of the capillaries, the small arteries, and the

Examining non-rarefaction effects in laminar micro-convective low subsonic (with negligible compressibility effects) gas flows is as important as the well-explored rarefaction effects. This study numerically analyzes one of the important non-rarefaction effects arising from steep density variations due to the steep temperature-gradients, in micro-convective air-flow. For the constant wall heat flux

In this study, a cooling radiator developed specifically for unmanned aerial vehicles was analyzed using computational fluid dynamics (CFD). The radiator consisted of turbulator pins (core side) placed between two vertical columns (column side). While the air passes from the core side, the cooling fluid takes place between two streams on the column side. CFD modeling of the radiator, which was developed

Channels not receiving the same amount of flow (flow maldistribution) is an important effectiveness loss for high effectiveness heat exchangers. This paper develops a finite difference model of a counter flow heat exchanger. It reproduced the simple NTU result for two channels exactly. For more than two channels, there is an edge effect, and the model agreed within 0.1% of the literature. Perfect agreement

This paper presents the creation of three-dimensional (3D) maps for selection of best Colebrook friction factor approximation. Twenty Colebrook approximations are observed in range of Reynolds numbers between 4000 and 108 and relative surface roughness less than 0.05. Colebrook approximations with the lowest relative errors at various combinations of Reynolds numbers and relative surface roughness

This paper proposes a numerical model of wicked heat pipes using a lumped parameter network. A lumped parameter network of a screen mesh wicked heat pipe is developed for the solid and fluid regions. Nodal analysis is applied to each node using the principles of conservation of mass, momentum, and energy. The resulting system of differential equations is solved using numerical integration. The lumped

In this study, the thermal and hydraulic performances of six different printed circuit heat exchanger (PCHE) configurations with supercritical liquefied natural gas as the working fluid are studied by a numerical method. Firstly, the thermal and hydraulic performances of the PCHE with airfoil fins are investigated at different operating pressures, which indicate that the PCHE with airfoil fins has

In this study, the effect of lubricating oil on the heat transfer characteristics of R600a condensing flow inside a horizontal micro-fin tube is experimentally investigated. The results are presented in three parts, including the characteristics of pure R600a condensation inside a smooth tube, the impact of using a micro-fin tube, and the effect of adding lubricating oil on the condensing heat transfer

This paper expounds the effect of horizontal spacing between two horizontally aligned circular cylinders on laminar natural convection to non-Newtonian power-law fluids. Numerical computations have been carried out for the following range of conditions: Grashof number (10 to 105), Prandtl number (0.71 to 100), horizontal spacing (0 to 20 times the cylinder diameter), and power-law index (0.4 to 1.6)

This study investigated the thermal performance of ultra-thin heat pipes (UTHPs). The total thickness of the heat pipe was 1 mm and the novel wick structure was copper braids modified to be superhydrophilic with higher capillary ability. This paper is divided into three parts, each focusing on the effect on the heat transfer performance of UTHPs, including the wettability of the wick, the filling ratio

Increasing attention has been paid to the flow and heat transfer in annular channels since their intensive applications in engineering. In this study, evaporation of the outer surface of two enhanced heat transfer tubes (2EHT) was compared to the performance of a smooth surface copper tube through experimental research. The refrigerant flowed in an annular space between the outer tube and the test

Printed circuit heat exchanger (PCHE) is a promising candidate of coolers used for SCO2 Brayton cycle. The thermal-hydraulic performance of SCO2 in a PCHE depends on the PCHE structure as well as the operating conditions of SCO2 due to its dramatic variation of thermal physical properties near the pseudo-critical point. This work experimentally investigated the thermal-hydraulic characteristics of

Accumulation of ice particles inside the pipes of an ice slurry refrigeration system is a problem that should be avoided to ensure the efficient performance of the system. In the present research, the swirling flow of ice slurry is numerically investigated using the Eulerian-Eulerian model coupled with the kinetic theory of granular flow. The swirling flow is generated by twisted tapes inserted into

Heat transfer induced by combined surface radiation and laminar natural convection in an open square cavity heated by three identical isothermal heat sources is studied numerically by using the multirelaxation time scheme of the lattice Boltzmann method. The working fluid is air. The heat sources, separated by adiabatic segments, are mounted on a vertical wall facing the aperture of the cavity and

