Fig 1 - uploaded by Yousef M. F. El Hasadi
Content may be subject to copyright.
Source publication
Development of the solid-liquid interface, distribution of the particle concentration field, as well as the development of thermo-solutal convection during solidification of colloidal suspensions in a differentially-heated cavity is investigated. The numerical model is based on the one-fluid-mixture approach combined with the single-domain enthalpy...
Similar publications
As the most promising materials for phase-change data storage, the pseudobinary mGeTe•nSb2Te3 (GST) chalcogenides have been widely investigated. Nevertheless, an in-depth understanding of the thermal-transport property of GST is still lacking, which is important to achieve overall good performance of the memory devices. Herein, by using first-princ...
The current work proposes for the first time an integrated set of simplified correlations for the thermal properties, i.e. effective thermal conductivity, effective specific heat and effective density, of commercial gypsum boards as a function of temperature that can be easily incorporated in dedicated computational tools in order to simulate the f...
Commonly used thermal analysis tools such as calorimeter and thermal conductivity meter are separated instruments and limited by low throughput, where only one sample is examined each time. This work reports an infrared based optical calorimetry with its theoretical foundation, which is able to provide an integrated solution to characterize thermal...
Abstract: 1,7-Heptanediammonium-dichlorodibromo-cobaltate (II), with molecular formula [(CH2)7(NH3)2]CoCl2Br2,
has been synthesized. It is triclinic P�1, a = 7.4042 (4) A ° , b = 10.3484 (5) A ° , c = 11.3554 (6) A ° , a = 66.289 (3)�
b = 78.425 (2)�, c = 86.546 (3)�. Its crystal structure contains distorted tetrahedral [CoCl2Br2]2- anions and zigz...
The transient thermal performance of phase change and heat and mass transfer in a two-phase closed thermosyphon are studied with computational fluid dynamics (CFD). A CFD model based on the volume of fluid technique is built. Deionized water is specified as the working fluid of this thermosyphon. The CFD model reproduces evaporation and condensatio...
Citations
... In response to the prevalent challenge of PCM's low thermal conductivity, researchers have embarked on a quest for innovative solutions. These encompass a diverse spectrum of methodologies, ranging from the incorporation of nanomaterials [29][30][31] and utilization of metal foams [32][33][34] to the implementation of PCMs within nano-/micro-encapsules [35][36][37] and, notably, the integration of fins [38,39]. Among these, the use of fins emerges as an approach that offers compelling economic and energetic advantages. ...
This research presents a novel approach of integrating fins into a sonochemical phase change material (PCM) reactor to tackle the challenge of low PCM thermal conductivity, with a focus on cooling the ultrasonic reactor. Through comprehensive numerical simulations using a Fluentbased CFD code, we analyze the thermal performance of the sono-PCM system with and without fins under varying power densities (45.5 and 85.6kW/m3) and operating times (up to 1h). Our results highlight the remarkable advantage of fins in accelerating the heat transfer and melting process, reducing the time for a 50% PCM melt by 28.1 and 45.2% for power densities of 45.5 and 85.6kW/m3, respectively. Enthalpy analysis further confirms the efficiency of the fins, demonstrating a reduction of 19% in water enthalpy after 1h for both power densities. Moreover, the presence of fins significantly enhances the heat recovery by the PCM, leading to 20.1 and 73.2% increase in PCM enthalpy for power densities of 45.5 and 85.6kW/m3, respectively. These enhancements are attributed to the increased surface area of contact provided by fins, which facilitate efficient heat dissipation within the bulk PCM. This study not only provides crucial insights into PCM systems with fins but also opens up avenues for advanced thermal energy management strategies, revolutionizing heat storage and transfer processes across various engineering applications.
... To overcome these limitations, researchers have explored various techniques to enhance the thermal conductivity of PCMs. These techniques include incorporating nanoparticles [18][19][20], microencapsulation [21][22][23], PCM loading in porous metal foams [24][25][26] and introducing fins within the PCM matrix [27,28]. Among these techniques, the incorporation of fins has emerged as a particularly promising strategy. ...
