Melting Heat Research Articles

Review on Transdermal Drug Delivery System

A transdermal drug is an adhesive patch with a prescription that is applied to the skin in order to penetrate the epidermis and enter the bloodstream. This frequently encourages the body's wounded area to mend. A benefit of a topical medicationThe advantage of this delivery method over oral, topical, intravenous, intramuscular, etc. medication delivery is that the patch allows for a controlled release of medication into the patient. This is typically achieved by either a porous membrane covering a medication reservoir or by body heat melting thin layers of medication embedded in the adhesive. Transdermal medication delivery allows for a consistent blood level profile, which minimizes systemic side effects, regulated drug release into the patient

Investigation and Root Cause Analysis of Transformer Metering Destruction by Arc Flash

An arc flash and fire in the secondary compartment of an industrial facility utility transformer resulted in destruction of newly installed electrical metering equipment. Inherent to this type of event are two loss-of-evidence challenges: extremely high heat burns or melts everything nearby, and urgency to restore normal operation may prevent comprehensive examination of the scene. The facility contractor’s operations staff conducted an initial root cause analysis. The contractor’s management called on an external forensic team to provide an independent assessment. Having an established investigation methodology allows the forensic examiner to better understand what was, and was not, evaluated by facility staff and prevents confirmation biases. This paper examines the facility’s report, addresses shortcomings in its conclusions, and goes on to detail the methods and reasoning behind the forensic team’s findings. The methodology presented in this paper is applicable to a wide range of industrial electrical fires.

Experimental study on the melting heat transfer characteristics of a phase change material under mechanical agitation

Phase change materials (PCMs) are extensively employed for the thermal management of electronic devices, but their low thermal conductivity often results in slow heat absorption and release in practical applications. Existing improvement measures primarily focus on enhancing heat conduction, while research from the perspective of convection is scarce. Therefore, an experimental study on the melting heat transfer characteristics of n-docosane under mechanical agitation (0–1600 RPM) was conducted at 4.7–34 kW/m2. Upon agitation, the heating wall temperature (Tw) rapidly decreases, while the PCM temperature, heat transfer coefficient and Nusselt number significantly increase, and their variation amplitude is positively correlated with the rotation speed. This can be attributed to enhanced liquid PCM convection and accelerated solid PCM melting. At 8.5 kW/m2, the Tw at 1600 RPM is approximately 27 °C lower than that at 0 RPM, leading to a fourfold increase in the Nusselt number. Tw decreases with increasing rotation diameter, especially at lower rotation speeds. From 30 to 50 mm, the temperature decreases by approximately 13 and 10 °C at 800 and 1600 RPM, respectively. Tw changes slightly with increasing rotation height. Agitation can reduce the increase in Tw caused by a higher heat flux. Agitation can quadruple the upper limit of heat flux from 8.5 to 34 kW/m2 while maintaining consistent thermal control requirements. The power consumption of agitation increases as the rotation speed and diameter increase, peaking at 10.1 W. Moreover, after considering the minimum start-up time, Tw, and power consumption, the optimal configuration is determined: a rotation height of 10 mm and a rotation diameter of 40 mm for 1600 RPM and 50 mm for 800 RPM. These findings hold significant implications for PCM-based thermal management, particularly in terms of incorporating active convection enhancement.

Optimized measurement of frozen soil thermal properties using a heat-pulse sensor

