Analysis Of Solidification Research Articles

Discharging Performance Analysis of MXene Nano‐Enhanced Phase Change Material for Double and Triplex Tube Thermal Energy Storage

ABSTRACTThe present study numerically investigates the energy and exergy analysis of solidification of phase change materials within a double tube and triple tube latent heat storage unit using ANSYS Fluent. Double tube and triple tube thermal energy storage system's thermal characteristics are examined using MXene nano‐enhanced phase change material to determine system efficiency, discharged energy, heat transfer rate, exergy destruction, entropy generation number, exergetic efficiency, liquid fraction, solidification temperature contours. The result revealed that the double tube thermal energy storage with pure cetyl alcohol PCM has 14.76% lower discharge exergy than MXene‐based nano‐enhanced phase change material in pure solidification. In a triple tube thermal energy storage system, the solidification time for MXene‐based nano‐enhanced phase change material is impressively reduced by 54.76% compared to a double tube system using pure phase change material. At a Fourier number of 0.00672, MXene nano‐enhanced phase change material exhibits an 11.69% higher Stefan number (St) than cetyl alcohol phase change material in a double tube thermal energy storage system. At 2400 s, pure phase change material and MXene nano‐enhanced phase change material generated 3.14% and 4.88% less entropy than pure cetyl alcohol in the triple tube thermal energy storage system. During the pure solidification process in a double tube thermal energy storage system, pure cetyl alcohol experiences 7.60% higher exergy destruction compared to MXene nano‐enhanced phase change material at a solidification time of 2400 s. In a triple tube thermal energy storage system, the discharging temperature for pure cetyl alcohol phase change material is 2.92% lower than that in a double tube system. Double tube thermal energy storage with pure cetyl alcohol discharged more efficiently over 2400 s. The triple tube thermal energy storage system solidified cetyl alcohol PCM 20.83% faster than pure phase change material due to MXene nanoparticles' better thermophysical properties. Thus, MXene‐based nano‐enhanced cetyl alcohol phase change material solidifies faster per volume in a triple tube thermal energy storage latent heat system.

X-ray computed tomography analysis of calcium chloride hexahydrate solidification

Latent Thermal Energy Storages (LTESs) are receiving increasing interest, since they offer many advantages to the field of Thermal Energy Storages (TESs), such as a nearly isothermal solid–liquid phase transition and a high energy storage density. To boost the transition towards a climate-neutral future, a lot of work is surely needed on Phase Change Materials (PCMs) which are used inside LTESs. Salt hydrates, a particular class of PCMs, are very attractive in terms of cost and volumetric latent enthalpy but present drawbacks that still limit their effective deployment in real applications, such as supercooling and phase separation (or segregation). The current work assesses the suitability of X-ray Computed Tomography (XCT) as a novel technique in the field of LTESs to study the solidification of phase-change materials. In this study, calcium chloride hexahydrate (CaCl2·6H2O) is chosen as a representative PCM and the results derived are shown to be repeatable. For the first time, the direct measurement of the volumetric liquid fraction is correlated to temperature measurements allowing for the visualisation of supercooling and the validation of an enthalpy-porosity numerical model, which could be useful in the design of LTES. XCT methodology offers unmatchable features as compared to the other method to measure the volumetric liquid fraction. Given its accuracy and the rigorous protocol, it can be considered as a benchmark for new liquid fraction measurement technologies but it also permits to study how the different PCMs melt and solidify, giving new insights on the mechanisms at the basis of the most crucial challenges, among those: subcooling, segregation, and metastable phase change.

Analysis of energy and exergy of eutectic phase change material solidification for various configuration-based triplex tube

