scholarly journals Thermal Charging Optimization of a Wavy-Shaped Nano-Enhanced Thermal Storage Unit

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1496
Author(s):  
Mohammad Ghalambaz ◽  
S.A.M. Mehryan ◽  
Ahmad Hajjar ◽  
Mohammad Yacoub Al Shdaifat ◽  
Obai Younis ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Phase Change ◽  
Volume Fraction ◽  
Thermal Storage ◽  
Wave Number ◽  
Storage Unit ◽  
Charging Time ◽  
Phase Change Heat Transfer ◽  
The Impact

A wavy shape was used to enhance the thermal heat transfer in a shell-tube latent heat thermal energy storage (LHTES) unit. The thermal storage unit was filled with CuO–coconut oil nano-enhanced phase change material (NePCM). The enthalpy-porosity approach was employed to model the phase change heat transfer in the presence of natural convection effects in the molten NePCM. The finite element method was applied to integrate the governing equations for fluid motion and phase change heat transfer. The impact of wave amplitude and wave number of the heated tube, as well as the volume concertation of nanoparticles on the full-charging time of the LHTES unit, was addressed. The Taguchi optimization method was used to find an optimum design of the LHTES unit. The results showed that an increase in the volume fraction of nanoparticles reduces the charging time. Moreover, the waviness of the tube resists the natural convection flow circulation in the phase change domain and could increase the charging time.

scholarly journals Latent Heat Thermal Storage in Non-Uniform Metal Foam Filled with Nano-Enhanced Phase Change Material

2021 ◽  
Vol 13 (4) ◽  
pp. 2401
Author(s):  
Mohammad Ghalambaz ◽  
S. A. M. Mehryan ◽  
Ahmad Hajjar ◽  
Mehdi A. Fteiti ◽  
Obai Younis ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Phase Change ◽  
Pore Size ◽  
Metal Foam ◽  
Volume Fraction ◽  
Heated Surface ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Charging Time

The melting heat transfer of CuO—coconut oil embedded in a non-uniform copper metal foam—was addressed. Copper foam is placed in a channel-shaped Thermal Energy Storage (TES) unit heated from one side. The foam is non-uniform with a linear porosity gradient in a direction perpendicular to the heated surface. The finite element method was applied to simulate natural convection flow and phase change heat transfer in the TES unit. The results showed that the porosity gradient could significantly boost the melting rate and stored energy rate in the TES unit. The best non-uniform porosity corresponds to a case in which the maximum porosity is next to a heated surface. The variation of the unit placement’s inclination angle is only important in the final stage of charging, where there is a dominant natural convection flow. The variation of porous pore size induces minimal impact on the phase change rate, except in the case of a large pore size of 30 pore density (PPI). The presence of nanoparticles could increase or decrease the charging time. However, using a 4% volume fraction of nanoparticles could mainly reduce the charging time.

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.

scholarly journals Heat Transfer Improvement in MHD Natural Convection Flow of Graphite Oxide/Carbon Nanotubes-Methanol Based Casson Nanofluids Past a Horizontal Circular Cylinder

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1444
Author(s):  
Abdulkareem Saleh Hamarsheh ◽  
Firas A. Alwawi ◽  
Hamzeh T. Alkasasbeh ◽  
Ahmed M. Rashad ◽  
Ruwaidiah Idris
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Natural Convection ◽  
Graphite Oxide ◽  
Volume Fraction ◽  
Casson Fluid ◽  
Convection Flow ◽  
Local Skin ◽  
Casson Nanofluid ◽  
The Impact

This numerical investigation intends to present the impact of nanoparticles volume fraction, Casson, and magnetic force on natural convection in the boundary layer region of a horizontal cylinder in a Casson nanofluid under constant heat flux boundary conditions. Methanol is considered as a host Casson fluid. Graphite oxide (GO), single and multiple walls carbon nanotubes (SWCNTs and MWCNTs) nanoparticles have been incorporated to support the heat transfer performances of the host fluid. The Keller box technique is employed to solve the transformed governing equations. Our numerical findings were in an excellent agreement with the preceding literature. Graphical results of the effect of the relevant parameters on some physical quantities related to examine the behavior of Casson nanofluid flow were obtained, and they confirmed that an augmentation in Casson parameter results in a decline in local skin friction, velocity, or temperature, as well as leading to an increment in local Nusselt number. Furthermore, MWCNTs are the most efficient in improving the rate of heat transfer and velocity, and they possess the lowest temperature.

