Showing papers on "Fin (extended surface) published in 2021"

Numerical investigation on thermal behaviour of 5 × 5 cell configured battery pack using phase change material and fin structure layout

Abstract: Lithium-ion battery, the indispensable part of electric vehicles or hybrid electric vehicles because of their high energy capacity and power density but usually suffer from a high temperature rise due to heat generation within a battery. This heat generation is mainly a function of the state of charge and charge/discharge rate. A passive technique like phase change material cooling has receiving a wide recognition due to its high latent heat, compact nature, and lightweight without consuming any external power. In this article, the thermal performance of the battery module containing 5 × 5 lithium-ion battery arranged in series and parallel is evaluated using phase change material. Initially, the performance of a battery module is examined with and without PCM at different discharge rate. It was found that more heat is accumulated at the interior portion of the battery pack due to mutual heating and low heat dissipation ability of PCM at a higher discharge rate. To improve such interior heat dissipation, different fin structure layout like Type I, Type II, Type III and Type IV are proposed and analysed using maximum temperature and average temperature distribution in a PCM based battery pack. It reveals that fin structure layout of Type III minimizes heat accumulation at the interior with adequate melting time among all. Furthermore, charge and discharge characteristics are investigated at different rate using rest time, convection effect and fin structure. The results indicated that use of rest time and increasing convection effect not only reduces maximum temperature but also recover melting fraction of PCM. Results also illustrate that the thermal performance of PCM based battery pack slightly get affected with the use of fin structure at lower convection, but decreases the maximum temperature by 8.17% at higher convection. Heat source a function of the state of charge and charge/discharge rate are given using Ansys-Fluent code and results are reported in the form of maximum temperature, average temperature and melting fraction.

Heat transfer enhancement in fin-and-tube heat exchangers – A review on different mechanisms

Abstract: Fin-and-tube heat exchangers are the mostly used heat exchangers for thermal energy conversion with wide range of applications such as air conditioning, refrigeration, automotive industry, electronic devices, and the like. Demand of more efficient cooling by more compact heat exchangers leads to tremendous researches on this subject. In this paper, a detailed review of experimental and numerical researches upon different mechanisms of heat transfer enhancement in fin-and-tube heat exchangers are performed and the relevant influences and operating conditions are thoroughly reviewed. Effects of different geometrical parameters on heat transfer and pressure drop in each mechanism are also discussed in details. Furthermore, comparisons between different mechanisms of heat transfer improvement and some novel compound designs of fin-and-tube heat exchangers are discussed. In addition, some special researches on surface treatment, particle deposition, thermal contact, and fabrication material in fin-and-tube heat exchangers are described. Finally, some developed correlations for calculation of heat transfer and pressure drop characteristics of fin-and-tube heat exchangers with their ranges of validation are classified and compared.

Heat transfer and entropy generation analysis of water-Fe3O4/CNT hybrid magnetic nanofluid flow in a trapezoidal wavy enclosure containing porous media with the Galerkin finite element method

Abstract: The present study addresses theoretically and computationally the performance of electrically conducting water-Fe3O4/CNT hybrid nanofluid in three-dimensional free convection and entropy generation in a wavy-walled trapezoidal enclosure. The enclosure has two layers—a hybrid nanoliquid layer and a permeable medium layer. A transverse magnetic field is acting in the upward direction. Newtonian flow is considered, and the modified Navier–Stokes equations are employed with Lorentz hydromagnetic body force, Darcian and Forchheimer drag force terms. The wavy side walls are heated while the top and vertical walls are adiabatic. An elliptic cylindrical cooled fin is positioned at the center of the cavity, and several different tilting angles of the fin are considered. The transformed, non-dimensional systems of coupled nonlinear partial differential equations with their corresponding boundary conditions are solved numerically with the Galerkin Finite Element Method (FEM) using the COMSOL Multiphysics software platform. The impact of Darcy number, Hartmann number, volume fraction, undulation number of the wavy wall and Rayleigh number (thermal buoyancy parameter) on the streamlines, isotherms and Bejan number contours are investigated. Extensive visualization of the thermal flow characteristics is included. With increasing Hartmann and Rayleigh numbers, the average Bejan number is reduced strongly whereas the average Nusselt number is only depleted significantly at very high values of Rayleigh and high Hartmann numbers. With increasing undulation number, a slight elevation in average Bejan number at intermediate Rayleigh numbers is noticed, whereas the average Nusselt number is substantially boosted, and the effect is maximized at a very high Rayleigh number where the average Nusselt number was increased by 35%. An increment in Darcy number (i.e., reduction in permeability of the porous medium layer) is observed to considerably elevate the average Nusselt number at high values of the Rayleigh number up to 20%, whereas the contrary response is computed in average Bejan number, where it showed a reduction by 10 times. The simulations apply to hybrid magnetic nanofluid fuel cells and electromagnetic nanomaterials processing in cavities.