This study delves into the energy and exergy analysis of eutectic PCM solidification within a triplex tube latent heat storage unit featuring inner tubes of triangular, pentagonal, square, and circular configurations, analyzed numerically. Results encompassing the impacts of mean temperature, solidification temperature, melting fraction, exergetic efficiency, exergy destruction, heat transfer rate, entropy generation number, and system efficiency on solidification time are presented and compared using contour maps and figures. The research also scrutinizes the effects of Fourier numbers on Stefan, Rayleigh, and Nusselt numbers for TES systems based on inner configurations. Past studies primarily concentrated on cylindrical shapes for all three tubes within triplex-tube heat exchangers, disregarding varied internal tube configurations. This investigation introduces novelty by investigating diverse innermost tube geometries (triangular, square, pentagonal, circular) within a triplex tube heat exchanger. The tangible advantages encompass enhanced thermal efficiency relevant to industries such as oil and gas, chemical processing, food and beverage, and power generation. The inner triangular triplex tube thermal energy storage (TES) system exhibits superior performance over pentagonal topologies, boasting stronger Stefan and Rayleigh numbers by 22.52% and 22.86%, respectively, at Fo = 0.0023. Eutectic PCM solidifies 50%, 65%, and 66% faster within triangular configurations than the triplex tube's pentagonal, square, and circular interiors.However, the pentagonal inner tube topology outperforms the triangular one by 13.36 % at a solidification time of 300 seconds. Eutectic PCM solidifies faster in triangular TTTES systems due to their 0.3%, 1.02%, and 1.10% lower heat transfer temperatures than pentagonal, square, and circular systems. Furthermore, in 1800 seconds of solidification, the triangular inner tube discharges 20.16%, 4.92%, and 3.37% more than pentagonal, square, and circular TES systems. Pentagonal, square, and circular inner tube topologies are 13.36%, 3.01%, and 3.84% less efficient than triangular TTTES systems. TES systems with triangular shapes achieve rapid solidification of eutectic PCM at 305.24K, establishing their efficiency over pentagonal, square, and circular configurations.

Numerical Investigations of Stirring Induced Flow on Solidification and Interface Behavior in Continuous Casting Mold With Bifurcated Nozzle

Abstract Electromagnetic stirring (EMS) is a technique that has the potential to improve steel quality with fine microstructure by fragmentation of dendrites and enhancing the inclusion removal. The success of implementing the EMS lies in the selection of key input parameters such as position, frequency, and current density of the stirrer. In the present study, an integrated mathematical model consisting of liquid steel solidification and two phase interface is numerically developed with the use of EMS. The enthalpy porosity and volume of fluid (VOF) model are adopted for numerical modeling analysis of solidification and interface level fluctuation, respectively. The results reveal that on moving EMS downwards decreases the maximum magnetic field value, widens the mushy zone, and promotes the stability of the interface. Current intensity and frequency are seen to have the opposite effect on stirring intensity and interface fluctuation. With an increase in frequency, both stirring intensity and interface level fluctuations decrease while the high liquid fraction region increases. Moreover, current density enhances the swirling flow intensity and homogenizes the liquid fraction, thereby promoting equiaxed grain formation. Interface fluctuation is seen to increase with current density.

Analysis of solidification of phase change material flowing through a channel with backward step: Effects of step curvature

Thermal energy storage (TES) allows to the conservation of energy, enhancing the overall system efficiency and balancing the supply and demand of energy. This article presents a computational analysis of the solidification process of melted paraffin wax phase change material (PCM) through a partially heated backward-facing step channel partially cooled from the bottom and top. Melted PCM enters through the left opening of the step channel and leaves through the right opening. The study examines two distinct cases: considering sharp stepped or angular corner, and stepped or streamlined corner (of radius r = 20 mm) with the same inlet flow and boundary conditions. A comprehensive numerical model is developed and solved using the finite volume-based computational approach. The overall thermal performance of the model during the solidification process is evaluated for the different Reynolds numbers (Re = 20 and 40) and temperature differences (ΔT = 20 and 25 °C) for the different time steps. Furthermore, the effect of backward step curvature on the solidification process is also analyzed. The results revealed that all the parameters (Re, ΔT, and curvature) affect the melted PCM flow structure as well as the solidification process inside the channel. Changing the sharp step corner into a streamlined one at the bottom of the channel led to the lowest lesser flow separation and faster solidification process. Therefore, a well-designed streamlined step corner and its shape could be used to increase the discharging speed of thermal energy storage units meaningfully. Furthermore, such designs, the placement of the heater and cooler location, and step curvature are the guiding factors for controlling the performance of the energy storage. With the change in the curvature, the energy efficiency can be increased and the solidification time is lowered by at least 5 %.