The water permeability, form drag coefficient and heat transfer coefficient of porous copper samples manufactured by the Lost Carbonate Sintering process were measured and analyzed. The permeability increased and the form drag coefficient decreased with increasing porosity and decreasing pore size. There existed an empirical relationship between the form drag coefficient and the permeability. The highest

Heat transfer to an oscillating vertical annular flow through a porous material is investigated experimentally. The flow media includes stationary stainless steel wool filter and monoethylene glycol (which is known as a coolant, heat transfer agent or antifreeze) as the working fluid. Reciprocating forced oscillations are imposed on the single-phase monoethylene glycol via a frequency controlled dc

The liquid flow and heat transfer performance in rectangular channels with winglets are determined numerically in the Reynolds number range of 100 to 300. Water with constant thermophysical properties is used as the working fluid and modeled to be Newtonian. Three-dimensional numerical simulations have been performed on a rectangular plain channel and a rectangular channel with five pairs of winglets

In this study, in-tube condensation was conducted for mass fluxes of 100, 75 and 50 kg/m2s, and temperature differences of 1, 3, 5, 8 and 10 °C. Measurements and flow regimes were captured at various mean vapor qualities between 0.1 and 0.9 inside an inclined smooth tube with an inside diameter of 8.38 mm and 1.49 m long. Fifteen distinct inclination angles from -90° to 90° were considered while the

Laminar natural convection in unconfined power-law fluids from two attached horizontal cylinders has been investigated numerically to elucidate the non-Newtonian behavior of the fluid over a wide range of pertinent parameters: Grashof number (10 to 105), Prandtl number (0.71 to 100), and power-law index (0.2 to1.8). The heat transfer characteristics are elucidated in terms of isotherms, local Nusselt

Nanofluids are suspensions of ultra-fine nanoparticles or tubes resulting in the nanofluids having thermal conductivities significantly higher than those of the conventional base fluid alone. The purpose of this study is to evaluate the thermo-physical properties, including thermal conductivity, viscosity, electrical conductivity and above all, convective heat transfer coefficient, of de-aggregated

Stable direct contact condensation of choked steam jets in subcooled water has been the focus of researchers during the last three decades. Comparatively fewer works were reported on unstable direct contact condensation of steam jets which typically occurs at low steam mass flux and low pool subcooling. The focus of this paper is on the study of unstable direct contact condensation of steam jets in

A wireless vacuum sensor based on the Pirani principle and Surface Acoustic Waves (SAW) has been designed, simulated and manufactured. The sensing unit is a heat conductivity gauge based on a passive SAW temperature sensor. The required heating energy is applied to the sensor by means of inductive coupling whereas the measurement signal is sent via a ceramic antenna. The sensor is a compact polymer

A novel structure for a shell-and-tube heat exchanger (STHX) with triple-layer flower baffles consisting of three blades is proposed in this article. This study also compares the performance of three heat exchangers with triple-layer flower baffles, double-layer flower baffles, and segmental baffles. In order to compare the hydrodynamics and heat transfer characteristics of the three heat exchangers

In this article, the thermal and frictional characteristics of interrupted wavy mini-channel are experimentally investigated as the wavy vortex generator miniature channel (WVGMC) using SiO2–H2O and Al2O3–H2O nanofluids. Its performance characteristics are compared to the common configurations of cooling mini-channels, that is, the wavy mini-channel (WMC), straight mini-channel (SMC), and the miniature

The present research conducts an experimental study on the thermal performance of the finned metal foam (FMF) heat sinks with phase change material. The dynamic temperature response of an FMF heat sink is analyzed and compared with the corresponding finned heat sink. The effects of porosity and pore density on the thermal performance of FMF heat sinks are analyzed. Furthermore, the enhancement ratio

While microchannel evaporator based cooling systems are efficient in removing high heat fluxes they are prone to the instability mechanism called pressure drop oscillation. The instability can lead to poor cooling performance, system fatigue and even mechanical failure of the cooling system. To address this challenge, a system level approach with dynamic control of cooling performance is studied in

Abstract The article presents the experimental results of flow boiling of water in single rectangular microchannels. Three rectangular copper microchannels having the same hydraulic diameter (0.56 mm) and length (62 mm) but different aspect ratios (width/height, 0.5, 2.56, and 4.94) were investigated using de-ionized water as the working fluid. The experiments were conducted over the experimental range

Atmospheric condensation is very important for multiple practical applications such as heat transfer, thermal management, aerospace, and condensate harvesting. Water droplets heterogeneously nucleate on the surfaces when the temperature is below the dew point temperature. The nucleation energy barrier for a condensed droplet varies significantly with the humidity content in the operating environment

