scholarly journals Investigation of Novel Composite Materials for Thermochemical Heat Storage Systems

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1042
Author(s):  
Salih Cem Akcaoglu ◽  
Zhifa Sun ◽  
Stephen Carl Moratti ◽  
Georgios Martinopoulos
Keyword(s):  
Thermal Conductivity ◽  
Heat Storage ◽  
Storage Systems ◽  
Space Heating ◽  
Energy Prices ◽  
Compression Pressure ◽  
Scanning Calorimetry ◽  
Thermochemical Heat Storage ◽  
Composite Pellets ◽  
Heat Storage Materials

Increasing energy prices make space heating more expensive every year in The Organisation for Economic Co-operation and Development (OECD) member countries. Thermochemical heat storage systems (THSS) can be used to reduce residential energy consumption for space heating and to control humidity. Utilizing compressed thermochemical pellets as heat storage materials is a way to increase volumetric energy storage capacity and to improve the performance of the THSS. In this work, expanded natural graphite (ENG), activated carbon (AC), strontium bromide, and magnesium sulphate were mixed in different mass ratios and compressed under applied pressures in a range of 0.77 to 5.2 kN⋅mm−2 to form composite pellets with a diameter of 12 and 25 mm, respectively, and a thickness from 1.5 to 25 mm. These pellets were characterized using thermogravimetric analysis and differential scanning calorimetry. Cyclic tests of hydration at 20 °C and dehydration at 85 °C were conducted to investigate changes in the surface morphology and the heat and mass transfer characteristics of the composite pellets. The permeability and thermal conductivity of the composite pellets were also measured. It was found that the structural stability of the pellets was enhanced by increasing the compression pressure. Utilizing AC and ENG in the composite mixture enhanced the porosity, thermal conductivity, and the permeability of the pellets.

Inorganic salt hydrates and zeolites composites studies for thermochemical heat storage

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ata Ur Rehman ◽  
Muhammad Zahir Shah ◽  
Shehla Rasheed ◽  
Wasim Afzal ◽  
Muhammad Arsalan ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Water Sorption ◽  
Inorganic Salt ◽  
Heat Storage ◽  
Water Molecules ◽  
Thermochemical Heat Storage ◽  
Dehydration Enthalpy ◽  
Salt Hydrates ◽  
Heat Storage Materials ◽  
Pure Salt

Abstract Salt hydrates (MgSO4 and ZnSO4) impregnated in zeolites, offer a variety of improvements, mostly providing a large surface area for salt hydrates and water molecules. A composite of 5 and 10% of salt contents were prepared as heat storage materials. The study’s finding showed that dehydration enthalpy of MgSO4 (1817 J g−1) and ZnSO4 (1586 J g−1) were 10 and 15% improved than pure salt hydrates by making composites. During the hydration process of composites, the water sorption is 30–37% improved and further the increasing of salt contents in composites enhances more 10% increase in the water resorption. The cyclicability of MgSO4/zeolite and ZnSO4/zeolite were 45 and 51% improved than their corresponding pure salt hydrates. The effect of humidity on the water sorption result reveals that composites of MgSO4/zeolite and ZnSO4/zeolite at 75% relative humidity (RH), the mass of water are 51 and 40% increase than 55% RH.

scholarly journals Optimal Design of Combined Two-Tank Latent and Metal Hydrides-Based Thermochemical Heat Storage Systems for High-Temperature Waste Heat Recovery

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4216 ◽  
Author(s):  
Serge Nyallang Nyamsi ◽  
Mykhaylo Lototskyy ◽  
Ivan Tolj
Keyword(s):  
Energy Storage ◽  
Melting Point ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Heat Storage ◽  
Waste Heat ◽  
Storage Systems ◽  
Storage System ◽  
Metal Hydrides ◽  
Thermochemical Heat Storage

