scholarly journals Solidification Enhancement in a Multi-Tube Latent Heat Storage System for Efficient and Economical Production: Effect of Number, Position and Temperature of the Tubes

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3211
Author(s):  
Min Li ◽  
Jasim M. Mahdi ◽  
Hayder I. Mohammed ◽  
Dmitry Olegovich Bokov ◽  
Mustafa Z. Mahmoud ◽  
...  
Keyword(s):  
Free Convection ◽  
Heat Storage ◽  
Liquid Fraction ◽  
Removal Rate ◽  
Heat Removal ◽  
Vertical Direction ◽  
Heat Transfer Fluid ◽  
Latent Heat Storage ◽  
Solidification Mode ◽  
The Impact

Thermal energy storage is an important component in energy units to decrease the gap between energy supply and demand. Free convection and the locations of the tubes carrying the heat-transfer fluid (HTF) have a significant influence on both the energy discharging potential and the buoyancy effect during the solidification mode. In the present study, the impact of the tube position was examined during the discharging process. Liquid-fraction evolution and energy removal rate with thermo-fluid contour profiles were used to examine the performance of the unit. Heat exchanger tubes are proposed with different numbers and positions in the unit for various cases including uniform and non-uniform tubes distribution. The results show that moving the HTF tubes to medium positions along the vertical direction is relatively better for enhancing the solidification of PCM with multiple HTF tubes. Repositioning of the HTF tubes on the left side of the unit can slightly improve the heat removal rate by about 0.2 in the case of p5-u-1 and decreases by 1.6% in the case of p5-u-2. It was found also that increasing the distance between the tubes in the vertical direction has a detrimental effect on the PCM solidification mode. Replacing the HTF tubes on the left side of the unit negatively reduces the heat removal rate by about 1.2 and 4.4%, respectively. Further, decreasing the HTF temperature from 15 °C to 10 and 5 °C can increase the heat removal rate by around 7 and 16%, respectively. This paper indicates that the specific concern to the HTF tube arrangement should be made to improve the discharging process attending free convection impact in phase change heat storage.

scholarly journals Impact of Tube Bundle Placement on the Thermal Charging of a Latent Heat Storage Unit

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1289
Author(s):  
Mohammad Ghalambaz ◽  
Amir Hossein Eisapour ◽  
Hayder I. Mohammed ◽  
Mohammad S. Islam ◽  
Obai Younis ◽  
...  
Keyword(s):  
Heat Transfer ◽  
General Circulation ◽  
Liquid Fraction ◽  
Tube Bundle ◽  
Melting Rate ◽  
Heat Transfer Fluid ◽  
Storage Unit ◽  
Latent Heat Storage ◽  
Four Levels ◽  
The Impact

The melting process of a multi-tube’s thermal energy storage system in the existence of free convection effects is a non-linear and important problem. The placement of heated tubes could change the convective thermal circulation. In the present study, the impact of the position of seven heat exchanger tubes was systematically investigated. The energy charging process was numerically studied utilizing liquid fraction and stored energy with exhaustive temperature outlines. The tubes of heat transfer fluid were presumed in the unit with different locations. The unit’s heat transfer behavior was assessed by studying the liquid fraction graphs, streamlines, and isotherm contours. Each of the design factors was divided into four levels. To better investigate the design space for the accounted five variables and four levels, an L16 orthogonal table was considered. Changing the location of tubes could change the melting rate by 28%. The best melting rate was 94% after four hours of charging. It was found that the tubes with close distance could overheat each other and reduce the total heat transfer. The study of isotherms and streamlines showed the general circulation of natural convection flows at the final stage of melting was the most crucial factor in the melting of top regions of the unit and reduces the charging time. Thus, particular attention to the tubes’ placement should be made so that the phase change material could be quickly melted at both ends of a unit.