OPTIMIZING SHRINKAGE DEFECTS IN GREY CAST IRON BUTTERFLY VALVE CASTING: A SIMULATION AND EXPERIMENT-BASED APPROACH

The study focused on addressing casting defects in green sand casting that have negatively impacted the quality of the butterfly valve body. By employing various methods such as observation, interviews, numerical experimentation, and simulation, the researchers aimed to develop and evaluate a sand-casting technique for the butterfly valve body. Solidworks software was used to model the component and its gating system, while ProCAST software enabled mold filling and solidification analyses. The goal was to minimize shrinkage porosities in the cast butterfly valve body by optimizing process parameters through numerical experiments and the Taguchi technique. Analysis of variance (ANOVA) using Minitab 18 software analyzed the results. Through this research, the sand mold-related defect was reduced from 10% to 3%, and the special shrinkage defect was reduced from 26% to 2% by using a simulation of casting.

Analysis of heat transfer and solidification within CANDU corium

Severe nuclear accidents which result in substantial damage to the reactor core have the potential to release radiation into the environment if the integrity of the reactor vessel is not maintained. In the event of a full loss of core cooling, the expected failure mechanism for Canada Deuterium Uranium (CANDU) calandria vessels is thermal stresses, which are influenced by the heat transfer within the corium. The current study uses computational fluid dynamics (CFD) to simulate the fluid flow, heat transfer, and crust formation in the corium using of full-scale CANDU calandria vessel. Uncertainties in the boundary conditions are considered with a sensitivity analysis. Results indicate that about 90% of the corium volume is in the mushy and solid form. The heat flux over the majority of the vessel wall is below the critical heat flux values and reaches the maximum value at the edge of the step region.

Continuous cooling and isothermal solidification analysis of AlSi10Mg using differential fast scanning calorimetry

This study investigates the solidification process of individual micro-sized AlSi10Mg particles using continuous cooling and isothermal differential fast scanning calorimetry (DFSC) methods at a range of cooling rates (from 500 K/s to 50,000 K/s) and temperatures (from 562 °C to 502 °C). The solidification microstructure consists of fine α-Al dendrites and (α-Al + Si) eutectics. Both dendrite arm spacing and eutectic spacing decrease with increasing cooling rate, as well as decreasing solidification temperature. The continuous cooling treatment exhibits finer microstructures compared to those observed in the isothermal treatment in the similar solidification temperature range. Overall, this study highlights the effectiveness of the DFSC methods, along with microstructure characterization, in analyzing the solidification process of individual powder particles over a wide range of cooling rates and temperatures.

Effect of inner channel geometry on solidification performance of phase change material (PCM) in double-pipe thermal energy storage

Advantages such as high energy storage density and low heat losses have made phase change materials (PCMs) preferable in energy storage. However, the very low thermal conductivity of PCMs is the most important obstacle to improving melting and solidification performance of PCMs. To improve the thermal conductivity of PCM, the combination of PCM with nanoparticles, fins, and metal foam is among the methods widely researched in the literature. The innovation of this study was to examine the effect of inner and outer channel configurations on the solidification rate in double-pipe energy storage with PCM. Thus, it was aimed to benefit from the same amount of stored energy more and at a lower cost. In this regard, solidification analyses were carried out for three different basic inner channel geometries. With the triangle-in-circle configuration, the solidification rate was increased by 5.5% to 13.2% compared to other configurations. It is anticipated that the data obtained in this study will be a guide for novel inner channel geometry designs that will increase solidification performance and heat transfer in double-pipe energy storage with PCM.

A New Approach of Solidification Analysis in Modular Latent Thermal Energy Storage Unit Based on Image Processing

The solidification process of RT18HC in a cylindrical shell and tube storage unit has been studied using a new methodology based on image processing. The main idea of the algorithm is to label the region of solidification and use statistical functions to calculate the dimensions of the solidification front over time. Said analysis includes two methods. The first method is to measure the solid fraction changes during solidification. The novelty of this method, as compared to other literature findings, is that pre-processing and calculation process occurs automatically via a calculation algorithm. This method is used to calculate the solid fraction of RT18HC which is reported to be a bit fast at the beginning that 40 % of its volume solidified in 1000 s while the rest of the process is completed in almost 6500 s. The second method is used to measure and calculate the thickness of the solid front by using image processing. This method’s error is calculated to be less than 7% throughout the entire process. The second method also acts as an experimental database of front thickness to use in a novel, simplified, semi-theoretical model proposed to calculate the solid front thickness as a function of time in this paper. It is also worth presenting solution extended by a general definition of thermal resistance for a cylindrical partition. The above study will enable the development of an enhanced and optimized model for complex geometries based on image processing techniques in the future. It will also allow the investigation of both processes i.e. solidification and melting alongside other influencing parameters such as the geometry of the storage unit in future.