The measurement of thermal properties in partially frozen soil is crucial for global climate models. As the primary method for soil thermal property measurement, the Dual-Probe Heat-Pulse (DPHP) sensor experiences significant errors when used in partially frozen soils. The application of heat pulses leads to ice melting, and the existing DPHP theory, which does not consider phase changes, fails to accurately determine thermal conductivity (k) and heat capacity (C) in the temperature range of − 5 °C to 0 °C. There is a lack of DPHP theory specifically designed for use in partially frozen soils. The existing DPHP theory employs the Infinite Linear Source (ILS) approximation, which does not account for the melting process and the moving ice-liquid interface in transient heat conduction theory. Currently, there is no effective and reliable method to assess DPHP errors associated with measuring the thermal properties of partially frozen soil. To accurately determine k and C in frozen soil, it is essential to perform an error analysis regarding ice melting caused by a DPHP heat pulse input. In this study, (1) we considered the latent heat of ice melting and a moving ice-liquid interface in finite element simulations and compared the results with an analytical solution presented by Paterson (1952); (2) we performed simulations of DPHP measurements based on the temperature-dependent ice content, liquid water content, and melting latent heat of three frozen soils used by Watanabe and Wake (2009); (3) based on COMSOL simulation results for the three frozen soils, we determined the optimal heating parameter combinations (heating duration, t0, and accumulated heating energy, ΔQ) to minimize DPHP measurement errors in frozen soil. The results showed that (1) Simulations that included the melting phase changes were in agreement with the analytical solution by Paterson (1952). (2) Including the ice-liquid moving interface significantly altered the spatial distribution characteristics of temperature, which were not captured by the ILS model in terms of the temperature distribution near the interface. (3) Below a temperature of − 5.5 °C, the simulations that included phase changes were consistent with measured results; (4) For partially frozen soils with initial temperatures ranging from − 0.5 °C to 0 °C, the relative errors in thermal conductivity fitted by the ILS model exceeded 100 %. To mitigate the influence of ice melting, we recommend using 200 < ΔQ < 400 J m−1 for sand, loam, and silt loam soils with 8 s < t0 < 60 s. For a loam soil with t0 = 60 s, ΔQ = 800 J m−1 should be used. For a silt loam soil with t0 = 60 s, we recommend using ΔQ = 600 J m−1. If the ILS model is chosen to calculate soil thermal properties, we recommend using 200 <ΔQ < 600 J m−1 and 30 s < t0 < 60 s for sandy and silt loam soils. For a loam soil, we recommend using 400 < ΔQ < 800 J m−1 and 30 s < t0 < 60 s.

The Role of Target Melting in Particle Impact Ignition with Inert Particulate

The high gas temperatures and oxygen pressures in the turbine of oxygen-rich turbomachinery put conventional engineering alloys such as IN718 at risk of particle impact ignition, i.e., metal fires initiated when particulate strikes a solid surface. The standard model of particle impact ignition assumes that the impacting particle must first ignite in order to kindle to the target material. Here, we invalidate this belief through particle impact ignition experiments which show that IN718 can ignite when struck by inert Al2O3 particles with supersonic impact velocities. Through post-mortem analysis of non-ignited samples, we find that subsonic particle impact causes minimal crater damage whereas supersonic particle impact leaves extensive crater plasticity and pileup, with evidence of molten ejecta near the impact site. Complementary finite element simulations of supersonic impact events confirm extreme adiabatic heating and localized melting. These findings demonstrate that particle impact can drive target ignition even in the absence of particle burning provided the thermal excursion at impact exceeds the melting point of the target material.

Statistical analysis of radiative solar trough collectors for MHD Jeffrey hybrid nanofluid flow with gyrotactic microorganism: entropy generation optimization

PurposeA parabolic trough solar collector is an advanced concentrated solar power technology that significantly captures radiant energy. Solar power will help different sectors reach their energy needs in areas where traditional fuels are in use. This study aims to examine the sensitivity analysis for optimizing the heat transfer and entropy generation in the Jeffrey magnetohydrodynamic hybrid nanofluid flow under the influence of motile gyrotactic microorganisms with solar radiation in the parabolic trough solar collectors. The influences of viscous dissipation and Ohmic heating are also considered in this investigation.Design/methodology/approachGoverning partial differential equations are derived via boundary layer assumptions and nondimensionalized with the help of suitable similarity transformations. The resulting higher-order coupled ordinary differential equations are numerically investigated using the Runga-Kutta fourth-order numerical approach with the shooting technique in the computational MATLAB tool.FindingsThe numerical outcomes of influential parameters are presented graphically for velocity, temperature, entropy generation, Bejan number, drag coefficient and Nusselt number. It is observed that escalating the values of melting heat parameter and the Prandl number enhances the Nusselt number, while reverse effect is observed with an enhancement in the magnetic field parameter and bioconvection Lewis number. Increasing the magnetic field and bioconvection diffusion parameter improves the entropy and Bejan number.Originality/valueNanotechnology has captured the interest of researchers due to its engrossing performance and wide range of applications in heat transfer and solar energy storage. There are numerous advantages of hybrid nanofluids over traditional heat transfer fluids. In addition, the upswing suspension of the motile gyrotactic microorganisms improves the hybrid nanofluid stability, enhancing the performance of the solar collector. The use of solar energy reduces the industry’s dependency on fossil fuels.