Latent heat storage for hot beverages

2019 ◽  
Vol 13 (3) ◽  
pp. 5653-5664
Author(s):  
M. S. M. Al-Jethelah ◽  
H. S. Dheyab ◽  
S. Khudhayer ◽  
T. K. Ibrahim ◽  
A. T. Al-Sammarraie
Keyword(s):  
Latent Heat ◽  
Food Industry ◽  
Heat Storage ◽  
Food Storage ◽  
Thermal Engineering ◽  
Engineering Applications ◽  
Latent Heat Storage ◽  
The Impact ◽  
Encapsulated Phase Change Material ◽  
Change Material

Latent heat storage has shown a great potential in many engineering applications. The utilization of latent heat storage has been extended from small scales to large scales of thermal engineering applications. In food industry, latent heat has been applied in food storage. Another potential application of latent heat storage is to maintain hot beverages at a reasonable drinking temperature for longer periods. In the present work, a numerical calculation was performed to investigate the impact of utilizing encapsulated phase change material PCM on the temperature of hot beverage. The PCM was encapsulated in rings inside the cup. The results showed that the encapsulated PCM reduced the coffee temperature to an acceptable temperature in shorter time. In addition, the PCM maintained the hot beverage temperature at an acceptable drinking temperature for rational time.

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.

scholarly journals Towards development of a prototype high-temperature latent heat storage unit as an element of a RES-based energy system (part 2)

2016 ◽  
Vol 64 (2) ◽  
pp. 401-408
Author(s):  
J. Karwacki ◽  
K. Bogucka-Bykuć ◽  
W. Włosiński ◽  
S. Bykuć
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Heat Storage ◽  
Heat Transfer Fluid ◽  
Storage Unit ◽  
Latent Heat Storage ◽  
Shell And Tube

Abstract This paper presents an experimental study performed with the general aim of defining procedures for calculation and optimization of shell-and-tube latent thermal energy storage unit with metals or metal alloys as PCMs. The experimental study is focused on receiving the exact information about heat transfer between heat transfer fluid (HTF) and phase change material (PCM) during energy accumulation process. Therefore, simple geometry of heat transfer area was selected. Two configurations of shell-and-tube thermal energy storage (TES) units were investigated. The paper also highlights the emerging trend (reflected in the literature) with respect to the investigation of metal PCM-based heat storage units in recent years and shortly presents unique properties and application features of this relatively new class of PCMs.

scholarly journals PENGGUNAAN PARAFFIN WAX SEBAGAI PENYIMPAN KALOR PADA PEMANAS AIR TENAGA MATAHARI THERMOSYPHON

ROTASI ◽  
2016 ◽  
Vol 18 (3) ◽  
pp. 76 ◽  
Author(s):  
Muhammad Nadjib
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Heat Storage ◽  
Paraffin Wax ◽  
Heat Transfer Fluid ◽  
Sensible Heat ◽  
Latent Heat Storage ◽  
Change Material