Solidification analysis for variable thickness aluminum castings: simulation and chill design insights

Manufacturing high-quality casting parts with complex geometries requires high engineering skill and precision. One essential quality concern is isolated hot spots within the castings, often in thick sections. Each hot spot must be consistently fed or mitigated through directional solidification techniques. The impact of various mold sands and the geometry of chill parts on solidification direction was investigated using specialized casting and general-purpose simulation programs. A parametric optimization method was employed to analyze directional solidification to adjust the geometry of the chill parts. The results indicate that employing diverse mold sands to enhance cooling in the thick sections was a viable strategy for achieving directional solidification in parts where the feeding pathway is obstructed due to changes in cross-section. Furthermore, the study revealed that intricate details in the chill part’s geometry are not critical; however, a minimum volume (or weight) was necessary for adequate directional solidification. Lastly, an easily applicable mathematical model has been developed to determine the required volume of chill parts to ensure successful directional solidification.

INFLUENCE OF Ti MICROALLOYING ON ZAMAK-5

ZAMAK-5 is a Zn-Al alloy which contains 3.9-4.3 % Al, 0.75-1.25 % Cu and 0.03-0.06 % Mg. Low melting temperature and good castability are some of the advantages of ZAMAK-5. In the present study, the composition of ZAMAK-5 alloy was modified by microalloying it with Ti. Alloying was accomplished by melting ZAMAK-5 at 450 and 650 oC and introducing Ti as Al10Ti master alloy. It was found by ICP analyses that modified alloys contained 0.01 and 0.03 wt.% Ti. Re-melting and casting of the alloyed samples were conducted at 650 oC under argon atmosphere. The modified alloy that contained 0.03 % Ti had near eutectic Zn-Al composition due to the increased amount of Al. The increase in the Al content was caused by master alloy addition. According to microstructural and solidification analyses, the modified alloy that contained 0.03 % Ti had lower liquidus temperature and less primary (η) dendrites in its microstructure. Alloying with Ti was found to increase hardness and bending strength of the base alloy. Alloy that was modified with 0.03 % Ti exhibited the highest hardness (102.3±2.8 HB10), compressive yield strength (290.0±5.0 MPa) and bending strength (661.4±30.5 MPa).

Melting and solidification analysis of paraffin phase change material in a circular space, molecular dynamics simulation

The increasing use of renewable energy sources has led to more studies in the field of eliminating the weaknesses of these sources. The use of energy storage systems is one of these things that increase the sustainability of renewable resources and reduce the share of fossil fuel resources in daily energy consumption. One of the most important things in heat storage systems is the use of suitable phase change materials (PCM). In this research, the behavior of paraffin, as a well-known PCM, is investigated on a molecular scale. For this purpose, an annular space has been selected as a nanochannel and the behavior of this material inside it has been investigated in different states. First, the thermal performance of this PCM is investigated. Then, the effect of its temperature on index parameters such as viscosity, heat flux, thermal conductivity, charge time, discharge time, and phase change time are evaluated. The research results show that increasing initial temperature (from 300 K to 350 K) improves the performance of PCM (the duration of charging and discharging are increased from 1.78 and 2.15 ns to 1.41 and 2.24 ns, respectively.). In addition, increasing the speed of the material also reduces the charging and discharging time to 1.65 and 2.09 ns, respectively. Increasing the diameter ratios also changes the indicator times to 2.18 and 2.03 ns, respectively.

