Optimization of Fin Parameters to Reduce Entropy Generation and Melting Time of a Latent Heat Storage Unit

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Lokesh Kalapala ◽  
Jaya Krishna Devanuri
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Entropy Generation ◽  
Transfer Rate ◽  
Heat Storage ◽  
Melting Time ◽  
Multi Objective Optimization ◽  
Storage Unit ◽  
Latent Heat Storage ◽  
Multi Objective

Abstract One of the challenges in the design and development of a latent heat storage unit (LHSU) is to increase the charging and discharging rates which are inherently low because of low thermal conductivity of phase change materials (PCM). Out of various heat transfer enhancement techniques, employing annular fins is very simple, efficient and no fabrication complexity is involved. Fin parameters (fin size and number of fins) significantly influence the enhancement in heat transfer rate. Hence, optimization of fin parameters is necessary for the efficient design of an LHSU. While designing an LHSU along with heat transfer rate, entropy generation should also be considered in order to make it exergetically efficient. Therefore, the present study is aimed at multi-objective optimization of annular fin parameters to minimize the melting time and entropy generation. Fin diameter and the number of fins are taken as the variables. The influence of these two variables on the melting time, average Nusselt number, energy stored, and distribution of entropy is presented. The melting rate is increased, and global entropy generation decreased by increasing the number of fins up to 15. An increase in the fin diameter reduced the melting time while entropy generation got increased. For the multi-objective optimization, the multi-objective optimization based on ratio analysis (MOORA) technique is chosen and the optimized values of fin diameter and number of fins are observed to be 80 mm and 15 respectively. Finally, optimized parameters are represented in non-dimensional form to make them applicable for any size of the LHSU.

Influence of fin parameters on melting and solidification characteristics of a conical shell and tube latent heat storage unit

2021 ◽  
pp. 1-37
Author(s):  
Lokesh Kalapala ◽  
Jaya Krishna Devanuri
Keyword(s):  
Cylindrical Shell ◽  
Latent Heat ◽  
Conical Shell ◽  
Heat Storage ◽  
Melting Time ◽  
Storage Unit ◽  
Latent Heat Storage ◽  
Efficient Operation ◽  
Shell And Tube ◽  
Melting And Solidification

Abstract Augmenting meting and solidification rates of latent heat storage unit (LHSU) is very much essential for its efficient operation. By the effective utilization of natural convection, rate of heat transfer can be enhanced and the conical shell is beneficent in this regard. Employing fins further improves the charging and discharging rates. Hence the current study is focused on analyzing melting and solidification characteristics of a conical shell and tube LHSU along with the effect of fin parameters viz. fin diameter and number of fins. Numerical analysis is chosen for this purpose and the performance is compared via melting/solidification times, energy stored, energy/exergy efficiencies. Initially the performance of unfinned conical shell is compared with the cylindrical shell without fins and then the effect of fin parameters is presented. For melting process conical shell is found to be superior to cylindrical shell. 34.46% reduction in melting time is noted by employing conical shell and rate of energy stored is also higher for conical shell. Increase in fin diameter caused an increase in melting time when 20 number of fins are used, whereas melting time got decreased with the increase in fin diameter when 5 number of fins are used. Hence, when a greater number of fins are employed lesser diameter is preferred for melting. For discharging process, conical shell took 60% more time than cylindrical shell. Even after employing fins, solidification time is not drastically reduced in comparison to cylindrical shell.

scholarly journals Effective Separation of a Water in Oil Emulsion from a Direct Contact Latent Heat Storage System

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2264 ◽  
Author(s):  
Sebastian Ammann ◽  
Andreas Ammann ◽  
Rebecca Ravotti ◽  
Ludger Fischer ◽  
Anastasia Stamatiou ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Latent Heat ◽  
Direct Contact ◽  
Heat Storage ◽  
Storage System ◽  
Heat Transfer Fluid ◽  
Storage Unit ◽  
Latent Heat Storage ◽  
Oil Emulsion ◽  
Water In Oil Emulsion

The problem of emulsification between Phase Change Material (PCM) and Heat Transfer Fluid (HTF) in direct contact latent heat storage systems has been reported in various studies. This issue causes the PCM to flow out of the storage tank and crystallize at unwanted locations and thus presents a major limitation for the proper operation of such systems. These anomalies become more pronounced when high HTF flow rates are employed with the aim to achieve fast heat transfer rates. The goal of this paper is to find a method which will enable the fast separation of the formed emulsion and thus the uninterrupted operation of the storage unit. In this study, three separation methods were examined and the use of superhydrophobic filters was chosen as the best candidate for the demulsification of the PCM and HTF mixtures. The filter was produced by processing of a melamine sponge with different superhydrophobic adhesives and was tested with emulsions closely resembling the ones formed in a real direct contact setup. The superhydrophobic filter obtained, was able to separate the emulsions effectively while presenting a very high permeability (up to 1,194,980 kg h−1 m−2 bar−1). This is the first time the use of a superhydrophobic sponge has been investigated in the context of demulsification in direct contact latent heat storage.

