Abstract A coal fired pusher type reheating furnace is simulated with the help of an efficient numerical model. The authors have improved over a numerical model developed in previous work to save more than 50% of computational time and thus making it feasible to use the model in large number of parametric studies. The transient movement of the billets is modelled as a steady-state problem with suitable

Abstract A numerical study on mixed convection is carried out through a partially filled brass wire mesh in a vertical channel. A heater embedded with aluminum plates is placed at the center of the vertical channel. The aluminum heater assembly is wrapped with brass wire mesh to facilitate more heat transfer. The vertical channel that consists of aluminum heater assembly with the brass wire mesh is

Abstract Natural convection heat transfer in a concentric horizontal annulus with annular fins is numerically studied. Due to the low thermal conductivity of water, CuO-water and Al2O3-water nanofluids were used as heat transfer fluids. The effect of three different parameters, including fin spacing, fin eccentricity, and fin thickness at different fin diameters and Rayleigh number range of 104 to

ABSTRACT Understanding and predictions of the local thermal-hydraulic performance of supercritical CO2 in channels of printed circuit heat exchanger geometries are of great importance to the design and optimization of the pre-cooler and recuperators in supercritical CO2 cycle. The local flow and heat transfer of supercritical CO2 in horizontal semicircular zigzag channel during cooling near the critical

ABSTRACT Plate heat exchanger (PHE) has been widely used in energy transport fields for its high efficiency and compact structure. However, fouling is an intractable issue which reduces heat transfer efficiency and increases pressure drop. In this study, an experimental investigation on composite fouling characteristics of Ni-P-PTFE nanocomposite coating in corrugated PHE was conducted to evaluate

Abstract The mathematical modeling of heat transfer in nanofluids based on the effects of additional particle forces was investigated with computational fluid dynamics simulations of titania-water nanofluid in a heated pipe flow. The additional particle forces analyzed were Brownian force, thermophoresis, Saffman’s lift force and Magnus lift force. The results were validated with an experimental work

A macrolayer formation model for predicting the critical heat flux (CHF) in saturated and subcooled pool boiling was proposed. The concept of this model was based on the bubble coalescence process, which was observed using a high-speed camera. In the present model, the thickness of the macrolayer was calculated assuming that the liquid volume remaining under the lower part of the bubble should contribute

The aim of the present study is to numerically investigate the thermal performance of a heat exchanger tube fitted with vortex generator inserts. In the present paper, three configurations of vortex generators—straight, double-curved, and triple-curved—are proposed to achieve the optimum configuration design that provides the highest thermal performance. The thermal performance results of the tubes

Multi-objective optimization of nanofluids in a microchannel heat sink was conducted to determine the highest Nusselt number and the lowest pressure drop. This was done by creating a design study consisting of four nanoparticles of Al2O3, CuO, ZnO and SiO2 with four diameters of 10, 30, 60 and 100 nm, nanoparticle volumetric concentrations of 0.001, 0.005, 0.01 and 0.05 and four base fluids of water

Numerical investigations of heat transfer and fluid flow have been carried out to study the effect of variation of longitudinal and transverse pitch-to-diameter ratios for a cross-flow heat exchanger with elliptical tubes. A total of seventeen configurations of varying compactness are investigated. This investigation also covers the effect of aspect ratio (0.40, 0.53, 0.78, 0.92 and 1.00) and tube

In this study, mixed convection heat transfer of silver-water nanofluid was experimentally investigated under laminar flow regime inside a horizontal rectangular channel filled with an open-cell copper foam. Thermophysical properties of silver-water nanofluid at 1000, 2000, and 4000 ppm concentrations were also measured. The morphological properties of copper foam were further measured by image processing

Fluid flow and heat transfer characteristics past four elliptic cylinders arranged in square configuration are numerically investigated in this study. An in-house finite element method code based on streamline upwind Petrov - Galerkin algorithm has been used for simulations of two-dimensional, incompressible and laminar flow of air. Analyses are carried out by changing geometric parameters such as

The public domain is inundated with discrepancies in numerical and experimental findings on the natural convection heat transfer performance of nanofluids in a cavity. This paper presents the experimental investigation of the natural convection of deionized water (DIW)-based zinc oxide (ZnO) nanofluid in a rectangular cavity. The ZnO nanoparticles (20 nm) were dispersed in DIW to formulate nanofluids

