Impact of periodic flow reversal of heat transfer fluid on the melting and solidification processes in a latent heat shell and tube storage system

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.

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Performance Evaluation of a Small-Scale Latent Heat Thermal Energy Storage Unit for Heating Applications Based on a Nanocomposite Organic PCM

ChemEngineering ◽

10.3390/chemengineering3040088 ◽

2019 ◽

Vol 3 (4) ◽

pp. 88 ◽

Cited By ~ 1

Author(s):

Maria K. Koukou ◽

George Dogkas ◽

Michail Gr. Vrachopoulos ◽

John Konstantaras ◽

Christos Pagkalos ◽

...

Keyword(s):

Heat Transfer ◽

Energy Storage ◽

Thermal Behavior ◽

Latent Heat ◽

Flow Rate ◽

Thermal Energy ◽

Thermal Energy Storage ◽

Heat Transfer Fluid ◽

Small Scale ◽

Solidification Processes

A small-scale latent heat thermal energy storage (LHTES) unit for heating applications was studied experimentally using an organic phase change material (PCM). The unit comprised of a tank filled with the PCM, a staggered heat exchanger (HE) for transferring heat from and to the PCM, and a water pump to circulate water as a heat transfer fluid (HTF). The performance of the unit using the commercial organic paraffin A44 was studied in order to understand the thermal behavior of the system and the main parameters that influence heat transfer during the PCM melting and solidification processes. The latter will assist the design of a large-scale unit. The effect of flow rate was studied given that it significantly affects charging (melting) and discharging (solidification) processes. In addition, as organic PCMs have low thermal conductivity, the possible improvement of the PCM’s thermal behavior by means of nanoparticle addition was investigated. The obtained results were promising and showed that the use of graphite-based nanoplatelets improves the PCM thermal behavior. Charging was clearly faster and more efficient, while with the appropriate tuning of the HTF flow rate, an efficient discharging was accomplished.

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Numerical investigation of heat transfer mechanism in a vertical shell and tube latent heat energy storage system

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2015.05.067 ◽

2015 ◽

Vol 87 ◽

pp. 698-706 ◽

Cited By ~ 62

Author(s):

Saeid Seddegh ◽

Xiaolin Wang ◽

Alan D. Henderson

Keyword(s):

Heat Transfer ◽

Energy Storage ◽

Numerical Investigation ◽

Latent Heat ◽

Storage System ◽

Energy Storage System ◽

Heat Energy ◽

Transfer Mechanism ◽

Heat Transfer Mechanism ◽

Shell And Tube

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Experimental Investigation of a Packed-Bed Latent Heat Thermal Storage System With Encapsulated Phase Change Material

Volume 6B: Energy ◽

10.1115/imece2014-38307 ◽

2014 ◽

Cited By ~ 10

Author(s):

Tanvir E. Alam ◽

Jaspreet Dhau ◽

D. Y. Goswami ◽

M. M. Rahman ◽

Elias Stefankos

Keyword(s):

Heat Transfer ◽

Experimental Study ◽

Latent Heat ◽

Flow Rate ◽

Storage System ◽

Volumetric Flow Rate ◽

Packed Bed ◽

Heat Transfer Fluid ◽

Encapsulated Phase Change Material ◽

Change Material

An experimental study on a laboratory scale prototype packed-bed latent heat thermal energy storage (TES) system is presented. Spherical capsules of sodium nitrate melting point of 306°C were used as the PCM and air was used as the heat transfer fluid (HTF). The storage system was operated between 286°C to 326°C and the volumetric flow rate of the HTF was varied from 110 m3/hr to 151 m3/hr. Temperature distribution along the bed and inside the capsules was monitored continuously during charging and discharging of the system. The effect of mass flow rate of the HTF on the charging and discharging time and on the pressure drop across the bed was also evaluated.

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