With the purpose of enhancing the heat management in the ultrasonic reactor, the present innovative research aims at the exploration of the thermal behavior of sonochemical reactor integrated with fins and phase change material (PCM), focusing on the influence of different liquid heights (LH). The performance of this combination (i.e., sonicated water, fins, and PCM) is investigated for the first time with consideration of the water volume variation. The interplay between fins, liquid height and heat transfer efficiency is explored through detailed numerical analysis of temperature profiles, PCM melt fractions, and enthalpy distributions. The numerical investigation has been conducted using a validated CFD model implemented in ANSYS Fluent® software. The results highlight the significant role of fins in accelerating the PCM melting process and improving heat transfer within the reactor. Notably, fins facilitates efficient conductive heat transfer during the early stages of melting. At t = 1000 s, PCM melt percentages of 22.2%, 32.6% and 30% were attained with fins, compared to 15%, 18% and 22% (without fins), for LH = 5.1, 10.2 and 15.3 cm, respectively. Therefore, LH = 10.2 cm showcased a 43.5% improvement at this specific time point (1000 s). Moving forward to t = 2000 s, the most favorable melting performance is achieved with LH = 15.3 cm, resulting in a melting percentage increase to 66% (with fins) compared to 44% (without fins). Besides, the inclusion of fins results in significant increases of 32.56% (5.1 cm), 57.6% (10.2 cm) and 14.4% (15.3 cm) in PCM enthalpy, while water temperature declined by approximately 4 K for LH = 5.1, 10.2 and 15.3 cm. These outcomes indicate clearly the importance of fins in improving the heat transfer from the irradiated water to the surrounding PCM in the annular space of the reactor.
... Most researches have focused on the utilization of fins and metal foams. While the addition of nanoparticles to PCM has demonstrated considerable improvements in heat latent storage within thermal energy storage systems [28][29][30][31], its application within PV systems is absent. Therefore, the primary objective of this study is to investigate the impact of incorporating nanoparticles into PCM within the context of nano-PCM/PV technology. ...
The primary objective of this research is to explore the impact of nanoparticles-infused PCM (phase change material) in the context of nano-PCM-PV technology (PV: photovoltaic panel). Computational investigations were conducted to evaluate the effectiveness of RT25HC, a paraffin wax PCM, in conjunction with various nanoparticles (MgO, TiO 2 , ZnO and CuO) in solar panel cooling. The study also considers the influence of PV module inclination angles (β: 0 to 90 •). High-resolution numerical simulations using the ANSYS-Fluent CFD platform were employed. The findings highlight the intricate relationship between nanoparticle addition, melting kinetics, electrical efficiency and PCM enthalpy. Specifically, the melting rate of RT25HC PCM exhibits notable differences between horizontal (β = 0 •) and inclined panels (β ∕ = 0 •), with a melting fraction of 12 % at t = 2 h for β = 0 • compared to 40-44 % for β ∕ = 0 •. Nanoparticles maintain a higher electrical efficiency (11.6 %) for horizontal panels, whereas inclined panels (β ∕ = 0 •) experience declining electrical efficiency (7.5 % at t = 8 h). For β = 0 • , the PCM system effectively maintains the surface panel's temperature constant at 44 • C for a long time (up to 8 h). However, when nano-PCM systems are introduced, this temperature stabilizes at a slightly lower value of 40 • C, representing a 4 • C reduction attributed to the presence of nanoparticles. Conversely, for β ∕ = 0, the surface panel's temperature stabilizes at 44 • C for up to t = 2 h, then experiences a sharp increase, ultimately reaching 120 • C at t = 8 h, regardless of the type or absence of nanomaterials. Overall, the most effective application of nano-PCM for cooling the PV panel was predicted at a horizontal orientation of the panel, regardless of the nanomaterial type.
... According to Fig. 4 (a)-(e), the variation of the fins' material as well as the inclination angle of solar panel have a negligible impact on the improvement of the fusion process of PCM. The findings of Fig. 4 (a)-(e) indicate the possible improvement of the PCM thermal behaviour through the integration of other innovative solutions such as nanoparticles [23,[38][39][40][41][42], metal foams [43][44][45][46][47], and micro/macroencapsulation [48][49][50]. ...