Oxidized carbon nanohorn water based nanofluids are attracting more and more attention for solar harvesting applications because of their peculiar features: stable suspension without any surfactant, higher solar absorbance values as compared to the base fluid, etc. However, these nanofluids are still matter of research because not all their properties have been comprehensively studied yet. This paper

Thermosyphons are amongst the most efficient passive heat transfer devices known nowadays. Due to heat and mass transfer limitations of working fluids, much effort is invested in developing a new generation of enhanced fluids, such as nanofluids. Previous studies reported improved thermal capacity when water was replaced by nanofluid. The interplay between nanoparticles and the evaporator surface is

Nanofluids have been used in several thermal management systems, as they contribute to the augmentation of the heat dissipation rates in many applications, especially those where heat pipes, pulsating heat pipes and loop heat pipes are used. Long term use of this type of device is required in order to increase their reliability, which requires chemical compatibility between the base fluid and the nanoparticle

In this study, microparticle coatings and nanoparticle coatings were fabricated on copper surfaces by an electrochemical deposition method and an electrophoretic deposition method, respectively. Pool boiling of NOVEC-649 was experimentally studied on the coated surfaces, concerning heat transfer, bubble dynamics and critical heat fluxes. Compared with a smooth surface, heat transfer coefficients and

This study focuses on the experimental characterization of fluid dynamics and heat transfer processes occurring at the interaction between a nanofluid droplet and a heated smooth surface. Time resolved thermography is used to detail the understanding of the role of the particles in wetting modification that affects the heat transfer mechanisms within different characteristic time scales. Gold and silver

We report in this study the experimental investigation of the dynamic viscosity of purified multi-walled carbon nanotubes (MWCNT) water and water-propylene glycol based nanofluids in the temperature range 10-80 °C. Four weight concentrations of MWCNTs are considered, between 0.005 and 0.1 wt.%. Triton X-100, a common nonionic surfactant, is used to disperse the nanotubes and stabilize the nanofluids

Commonly, heat transfer performance of a nanofluid is enhanced by increasing the mass fraction of nanoparticles due to an improvement of the thermo-physical properties. However, increasing the number of nanoparticles in the base fluid will result in an increase of the nanofluid viscosity. This research aims to investigate natural convective heat transfer for an electric heater filled with various Al2O3-water

Developing materials that efficiently combine cutting-edge technology with competitive costs so as to meet technical, economic and, last but not least, environmental challenges are a must in the field of materials engineering and beyond. Ionic liquids are heat transfer fluids that offer a wide range of advantageous properties. One of the most recent applications of these complex ionic liquids and nanomaterial

In order to enhance the heat transfer performance, the screen mesh wick and the inside wall of the container of a heat pipe were pre-coated with a silica nanoparticle layer. When the screen mesh was coated, the thermal resistance decreased by 47% on average. This would be attributed to enhanced wicking performance of screen mesh by the nanoparticle layer. When the container inside wall was coated,

In this paper, the numerical analysis of an impinging jet of Al2O3-water nanofluid in laminar and turbulent flow is carried out by using ANSYS. The main purpose of the paper is to describe the effects on heat transfer through a parametric analysis by varying jet-to-plate distance, volume fraction of nanoparticles and Reynolds number based on jet diameter. To assess how all these parameters affect the

In this paper a numerical investigation in metal porous structures with Kelvin cell model is carried out on water/Al2O3 nanofluids using the single-phase model. The examined foams are characterized by a porosity of 0.95 and different values of cells per inch (CPI), equal to 10 and 20 CPI. Three different values of Al2O3 nanoparticle volume concentrations equal to 0, 2 and 4% are used. Results are presented

Selected Papers from the 1st International Conference on Nanofluids (ICNf). Heat Transfer Engineering. Accepted .