A jet impingement cooling device was designed with jet-adjacent fluid extraction ports distributed throughout the impingement array. The device was fabricated from a photopolymer material using a three-dimensional printing technique and tested for flow resistance and cooling performance using water as the working fluid. Parallel to physical experiments, computational simulations were performed using

The objective of this article is to analyze complex micro-channels with wire-net and S-shaped perturbators and implement a reduced order modeling (ROM) approach to assess the entire heat exchanger performance and validate through experiments. Shifting the critical Reynolds number to lower values using perturbators decreases the pressure losses and enhance the thermal efficiency. There is an optimum

(2020). Selected Papers from the 6th Micro & Nano Flows Conference. Heat Transfer Engineering. Ahead of Print.

The use of Milli-Channel Heat Exchangers (MCHE) presents numerous assets: efficient heat transfer, huge compactness, and limited pressure drop. For an engineer, the Fanning friction factor and the convective heat transfer coefficient are two main parameters to describe the performance of a heat exchanger. A brazed MCHE with rectangular channels in stainless steel made by the Institut für Mikrotechnik

Numerical investigation of natural convection from heat-conductive source enveloped by a porous layer in a cavity is presented. The right and left walls of the cavity are maintained at the same cold temperature, whereas the top and bottom walls are thermally insulated. A developed program (based on the finite-volume method and the semi-implicit method for pressure-linked equations algorithm) was utilized

An experimental investigation of single-phase and two-phase (evaporation and condensation) heat transfer and pressure drop characteristics is performed for five micro-fin tubes with various geometries using refrigerant R22 as the working fluid. The mass flux is in the range of 130–550 kg/m2s. Evaporation tests are conducted at 6 °C saturation temperature, 0.1 inlet quality and 0.9 outlet quality, while

For non-axisymmetric conditions, the traditional fluid mean (bulk) temperature at a tube cross section, subjected to constant heat flux, can be higher than the temperature of a point on the wall. This results in a mismatch between the direction of applied heat flux and the temperature difference resulting in (misleading) negative peripheral heat transfer coefficient and Nusselt number (Nu). The resulting

A number of analytical solutions for moving bed heat exchangers (MBHEs) have been recently obtained by means of Laplace transforms. In this work, an alternative method for obtaining the analytical solution for a co-current parallel-plate MBHE is presented, by means of orthogonal expansions and integral transform techniques. This methodology provides a more robust approach for solving the problem, and

The work deals with a thermodynamic analysis of finned liquid-gas cross-flow heat exchangers. Analyzing such devices, it is important to determine the heat transfer coefficients on the liquid and the gas side. The analysis basic problem is determination of the of the heat transfer coefficient from the finned surfaces to the flowing gas due to a non-uniform flow of gas through the exchanger. The form

This article discusses the effect of application of antifreeze substances on thermohydraulic parameters and energy consumption of a heating installation with convective radiators. A comparative theoretical and computational analysis is performed for water and two alternative heating mediums: a 50% aqueous solution of ethylene glycol and propylene glycol. It is indicated that antifreeze substances and

The article presents the construction of modular a shell and tube heat exchanger, which is proposed for food industry. Authors analyzed possibilities of applying this type of heat exchanger to recover waste heat from a heating boiler used in food production companies. Recovered waste heat can be utilized for palm oil heating, which is a common ingredient used in food companies. This construction of

The article presents an inverse method for the reconstruction of the spatial distribution of the heat transfer coefficient (HTC) for impinging jets. Single jet influence the heat exchange on limited range, thus the HTC is reconstructed for an array of jets. In this article, there is a discussion regarding an influence of the geometrical parameters and Reynolds number on the spatial distribution of

The article discusses the possibility of accelerating the startup of a steam boiler with natural circulation. During startup and load changes in thick-walled pressure elements of boilers operating at high temperatures, high thermal stresses are caused. Critical elements that limit the rate of change of working fluid units include drums, fresh steam superheater outlet chamber, injection chamber of steam

In order to safely absorb charged particle beams prepared for various experimental facilities at the European Organization for Nuclear Research (CERN) an external dump is installed at the end of the Proton Synchrotron (PS) transfer line. This dump currently consists of stacked cast iron blocks surrounded by concrete shielding. This paper analyzes the thermal performance of the PS external dump under