Hydro-thermal performance of normal-channel facile heat sink using TiO2-H2O mixture (Rutile–Anatase) nanofluids for microprocessor cooling

Abstract: Thermal management of microelectronics is a challenging task in modern high heat generating devices. In this work, thermal performance of normal-channel facile heat sink has been investigated using water and TiO2-H2O (mixture of Rutile and Anatase) nanofluids with volumetric concentration of 0.005% and 0.01%. The maximum reduction in base temperature was noted for TiO2-H2O (∅ = 0.01%) and TiO2-H2O (∅ = 0.005%) as 8.2% and 5.5%, respectively, when compared with water. The thermal performance of normal-channel facile heat sink was then compared with the mini-channel integral fin heat sink. The base temperature of normal-channel facile heat sink was found very close to mini-channel integral fin heat sink with a maximum difference of 1.8%. The total cost to fabricate mini-channel heat sink was almost 5.3 times greater than normal-channel heat sink. So, the normal-channel heat sink has economical advantage over the mini-channel heat sink in terms of lower fabrication cost with similar thermal performance. However, the pressure drop was found greater for normal-channel as compared to mini-channel heat sink. The experimental results of normal-channel facile heat sink were also validated numerically, and a good agreement was found.

Experimental investigations on jet impingement solar air collectors using pin-fin absorber:

Abstract: In this paper, the performances of a novel jet impingement solar air collector (JISAC) using flat and pin-fin absorbers were experimentally investigated. The experimental observations in a JISAC ha...

Performance analysis of arc rib fin embedded in a solar air heater

Abstract: A thermal model is developed for analysing the influences of arc rib fin arrangement and length of absorber plate on the heat transfer characteristics of a solar air heater. The arc rib fin arrangement is designed by varying the fin relative roughness height ratio (e/De) in the absorber plate. Solar air heater with fixed arc rib fin configuration with e/De (0.0422) and variable arc rib fin configuration with two different relative roughness height ratios of e/De (0.0422 and 0.0541) are modelled. The influence of absorber plate length (1 and 2 m) on the solar air heater performance is compared with the configurations mentioned above at various mass flow rates of air (0.02 kgs−1 to 0.06 kgs−1). The outlet air temperature of solar air heater, mean absorber plate temperature, heat transfer characteristics (Nusselt number and frictional factor), pressure drop, thermo-hydraulic performance parameter, efficiencies (thermal, effective, and exergy), collector efficiency factor, and collector heat removal factor are predicted at different air flow rates. The variable arc rib fin arrangement in the solar air heater leads to maximum utilization of available solar energy from the absorber plate, and reported maximum outlet air temperature and lower mean absorber plate temperature when compared to fixed arc rib fin arrangement and smooth duct. Further, the variable arc rib fin arrangement has better heat transfer and thermo-hydraulic characteristics than the fixed arc rib fin arrangement and smooth duct. Thus implementation of the variable arc rib fin arrangement will significantly enhance the overall performance of the solar air heater.

Phase change material heat transfer enhancement in latent heat thermal energy storage unit with single fin: Comprehensive effect of position and length

Abstract: In this study, the comprehensive effect of position and length of the fin in a latent heat thermal energy storage (LHTES) unit with a single fin on the melting and solidification of the phase-change materials (PCMs) was explored by transient numerical simulations. By analyzing the liquid-solid interfaces, temperature distributions, velocity vector and phase change rate, the melting and solidification characteristics of PCM and heat transfer enhancement mechanism of the fin with various length ratios and height ratios were understood in detail. The results illustrated that the total melting time was significantly reduced by increasing the fin length and lowing the fin position simultaneously. On the other hand, lowering the fin position would result in non-uniform temperature distribution during the solidification process. More importantly, considering the contradiction in fin position between melting and solidification, an optimal position of the fin corresponding to different fin lengths was suggested. Besides, a disparity between heat storage/release and phase transition was quantitatively discussed.