The objectives of the present research work are the three-dimensional computational analysis and predictions on double-diffusive natural convection in a cubic cavity filled with Cu-Al2O3/water micropolar hybrid nanofluid. The governing equations are carefully modified employing vorticity-vector potential formulation and are solved by the finite volume method. Performance enhancement of Cu-Al2O3/water

This study reports on a mathematical model for predicting the fluid and heat flow characteristics of a Z-shaped corrugated foam heat sink. Experiments were carried out to validate local as well as overall pressure drop predictions. The mathematical model was further validated against corrugated carbon foam experimental measurements from the literature. A general flow parameter emerges from the formulation

In this study, heat transfer, flow characteristics, and entropy generation of turbulent TiO2/water nanofluid flow in the spiral coil tube were analytically investigated considering the nanoparticle volume fraction, curvature ratio, flow rate and inlet temperature between 0.01-0.05 percent, 0.03-0.06, 1.3-3.3 l/min, and 15-27 °C, respectively. Results showed that the augmentation of the nanoparticle

Condensation heat transfer on stainless steel tube utilizing superhydrophobic coatings was investigated. The electrophoretic deposition and spraying methods were employed to coat the tubes’ outer surface. The mixture that was synthesized for spray coating was a hybrid paint. It incorporated polyurethane matrix and a colloidal suspension containing organic nanoparticles. The hybrid paint had a proper

The enhancement with porous media involvement is estimated and compared for three varieties of shell and tube heat exchangers (STHXs), with helical, segmental and clamping anti-vibration baffles, with two variations, viz., porosity value and dimension of this media (radius). In this study, further improvement in the thermo-hydraulic performance of the anti-vibration baffles design of STHX was investigated

The hot wire chemical vapor deposition method was applied for fabrication of hydrophobic fluoropolymer coatings on the surface of tubular heaters. The effect of hydrophobic surfaces (with static contact angle of 125°) on the local and integral heat transfer characteristics was studied during boiling of saturated water at atmospheric pressure, including high speed visualization. The heat transfer enhancement

Three-dimensional numerical simulations are conducted to calculate the surface heat transfer coefficient (HTC) of the water jet impinging on a TA2/Q235B clad plate. The accuracy of the simulation model is validated by experiment. The simulation results are basically in agreement with the experimental results. The effect of clad plate temperature and thickness, jet height, orifice diameter, and orifice

Many experimental and numerical investigations of arrays of impingement cooling jets have been performed. A lot of them have addressed the problem of cooling with jets directed perpendicularly or inclined to the planar plate. However, in many technical applications contour of the cooled surface is more complex. One of the examples is a casing of the low-pressure turbine of the jet engine. It’s shape

Threshold crude oil fouling models use activation energy in the deposition rate term to predict the initial fouling rates. It has been reported in the literature that fluid velocity has a strong influence on activation energy, which does not agree well with the principles of chemical reaction engineering. Besides, the existing threshold fouling models always predict an increase in the fouling rate

Numerical simulations were carried out to investigate the swirling decaying flow generated by a novel axial guide vane swirler with profiled blades and no supporting device in a tube and its effect on heat transfer and pressure drop compared to a developed turbulent flow in a no swirl tube. Reynolds number ranged from 10,000 to 200,000. Turbulence was modelled using a k−ω Shear Stress Transport model

Film cooling using coolant jets is effective for increasing the cooling effectiveness of turbines. In the present study, large eddy simulation was employed for predicting small-scale vortices in the film-cooling process with different blowing ratios (BRs). The counter-rotating vortex pair (CRVP) was compared with the hairpin vortex, and results indicated the CRVP was the cross section of hairpin vortex

The present work numerically studied the enhanced heat transfer mechanism of the coupled fields of detached and spiral vortices in symmetrical and asymmetrical spirally corrugated tubes. The heat transfer and viscous dissipation were analyzed by evaluating the entropy combined with the flow patterns, and the global entropy generation rate was analyzed by considering the local Nusselt number and friction

Utilizing energy efficiently could greatly relieve current energy crisis. Therefore, in this article, a simple supercritical CO2 Brayton cycle for waste heat recovery from gas turbine is presented. The system uses ambient air as its cold source, which is more convenient and economic. Considering temperature difference between heat source and turbine inlet, it is of great significance to research the