One of the biggest challenges of modern technology is the production of clean energy from available resources such as wind, sun, and sea. The solar panel is considered as a potent tool for the production of green electric energy from solar irradiation. However, the performance of photovoltaic systems is related to the effectiveness of the integrated cooling system. In the present paper, PCM (RT35HC) has been used as a cooling process, which is placed in the back container of the photovoltaic unit. To enhance the thermal performance of PCM, a set of fins of different materials (graphite, copper, steel, and titanium) has been integrated into the cooling enclosure. Additionally , the performance of the solar panel has been investigated with the variation of the inclination angle (β = 0, 30, 45, 75, and 90°). Independently of the fins' material and the inclination angle (β) of the PV-system, the presence of fins has relatively enhanced the energetical efficiency of the solar panel, especially with the adoption of graphite and copper materials. With the use of graphite and copper, the mean temperature of the solar panel was reduced by 3°C compared to the case of steel and titanium. The overall PV temperature was stabilized at around 40°C. Despite the promising findings retrieved from the present work, the thermal behaviour of the PCM-based cooling system should be improved with the use of other solutions such as the integration of nanopar-ticles, metal foams, micro/macro-encapsulation…etc.
... In spite of the promising advantages of PCMs, the major drawback of these 3.08 × 10 −3 materials for effective utilization is their inherently low thermal conductivity, which limits their application in thermal-energy storage [2,[13][14][15][16]. Therefore, a large number of technical solutions, i.e. addition of nanoparticles to PCM [16][17][18][19][20][21][22][23], use of metal foams [16,17,22,[24][25][26][27][28], involvement of fins [17,29,30] and micro/macroencapsulation [16,[31][32][33], etc., has been analyzed in different storage tank configurations-in the purpose to increase the heat-transfer (energy recovery) and reduce the melting/solidification time. These techniques are assessed numerically and experimentally (using CFD models) for increasing the thermal performance of hydrogen in metal hydride storage tanks. ...
To keep sonochemical reactors at a constant temperature, cryothermostat systems (equipped with a pump, cooling fluids, and tubing) are commonly used. The cryothermostat serves a dual purpose, supplying both heating and cooling as needed to keep the temperature stable. However, this device is an energy consumer, especially when the sonochemical reaction is carried out over an extended period of time (hours to days). As a result, alternative systems are required to reduce the operating cost of sonosystems. The present work introduces the first approach of incorporating phase change materials (PCMs) for the recovery and storage of heat dissipated from ul-trasonic reactors (i.e. the sono-PCM reactor approach). The purpose of the project is to go as far as replacing the circulating fluid-based cooling system with a small PCM unit capable of absorbing the generated heat flux and storing it in the form of latent heat (with phase change). The analysis was made on sonicated water (300 mL) in a standing wave ultrasonic reactor operating at 300 kHz, where the dissipated heat flux was measured calorimetri-cally. After that, using a computational fluid dynamics (CFD) model (implemented in ANSYS Fluent® software), the energetic performance of the PCM unit was assessed by tracking the system (i.e. the sono-PCM reactor) response (i.e. average and spatial evolutions of temperature, enthalpy, total energy, velocity and PCM-melting ki-netics) to the imposed acoustic energy. Paraffin RT31 was selected as PCM because of its suitable characteristics such as low melting point (27-31°C) and high thermal energy storage capacity (165 kJ kg −1). Despite the relatively low thermal conductivity of the used PCM (0.2 W m − 1°C − 1), promising results have been obtained in terms of thermal energy management and storage using a phase change material (PCM) instead of a water-cooling system. Future innovative modifications are expected for the thermal unit in order to enhance its energetic performance in combination with the sonoreactor.
... In general, the low thermal conductivity of PCMs is regarded as the main drawback of this category of materials (especially the paraffin wax family). Consequently, a huge number of innovative solutions (addition of nanomaterials to PCM [17][18][19], use of metal foams [20][21][22], involvement of fins [23,24] and micro/macro-encapsulation [25][26][27]) has been deduced for the improvement of the thermal conductivity of these materials as well as the reduction of melting/solidification time. ...
