scholarly journals Numerical study on Finned Latent Heat Storage for Tri-generation System

2018 ◽  
Vol 4 (2) ◽  
pp. 119-129
Author(s):  
Guangya Zhu ◽  
Tin-Tai Chow
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Latent Heat ◽  
Heat Storage ◽  
High Energy ◽  
Pollutant Emissions ◽  
High Energy Density ◽  
Distinct Advantage ◽  
Generation System ◽  
Latent Heat Storage

Tri-generation system combines the supply of electric power, heating and cooling energy into one single system. Compared to the separated energy generation systems, the advantages lie in its higher efficiency, reliability and flexibility, as well as the reduced pollutant emissions. Yet the mismatch in system electricity and thermal demands often downgrades its effectiveness and economic merits. At this end, the adoption of thermal energy storage can be a practical means of improvement. Among the various choices, the finned latent heat storage using phase change material is distinct advantage owing to its high energy density. On the other hand, the finned latent heat storage design requires a detailed analysis of the heat transfer process. In this paper, our numerical model is introduced for use in simulating the associated complex heat transfer processes. The accuracy of the numerical model has been verified making use of the published experimental data available from the literature. Furthermore, our follow-up parametric study shows that the increase of fin thickness will improve the heat transfer performance for a given design configuration and the better heat transfer can be achieved with the reduction in fin length and fin spacing as well.

Zinc-rich eutectic alloys for high energy density latent heat storage applications

2017 ◽  
Vol 705 ◽  
pp. 714-721 ◽  
Author(s):  
E. Risueño ◽  
A. Faik ◽  
A. Gil ◽  
J. Rodríguez-Aseguinolaza ◽  
M. Tello ◽  
...  
Keyword(s):  
Energy Density ◽  
Latent Heat ◽  
Heat Storage ◽  
High Energy ◽  
High Energy Density ◽  
Eutectic Alloys ◽  
Latent Heat Storage

scholarly journals Experimental Feasibility Study of a Direct Contact Latent Heat Storage Using an Ester as a Bio-Based Storage Material

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 511
Author(s):  
Lukas Hegner ◽  
Stefan Krimmel ◽  
Rebecca Ravotti ◽  
Dominic Festini ◽  
Jörg Worlitschek ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Environmental Impact ◽  
Latent Heat ◽  
Direct Contact ◽  
Heat Storage ◽  
Renewable Energy Sources ◽  
High Energy ◽  
Latent Heat Storage ◽  
Material Combination ◽  
First Time

Latent heat storage (LHS) represents a valuable technology for the integration of intermittent renewable energy sources in existing and future energy systems. Improvements in LHS can be sought by enhancing heat transfer efficiency, compactness and diminishing the environmental impact of storage systems. In this paper, direct contact latent heat storage (DC-LHS) using esters as phase change material (PCM) is proposed as a promising compact storage technology to achieve high performance both in terms of heat transfer and sustainability. The technology allows for the heat transfer fluid (HTF) to flow directly through the PCM, forming a large amount of small droplets and thus providing a large heat exchange surface area between the two materials. At the same time, using biobased esters as PCM, gives the technology clear ecological advantages when compared to alternative types of compact energy storage. Furthermore, no complex heat transfer enhancing structures are necessary in a DC-LHS, further reducing the environmental impact and enabling very high energy densities. In this paper, the feasibility of this concept is explored for the first time by developing and testing an experimental DC-LHS device using methyl palmitate as PCM and water as HTF. The thermal performance and stability of the material combination are analysed by different melting–solidification experiments and distinctive effects are identified and comprehensively discussed for the first time. The basic concept as well as the novel material combination are validated. The study finds the critical challenges that must be overcome in order for this highly promising technology to be successfully implemented.

scholarly journals Effective Separation of a Water in Oil Emulsion from a Direct Contact Latent Heat Storage System

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2264 ◽  
Author(s):  
Sebastian Ammann ◽  
Andreas Ammann ◽  
Rebecca Ravotti ◽  
Ludger Fischer ◽  
Anastasia Stamatiou ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Latent Heat ◽  
Direct Contact ◽  
Heat Storage ◽  
Storage System ◽  
Heat Transfer Fluid ◽  
Storage Unit ◽  
Latent Heat Storage ◽  
Oil Emulsion ◽  
Water In Oil Emulsion

The problem of emulsification between Phase Change Material (PCM) and Heat Transfer Fluid (HTF) in direct contact latent heat storage systems has been reported in various studies. This issue causes the PCM to flow out of the storage tank and crystallize at unwanted locations and thus presents a major limitation for the proper operation of such systems. These anomalies become more pronounced when high HTF flow rates are employed with the aim to achieve fast heat transfer rates. The goal of this paper is to find a method which will enable the fast separation of the formed emulsion and thus the uninterrupted operation of the storage unit. In this study, three separation methods were examined and the use of superhydrophobic filters was chosen as the best candidate for the demulsification of the PCM and HTF mixtures. The filter was produced by processing of a melamine sponge with different superhydrophobic adhesives and was tested with emulsions closely resembling the ones formed in a real direct contact setup. The superhydrophobic filter obtained, was able to separate the emulsions effectively while presenting a very high permeability (up to 1,194,980 kg h−1 m−2 bar−1). This is the first time the use of a superhydrophobic sponge has been investigated in the context of demulsification in direct contact latent heat storage.