Effect of Fin Orientation on Melting Process in Horizontal Double Pipe Thermal Energy Storage Systems

2021 ◽  
pp. 1-16
Author(s):  
Nesrine Boulaktout ◽  
El-Hacène Mezaache ◽  
Mohamed Teggar ◽  
Müslüm Arici ◽  
K.A.R. Ismail ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage Systems ◽  
Melting Process ◽  
Storage Unit ◽  
Charging Time ◽  
Thermal Energy Storage Systems

Abstract Immersion of fins in latent heat thermal energy storage systems has been used as an influential approach to remedy the poor thermal conductivity of phase-change materials. Present paper numerically investigates heat transfer and phase change improvement by means of longitudinal fins in a shell and tube thermal energy storage unit. The main aim of this study is to investigate the effect of fin orientation on the performance of the storage unit. Six configurations of different fin numbers (2, 4 and 8 fins) and orientations (π/2, π/4, and π/8) are tested. For simulations, a 2D mathematical model incorporating the enthalpy-porosity method and finite volume techniques are established and solved by ANSYS-Fluent. The numerical predictions are successfully validated by comparison with experimental and numerical data from the literature. Heat transfer characteristics and melting process are analyzed through streamlines, isotherms, mean temperature, heat flux and heat transfer coefficient as well as transient melting front position and liquid fractions. Results show that orientation of fins has significant impact on the charging time for two cases (2 and 4 fins) whereas no significant reduction in charging time was obtained for the case of 8 fins. In case of utilizing 2 fins, a fin orientation of 0° (vertical fins) shortens the charging time by up to 2.5 folds compared to the horizontal fins (90°). These results could help designing efficient latent thermal energy storage units.

scholarly journals Investigation of the Use of an Inorganic Aqueous Solution in Aluminum-Made Phase-Change Heat Transfer Devices

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Qi Yao ◽  
Michael J. Stubblebine ◽  
Ivan Catton
Keyword(s):  
Heat Transfer ◽  
Aqueous Solution ◽  
Natural Convection ◽  
Phase Change ◽  
Aluminum Surface ◽  
Back Flow ◽  
Convection Cooling ◽  
Phase Change Heat Transfer ◽  
Aluminum Passivation ◽  
Inorganic Aqueous Solution

An inorganic aqueous solution, known as IAS, has shown its compatibility with aluminum phase-change heat transfer devices. When using IAS in aluminum devices, aluminum prefers to react with the two oxidizers, permanganate and chromate, rather than water to generate a thin and compact layer of aluminum oxide, which protects the aluminum surface and prevents further reactions. In addition, an electrochemical theory of aluminum passivation is introduced, and the existence of an electrochemical cycle is demonstrated by an aluminum thermosiphon test. The electrochemistry cycle, built up by liquid back flow and tube wall, allows the oxidizers to passivate the aluminum surface inside the device without being directly in contact with it. However, failure was detected while using IAS in thermosiphons with air natural convection cooling. The importance of a continuous liquid back flow to aluminum passivation in phase-change heat transfer devices is pointed out, and a vertical thermosiphon test with natural convection cooling is used to demonstrate that a discontinuous liquid back flow is the main reason of the failures.

scholarly journals Numerical Investigation of Heat Transfer with Natural Convection in a Regularly Heated Elliptical Cylinder Submerged in a Square Fence Loaded With a Nanofluid

2021 ◽  
Vol 15 ◽  
pp. 223-232
Author(s):  
Djedid Taloub ◽  
Adelkarim Bouras ◽  
Zied Driss
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Volume Fraction ◽  
Fixed Temperature ◽  
Nusselt Numbers ◽  
Numerical Research ◽  
Finite Volume Approach ◽  
The Impact ◽  
Rayleigh Numbers ◽  
Transfer Flow