As an alternative to a water-based cooling system for a sonoreactor, the present work presents for the first time the use of a phase change material for the management and storage of the dissipated heat within the sonicated water. The performance of the PCM is analyzed as a function of liquid height (LH = 5.1, 10.2, 15.3, and 20.4 cm) at a frequency of 300 kHz and two electric powers (PE = 20 and 60 W). The effective powers dissipated in the irradiated water were determined by the calorimetric technique. A computational fluid dynamics (CFD) model (implemented in ANSYS Fluent® software), was used for the analysis of the combined system (sonoreactor + PCM-thermal unit) at different operating conditions (liquid height and electric power). By analyzing the different outputs (variation of temperature, velocity, enthalpy, liquid fraction of PCM) of the used CFD model, more clarifications are provided about the behaviour of the combined system (sonoreactor + PCM-thermal unit) as function of the liquid height (5.1-20.4 cm) and electric power (20 and 60 W). In terms of temperature, velocity, enthalpy and liquid fraction of the PCM, promising results were obtained in spite of the low thermal conductivity of the employed PCM. The best performance of the combined system (sonoreactor and thermal unit) was obtained at the liquid height of 15.3 cm (corresponding to a water volume of 300 mL) with a similar behaviour (evolution of temperature, velocity, enthalpy, and liquid fraction of the PCM) at both electric powers (i.e., 20 and 60 W) with an intensified response at the PE = 60 W.
... The low heat conductivity of PCMs is regarded as the primary disadvantage of this material class (especially for the paraffin wax family). Recently, numerous creative techniques for improving the thermal conductivity of various PCMs have been proposed, including the inclusion of nanomaterials to PCM [13][14][15][16][17], the usage of metal foams [18][19][20][21][22][23][24], involvement of fins [25][26][27][28][29][30][31], and micro-/macro-encapsulation [32][33][34]. For example, Zhao et al. [35] examined the heat exchange of paraffin wax-PCM in copper foams during the melting and solidification cycles. ...
The melting/solidification of PCM “phase change material” (C19-C20) and cooling/heating of air (HTF “heat transfer fluid”) have been analyzed under the variation of temperature, by an increment of 2 K, on the external side of the heat exchanger (Tw). Aluminium foam (20%, v/v) was used to improve the thermal conductivity of the adopted PCM (C19-C20). Eight cases were investigated during the melting (Tw: from 310-324 K) and solidification (Tw: from 284-298 K) periods of PCM (C19-C20). It has been shown that the melting/freezing processes of PCM were enhanced by increasing (from 310 to 324 K)/decreasing (from 298 to 284 K) the temperature on the external side of the heat exchanger. On the other side, the cooling/heating mechanisms of air were found to be less dependent on the temperature of the external side of the thermal unit. Additionally, it was observed that the decreasing/increasing of air (HTF) temperature were more rapid than the fusion/freezing processes of PCM. Based on the mass fraction profiles of the liquid PCM, it was retrieved that the fusion and solidification mechanisms proceeded in a quasihomogeneous way as the melting or freezing of PCM were observed to take place gradually all around the center of the heat exchanger. Compared to the fusion process of PCM, its freezing regime was observed to be more slower.
... Which is a special version of the one fluid mixture model used by the material science community for alloy casting simulations [19]. El Hasadi and Khodadadi used the one fluid mixture model to investigate the freezing process of the NePCM [20][21][22][23], and El Hasadi for melting of NePCM [24]. There are a few other investigations that used a similar model developed by El Hasadi and Khodadadi [18] to model the freezing process of the NePCM [25][26][27] they showed the extreme importance of the redistribution of the particles in the overall performance of the NePCM. ...
... These interactions, however, are still accounted for in the thermo-physical properties of the mixture. The current model is developed by the author, and has undergone rigorous testing and validation for various cases of solidification and melting of NePCM suspensions [18,[20][21][22]24]. The basic governing equations are the following: ...
