Showing papers on "Heat transfer published in 2019"
TL;DR: In this article, the variation of energy storage efficiency, Finite element method has been employed to show the variation in energy storage energy efficiency, important selected parameters are nanofluid concentration, angle of V shaped fin, copper oxide particle size and length of fin.
407 citations
TL;DR: In this article, the authors present a critical review of heat transfer applications of nanofluids, including radiators, circular tube heat exchangers, plate heat exchanger, shell and tube heat exchange, and heat sinks.
Abstract: This paper presents a critical review of heat transfer applications of nanofluids. The effects of nanoparticle concentration, size, shape, and nanofluid flow rate on Nusselt number, heat transfer coefficient, thermal conductivity, thermal resistance, friction factor and pressure drop from numerous studies reported recently are presented. Effects of various geometric parameters on heat transfer enhancement of system using nanofluids have also been reviewed. Heat transfer devices covered in this paper include radiators, circular tube heat exchangers, plate heat exchangers, shell and tube heat exchangers and heat sinks. Various correlations used for experimental validation or developed in reviewed studies are also compiled, compared and analyzed. The pros and cons associated to the applications of nanofluids in heat transfer devices are presented in details to determine the future direction of research in this arena.
388 citations
TL;DR: In this paper, a comprehensive review of published articles addressing passive enhancement of pool boiling using surface modification techniques is provided, including macroscale, microscale, and nanoscale surfaces, as well as multiscale (hybrid-scale), and hybrid-wettability techniques.
343 citations
TL;DR: In this paper, the effect of porosity and pore density on heat transfer, thermal conductivity, specific heat, latent heat and charging/discharging time are critically reviewed.
336 citations
TL;DR: In this article, the impact of using fins and nano-sized materials on performance of discharging system was investigated, and the mathematical model has been offered in the form of PDE's, which were solved using Galerkin FEM.
336 citations
TL;DR: In this paper, a review on application of nanofluids in heat exchangers has been addressed, and it can be concluded that the use of nanophotonics in most cases improves heat transfer, which reduces the volume of heat exchanger, saving energy, consequently water consumption and industrial waste.
325 citations
22 Jan 2019
TL;DR: In this article, the authors present a model for two-phase flow in pool and film Boiling, and demonstrate the fluid mechanics and fluid mechanics aspects of these two phases of flow.
Abstract: Preface Nomenclature Contributors 1.Vapor Liquid Equilibrium Properties 2.Representation of Solid-Liquid-Vapor Phase Interactions 3.Boiling Curve 4.Nucleate Boiling 5.Enhancement Techniques in Pool Boiling 6.Critical Heat Flux in Pool Boiling 7.Film and Transition Boiling 8.Introduction and Basic Models 8.Fluid Mechanics Aspects of Two-Phase Flow 9.Fluid Mechanics Aspects of Two-Phase Flow 10.Two-Phase Flow Instabilities 11.Critical Two-Phase Flow 12.Two-Phase Flow and Boiling Heat Transfer in Tube Bundles 13.External Flow Film Boiling 14.Augmentation Techniques and External Flow Boiling 15.Flow Boiling in Circular Tubes 16.Flow Boiling in Advanced Geometries and Applications 17.CHF and Post-CHF (Post-Dryout) Heat Transfer 18.Flow Boiling Augmentation 19.Film Condensation 20.Dropwise Condensation 21.Direct Contact Condensation 22.Augementation Techniques in External Condensation 23.Heat Transfer and Pressure Drop in Internal Flow Condensation 24.Augementation Techniques and Condensation Inside Advanced Geometries 25.Instrumentation in Boiling and Condensation Studies Conversion Factors for Commonly Used Quantities Conversion Factors in Different Units Index
262 citations
TL;DR: In this paper, a combined turbulator was proposed to achieve good thermal performance, in which the height of turbulator (b) has been selected and its variation as well as Reynolds number was demonstrated in outputs.
259 citations
TL;DR: In this article, the authors focused on various flow and heat transfer modes of nanofluid, metal foam and the combination of the two, with the physical properties of nanophluid and metal foam summarized.
