Vibration-enhanced direct contact heat exchange using gallium as a solid phase change material

Al-Omari, Salah Addin Burhan; Ghazal, Abdallah; Elnajjar, Emad; Qureshi, Zahid Ahmed

doi:10.1016/j.icheatmasstransfer.2020.104990

Cited by 24 publications

(3 citation statements)

References 31 publications

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“…Furthermore, they concluded that all melting and solidification processes lasted less than an hour despite their unoptimized system. Al Omari et al 19 scrutinized the influences of vibrations on the DC heat transfer between hot water and a heat sink comprised of a PCM. Comparing the results obtained under vibrations and static conditions, they observed a sharp enhancement in the cooling rate of hot water when the vibrational effects were brought to bear.…”

Section: List Of Symbolsmentioning

confidence: 99%

Multi-objective optimization of multiple droplet impacts on a molten PCM using NSGA-II optimizer and artificial neural network

Faghiri

Poureslami

Aria

et al. 2023

Sci Rep

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Embracing an interaction between the phase change material (PCM) and the droplets of a heat transfer fluid, the direct contact (DC) method suggests a cutting-edge solution for expediting the phase change rates of PCMs in thermal energy storage (TES) units. In the direct contact TES configuration, when impacting the molten PCM pool, droplets evaporate, provoking the formation of a solidified PCM area (A). Then, they reduce the created solid temperature, leading to a minimum temperature value (Tmin). As a novelty, this research intends to maximize A and minimize Tmin since augmenting A expedites the discharge rate, and by lowering Tmin, the generated solid is preserved longer, resulting in a higher storage efficacy. To take the influences of interaction between droplets into account, the simultaneous impingement of two ethanol droplets on a molten paraffin wax is surveyed. Impact parameters (Weber number, impact spacing, and the pool temperature) govern the objective functions (A and Tmin). Initially, through high-speed and IR thermal imaging, the experimental values of objective functions are achieved for a wide range of impact parameters. Afterward, exploiting an artificial neural network (ANN), two models are fitted to A and Tmin, respectively. Subsequently, the models are provided for the NSGA-II algorithm to implement multi-objective optimization (MOO). Eventually, utilizing two different final decision-making (FDM) approaches (LINMAP and TOPSIS), optimized impact parameters are attained from the Pareto front. Regarding the results, the optimum amount of Weber number, impact spacing, and pool temperature accomplished by LINMAP and TOPSIS procedures are 309.44, 2.84 mm, 66.89 °C, and 294.98, 2.78 mm, 66.89 °C, respectively. This is the first investigation delving into the optimization of multiple droplet impacts for TES applications.

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Section: List Of Symbolsmentioning

confidence: 99%

Multi-objective optimization of multiple droplet impacts on a molten PCM using NSGA-II optimizer and artificial neural network

Faghiri

Poureslami

Aria

et al. 2023

Sci Rep

View full text Add to dashboard Cite

show abstract

“…There was no comparison made between the enhancement of fins and vibration. Al Omari et al [59] experimentally studied the effect of vibration on the cooling of hot water using gallium PCM in a cylindrical direct contact heat exchanger. Vertical sinusoidal vibration was applied at 20 and 50 Hz with amplitudes of 0.3, 0.5, and 0.7 mm.…”

Section: Vibrationmentioning

confidence: 99%

A Review on Active Heat Transfer Enhancement Techniques within Latent Heat Thermal Energy Storage Systems

Shank

Tiari

2023

Energies

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Renewable energy resources require energy storage techniques to curb problems with intermittency. One potential solution is the use of phase change materials (PCMs) in latent heat thermal energy storage (LHTES) systems. Despite the high energy storage density of PCMs, their thermal response rate is restricted by low thermal conductivity. The topic of heat transfer enhancement techniques for increasing thermal performance of LHTES systems has mainly focused on passive heat transfer enhancement techniques with less attention towards active methods. Active heat transfer enhancement techniques require external power supplied to the system. In this paper, recent advances in active heat transfer enhancement techniques within LHTES systems are reviewed, including mechanical aids, vibration, jet impingement, injection, and external fields. The pertinent findings related to the field are summarized in relation to the charging and discharging processes of PCMs. Suggestions for future research are proposed, and the importance of additional energy input for storage is discussed.

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“…Fortunately, different from the passive techniques, the active techniques do not have these limitations and they can make full use of the heat storage performance of the PCM in the system. Some examples of active heat transfer enhancement techniques include ultrasonic wave [19], magnetic field [20], mechanical vibration [21] and electrohydrodynamic (EHD) [22]. For more details on the recent progress of active heat transfer enhancement technologies for PCM melting, we refer the reader to the recent review presented by Wu et al [23].…”

Section: Introductionmentioning

confidence: 99%

Electrohydrodynamic Enhancement of Phase Change Material Melting in Circular-Elliptical Annuli

Wang

Huang

2021

Energies

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Phase change material (PCM) has received significant attention due to its great potential for thermal energy storage. However, the major undesirable property of PCM is related to its low thermal conductivity. In this work, the electrohydrodynamic (EHD) enhancement of PCM melting in circular-elliptical annuli is investigated numerically by using the lattice Boltzmann method (LBM). The key motivation for our choice of the elliptical shape is due to the fact that the more curved elliptical surface corresponds to stronger charge injection strength, which may lead to stronger flow field, and the consequent increase of heat transfer rate. The influences of several non-dimensional parameters, including electric Rayleigh number T, thermal Rayleigh number (Ra) and the aspect ratio (AR) of the inner ellipse are investigated in detail. Based on the numerical results, it is found that the radial electro-convective flow induced by the external electric field makes a significant contribution to the enhancement of melting heat transfer, and specially, the maximum time saving in some cases is more than 85%. Moreover, we observe that when the Coulomb force is dominant over the buoyancy force, no matter the inner elliptical tube is oriented horizontally or vertically, the total melting times in these two cases are nearly the same, and the melting performance obtained for the circular electrode is usually better than the other cases. However, when the flow regime is dominated by the buoyancy force, the use of a slender vertical-oriented elliptical electrode instead of the circular one is more efficient.

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Vibration-enhanced direct contact heat exchange using gallium as a solid phase change material

Cited by 24 publications

References 31 publications

Multi-objective optimization of multiple droplet impacts on a molten PCM using NSGA-II optimizer and artificial neural network

Multi-objective optimization of multiple droplet impacts on a molten PCM using NSGA-II optimizer and artificial neural network

A Review on Active Heat Transfer Enhancement Techniques within Latent Heat Thermal Energy Storage Systems

Electrohydrodynamic Enhancement of Phase Change Material Melting in Circular-Elliptical Annuli

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