Pemanas Air Tenaga Matahari (PATM) konvensional umumnya menggunakan air sebagai penyimpan energi termal. Pemakaian sensible heat storage (SHS) ini memiliki kekurangan, diantaranya adalah densitas energinya rendah. Di sisi lain, latent heat storage (LHS) mempunyai sifat khas yaitu densitas energinya tinggi karena melibatkan perubahan fasa dalam penyerapan atau pelepasan kalor. Material LHS sering disebut phase change material (PCM). Penggunaan PCM pada PATM menarik dilakukan untuk meningkatkan densitas energi sistem. Penelitian ini bertujuan untuk menyelidiki perilaku termal penggunaan paraffin wax di dalam tangki PATM jenis thermosyphon. Penelitian menggunakan kolektor matahari pelat datar dan tangki thermal energy storage (TES) yang dipasang secara horisontal di sisi atas kolektor. Di dalam tangki terdapat alat penukar kalor yang terdiri dari sekumpulan pipa kapsul dimana di dalamnya berisi paraffin wax. Air digunakan sebagai SHS dan heat transfer fluid (HTF). Termokopel dipasang di sisi HTF dan sisi PCM. Piranometer dan sensor temperatur udara luar diletakkan di dekat kolektor matahari. Pengambilan data dilakukan selama proses charging. Temperatur HTF, PCM dan intensitas radiasi matahari direkam setiap 30 detik. Data ini digunakan untuk mengetahui evolusi temperatur HTF dan PCM. Berdasarkan evolusi temperatur ini kemudian dianalisis perilaku termal PATM. Hasil dari penelitian ini adalah bahwa paraffin wax telah berfungsi sebagai penyimpan energi termal bersama air di dalam tangki PATM jenis thermosyphon. PCM memberi kontribusi yang cukup signifikan terhadap kapasitas penyimpanan energi sistem. Efisiensi kolektor lebih optimal karena PCM dapat mempertahankan stratifikasi termal sampai akhir charging. Adanya PCM mampu mengendalikan penurunan efisiensi pengumpulan energi saat intensitas radiasi matahari menurun. Alat penukar kalor yang digunakan cukup efektif yang ditandai dengan kecepatan pemanasan rata-rata antara HTF dan PCM yang tidak berbeda jauh.

scholarly journals Thermal Stratification Performance of a Packed Bed Latent Heat Storage System during Charging

2018 ◽  
Vol 64 ◽  
pp. 03001
Author(s):  
Mawire Ashmore ◽  
Lentswe Katlego ◽  
Lugolole Robert ◽  
Okello Denis ◽  
Nyeinga Karidewa
Keyword(s):  
Latent Heat ◽  
Flow Rate ◽  
Thermal Stratification ◽  
Heat Storage ◽  
Storage System ◽  
Packed Bed ◽  
Heat Transfer Fluid ◽  
Latent Heat Storage ◽  
Flow Rates ◽  
Peak Value

Experimental thermal stratification evaluation of a packed bed latent heat storage is done during charging cycles. The packed bed latent heat storage system consists of adipic acid encapsulated in aluminum spheres. Sunflower oil is used as the heat transfer fluid during charging cycles. Stratification number profiles are used to evaluate thermal stratification in the storage system. Charging experiments are carried out with three different flow-rates (4 ml/s, 8 ml/s and 12 ml/s). Charging experiments are also done using the same flow-rate (8 ml/s) with three different set heater temperatures (220 °C, 240 °C and 260 °C). The lowest charging flow-rate (4 ml/s) shows the best variation of the stratification number profile since it shows the least drop from the peak value and the shortest charging interval. Different set heater temperatures show almost identical stratification number profiles. The effect of the charging flow-rate is more significant than the effect of the charging set heater temperature when evaluating thermal stratification for this particular system.

High Temperature Thermochemical Energy Storage Using Packed Beds

2016 ◽  
Author(s):  
Qasim A. Ranjha ◽  
Nasser Vahedi ◽  
Alparslan Oztekin
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Energy Storage ◽  
Solar Energy ◽  
Latent Heat ◽  
High Temperatures ◽  
Heat Storage ◽  
Three Dimensional ◽  
Heat Transfer Fluid ◽  
Latent Heat Storage

Thermal energy storage units are vital for development of the efficient solar power generation systems due to fluctuating nature of daily and seasonal solar radiations. Two available efficient and practical options to store and release solar energy at high temperatures are latent heat storage and thermochemical storage. Latent heat storage can operate only at single phase change temperature. This problem can be avoided by some of the thermochemical storage systems in which solar energy can be stored and released over a range of high temperature by endothermic and exothermic reactions. One such reaction system is reversible reaction involving dehydration of Ca(OH)2 and hydration of CaO. This system is considered in the present study to model a circular fixed bed reactor for storage and release of heat at high temperatures. Air is used as heat transfer fluid (HTF) flowing in an annular shell outside the bed for charging and discharging the bed. The bed is filled with CaO/Ca(OH)2 powders with particles diameter of the order 5μm. Three dimensional transient model has been developed and simulations are performed using finite elements based COMSOL Multiphysics. Conservation of mass and energy equations, coupled with reaction kinetics equations, are solved in the three dimensional porous bed and the heat transfer fluid channel. Parametric study is performed by varying HTF parameters, bed dimensions and process conditions. The results are verified through a qualitative comparison with experimental and simulation results in the literature for similar geometric configurations.

