scholarly journals Evaluation of the Melting Performance in a Conical Latent Heat Thermal Unit Having Variable Length Fins

2021 ◽  
Vol 13 (5) ◽  
pp. 2667
Author(s):  
Mohammad Ghalambaz ◽  
S.A.M. Mehryan ◽  
Mahboobeh Mahdavi ◽  
Obai Younis ◽  
Mohammad A. Alim
Keyword(s):  
Aspect Ratio ◽  
Phase Change ◽  
Latent Heat ◽  
Optimum Design ◽  
Thermal Energy ◽  
Volume Fraction ◽  
Melting Rate ◽  
Design Parameters ◽  
Convection Flow ◽  
Taguchi Optimization

A conical shell-tube design with non-uniform fins was addressed for phase change latent heat thermal energy storage (LHTES). The shell was filled with nano-enhanced phase change material (NePCM). The cone aspect ratio of the shell and the fins aspect ratio were adopted as the geometrical design parameters. The type and volume fraction of the nanoparticles were other design parameters. The investigated nanoparticles were alumina, graphite oxide, silver, and copper. The finite element method was employed to solve the natural convection flow and phase change thermal energy equations in the LHTES unit. The Taguchi optimization method was utilized to maximize the melting rate in the unit. Two cases of ascending and descending conical shells were investigated. The outcomes showed that the shell-aspect ratio and fin aspect ratio were the most important design parameters, followed by the type and concentration of nanoparticles. Both ascending and descending designs could lead to the same melting rate at their optimum design. The optimum design of LHTES could improve the melting rate by up to 18.5%. The optimum design for ascending (descending) design was a plain tube (a cone aspect ratio of 1.17) filled by 4.5% alumina-Bio-PCM (1.5% copper-Bio-PCM).

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.

Shape Factor in the Latent-Heat-Thermal-Energy-Storage Systems

2001 ◽  
Author(s):  
Sergei Fomin
Keyword(s):  
Energy Storage ◽  
Aspect Ratio ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage Systems ◽  
Melting Rate ◽  
Energy Storage Systems ◽  
Cross Sectional ◽  
Thermal Energy Storage Systems

Abstract An approximate mathematical model of contact melting of an unfixed material in an elliptical capsule is developed. The main characteristic scales and non-dimensional parameters, which describe the principal features of the melting process, are found. Choosing the special heat flux distribution on the wall of the capsule allows us to derive a closed-form evolution equation for the motion of the solid, which also determines the melting rate. It is shown that the melting rate depends on the shape of the capsule. The elliptical capsules show higher rate of melting than the circular ones. The vertically elongated capsules provide more effective melting than the horizontally elongated ones, even though they have the same aspect ratio and vertical cross-sectional areas. The time required for complete melting can be achieved by the right choice of the shape of the capsule, which is specified by the value of the aspect ratio. This is especially important for the design of practical latent-heat-thermal-energy-storage systems.

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.

scholarly journals Latent Heat Phase Change Heat Transfer of a Nanoliquid with Nano–Encapsulated Phase Change Materials in a Wavy-Wall Enclosure with an Active Rotating Cylinder

2021 ◽  
Vol 13 (5) ◽  
pp. 2590
Author(s):  
S. A. M. Mehryan ◽  
Kaamran Raahemifar ◽  
Leila Sasani Gargari ◽  
Ahmad Hajjar ◽  
Mohamad El Kadri ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Wavy Wall ◽  
Governing Equations ◽  
Stefan Number ◽  
Change Material