During this first paper, numerical research from the natural convection of steady-state laminar heat transfer into a horizontal ring within a heated internal elliptical surface and a cold external square surface is presented. A Cu - water nanofluid, traverses this annular space. For different thermal Rayleigh numbers varying from 103 to 2.5x105 and different volume fractions from the nanoparticles. The arrangement from equations directing the problem was resolved numerically with the Fluent computational language founded on the finite volume approach. Based approaching the Boussinesq approach. The interior and exterior surfaces from the two cylinders are maintained at a fixed temperature. We investigated the impacts of various thermal Rayleigh numbers, the volume fraction from the nanoparticles, and the effect of the eccentricity of the internal cylinder on the natural convection. The results are shown within the figure of isocurrents, isotherms, and mean and local Nusselt numbers. The objective of this investigation is to examine the impact of different parameters on the heat transfer flow.

scholarly journals The Effect of Variable-Length Fins and Different High Thermal Conductivity Nanoparticles in the Performance of the Energy Storage Unit Containing Bio-Based Phase Change Substance

2021 ◽  
Vol 13 (5) ◽  
pp. 2884
Author(s):  
Mohammad Ghalambaz ◽  
Seyed Abdollah Mansouri Mehryan ◽  
Masoud Mozaffari ◽  
Obai Younis ◽  
Aritra Ghosh
Keyword(s):  
Natural Convection ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Volume Fraction ◽  
Optimization Method ◽  
Melting Rate ◽  
Storage Unit ◽  
Taguchi Optimization ◽  
Energy Storage Unit

Thermal Energy Storage (TES) is a key feature in the sizing of thermal systems and energy management. The Phase Change Material (PCM) can store a huge amount of heat in the form of latent heat. However, a good design of the TES unit is required to absorb thermal energy and charge quickly. In the present study, a combination of optimum fin design and nanoadditives are used to design a shell and tube shape TES unit. The Taguchi optimization method is employed to maximize the melting rate by optimizing the arrangement shape of fins and the type and the volume fractions of nanoparticles. The results showed that long fins should be mounted at the bottom and short fins at the top, so that the PCM melts down at the bottom quickly, and consequently, a natural convection circulation occurs at the bottom and advances in the solid PCM. The short fins at the top allow a good natural convection circulation at the top. An increase in the volume fraction of nanoparticles increases the melting rate. An optimum design shows a 20% more melting rate compared to a poor design.

scholarly journals The Thermal Charging Performance of Finned Conical Thermal Storage System Filled with Nano-Enhanced Phase Change Material

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1605
Author(s):  
Mohammad Ghalambaz ◽  
Hassan Shirivand ◽  
Kasra Ayoubi Ayoubloo ◽  
S.A.M. Mehryan ◽  
Obai Younis ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Phase Change ◽  
Inclination Angle ◽  
Conical Shell ◽  
Volume Fraction ◽  
Small Radius ◽  
Design Parameters ◽  
Small Aspect Ratio ◽  
Charging Time

A latent heat thermal energy storage (LHTES) unit can store a notable amount of heat in a compact volume. However, the charging time could be tediously long due to weak heat transfer. Thus, an improvement of heat transfer and a reduction in charging time is an essential task. The present research aims to improve the thermal charging of a conical shell-tube LHTES unit by optimizing the shell-shape and fin-inclination angle in the presence of nanoadditives. The governing equations for the natural convection heat transfer and phase change heat transfer are written as partial differential equations. The finite element method is applied to solve the equations numerically. The Taguchi optimization approach is then invoked to optimize the fin-inclination angle, shell aspect ratio, and the type and volume fraction of nanoparticles. The results showed that the shell-aspect ratio and fin inclination angle are the most important design parameters influencing the charging time. The charging time could be changed by 40% by variation of design parameters. Interestingly a conical shell with a small radius at the bottom and a large radius at the top (small aspect ratio) is the best shell design. However, a too-small aspect ratio could entrap the liquid-PCM between fins and increase the charging time. An optimum volume fraction of 4% is found for nanoparticle concentration.

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