As a new type of cone flowmeter, the bi-directional cone flowmeter is a promising device for metering the cryogenic fluid due to its excellent advantages. This work presents a numerical study on the cavitating flow characteristics of liquid nitrogen in the bi-directional cone flowmeters based on a modified cavitation model with thermal effects. The influences of some factors, including operating conditions

Piezoelectric fan driven forced convection is investigated with a three-dimensional numerical model by employing a dynamic mesh technique for varying fin-array width with increasing number of fins. Two different types of boundary settings have been tested. In the boundary setting-I, a fixed heat flux value distributed uniformly among the fins, whereas a constant heat flux is applied to the base of

The results of an experimental study of the influence of longitudinal positive and negative pressure gradients in a rectangular flat channel with a backward-facing step on turbulent heat transfer in the zones of separation, attachment and relaxation of the flow are presented. The studies were carried out in a turbulent flow regime at Reynolds numbers 4 × 103–1.2×104. The height of the step was equal

Leidenfrost (LF) and rewetting (RWT) phenomenon are both closely related and involved for the cooling of a very hot object utilizing a suitable cooling agent. The present study focusses on the influence of different parameters on both LF and RWT phenomenon of vertical tubes by bottom flooding. The various parameters primarily include the quantity or injection rate of the coolant (CLNT), type of CLNT

In this paper, numerical simulation is performed to predict combined impingement and film cooling on a model of the turbine blade leading edge by the heat flow coupling method. The first stage rotor blade leading edge of the GE-E3 engine high pressure turbine is adopted for the simulation. The relative performances of turbulence models are compared with experimental data and the results show that standard

Microwave has been widely used in pyrolysis of waste lubricating oil, but the uneven electromagnetic field distribution seriously affects the product distribution and even aggravates coking in pyrolysis process, where the pyrolizer structure plays a dominant role. Four structures were simulated in the continuous pyrolysis of waste lubricating oil under microwave irradiation, including single circular

Selected Papers from the 5th International Workshop on Heat/Mass Transfer Advances for Energy Conservation and Pollution Control (IWHT2019). Heat Transfer Engineering. Accepted .

Mixed convection flow in a lid-driven cavity in the presence of a uniform partial magnetic field is investigated utilizing the pseudo spectral method based on polyharmonic spline radial basis functions. The two-dimensional problem is concerned in a unit square cavity designed by adiabatic horizontal walls and vertical walls with constant temperatures. The top wall moves either in the positive x or

The three-dimensional transient heat transfer analysis of multilayer functionally graded graphene platelets reinforced composite (FG-GPLRC) truncated conical shells subjected to asymmetric thermal shock is presented. In order to include the effect of finite heat wave speed, the non-Fourier heat conduction law is employed. The multilayer FG-GPLRC truncated conical shells are composed of perfectly bonded

This paper presents a novel approach to visualize the flow boiling in round tubes under “diabatic conditions”. In the visualization test section, a 3D printed round tube is placed inside a glass tube with secondary fluid at a higher temperature flowing in the annulus between the two tubes thus providing diabatic conditions. Experimental work was conducted for evaporating R410A flow in a horizontal

Ammonia (NH3) is attracting attention as a carbon-free fuel that does not emit carbon dioxide, but there is concern that a large amount of nitrogen oxides is emitted during its combustion. The mixtures of NH3 and city gas are used as fuels, and the effectiveness of Moderate or Intense Low-oxygen Dilution (MILD) combustion to reduce nitric oxide (NO) emissions is investigated through zero-dimensional

(2020). Selected Papers from the 5th International Conference on Polygeneration (ICP 2019). Heat Transfer Engineering. Ahead of Print.

Numerical optimization of heat and fluid flow over staggered tube banks are investigated for both unfinned and axially finned tube banks. Ansys Fluent software is utilized for numerical computations. To find maximum total heat transfer and minimum volume of tube bank for the given mass flow rate, allowable pressure drop and tube bank effectiveness; A Multi-objective Genetic Algorithm II is used. Optimum

This paper presents the influence of zigzag ribs placed on an air heater section of a force convective cabinet dryer on thermal, and fluid flow behaviors in the air heater section and temperature distribution in a cabinet dryer section. The experimental study was carried out in simulated conditions: a uniform absorbed thermal energy and an inlet air velocity under forced convection in the Reynolds

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