252 citations
TL;DR: In this article, a double twisted tape was inserted in a H2O pipe to help its conductivity and a finite volume method was used to describe the flow and energy balance.
250 citations
TL;DR: In this paper, the authors studied free convective flow and heat transfer of a suspension of nano-encapsulated phase change materials (NEPCMs) in an enclosure and found that the enhancement of heat transfer is highly dependent on the non-dimensional fusion temperature, θf, and very good performance can be achieved in the range of ¼ < θ f < 0.
TL;DR: In this article, a numerical approach is applied to analyze the thermal behavior of alumina nanofluid in a duct, and neural network is employed to estimate the heat transfer rate.
TL;DR: In this article, a thermal management module with a sandwich structure consisting of a battery, phase change material, and heat pipe is assembled, and a lumped thermal model is built to consider the coupling of battery heat generation.
TL;DR: In this paper, the unsteady flow and heat transfer past a stretching/shrinking sheet in a hybrid nanofluid is studied, and the governing equations of the problem are transformed to the similarity equations by using similarity transformation technique.
TL;DR: In this article, the analysis of magnetizable hybrid nanofluid of MWCNT-Fe3O4/H2O inside a circular cavity with two circular heaters was conducted.
TL;DR: In this paper, a novel form-stable and thermally induced flexible composite PCM inspired by shape memory polymers was successfully prepared, where paraffin (PA) with large latent heat was employed as PCM, olefin block copolymer (OBC) performed as the supporting material and expanded graphite (EG) was the additives for thermal conductivity enhancement.
TL;DR: In this article, the effects of second order slip on plane Poiseuille nanofluid under the influence of Stefan blowing in a channel are discovered, and the starring role of heat transfer, magnetic field and porosity are all together taken into account.
TL;DR: In this paper, the authors evaluated the thermohydraulic attributes of a hybrid nanofluid containing graphene-silver nanoparticles in a microchannel heat sink equipped with the ribs and secondary channels.
TL;DR: In this article, a review of the literature on the area of heat transfer improvement employing a combination of nanofluid and inserts is performed, and the progress made and current challenges for each combined system are discussed, and some conclusions and suggestions are made for future research.
Abstract: Improving heat transfer is a critical subject for energy conservation systems which directly affects economic efficiency of these systems. There are active and passive methods which can be employed to enhance the rate of heat transfer without reducing the general efficiency of the energy conservation systems. Among these methods, passive techniques are more cost-effective and reliable in comparison with active ones as they have no moving parts. To achieve further improvements in heat transfer performances, some researchers combined passive techniques. This article performs a review of the literature on the area of heat transfer improvement employing a combination of nanofluid and inserts. Inserts are baffles, twisted tape, vortex generators, and wire coil inserts. The progress made and the current challenges for each combined system are discussed, and some conclusions and suggestions are made for future research.
TL;DR: In this article, a similarity technic is applied to alter governing energy and momentum equations into non-linear ordinary differential ones that contain the convenient boundary conditions and used the Duan-Rach Approach (DRA) to solve them.
Abstract: In this paper, the researchers explore heat transfer and magneto-hydrodynamic flow of hybrid nanofluid in a rotating system among two surfaces. The upper and lower plates of the system are assumed penetrable and stretchable, respectively. The thermal radiation and Joule heating impacts are considered. A similarity technic is applied to alter governing energy and momentum equations into non-linear ordinary differential ones that contain the convenient boundary conditions and used the Duan-Rach Approach (DRA) to solve them. Influences of assorted parameters including rotation parameter, suction/blowing parameter, radiation parameter, Reynolds number, hybrid nanofluid volume fraction, and magnetic parameter on temperature and velocity profiles are examined. Also, a correlation for the Nusselt number has been developed in terms of the acting parameters of the present study. The outcomes indicate that Nusselt number acts as an ascending function of injection and radiation parameters, as well as volume fraction of nanofluid.
