scholarly journals Numerical Simulation of the Heat Transfer Behavior of a Zigzag Plate Containing a Phase Change Material for Combustion Heat Recovery and Power Generation

2016 ◽  
Vol 2016 ◽  
pp. 1-11
Author(s):  
Peilun Wang ◽  
Pengxiang Song ◽  
Yun Huang ◽  
Zhijian Peng ◽  
Yulong Ding
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Materials ◽  
Experimental System ◽  
Melting Rate ◽  
Input Power ◽  
Heat Transfer Fluid ◽  
Combustion Heat ◽  
Simulation Results ◽  
Fixed Input

This study presents a numerical analysis of the melting process of phase change materials (PCMs) within a latent heat thermal energy storage (LHTES) system employing zigzag plate. The numerical model used NaCl-MgCl2 mixture as PCMs and hot air as heat transfer fluid (HTF). An experimental system was built to validate the model, and the experimental data agrees reasonably well with the simulation results. The simulation results revealed the effects of the Reynolds and Stefan numbers and the surface topography of the zigzag plate on the charging process. Besides, the effect of the relationship between Reynolds and Stefan numbers on the charging process under a new boundary condition employing a fixed input power was studied. It is found that by modifying the shape of the zigzag plate surface it is feasible to enhance the heat transfer of the LHTES unit remarkably. The melting rate of PCMs increases with the value of Ste or Re numbers with only one of them changing; however, the melting rate of PCMs decreases with the increasing Ste (or decreasing Re) in a fixed input power condition.

scholarly journals Numerical Simulation of the Impact of the Heat Source Position on Melting of a Nano-Enhanced Phase Change Material

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1425
Author(s):  
Tarek Bouzennada ◽  
Farid Mechighel ◽  
Kaouther Ghachem ◽  
Lioua Kolsi
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Numerical Study ◽  
Melting Rate ◽  
Heat Transfer Fluid ◽  
Commercial Code ◽  
Tube Position ◽  
The Impact ◽  
Change Material

A 2D-symmetric numerical study of a new design of Nano-Enhanced Phase change material (NEPCM)-filled enclosure is presented in this paper. The enclosure is equipped with an inner tube allowing the circulation of the heat transfer fluid (HTF); n-Octadecane is chosen as phase change material (PCM). Comsol-Multiphysics commercial code was used to solve the governing equations. This study has been performed to examine the heat distribution and melting rate under the influence of the inner-tube position and the concentration of the nanoparticles dispersed in the PCM. The inner tube was located at three different vertical positions and the nanoparticle concentration was varied from 0 to 0.06. The results revealed that both heat transfer/melting rates are improved when the inner tube is located at the bottom region of the enclosure and by increasing the concentration of the nanoparticles. The addition of the nanoparticles enhances the heat transfer due to the considerable increase in conductivity. On the other hand, by placing the tube in the bottom area of the enclosure, the liquid PCM gets a wider space, allowing the intensification of the natural convection.

scholarly journals Investigation of the dynamic characteristics of a thermal energy storage unit filled with multiple phase change materials

2018 ◽  
Vol 22 (Suppl. 2) ◽  
pp. 527-533 ◽  
Author(s):  
Xiaoyan Li ◽  
Rongpeng Huang ◽  
Xinyue Miao ◽  
Xuelei Wang ◽  
Yabin Liu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Storage Systems ◽  
Heat Transfer Fluid ◽  
Energy Storage Systems ◽  
Thermal Energy Storage Systems

In order to improve the thermal performance of thermal energy storage systems, a packed bed thermal energy storage systems unit using spherical capsules filled with multiple phase change materials (multi-PCM) for use in conventional air-conditioning systems is presented. A 3-D mathematical model was established to investigate the charging characteristics of the thermal energy storage systems unit. The optimum proportion between the multi-PCM was identified. The effects of heat transfer fluid-flow rate and heat transfer fluid inlet temperature on the liquid phase change materials volume fraction, charging time and charging capacity of the thermal energy storage system unit are studied. The results indicate that the charging capacity of multi-PCM units is higher than that of the conventional single-PCM (HY-2). For proportions 0:1:0, 2:3:3, 3:2:3, 3:3:2, 4:1:3, and 4:2:2, the charging capacity decreases by approximately 24.84%, 14.69%, 6.47%, 3.82%, and 1.13%, respectively, compared to the 4:2:2 proportion. Moreover, decreasing the heat transfer fluid inlet temperature can obviously shorten the complete charging time of the thermal energy storage systems unit.