Transient Analysis of Fluid Flow, Solidification, and Inclusion Behavior in Electromagnetically Stirred Bloom Caster Mold Using Bifurcated Submerged Entry Nozzle

Herein, the effect of bifurcated submerged entry nozzle (SEN) port angles on transient flow, solidification, and inclusion behavior in a bloom caster mold with electromagnetic stirring (EMS) is investigated. A 3D numerical model is developed to simulate the process, including time‐varying electromagnetic field and Lagrangian inclusion tracking approach, by varying inclusion density and size. The inclusion is modeled to be entrapped in the solidified shell when primary dendrite arm spacing (PDAS) is greater than inclusion size. As compared to the case without use of EMS, the percentage of shell thickness at the strand outlet is seen to increase by 22.18%, 9.45%, 8.03%, 9.31%, and 13.40% for different port angle values of 0°, 15°, 20°, 25°, and 30°, respectively, with EMS. The results show that EMS significantly influences the flow behavior by generating the swirl flow pattern that hinders the movement of inclusion downward in the domain. The bifurcated SEN with 30° port angle (without EMS) is seen to reduce inclusion entrapment and hence enhance inclusion removal. The outcome of present research may provide useful insights for optimizing the parameters of bloom caster mold to improve product quality, reduce production costs, and increase overall efficiency.

Effect of fin configuration and orientation of latent heat storage system on the melting and solidification performance

Phase change materials (PCMs) are used to store thermal energy. They possess high specific energy at nearly constant temperatures. The usage of the PCMs is limited due to their very low thermal conductivity, which results in poor heat transfer. To overcome this problem usage of fins is a potential technique. In the current analysis, the surface area of the heat transfer fluid (HTF) tube is increased by radial (R-type), spiral (S-type), and longitudinal (L-type) fins. A 3D numerical analysis of melting and solidification is carried out on R-type, S-type, and L-type shell and tube (S&T) PCM heat exchanger (HX) by considering the inclination effects. Lauric acid is used as PCM. Phase change time, energy ratio, and exergy efficiency are considered to analyze the performance of HXs. MOORA analysis is carried out to select the best HX. It is observed that R-type HX at the vertical position has shown better performance among the selected HXs. Among the considered geometries, the maximum average exergy efficiency is obtained for 45° inclination with R-type HX and minimum for horizontally positioned L-type HX during both melting and solidification. The charging time of the vertically positioned HX, when compared to 45o oriented HX with R type, S type, and L type HX is observed to decrease by 47.5%, 45.7%, and 23%, respectively.

Analysis of melting and solidification performance of bionic snowflake fin horizontal Triplex-tube latent heat storage system based on response surface method

For the low thermal conductivity of phase change materials and other characteristics, a crossed snowflake fin Triplex-tube thermal energy storage (TTES) is proposed, and the analysis of melting and solidification of phase change material (PCM) by applying the numerical simulation method in the comprehensive thermal performance study. The three-casing phase change heat storage unit filled with RT55 is the object of this paper, and firstly, the cross distribution of snowflake fins into 8 fins is studied, and in the analysis of the thermal performance of TTES, the integrated heat storage (release) time, heat storage (release) and heat storage (release) temperature are used as evaluation indicators. By investigating the melting and solidification properties of PCM, the bifurcation angle of the best thermal performance is 60°, and the best fin profile is obtained by reasonable simplification for the purpose of maximum heat storage. The response surface method (RSM) is then used to optimize the size structure of the fins for the purpose of maximum melting heat storage and maximum solidification heat release of TTES, and the heat function equations of the melting and solidification processes of PCM are fitted, and the optimal regions of the melting and solidification processes of TTES are obtained. Finally, the optimization results show that when the length of the fin is 11 mm and the width of the fin is 0.8 mm, TTES has the best overall thermal performance. Compared with before optimization, the heat of PCM melting accumulation increased by 3.92 kJ and the heat of PCM solidification exotherm increased by 5.773 kJ.

Numerical analysis of droplet breakup, cooling, and solidification during gas atomisation

ABSTRACT As gas atomisation has been the main method for producing high-performance spherical powders in the past decades, its application in the production of metallic powders has become one of the main research subjects in this field. Since it is challenging to directly observe the atomising gas and to investigate melt flow states by experiments, numerical simulation is attracting increasing interest in studying the gas atomisation process. In this work, various computational fluid dynamics models were implemented to simulate the gas atomisation process. With the models, the droplet breakup, cooling, and solidification within the coupled process were investigated. The final mean particle size was predicted through numerical simulations and compared with the statistics extracted from the gas atomisation process, which shows that a reasonable mass median diameter of the particle can be predicted numerically. The results also show a clear relationship between the breakup trajectory and the resulting particle size.