TL;DR: In this article, the authors investigated the thermal performance of the conventional walls of buildings in Isfahan, Iran with the inclusion of thirteen different phase change materials (PCM) including plaster, clay brick, and cement.
TL;DR: In this paper, the exothermic reactions model with constant heat source in the porous media with strong memory effects is considered and the mathematical equation of the problem is confined in a fractional energy balance equation (FEBE), which furnishes the temperature portrayal in conduction state having uniform heat source on steady state.
TL;DR: In this paper, the non-uniform solar flux features in four CSP technologies including the parabolic-trough collector, the linear Fresnel collector and the solar power tower were reviewed, and a recommendation for the optimization of the solar collector was provided.
TL;DR: In this article, the authors used a triangular wave form of conductive corrugated partition for free convection in a cavity with a corrugation partition which have different fluids on different parts of the partition was numerically examined.
Chinese Academy of Sciences1, University of Nevada, Reno2, Central South University3, Shanghai Jiao Tong University4, Nanjing University5, Massachusetts Institute of Technology6, Georgia Institute of Technology7, National Institute of Advanced Industrial Science and Technology8, University of Tokyo9
TL;DR: The graphene monolith has an ultra-high through-plane thermal conductivity of 143 W m-1 K-1 exceeding that of many metals, and a low compressive modulus comparable to that of silicones, demonstrating the superior ability to solve the interfacial heat transfer issues in electronic systems.
Abstract: Along with the technology evolution for dense integration of high-power, high-frequency devices in electronics, the accompanying interfacial heat transfer problem leads to urgent demands for advanced thermal interface materials (TIMs) with both high through-plane thermal conductivity and good compressibility. Most metals have satisfactory thermal conductivity but relatively high compressive modulus, and soft silicones are typically thermal insulators (0.3 W m-1 K-1). Currently, it is a great challenge to develop a soft material with the thermal conductivity up to metal level for TIM application. This study solves this problem by constructing a graphene-based microstructure composed of mainly vertical graphene and a thin cap of horizontal graphene layers on both the top and bottom sides through a mechanical machining process to manipulate the stacked architecture of conventional graphene paper. The resultant graphene monolith has an ultrahigh through-plane thermal conductivity of 143 W m-1 K-1, exceeding that of many metals, and a low compressive modulus of 0.87 MPa, comparable to that of silicones. In the actual TIM performance measurement, the system cooling efficiency with our graphene monolith as TIM is 3 times as high as that of the state-of-the-art commercial TIM, demonstrating the superior ability to solve the interfacial heat transfer issues in electronic systems.
TL;DR: In this paper, the effects of mass transfer on second grade fluid flow subjected to the heat transfer incorporated with the relaxation time to reach the state of equilibrium on or after a state of upheaval is analyzed.
TL;DR: In this article, a two-dimensional axisymmetric simulation model with natural convection was established for the shell-and-tube thermal energy storage unit, and the effects of the metal foam location and porosity on the heat storage performance were studied.
TL;DR: In this paper, a 3D heat transfer finite element model for laser powder-bed fusion (LPBF) was developed for accurately predicting melt pool dimensions and surface features, which can be used to reduce the process/material development costs.
Abstract: In this article, a 3-dimensional heat-transfer finite element model for Laser Powder-Bed Fusion (LPBF) was developed for accurately predicting melt pool dimensions and surface features. The sole deployment of trial-and-error experiments for arriving at optimal process parameters is very costly and time-consuming, thus the developed model can be used to reduce the process/material development costs. A literature review of heat source models was presented. Eight commonly used heat source models are evaluated and compared. All of their simulated depths are smaller than the experimental result, which may be due to the melt pool convection and inconstant laser absorptivity in the reality during the experiment. In order to enable the numerical model to predict melt pool dimensions for different combinations of process parameters, a novel model including expressions of varied anisotropically enhanced thermal conductivity and varied laser absorptivity is proposed and verified by both the melt pool dimensions and track surface morphology. It is found that the heat source expressions can be linear while causing the simulation results to be in better agreement with both experimental melt pool dimensions and track surface morphology.