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.

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.

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.

Experimental Investigation on a Latent Heat Thermal Storage Unit for Solar Cooling Application

Green ◽  
2011 ◽  
Vol 1 (2) ◽  
Author(s):  
L. Chidambaram ◽  
A. S. Ramana ◽  
G. Kamaraj ◽  
R. Velraj
Keyword(s):  
Solar Energy ◽  
Latent Heat ◽  
Solar Collector ◽  
Heat Storage ◽  
Storage System ◽  
Thermal Storage ◽  
Environmental Crisis ◽  
Storage Unit ◽  
Latent Heat Storage ◽  
Solar Cooling

AbstractConventional cooling technologies that utilize harmful refrigerants consume more energy and cause peak loads leading to negative environmental impacts. As the world grapples with the energy and environmental crisis, there is an urgent need to develop and promote environmentally benign sustainable cooling technologies. Solar cooling is one such promising technology, given the fact that solar energy is the cheapest and most widely available renewable energy that matches the cooling load requirements. However thermal storage systems are essential to overcome the disadvantage of the intermittent nature of solar energy and variations in the cooling demand. The enhanced utilization of solar energy and other consequences of thermal storage integrated systems have gained the attention of researchers in recent years. The concept of combined sensible and latent heat storage system is successfully introduced in several applications and it has many advantages. This paper presents the performance of the solar collector system and the charging characteristics of a PCM based latent heat thermal storage unit, which is designed to provide continuous supply of heat for the operation of 1 kW vapor absorption refrigeration unit. Investigations on PCM integrated thermal storage system have revealed improvement in heat storage capacity, lower heat loss and an increased solar collector efficiency due to better thermal stratification.

Experimental Study of Thermal Energy Storage Using Natural Porous Media

2017 ◽  
Author(s):  
A. J. Al Edhari ◽  
C. C. Ngo
Keyword(s):  
Experimental Study ◽  
Porous Media ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Thermal Storage ◽  
Heat Transfer Fluid ◽  
Storage Unit ◽  
Storage Media

Thermal energy storage has been an area of research interest due to the need to store solar energy or excess energy for later use in many applications including district heating. The focus of a lot of research is on exotic and expensive storage media. This paper presents an experimental study of thermal energy storage using porous media readily available and commonly found in nature such as sand, soil, pebble rocks and gravel. This study also considers a simple and inexpensive thermal storage system which could be constructed easily and examines what could be done to increase the thermal storage performance. The thermal storage system examined in the present study was a thermal energy storage unit with embedded horizontal pipes carrying water as the heat transfer fluid for thermal charging. Different thermal storage configurations were examined by adjusting the thermal charging temperature and using different storage media. The temperature distribution within the storage media was monitored for 10 hours using a data acquisition system with K-type thermocouples. The results indicate that a thermal storage system using sand as storage media is slightly better compared with gravel or pebble rocks as storage media.

scholarly journals Pore-Scale Investigation on Natural Convection Melting in a Square Cavity with Gradient Porous Media

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4274
Author(s):  
Jiangxu Huang ◽  
Kun He ◽  
Lei Wang
Keyword(s):  
Porous Media ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Thermal Performance ◽  
Liquid Fraction ◽  
Particle Diameter ◽  
Numerical Data ◽  
Melting Time ◽  
Pore Scale ◽  
Square Cavity

In this paper, natural convection melting in a square cavity with gradient porous media is numerically studied at pore-scale level by adopting the lattice Boltzmann method. To generate the gradient porous media, a Monte Carlo technique based on the random sampling principle is used. The effects of several factors, such as Rayleigh number, gradient porosity structure, gradient direction, and particle diameters on natural convection melting are investigated in detail. Based on the numerical data, it is observed that the thermal performance of the gradient porous media always depends on the Rayleigh number and, specifically, as the Rayleigh number is set to 106, the total melting time obtained for the case of the negative gradient porous media is always shorter than the cases of positive gradient and uniform porous media. However, if the Rayleigh number is equal to 104, at which the heat transfer is dominated by the heat conduction, it is noted that the performance of the positive gradient porous media is better than the other cases. To have a better understand on this point, various simulations are also performed and we found that there usually exists a critical value of Rayleigh number to determine the thermal performance of the gradient porous media. Moreover, our numerical results also show that the influence of the particle diameter on the liquid fraction is insignificant as Rayleigh number is set to 104, while it has a great impact on the liquid fraction when Rayleigh number equals 106.

Analysis of New Heat Exchanger Performance in Phase Change Energy Storage

2014 ◽  
Vol 1061-1062 ◽  
pp. 638-644 ◽  
Author(s):  
Yu Qiu ◽  
Xi Luo ◽  
Qiong Fen Yu ◽  
Yong Feng Xu ◽  
Cong Bin Leng ◽  
...  
Keyword(s):  
Heat Flux ◽  
Heat Exchanger ◽  
Phase Change ◽  
Thermal Storage ◽  
Heat Transfer Fluid ◽  
Melting Time ◽  
Heating Wall ◽  
Maximum Heat ◽  
Tube Heat Exchanger ◽  
Shell And Tube

Based on traditional shell-and-tubeheat exchanger, a new heat exchanger which applies to phase change thermal storage was proposed. The thermal storage process of new heat exchanger and shell-and-tube heat exchanger which use paraffin as phase change material and use water as heat-transfer fluid can be simulated by CFD software, respectively. The changes of liquid fraction and heat flux density along with time have been got by computer stimulation. It can be found that maximum heat flux of the new heat exchanger heating wall is 2.5 times than shell-and-tube heat exchanger, melting time of the new heat exchanger is 5 times than shell-and-tube heat exchanger. From the two aspects, the heat storage effect of new heat exchanger is better than conventional concentric tube heat exchanger.

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