A Nano-Encapsulated Phase-Change Material (NEPCM) suspension is made of nanoparticles containing a Phase Change Material in their core and dispersed in a fluid. These particles can contribute to thermal energy storage and heat transfer by their latent heat of phase change as moving with the host fluid. Thus, such novel nanoliquids are promising for applications in waste heat recovery and thermal energy storage systems. In the present research, the mixed convection of NEPCM suspensions was addressed in a wavy wall cavity containing a rotating solid cylinder. As the nanoparticles move with the liquid, they undergo a phase change and transfer the latent heat. The phase change of nanoparticles was considered as temperature-dependent heat capacity. The governing equations of mass, momentum, and energy conservation were presented as partial differential equations. Then, the governing equations were converted to a non-dimensional form to generalize the solution, and solved by the finite element method. The influence of control parameters such as volume concentration of nanoparticles, fusion temperature of nanoparticles, Stefan number, wall undulations number, and as well as the cylinder size, angular rotation, and thermal conductivities was addressed on the heat transfer in the enclosure. The wall undulation number induces a remarkable change in the Nusselt number. There are optimum fusion temperatures for nanoparticles, which could maximize the heat transfer rate. The increase of the latent heat of nanoparticles (a decline of Stefan number) boosts the heat transfer advantage of employing the phase change particles.

scholarly journals Nano-Enhanced Phase Change Materials in Latent Heat Thermal Energy Storage Systems: A Review

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3821
Author(s):  
Kassianne Tofani ◽  
Saeed Tiari
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Storage Systems ◽  
Heat Pipes ◽  
Energy Storage Systems ◽  
Thermal Energy Storage Systems

Latent heat thermal energy storage systems (LHTES) are useful for solar energy storage and many other applications, but there is an issue with phase change materials (PCMs) having low thermal conductivity. This can be enhanced with fins, metal foam, heat pipes, multiple PCMs, and nanoparticles (NPs). This paper reviews nano-enhanced PCM (NePCM) alone and with additional enhancements. Low, middle, and high temperature PCM are classified, and the achievements and limitations of works are assessed. The review is categorized based upon enhancements: solely NPs, NPs and fins, NPs and heat pipes, NPs with highly conductive porous materials, NPs and multiple PCMs, and nano-encapsulated PCMs. Both experimental and numerical methods are considered, focusing on how well NPs enhanced the system. Generally, NPs have been proven to enhance PCM, with some types more effective than others. Middle and high temperatures are lacking compared to low temperature, as well as combined enhancement studies. Al2O3, copper, and carbon are some of the most studied NP materials, and paraffin PCM is the most common by far. Some studies found NPs to be insignificant in comparison to other enhancements, but many others found them to be beneficial. This article also suggests future work for NePCM and LHTES systems.

scholarly journals Phase-Transition Thermal Charging of a Channel-Shape Thermal Energy Storage Unit: Taguchi Optimization Approach and Copper Foam Inserts

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1235
Author(s):  
Mohammad Ghalambaz ◽  
Seyed Abdollah Mansouri Mehryan ◽  
Ahmad Hajjar ◽  
Obai Younis ◽  
Mikhail A. Sheremet ◽  
...  
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Metal Foam ◽  
Volume Fraction ◽  
Foam Layer ◽  
Storage Unit ◽  
Energy Storage Unit ◽  
Copper Foam

Thermal energy storage is a technique that has the potential to contribute to future energy grids to reduce fluctuations in supply from renewable energy sources. The principle of energy storage is to drive an endothermic phase change when excess energy is available and to allow the phase change to reverse and release heat when energy demand exceeds supply. Unwanted charge leakage and low heat transfer rates can limit the effectiveness of the units, but both of these problems can be mitigated by incorporating a metal foam into the design of the storage unit. This study demonstrates the benefits of adding copper foam into a thermal energy storage unit based on capric acid enhanced by copper nanoparticles. The volume fraction of nanoparticles and the location and porosity of the foam were optimized using the Taguchi approach to minimize the charge leakage expected from simulations. Placing the foam layer at the bottom of the unit with the maximum possible height and minimum porosity led to the lowest charge time. The optimum concentration of nanoparticles was found to be 4 vol.%, while the maximu possible concentration was 6 vol.%. The use of an optimized design of the enclosure and the optimum fraction of nanoparticles led to a predicted charging time for the unit that was approximately 58% shorter than that of the worst design. A sensitivity analysis shows that the height of the foam layer and its porosity are the dominant variables, and the location of the porous layer and volume fraction of nanoparticles are of secondary importance. Therefore, a well-designed location and size of a metal foam layer could be used to improve the charging speed of thermal energy storage units significantly. In such designs, the porosity and the placement-location of the foam should be considered more strongly than other factors.

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