Analysis of natural convection heat transfer and solidification within a corium simulant

In the event of a severe nuclear accident such as that at the Fukushima Daiichi Nuclear Power Plant (NPP) in 2011, it is essential to minimize the release of radioactive material into the environment. Studies on Canada Deuterium Uranium (CANDU) reactors showed that thermal stresses are a potential threat to vessel wall integrity. There is thus a need to analyse the heat transfer and fluid flow within the corium and determine the spatial distribution of heat flux at the calandria vessel wall to ensure the ex-vessel cooling is sufficient. Canadian Nuclear Laboratories (CNL) designed and conducted an experiment to analyse the heat transfer within the corium using a 1/5 scale CANDU calandria vessel with molten salts as the corium simulant. The current study used computational fluid dynamics (CFD) to simulate the heat transfer and crust formation in the experiment to provide insight into the flow pattern and heat transfer and to assess the adequacy of the CFD modelling. Unsteady Reynolds-Averaged Navier–Stokes (URANS) and enthalpy-based solidification models were used to simulate the experiment. The numerical results show that crust forms along the vessel wall up to an approximate polar angle of 42°. There are natural convection circulations close to the top surface, and boundary layers form along the vessel wall. The results predicted by the numerical model match closely with the experimental results.

Solidification analysis in an ice-on-coil ice storage system: Experimental and numerical approaches

Rapid economic growth has led to energy resources shortages, creating unique challenges for developing countries whose activities depend on energy. Thermal energy storage is an important field of technology that can be deployed as a reliable method to decrease net energy usage. For example, ice storage systems are one of the most efficient methods for saving cold energy. In this work, a combined experimental and numerical study has been carried out on the freezing process or solidification as charge mode in a novel ice-on-coil cold storage system with coil tube. Initial experimental results show that the initially designed evaporator, horizontal shell and coil tube heat exchanger (used to transfer cold energy between a mixture of water/ethylene glycol and refrigerant) failed to form uniform ice on the outer surface of the coil tube inside the ice tank. Also, the thickness of ice decreases from the top to the bottom of the coil, while trying to create a uniform thickness of ice around the coil is one of the main challenges in improving the performance of the proposed cold storage system. In the second part of this work, baffles are inserted inside the evaporator to create transverse fluid flows and to prevent shortcut flow, which leads to better heat transfer rates and, consequently, more uniform ice production around the coil tube. The results depict that although baffle placement demonstrates a slightly positive impact on improving the ice thickness along the coil, overall, it fails to eliminate the non-uniformity of ice production along the entire length of the coil tube. In the third section, a modified evaporator with four connected horizontal-placed coils is employed. According to the obtained results, it can be concluded that after 180 min, by employing the modified evaporator, ice thickness has increased by 14.71, 13.51, and 3.39 % in the bottom, middle, and top of the coil, respectively. It can be seen that utilizing the modified version of evaporator with four horizontal-placed coils leads to enhancement in the ice thickness specially at the bottom of the coil where the ice thickness is less than for the rest of the examined points, which was considered as one of the weaknesses of the primary system. Finally, in the last section, to realize better the solidification process around the coil tube inside the ice storage tank, the ice production process is modeled by performing three-dimensional simulations based on the finite volume method. The proposed model is then validated by using the experimental results.

Simulation Based Fluidity and Solidification Analysis of Aluminium-Copper Sand Cast Alloy

Aluminium-copper alloys are known for their very good strength at high temperature .Addition of copper improves the strength at high temperatures due to precipitation strengthening. Fluidity in casting is the major factor which affects the cast quality of the final components. Addition of Silicon with copper in Aluminium improves fluidity and finally quality of the cast components. But presence of Silicon adversely affects the strength at high temperature. In the present work cooling curve analysis of Al-Cu alloy (without Silicon) is done for different wt% of copper addition. The current study for Al-Cu alloy is based on sand casting method as it is one of the cost effective manufacturing method. Cooling curve obtained from the simulation results used to predict the fluidity, microstructure of the alloy when copper wt% is varied. Predicted microstructure and grain structure from the cooling curve goes well with the microstructure studied from shop floor casting .In the present work “Z-cast” casting simulation software is used for casting simulation. Among three different alloy composition studied aluminium with 8% copper gives the best results when compared on the basis of grain size .But fluidity analysis reveal poor fluidity for the alloy having 8 wt% of copper. The current analysis helps to study the optimum aluminium –copper alloy composition that can be used in high temperature applications.