The integration of thermal energy storage systems (TES) in waste-heat recovery applications shows great potential for energy efficiency improvement. In this study, a 2D mathematical model is formulated to analyze the performance of a two-tank thermochemical heat storage system using metal hydrides pair (Mg2Ni/LaNi5), for high-temperature waste heat recovery. Moreover, the system integrates a phase change material (PCM) to store and restore the heat of reaction of LaNi5. The effects of key properties of the PCM on the dynamics of the heat storage system were analyzed. Then, the TES was optimized using a genetic algorithm-based multi-objective optimization tool (NSGA-II), to maximize the power density, the energy density and storage efficiency simultaneously. The results indicate that the melting point Tm and the effective thermal conductivity of the PCM greatly affect the energy storage density and power output. For the range of melting point Tm = 30–50 °C used in this study, it was shown that a PCM with Tm = 47–49 °C leads to a maximum heat storage performance. Indeed, at that melting point narrow range, the thermodynamic driving force of reaction between metal hydrides during the heat charging and discharging processes is almost equal. The increase in the effective thermal conductivity by the addition of graphite brings about a tradeoff between increasing power output and decreasing the energy storage density. Finally, the hysteresis behavior (the difference between the melting and freezing point) only negatively impacts energy storage and power density during the heat discharging process by up to 9%. This study paves the way for the selection of PCMs for such combined thermochemical-latent heat storage systems.

scholarly journals Thermal properties of thermochemical heat storage materials

2020 ◽  
Vol 22 (8) ◽  
pp. 4617-4625 ◽  
Author(s):  
Julianne E. Bird ◽  
Terry D. Humphries ◽  
Mark Paskevicius ◽  
Lucas Poupin ◽  
Craig E. Buckley
Keyword(s):  
Thermal Properties ◽  
Energy Storage ◽  
Transport Properties ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Heat Storage ◽  
Energy Storage Materials ◽  
Storage Materials ◽  
Thermochemical Heat Storage ◽  
Heat Storage Materials

The thermal transport properties of potential thermal energy storage materials have been measured using identical conditions enabling direct comparison.

High Performance PCM-Graphite Heat Storage Systems for Solar Process Heat

2009 ◽  
Author(s):  
R. Schmitt ◽  
M. Ro¨mmler ◽  
W.-D. Steinmann ◽  
R. Tamme
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Latent Heat ◽  
Alternative Energy ◽  
Heat Storage ◽  
Storage Systems ◽  
Thermal Power ◽  
Graphite Composite ◽  
Graphite Heat ◽  
Process Heat

Increasing energy prices and shortage of fossil fuels lead to a growing interest in alternative energy sources. In combination with energy storage systems the generation of solar process heat can be provided independent from the weather leading for example to a cost efficient stabilization of power output. For this application latent heat storage units with phase change materials (PCMs) can be designed to store solar process heat within a narrow temperature interval utilizing the high storage density of the different PCMs. This is achieved using the latent heat of melting in the melting / solidification process, or the latent heat of re-crystallization in a solid / solid phase transition. However, this advantage can only be used in technical applications if the heat transfer in the PCM is sufficiently high. As most pure PCMs exhibit a low thermal conductivity (about 1 W/(m·K) or less), methods to improve heat transfer in PCMs have been under investigation for decades. The heat transfer in a PCM can be increased by addition of high conductive materials. Due to its superior properties — high thermal conductivity, good processibility, and chemical inertness — graphite has distinct advantages for this purpose. Depending on the requirements of the respective application, various routes to combine PCM and graphite are used. For example, besides the fabrication of PCM/graphite composite materials, the increase of heat exchanger surface by highly thermal conductive graphite plates is a favorable method for large scale applications, in particular. Effective thermal conductivities up to 30 W/(m·K) have been realized. This paper gives an overview of actual and potential applications of PCM/graphite heat storage systems focusing to store solar heat for high temperature applications, such as process heat generation and solar thermal power plants.

scholarly journals Thermal energy storage and thermal conductivity properties of Octadecanol-MWCNT composite PCMs as promising organic heat storage materials

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Amir Al-Ahmed ◽  
Ahmet Sarı ◽  
Mohammad Abu Jafar Mazumder ◽  
Gökhan Hekimoğlu ◽  
Fahad A. Al-Sulaiman ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Heat Storage ◽  
Storage Materials ◽  
Heat Storage Materials

scholarly journals Experimental Results of a 3 kWh Thermochemical Heat Storage Module for Space Heating Application

2014 ◽  
Vol 48 ◽  
pp. 320-326 ◽  
Author(s):  
Christian Finck ◽  
Ellemieke Henquet ◽  
Christiaan van Soest ◽  
Henk Oversloot ◽  
Ard-Jan de Jong ◽  
...  
Keyword(s):  
Heat Storage ◽  
Experimental Results ◽  
Space Heating ◽  
Thermochemical Heat Storage
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