scholarly journals Solidification Enhancement in a Triple-Tube Latent Heat Energy Storage System Using Twisted Fins

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7179
Author(s):  
Xinguo Sun ◽  
Jasim M. Mahdi ◽  
Hayder I. Mohammed ◽  
Hasan Sh. Majdi ◽  
Wang Zixiong ◽  
...  
Keyword(s):  
Energy Storage ◽  
Latent Heat ◽  
Liquid Fraction ◽  
Storage System ◽  
Solidification Time ◽  
Heat Transfer Fluid ◽  
Inlet Temperature ◽  
Tube Heat Exchanger ◽  
Current Path ◽  
The Impact

This work evaluates the influence of combining twisted fins in a triple-tube heat exchanger utilised for latent heat thermal energy storage (LHTES) in three-dimensional numerical simulation and comparing the outcome with the cases of the straight fins and no fins. The phase change material (PCM) is in the annulus between the inner and the outer tube, these tubes include a cold fluid that flows in the counter current path, to solidify the PCM and release the heat storage energy. The performance of the unit was assessed based on the liquid fraction and temperature profiles as well as solidification and the energy storage rate. This study aims to find suitable and efficient fins number and the optimum values of the Re and the inlet temperature of the heat transfer fluid. The outcomes stated the benefits of using twisted fins related to those cases of straight fins and the no-fins. The impact of multi-twisted fins was also considered to detect their influences on the solidification process. The outcomes reveal that the operation of four twisted fins decreased the solidification time by 12.7% and 22.9% compared with four straight fins and the no-fins cases, respectively. Four twisted fins improved the discharging rate by 12.4% and 22.8% compared with the cases of four straight fins and no-fins, respectively. Besides, by reducing the fins’ number from six to four and two, the solidification time reduces by 11.9% and 25.6%, respectively. The current work shows the impacts of innovative designs of fins in the LHTES to produce novel inventions for commercialisation, besides saving the power grid.

scholarly journals Comparing water and paraffin PCM as storage mediums for thermal energy storage applications

2019 ◽  
Vol 116 ◽  
pp. 00057
Author(s):  
Christos Pagkalos ◽  
Michalis Gr. Vrachopoulos ◽  
John Konstantaras ◽  
Kostas Lymperis
Keyword(s):  
Energy Storage ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Heat Storage ◽  
Heat Transfer Fluid ◽  
Computational Domain ◽  
Sensible Heat ◽  
Latent Heat Storage ◽  
Storage Mechanism

A CFD analysis is performed in two different heat storage mediums, water and paraffin phase change material (PCM), in order to evaluate and compare the two mediums for use in heating thermal energy storage (HTES) applications. The two mediums use different heat storing mechanisms, namely water uses Sensible Heat Storage, and the PCM Latent heat storage. The applied computational domain represents a single tube of a heat exchanger (HE), and so it comprises of a copper tube with aluminium fins. The geometric characteristics of the domain are taken in accordance with commercially used HE’s for HTES applications [1]. The characteristics studied are the stored energy of the system, the temperature of the heat transfer fluid (HTF) in the outlet and the temperature of the storage medium. The results of the simulations showed that for the same mass of storage mediums, the PCM can store more energy than water, for the same temperature of the HTF, as expected. Also, the temperature of the medium for the sensible heat storage rises linearly with the energy stored inside it, while in the latent heat storage mechanism, the temperature of the medium rises linearly till the melting (or solidification) of it, then stays almost steady until the melting of the whole volume and then rises again until it reaches the temperature of the HTF.

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