Critical review and future prospects for desiccant coated heat exchangers: Materials, design, and manufacturing

Abstract: Solid desiccant dehumidification is a promising alternative to vapor compression-based air-dehumidification to reduce energy consumption and improve air quality. Desiccant coated heat exchanger (DCHE), as one type of solid desiccant dehumidification system, can improve system performance and efficiency. The thermal performance and moisture removal capability of the DCHE greatly influence its dehumidification performance. The present work aims to critically analyze the designs, materials, and manufacturing methods of heat exchangers used for solid desiccant coating and look into recent developments in regular heat exchangers, potentially deployed as a substrate for DCHE applications. A comprehensive literature review of publications regarding solid desiccant materials, heat exchangers, manufacturing and coating methods, binder materials, and the performance of heat exchangers has been developed. Alternative heat exchangers are described as better options than fin and tube heat exchangers that have been considered thus far for DCHE applications. Additionally, the heat exchanger's manufacturing process and materials over their thermal and mass exchange performance have been analyzed. Despite the widespread use of fin and tube heat exchangers for solid desiccant coating, recent developments in heat exchanger design, and related fields such as manufacturing methods and materials, open the possibilities for their application in solid desiccant dehumidification systems. Finally, the authors provide their outlook on possible developments of DCHE technology, aiming to increase systems' energy and dehumidification performance.

Numerical investigation on the characteristics of flow and heat transfer enhancement by micro pin-fin array heat sink with fin-shaped strips

Abstract: Targeted at improving microfluidic cooling for the use of micro heat sink in electronic chips, a novel fin-shaped pin-fin array heat sink is proposed. In this study, the mechanism of flow and heat transfer, the arrangements of pin-fin layout, the characteristics of single-phase flow and heat transfer among the micro cylinder pin-fin heat sink, micro fin-shaped pin-fin heat sink of A、B、C types are investigated. It’s showed that stagger micro fin-shaped A pin-fin (SMFAP) exhibits the best hydro-thermal performance. At high Reynolds number, the average Nusselt number of SMFAP reaches up to two times of the in-line micro cylinder pin-fin (IMCP). Moreover, the structure of fin-shaped pin-fin can enhance heat transfer by increasing Nu, while weaken heat transfer by large pressure drop. Therefore, the non-dimensional parameter PEC is adopted to evaluate the heat transfer performance of heat sink. When Re is 800, the PEC of SMFAP reaches to its maximum value of 1.4. SMFAP can effectively enhance heat transfer, while stagger micro fin-shaped B pin-fin(SMFBP) and stagger micro fin-shaped C pin-fin (SMFCP) are not obviously. It’s concluded that different structures of fin-shaped pin-fin will affect the separation point of flow, thus affecting the size of vortex behind the cylinder.

Fractional Modeling of Fin on non-Fourier Heat Conduction via Modern Fractional Differential Operators

Abstract: The enhancement of heat transfer for electronic kits and automobiles has become highly dependent on the finned heat exchangers; this is because fin provides high heat transfer rate and superior performance with a significant temperature reduction. In this manuscript, a fractional modeling of non-Fourier heat conduction problem of a fin is proposed within the periodic temperature boundary condition. The mathematical modeling is performed via classical theory of heat conduction that is directly proportional to temperature gradient through which hyperbolic heat conduction equation for a fin is generated. The hyperbolic heat conduction equation for a fin is fractionalized via modern approaches of fractional differentiations, namely Atangana–Baleanu and Caputo–Fabrizio differential operators. In order to have analyticity of hyperbolic heat conduction equation for a fin, we invoked the mathematical techniques of Laplace transform. The exact solutions of temperature distribution have been obtained in terms of Fox-H and Mittag–Leffler functions with the product of convolution. The solutions of temperature distribution have been classified into integer verses non-integer theories by making fractional parameters $$ \alpha = \beta = 1 $$ and $$ \alpha e \beta e 1 $$ , respectively. Our results suggest that due to variability of different rheological parameters on temperature distribution, the cooling process is faster via fractional models in comparison to non-fractional model. Additionally, it is also observed that thermal wave propagates at a specific time results the reciprocal trend in temperature distribution.