scholarly journals Metal Hydride Beds-Phase Change Materials: Dual Mode Thermal Energy Storage for Medium-High Temperature Industrial Waste Heat Recovery

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3949 ◽  
Author(s):  
Serge Nyallang Nyamsi ◽  
Ivan Tolj ◽  
Mykhaylo Lototskyy
Keyword(s):  
Phase Change ◽  
Latent Heat ◽  
Metal Hydride ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Heat Storage ◽  
Waste Heat ◽  
Metal Hydrides ◽  
Thermochemical Heat Storage ◽  
Change Material

Heat storage systems based on two-tank thermochemical heat storage are gaining momentum for their utilization in solar power plants or industrial waste heat recovery since they can efficiently store heat for future usage. However, their performance is generally limited by reactor configuration, design, and optimization on the one hand and most importantly on the selection of appropriate thermochemical materials. Metal hydrides, although at the early stage of research and development (in heat storage applications), can offer several advantages over other thermochemical materials (salt hydrates, metal hydroxides, oxide, and carbonates) such as high energy storage density and power density. This study presents a system that combines latent heat and thermochemical heat storage based on two-tank metal hydrides. The systems consist of two metal hydrides tanks coupled and equipped with a phase change material (PCM) jacket. During the heat charging process, the high-temperature metal hydride (HTMH) desorbs hydrogen, which is stored in the low-temperature metal hydride (LTMH). In the meantime, the heat generated from hydrogen absorption in the LTMH tank is stored as latent heat in a phase change material (PCM) jacket surrounding the LTMH tank, to be reused during the heat discharging. A 2D axis-symmetric mathematical model was developed to investigate the heat and mass transfer phenomena inside the beds and the PCM jacket. The effects of the thermo-physical properties of the PCM and the PCM jacket size on the performance indicators (energy density, power output, and energy recovery efficiency) of the heat storage system are analyzed and discussed. The results showed that the PCM melting point, the latent heat of fusion, the density and the thermal conductivity had significant impacts on these performance indicators.

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.

Phase Change Material as Pump in an Organic Rankine Cycle

2014 ◽  
Vol 575 ◽  
pp. 662-667
Author(s):  
Barghav Subramony Hariharan ◽  
Kaushik Suresh
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Electrical Energy ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Change Material

Organic Rankine Cycles (ORC) is predominantly used in waste heat recovery applications because of their low temperature working range. The main efficiency enhancement operation in an Organic Rankine Cycle is reducing the pump work .The pump converts electrical energy to flow energy. This input reduced and output maintained at the same level gives us a more efficient waste heat recovery system. The pump work can also be achieved by using a material that has the ability to expand on heating and revert back to its original state on cooling. The expansion property of the material is used to compress and drive the operating fluid through the cycle. Material that was observed to possess such properties was Phase Change Material. Conventionally PCM were used as thermal storage to preheat the working fluid in an ORC but a novel idea is to make the PCM utilize the heat rejected from the condenser and do the pump work. This paper discusses the various desirable properties of PCM to perform pump work efficiently and also the general layout and working of ORC system using PCM. The working fluid selected is toluene

Performance analysis of latent heat storage system by fin orientation and nano added PCM for diesel engine waste heat recovery

2020 ◽  
Author(s):  
Karthikeyan Paramasivam ◽  
Kanimozhi Balakrishnan ◽  
Kumarasubramanian Ramar ◽  
Yuvaraja Subramani ◽  
Swaraj Bikram Samal ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Performance Analysis ◽  
Latent Heat ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Heat Storage ◽  
Waste Heat ◽  
Storage System ◽  
Latent Heat Storage

Oxidation Resistance and Plating Encapsulation of Cu-Based Alloys as Phase Change Materials for High-Temperature Heat Storage

2013 ◽  
Vol 537 ◽  
pp. 292-297
Author(s):  
Guo Cai Zhang ◽  
Jian Qiang Li ◽  
Bing Qian Ma ◽  
Zhe Xu ◽  
Zhi Jian Peng ◽  
...  
Keyword(s):  
Phase Change ◽  
Oxidation Resistance ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Waste Heat ◽  
Small Addition ◽  
Temperature Heat ◽  
Electric Generation

Cu-based alloys have been regarded as one of the most promising phase change materials (PCMs) in industrial waste heat recovery and solar thermal electric generation. In this paper, the oxidation behavior and the containment of liquid Cu were investigated. It was found that with the small addition of aluminum, the oxidation resistance of Cu-based PCMs was greatly enhanced. Notably, its latent heat density remained high. The containment of PCMs was achieved by depositing a Ni-base exterior coating on Cu spheres through barrel plating, rack plating and electroless plating processes. The deposition rates, surface topography, and the crystallography of the coatings depended largely on the plating process. The cyclic thermal was tested at last.

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