Exergetic Analysis of Energy Storage using Multiple Phase-Change Materials

1996 ◽  
Vol 118 (3) ◽  
pp. 242-248 ◽  
Author(s):  
Z.-X. Gong ◽  
A. S. Mujumdar
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Infinite Number ◽  
Phase Change Materials ◽  
Heat Transfer Fluid ◽  
Distributed Model ◽  
Multiple Phase ◽  
Charge Process ◽  
Exergetic Analysis

This paper presents an exergetic analysis of the charge process in energy storage using multiple phase-change materials (PCMs). Thermal storage using two, three, five, as well as an infinite number of PCMs is analyzed with a distributed model for the heat transfer fluid. Analytical results show the relative merits of using multiple PCMs compared with a single PCM for thermal energy storage. Sample results are presented and discussed.

Thermal Measurement System for Phase Change Materials

2012 ◽  
Author(s):  
R. Adinberg ◽  
D. Zvegilsky
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Materials ◽  
Heating Temperature ◽  
Thermal Storage ◽  
Potassium Nitrate ◽  
Heat Transfer Fluid ◽  
Analysis Model ◽  
Latent Heat Storage ◽  
Thermal Measurements

A lab scale set-up designed based on reflux heat transfer is used for studying latent heat storage for concentrating solar power systems. Phase change materials (PCM) with temperature of fusion range between 300 and 400°C are being tested using this system, including metal alloys and inorganic salts. In the present configuration, the system provides thermal measurements of PCM specimens of about 1000 g under heating temperature up to 450°C and enables simultaneous studying calorimetric properties of the loaded materials and heat transfer effects developed in the thermal storage process composed of charge and discharge phases. The measurement technique includes a thermal analysis model aimed at evaluating the experimental data. Results of the thermal measurements conducted with a thermal storage medium composed of potassium nitrate KNO3 (m.p. 334°C) as PCM and Diphyl (synthetic thermal oil, max working temperature 400°C) as the heat transfer fluid are presented and discussed in this study.

Numerical Model for Storage Systems Based on Phase-Change Materials

2011 ◽  
Author(s):  
Adriano Sciacovelli ◽  
Vittorio Verda ◽  
Francesco Colella
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Materials ◽  
Storage Systems ◽  
Numerical Procedure ◽  
Thermal Storage ◽  
Operating Conditions ◽  
Heat Transfer Fluid ◽  
Inlet Temperature ◽  
Technical Problems

Phase-change materials (PCM) are particularly promising for thermal storage in various energy plants as solar plants, district heating, heat pumps, etc. mainly because of the possibility to reduce the volume of storage tanks, but also because the problems related with thermal stratification are considerably reduced. On the other hand, research is necessary in order to address technical problems, mainly related to the heat transfer in the medium, which needs to be enhanced in order to achieve reasonable charging and discharging processes. The present paper describes the application of computational fluid-dynamics (CFD) for the analysis of PCM thermal storage systems. The numerical analysis is directed at understanding the role of buoyancy-driven convection during constrained solidification and melting inside a shell-and-tube geometry. The 2D model is based on a finite-volume numerical procedure that adopts the enthalpy method to take in account the phase change phenomenon. The time-dependent simulations show the melting phase front and melting fraction of the PCM and incorporate the fluid flow in the liquid phase. The obtained temperature profiles are compared to a set of experimental data available in the literature. The results show that during the melting process natural convection within the PCM has non negligible effects on the behavior of the system. The numerical simulations of the solidification process show that the increasing solid fraction of the PCM inhibits the buoyancy in the remaining liquid portion of the phase-change-material. Furthermore, the paper discusses the effects on the phase-change processes of the main operating conditions, including inlet temperature and mass flow rate of the heat transfer fluid.

Experimental Study on Thermal Characteristics of Finned Coil LHSU Using Paraffin as Phase Change Material

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Guansheng Chen ◽  
Nanshuo Li ◽  
Huanhuan Xiang ◽  
Fan Li
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Phase Change ◽  
Phase Change Material ◽  
Water Flow ◽  
Water Flow Rate ◽  
Thermal Characteristics ◽  
Heat Transfer Fluid ◽  
Latent Heat Storage ◽  
Change Material

It is well known that attaching fins on the tubes surfaces can enhance the heat transfer into and out from the phase change materials (PCMs). This paper presents the results of an experimental study on the thermal characteristics of finned coil latent heat storage unit (LHSU) using paraffin as the phase change material (PCM). The paraffin LHSU is a rectangular cube consists of continuous horizontal multibended tubes attached vertical fins at the pitches of 2.5, 5.0, and 7.5 mm that creates the heat transfer surface. The shell side along with the space around the tubes and fins is filled with the material RT54 allocated to store energy of water, which flows inside the tubes as heat transfer fluid (HTF). The measurement is carried out under four different water flow rates: 1.01, 1.30, 1.50, and 1.70 L/min in the charging and discharging process, respectively. The temperature of paraffin and water, charging and discharging wattage, and heat transfer coefficient are plotted in relation to the working time and water flow rate.

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