Thermal Conductivity Enhancement in a Latent Heat Storage Device

2013 ◽  
Vol 860-863 ◽  
pp. 590-593
Author(s):  
Cha Xiu Guo ◽  
Ding Bao Wang ◽  
Gao Lin Hu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Solid State ◽  
Liquid Phase ◽  
Phase Change ◽  
Latent Heat ◽  
Heat Storage ◽  
Storage Device ◽  
Latent Heat Storage ◽  
Conductivity Enhancement

High conductivity porosity materials are proposed to enhance the phase change materials (PCM) in order to solve the problem of low conductivity of PCM in the latent heat storage device (LHSD), and two-dimensional numerical simulation is conducted to predict the performance of the PCM by CFD software. During the phase change process, the PCM is heated from the solid state to the liquid phase in the process of melting and from the liquid phase to the solid state in the solidification process. The results show that porosity materials can improve heat transfer rate effectively, but the effect of heat transfer of Al foam is superior to that of graphite foam although the heat storage capacity is almost the same for both. The heat transfer is enhanced and the solidification time of PCM is decreased since the effective thermal conductivity of composite PCM is increased.

scholarly journals Neopentyl Glycol as Active Supporting Media in Shape-Stabilized PCMs

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3169 ◽  
Author(s):  
Angel Serrano ◽  
Jean-Luc Dauvergne ◽  
Stefania Doppiu ◽  
Elena Palomo Del Barrio
Keyword(s):  
Phase Transition ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Solid Phase ◽  
High Energy ◽  
High Energy Density ◽  
Latent Heat Storage ◽  
Neopentyl Glycol ◽  
Solid Liquid ◽  
Latent Heats

The present work explores the feasibility of using polyalcohols with solid-solid phase transition as active supporting matrix of n-alkanes in shape-stabilized phase change materials (SSPCMs). It is well-established that the use of SSPCM avoids leakage and increases stability and easy handling of solid-liquid PCMs. Nevertheless, the resulting composite exhibits a loss of heat storage capacity due to the volume occupied by the supporting material, which does not contribute to latent heat storage. Therefore, the objective of this work is to combine solid-liquid PCMs (alkanes) with solid-solid PCMs (polyalcohols), both exhibiting a phase transition in the same range of temperature, to obtain high energy density SSPCMs. Towards that goal, the performance of Neopentyl Glycol (NPG) and Docosane as a new energetic SSPCM has been proved. The NPG-Docosane chemical compatibility and its outstanding wettability facilitate the propitious association of both materials. The higher capillary forces obtained by decreasing the NPG crystal size together with the addition of expanded graphite (EG) allowed to obtain a maximum Docosane content of 60 wt%. The addition of EG improves the shape stability at the time that increases the heat transfer properties of the composites. The analysis showed that the components of the obtained SSPCMs are able to combine their latent heats, achieving a maximum value of 210.74 J/g for the highest Docosane content. This value is much higher than those latent heats exhibited by existing SSPCMs in the same working temperature range.

scholarly journals Comparison of Heat Transfer Enhancement Techniques in Latent Heat Storage

2020 ◽  
Vol 10 (16) ◽  
pp. 5519 ◽  
Author(s):  
William Delgado-Diaz ◽  
Anastasia Stamatiou ◽  
Simon Maranda ◽  
Remo Waser ◽  
Jörg Worlitschek
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Latent Heat ◽  
Heat Transfer Performance ◽  
Thermal Power ◽  
High Energy ◽  
High Energy Density ◽  
Evaluation Procedure ◽  
Transfer Performance ◽  
Experimental Conditions

Latent Heat Energy Storage (LHES) using Phase Change Materials (PCM) is considered a promising Thermal Energy Storage (TES) approach as it can allow for high levels of compactness, and execution of the charging and discharging processes at defined, constant temperature levels. These inherent characteristics make LHES particularly attractive for applications that profit from high energy density or precise temperature control. Many novel, promising heat exchanger designs and concepts have emerged as a way to circumvent heat transfer limitations of LHES. However, the extensive range of experimental conditions used to characterize these technologies in literature make it difficult to directly compare them as solutions for high thermal power applications. A methodology is presented that aims to enable the comparison of LHES designs with respect to their compactness and heat transfer performance even when largely disparate experimental data are available in literature. Thus, a pair of key performance indicators (KPI), ΦPCM representing the compactness degree and NHTPC, the normalized heat transfer performance coefficient, are defined, which are minimally influenced by the utilized experimental conditions. The evaluation procedure is presented and applied on various LHES designs. The most promising designs are identified and discussed. The proposed evaluation method is expected to open new paths in the community of LHES research by allowing the leveled-ground contrast of technologies among different studies, and facilitating the evaluation and selection of the most suitable design for a specific application.

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