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.

scholarly journals Performance Improvement of a Household Refrigerator using Phase Change Material

2021 ◽  
Vol 16 (1) ◽  
pp. 032-041
Author(s):  
Pradeep N ◽  
Somesh Subramanian S
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Energy Savings ◽  
Storage System ◽  
Thermal Storage ◽  
Latent Heat Storage ◽  
Peak Loads ◽  
Change Material

Thermal energy storage through phase change material has been used for wide applications in the field of air conditioning and refrigeration. The specific use of this thermal storage has been for energy storage during low demand and release of this energy during peak loads with potential to provide energy savings due to this. The principle of latent heat storage using phase change materials (PCMs) can be incorporated into a thermal storage system suitable for using deep freezers. The evaporator is covered with another box which has storage capacity or passage through phase change material. The results revealed that the performance is increased from 3.2 to 3.5 by using PCM.

scholarly journals Thermal Storage of Nitrate Salts as Phase Change Materials (PCMs)

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7223
Author(s):  
Marco A. Orozco ◽  
Karen Acurio ◽  
Francis Vásquez-Aza ◽  
Javier Martínez-Gómez ◽  
Andres Chico-Proano
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Sodium Nitrite ◽  
Phase Change Materials ◽  
Storage Capacity ◽  
Thermal Storage ◽  
Potassium Nitrate ◽  
Ternary Mixtures ◽  
Scanning Calorimetry ◽  
Nitrate Salts

This study presents the energy storage potential of nitrate salts for specific applications in energy systems that use renewable resources. For this, the thermal, chemical, and morphological characterization of 11 samples of nitrate salts as phase change materials (PCM) was conducted. Specifically, sodium nitrate (NaNO3), sodium nitrite (NaNO2), and potassium nitrate (KNO3) were considered as base materials; and various binary and ternary mixtures were evaluated. For the evaluation of the materials, differential Fourier transform infrared spectroscopy (FTIR), scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) to identify the temperature and enthalpy of phase change, thermal stability, microstructure, and the identification of functional groups were applied. Among the relevant results, sodium nitrite presented the highest phase change enthalpy of 220.7 J/g, and the mixture of 50% NaNO3 and 50% NaNO2 presented an enthalpy of 185.6 J/g with a phase change start and end temperature of 228.4 and 238.6 °C, respectively. This result indicates that sodium nitrite mixtures allow the thermal storage capacity of PCMs to increase. In conclusion, these materials are suitable for medium and high-temperature thermal energy storage systems due to their thermal and chemical stability, and high thermal storage capacity.

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 A novel empirical heat transfer model for a solar thermal storage process using phase change materials

Energy ◽  
2019 ◽  
Vol 168 ◽  
pp. 222-234 ◽  
Author(s):  
Yu Bie ◽  
Ming Li ◽  
Fei Chen ◽  
Grzegorz Królczyk ◽  
Lin Yang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Materials ◽  
Thermal Storage ◽  
Heat Transfer Model ◽  
Solar Thermal ◽  
Transfer Model ◽  
Storage Process

Experimental Study and Numerical Simulation on Thermal Energy Storage Characteristics of Composite Phase Change Materials in Annular Space of Vertical Double-Pipe Heat Exchanger

2014 ◽  
Vol 1053 ◽  
pp. 143-149 ◽  
Author(s):  
Xiao Hong Liu ◽  
Zi Ye Ling ◽  
Peng Sun ◽  
Xiao Ming Fang ◽  
Tao Xu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Thermal Storage ◽  
Annular Space ◽  
Double Pipe ◽  
Storage Characteristics

Experimental system on thermal energy storage characteristics of phase change materials (PCMs) in annular space of a vertical double-pipe heat exchanger was set up. The thermal storage performance of paraffin and paraffin/expanded graphite composite PCM with the mass fraction of 70% paraffin was compared. The Fluent software was used to simulate the temperature field of the composite PCM during the thermal storage process. The results show that, for the paraffin, in the sensible heat storage phase, because the heat transfer process is controlled by the heat conduction, the temperature in paraffin gradually reduces from the inside to the outside of the annular space. But for the phase change thermal storage phase, solid-liquid phase change heat transfer is controlled by natural convection and the effect of buoyancy, the temperature in paraffin reduces from top to bottom, from the inside to the outside of the annular space. For the composite PCM, heat transfer is controlled only by the heat conduction process, both the sensible and latent heat storage process, the temperature in the composite PCM decreases from bottom to top, from inside to outside of the annular space. As the thermal conductivity of composite PCM is 15.65 times of paraffin, the thermal energy storage time is shortened by 86.6% than paraffin. The temperature fields of composite PCM in different time are obtained by numerical simulation method, the measured temperatures and simulation results are in good agreement.

Simulation Investigation for Heat Transfer in Fin-Tube Thermal Storage Unit with Phase Change Material

2010 ◽  
Vol 168-170 ◽  
pp. 895-899 ◽  
Author(s):  
Jian You Long
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Thermal Storage ◽  
Heat Transfer Fluid ◽  
Outlet Temperature ◽  
Water Heater ◽  
Storage Unit ◽  
Fin Tube ◽  
Change Material

This paper addresses a simulation investigation of a fin-tube thermal storage unit involving phase change process dominated by heat conduction. The heat transfer of fin-tube thermal storage unit with phase change material (PCM) was simulated by Fluent. Graphical results including outlet temperature of heat transfer fluid (HTF), average temperature of PCM and phase front interface of solid and liquid phase of PCM versus time and fin distance were presented and discussed. According to simulation results, it was concluded that only the fin-tube thermal storage unit with fin distance of 12fin/inch could satisfied the request of heat release performance of household heat pump water heater for shower.

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