Numerical Investigation of Charging and Discharging Processes of a Shell and Tube Nano-Enhanced Latent Thermal Storage Unit

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
Khaoula Nedjem ◽  
Mohamed Teggar ◽  
Kamal Adbel Radi Ismail ◽  
Driss Nehari
Keyword(s):  
Thermal Conductivity ◽  
Numerical Model ◽  
Thermal Performance ◽  
Phase Change Materials ◽  
Control Volume ◽  
Thermal Storage ◽  
Solar Thermal ◽  
Melting Time ◽  
Storage Unit ◽  
Shell And Tube

Abstract Phase change materials (PCMs) generally suffer from low thermal conductivity which limits their application in thermal systems. The effective thermal conductivity may be improved by including fins, metallic powders, fine wires, and nanoparticles. The objective of this study is to investigate the thermal performance of graphene nanoplatelets (GNPs) dispersed in small quantities in 1-tetradecanol (C14H30O) PCM. This nano-enhanced PCM (NPCM) is placed in the annular space of a shell and tube in a solar thermal storage unit. The numerical simulations have been carried out using a numerical model based on the enthalpy-porosity and the control volume methods. The numerical model has been successfully validated by comparison with experimental data available in the literature. The numerical results showed that the higher the GNPs concentration, the lower the stored energy. The higher the GNPs concentration the shorter the discharging time. But, during the charging process, though the reduction in the melting time by 9.5% for GNPs concentration increase from 0 to 1 wt%, the melting time increased in contrast by 10.5% for GNPs content increasing from 1 to 3 wt%. For the GNPs concentration of 3 wt%, the heat transfer rate enhancement was limited by an undesirable increase in viscosity which led to weak natural convection and hence a longer charging time. Thus, the GNPs concentration of 1 wt% showed better thermal performance than that of 3 wt% concentration. These results may guide the improvement of solar thermal storage by dispersing GNPs in PCM.

Heat Transfer Characterization and Optimization of Latent Heat Thermal Storage System Using Fins for Medium Temperature Solar Applications

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Asmita Shinde ◽  
Sankalp Arpit ◽  
Pramod KM ◽  
Peddy V C. Rao ◽  
Sandip K. Saha
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Latent Heat ◽  
Optimum Design ◽  
Thermal Performance ◽  
Storage System ◽  
Thermal Storage ◽  
Solar Thermal ◽  
Medium Temperature ◽  
Fin Thickness

While solar thermal power plants are increasingly gaining attention and have demonstrated their applications, extending electricity generation after the sunset using phase change material (PCM) still remains a grand challenge. Most of the organic PCMs are known to possess high energy density per unit volume, but low thermal conductivity, that necessitates the use of thermal conductivity enhancers (TCEs) to augment heat transfer within PCM. In this paper, thermal performance and optimization of shell and tube heat exchanger-based latent heat thermal energy storage system (LHTES) using fins as TCE for medium temperature (<300 °C) organic Rankine cycle (ORC)-based solar thermal plant are presented. A commercial grade organic PCM, A164 with melting temperature of 168.7 °C is filled in the shell side and heat transfer fluid (HTF), Hytherm 600 flows through the tubes. A three-dimensional numerical model using enthalpy technique is developed to study the solidification of PCM, with and without fin. Further, the effect of geometrical parameters of fin, such as fin thickness, fin height, and number of fin on the thermal performance of LHTES, is studied. It is found that fin thickness and number of fin play significant role on the solidification process of PCM. Finally, the optimum design of the fin geometry is determined by maximizing the combined objective of HTF outlet temperature and solid fraction of PCM at the end of the discharging period. The latent heat thermal storage system with 24 fins, each of 1 mm thickness and 7 mm height, is found to be the optimum design for the given set of operating parameters.