Nanostructured phase change materials (NePCM) are phase change materials that contain different types and sizes of colloidal I removed the word sizes particles. Many investigations in the literature assess those type of phase change materials to investigate their thermal performance. However, there is a discrepancy between the experimental observations and numerical results of the melting process of the NePCM because most numerical models do not count for the mass transfer of the particles. In the current work, we will investigate the melting process of NePCM that consists of copper nanoparticles suspended in water for the geometry of a square cavity, heated from the two sides, cooled from one side, and the remaining side is thermally insulated. Our numerical model will account for the mass transfer of the particles using a one-fluid mixture and the enthalpy porosity model for accounting for the phase change process. We found that adding the particles will lead to the deceleration of the melting process, as described by the experiments, because of the reduction of the convection intensity. We found that for NePCM suspension containing 10% of nanoparticles by mass, the deceleration of melting will be about 2.2% compared to pure water. Most of the particles are convected away by the flow cells toward the bottom side of the cavity, especially near the isolated right side of the cavity. Our findings indicate that incorporating mass transport of particles leads to a significantly improved prediction of the melting behavior of the NePCM.
... This is because the low thermal conductivity of PCMs reduces the rate of heat transfer and increases the time needed for charging or discharging in thermal units. Recently, various innovative solutions have been proposed for the improvement of the thermal conductivity of the different PCMs through the addition of nanomaterials to PCM [17][18][19][20][21], use of metal foams [22][23][24][25], involvement of fins [26][27][28][29][30][31][32], and micro/macro-encapsulation [33][34][35]. For example, Hajizadeh et al. [36] employed a duct with PCM and nanopowder (CuO) in the outer layer, while cold air circulates through the inner zone. ...
In a cylindrical shell and multi-tube heat exchanger (of large configuration), the incorporation of four distinct nanoparticles (Al 2 O 3 , MgO, SiO 2 , and SnO 2) at various concentrations (0%-5%, v/v) into PCM (RT82) was investigated during the solidification process. A numerical model was developed and validated through experimental and theoretical findings found in literature. Whatever the metal oxides' concentration, a clear enhancement of the freezing rate of PCM was observed over its solidification period, where this improvement was boosted proportionally with the rise of metal oxides concentration. However, the worst performance of the nano-PCM system was obtained using SnO 2 nanoparticles, where a total solidification of PCM is observed after 26000 s for 5% (v/v) SnO 2. In contrast, the best performance was resulted using SiO 2 , for which a total hardening of PCM was reached after 21000 s for 5% (v/v) silicon dioxide. This means that a reduction of 19.23% of the freezing period was obtained using SiO 2 compared to SnO 2 system at the same volume fraction (5%). It was found that in presence of nanoparticles (nano-PCM system), the solidification rate of PCM is in the order: SiO 2 >MgO > Al 2 O 3 >SnO 2. According to the thermo-physical properties of metal oxides, it was found that the enhancing role of nanoparticles (toward PCM solidification) is density-dependent. Therefore, the effect of heat capacity may be overlooked.
... According to the results, it was discovered that the high rate of heat distribution caused by the addition of nanoparticles is very auspicious for use in applications of thermal energy storage. Hasadi and Khodadadi [23] investigated the size of nanoparticles and the effect of the separation coefficient on solutal-thermo convection throughout the freezing of water/alumina-nanoparticles and water/copper-nanoparticles colloidal suspensions. Their research showed that the thermo-solutal convection intensity increased with increasing nanoparticle size, or the segregation factor decreased. ...
In this experimental research, in order to obtain the effect of excess lithium in the cathode lithium ionization stage in a nonstoichiometric manner, the cathode precursor with (Ni0.3Mn0.5Co0.2) composition was synthesized as hydroxide using the co-precipitation process. Then, lithium was added with different amounts of lithium hydroxide (LiOH) to investigate the effect of excess lithium in the Lix(Ni0.3Mn0.5Co0.2)O2 composition on the electrochemical properties of the cathode. The results of battery charge–discharge tests for all three synthesized samples at rates of 5C-0.5 indicate that the sample Li1.5(Ni0.3Mn0.5Co0.2)O2 has the best electrochemical performance. So that at 1C discharge rate, its capacity was 200 mAh/g, and after 30 cycles, its capacity reached 138 mAh/g with a 5C discharge rate. The electrochemical impedance analysis showed that the sample Li1.5(Ni0.3Mn0.5Co0.2)O2 has the lowest internal resistance. The results show that increasing the amount of excess lithium is optimal for improving battery performance. In nonstoichiometric mode, increasing the amount of lithium to Li1.5 has been associated with improved performance and above this value leads to a decrease in battery performance.