Enrichment of heat transfer in a latent heat storage unit using longitudinal fins

Heat Transfer ◽  
2020 ◽  
Vol 49 (5) ◽  
pp. 2659-2685
Author(s):  
Digant S. Mehta ◽  
Bhavesh Vaghela ◽  
Manish K. Rathod ◽  
Jyotirmay Banerjee
Keyword(s):  
Heat Transfer ◽  
Latent Heat ◽  
Heat Storage ◽  
Storage Unit ◽  
Latent Heat Storage

Thermodynamic Analysis of Latent Heat Storage in a Shell-and-Tube Heat Exchanger

1992 ◽  
Vol 114 (2) ◽  
pp. 93-99 ◽  
Author(s):  
Ch. Charach ◽  
A. Zemel
Keyword(s):  
Heat Transfer ◽  
Latent Heat ◽  
Entropy Generation ◽  
Gas Flow ◽  
Heat Storage ◽  
Cylindrical Tube ◽  
Design Parameters ◽  
Storage Process ◽  
Latent Heat Storage ◽  
Tube Heat Exchanger

This work addresses the entropy generation aspects of a latent heat storage in which the energy delivered by a hot gas flowing through a cylindrical tube induces melting of the material surrounding the tube. The heat transfer for conduction-dominated melting is analyzed, taking into account the two-dimensional effects. The storage process irreversibilities associated with both the gas flow and the heat transfer (including entropy generation in the melted layer) are considered. The number of entropy generation units, which is a measure of the thermodynamic imperfection of the energy storage process, is expressed as a function of the main design parameters of the system. Analytic bounds and simplified asymptotic expressions for this quantity are derived. The results are compared with earlier one-dimensional studies.

scholarly journals Role of honeycomb structure in improving the melting process of a phase change material inside a latent heat storage unit

2021 ◽  
Vol 19 ◽  
pp. 589-592
Author(s):  
M. Hariss ◽  
◽  
M. El Alami ◽  
A. Gounni
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Numerical Study ◽  
Melting Process ◽  
Honeycomb Structure ◽  
Melting Time ◽  
Storage Unit ◽  
Latent Heat Storage ◽  
The Impact

In this work, a numerical study is performed to analyze the impact of honeycomb structure on heat transfer within the PCM. The modeling is based on a transient calculation making it possible to analyze the phase change of the paraffin using the commercial software "Fluent" based on the enthalpy-porosity model. The results showed that the impregnation of a metal matrix in a rectangular enclosure helps to decrease the melting time and thus improve the heat transfer within the PCM.

Effect of tilt angle on the multi-pipe channel with sinusoidal/curved walls – numerical modelling based on finite volume method

2019 ◽  
Vol 29 (5) ◽  
pp. 1590-1605 ◽  
Author(s):  
Payam Hooshmand ◽  
Mohammad Bahrami ◽  
Navid Bagheri ◽  
Meysam Jamshidian ◽  
Emad Hasani Malekshah
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Transfer Rate ◽  
Entropy Generation ◽  
Transfer Rate ◽  
Pure Water ◽  
Cuo Nanoparticles ◽  
Operating Conditions ◽  
Cold Temperatures ◽  
Content Type

Purpose This paper aims to investigate the two-dimensional numerical modeling of fluid flow and heat transfer in a fluid channel. Design/methodology/approach The channel is filled with the CuO-water nanofluid. The KKL model is used to estimate the dynamic viscosity and considering Brownian motion. On the other hand, the influence of CuO nanoparticles’ shapes on the heat transfer rate is taken account in the simulations. The channel is included with several active pipes with hot and cold temperatures. Furthermore, the external curved and sinusoidal walls have cold and hot temperatures, respectively. Findings Three different tilt angles are considered with similar boundary and operating conditions. The Rayleigh numbers, solid volume fraction of CuO nanoparticles in the pure water and the tilt angles are the governing parameters. Different cases studies, such as streamlines, heat transfer rate, local and total entropy generation and heatlines, are analysed under influences of these governing parameters. Originality/value The originality of this work is investigation of fluid flow, heat transfer and entropy generation within a nanofluid filled channel using FVM.

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