Numerical and Experimental Investigation of Shell-and-Tube Phase-Change Material Thermal Energy Storage Unit

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Thomas H. Sherer ◽  
Yogendra Joshi
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Control Volume ◽  
Heat Transfer Fluid ◽  
Transient Temperature ◽  
Storage Unit ◽  
Shell And Tube

Solid liquid phase-change materials (PCMs) present a promising approach for reducing data center cooling costs. We review prior research in this area. A shell-and-tube PCM thermal energy storage (TES) unit is then analyzed numerically and experimentally. The tube bank is filled with commercial paraffin RUBITHERM RT 28 HC PCM, which melts as the heat transfer fluid (HTF) flows across the tubes. A fully implicit one-dimensional control volume formulation that utilizes the enthalpy method for phase change has been developed to determine the transient temperature distributions in both the PCM and the tubes themselves. The energy gained by a column of tubes is used to determine the exit bulk HTF temperature from that column, ultimately leading to an exit HTF temperature from the TES unit. This paper presents a comparison of the numerical and experimental results for the transient temperature profiles of the PCM-filled tubes and HTF.

scholarly journals CFD Model of Shell-and-Tube Latent Heat Thermal Storage Unit Using Paraffin as a PCM

2021 ◽  
Author(s):  
Maher Mohammad Al-Maghalseh
Keyword(s):  
Nusselt Number ◽  
Liquid Fraction ◽  
Storage System ◽  
Numerical Data ◽  
Thermal Storage ◽  
Melting Time ◽  
Cfd Modelling ◽  
Storage Unit ◽  
Temperature Distributions ◽  
Shell And Tube

This chapter validates the capability of CFD modelling technique to accurately describe processes in the thermal storage system with the PCM. For validation purposes, CFD modelling using FLUENT ANSYS was conducted and the predicted results were compared with the experimental and numerical data from the literature. The comparison between experimental and numerical results was carried out in terms of the temperature distributions and average volume of the PCM liquid fraction. Additionally, the detailed parametric study of the storage system with the PCM was performed and results obtained were discussed with dimensional correlations for the Nusselt number being proposed to be used in the designing process. Finally, a correlation was developed to estimate the total melting time at the thermal storage system.

scholarly journals Experimental thermal performance comparison of pure and metal foam-loaded PCMs

2021 ◽  
Vol 2116 (1) ◽  
pp. 012058
Author(s):  
M Silvestrini ◽  
M Falcone ◽  
F Salvi ◽  
C Naldi ◽  
M Dongellini ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Thermal Performance ◽  
Phase Change Materials ◽  
Metal Foam ◽  
Melting Process ◽  
Metal Foams ◽  
Performance Comparison ◽  
Melting Time ◽  
Porous Metals

Abstract The thermal performance of latent heat thermal energy storage (LHTES) systems considerably depends on thermal conductivity of adopted phase change materials (PCMs). To increase the low thermal conductivity of these materials, pure PCMs can be loaded with metal foams. In this study, the melting process of pure and metal-foam loaded phase change materials placed in a rectangular shape case is experimentally investigated by imposing a constant heat flux at the top. Two different paraffin waxes with melting point of about 35°C are tested. The results obtained with pure PCM are compared with those achieved from the use of PCM combined with two different porous metals: a 10 PPI aluminum foam with 96% porosity and a 20 PPI copper foam with 95% porosity. The results demonstrate how metal foams lead to a significant improvement of conduction heat transfer reducing significantly the melting time and the temperature difference between the heater and PCM.

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 Experimental Evaluation of Nano-Enhanced Phase Change Materials in a Finned Storage Unit

2020 ◽  
Vol 10 (3) ◽  
pp. 5814-5818
Author(s):  
M. A. Aichouni ◽  
N. F. Alshammari ◽  
N. Ben Khedher ◽  
M. Aichouni
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Performance ◽  
Phase Change Materials ◽  
Performance Enhancement ◽  
Renewable Energy Sources ◽  
Heating System ◽  
Al2o3 Nanoparticles ◽  
Storage Unit ◽  
Experimental Apparatus

The intermittent nature of renewable energy sources such as solar and wind necessitates integration with energy-storage units to enable realistic applications. In this study, thermal performance enhancement of the finned Cylindrical Thermal Energy Storage (C-TES) with nano-enhanced Phase Change Material (PCM) integrated with the water heating system under Storage, Charging and Discharging (SCD) conditions were investigated experimentally. The effects of the addition of copper oxide (CuO) and aluminum oxide (Al2O3) nanoparticles in PCM on thermal conductivity, specific heat, and on charging and discharging performance rates were theoretically and experimentally investigated and studied in detail. The experimental apparatus utilized paraffin wax as PCM, which was filled in Finned C-TES to conduct the experiments. The experimental results showed a positive improvement compared with the non-nano additive PCM. The significance and originality of this project lies within the evaluation and identification of preferable metal-oxides with higher potential for improving thermal performance.

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