Using specularity content to evaluate eight geothermal heat flow maps of Totten Glacier

Abstract. Geothermal heat flow (GHF) is the dominant factor affecting the basal thermal regime of ice sheet dynamics. But it is poorly defined for the Antarctic ice sheet. We compare the basal thermal state of the Totten Glacier catchment as simulated by eight different GHF datasets. We use a basal energy and water flow model coupled with a 3D full-Stokes ice dynamics model to estimate the basal temperature, basal friction heat and basal melting rate. In addition to the location of subglacial lakes, we use specularity content of the airborne radar returns as a two-sided constraint to discriminate between local wet or dry basal conditions and compare the returns with the basal state simulations with different GHFs. Two medium magnitude GHF distribution maps derived from seismic modelling rank well at simulating both cold- and warm-bed regions, the GHFs from Shen et al. (2020) and Shapiro and Ritzwoller (2004). The best-fit simulated result shows that most of the inland bed area is frozen. Only the central inland subglacial canyon, co-located with high specularity content, reaches the pressure melting point consistently in all the eight GHFs. Modelled basal melting rates in the slow-flowing region are generally 0–5 mm yr−1 but with local maxima of 10 mm yr−1 at the central inland subglacial canyon. The fast-flowing grounded glaciers close to the Totten ice shelf are lubricating their bases with meltwater at rates of 10–400 mm yr−1.

Experimental investigation into mechanical, thermal, and shape memory behavior of thermoresponsive PU/MXene shape memory polymer nanocomposite

This research presents an experimental investigation into the mechanical, thermal, and shape memory behavior of a thermos-responsive polyurethane (PU) reinforced with 0–1.0 wt % of MXene (Ti3C2Tx) nanofiller. The PU/MXene nanocomposites were fabricated using sonication and injection molding route. The 0.5 wt % PU/MXene nanocomposite showed the optimum mechanical properties i.e. tensile modulus, tensile strength, and hardness value, which are improved by 22, 281, and 19 %, respectively, compared to pure PU. The improvement is observed in melting temperature (Tm), the heat of melting (hm), crystallization temperature (Tc), and the heat of crystallization (hc) results. The percentage of crystallinity revealed enhancements of 6 %, 18 %, 24 %, and 34 % for 0.1, 0.2, 0.3, and 0.5 wt % PU/MXene samples respectively compared to pure PU. The findings from the shape recovery experiments demonstrated that the inclusion of MXene has no impact on both the shape fixity and shape recovery performance. The PU/MXene nanocomposite with improved mechanical and thermal properties can find potential applications in robotics actuators, medical devices, sensors, etc.

INSIGHT INTO THE IMPACT OF MELTING HEAT TRANSFER AND MHD ON STAGNATION POINT FLOW OF TANGENT HYPERBOLIC FLUID OVER A POROUS ROTATING DISK

Melting heat transfer plays a crucial role in many industrial devices, including heat exchangers, air conditioning, and metal casting. Considering these uses the heat transmission in three-dimensional tangent hyperbolic fluid flow is evaluated. The effects of magnetohydrodynamics (MHD), Ohmic heating, porous medium and melting heat transfer at the boundary are applied to the stretching rotating disk. The governing equations are transformed into a nondimensional form after applying a similarity transformation. The simplified ordinary differential equations contain various dimensionless terms, and the results of these variables are obtained by the bvp4c method. The graphical and tabular results for existing parameters are displayed. For the validation of our results, a comparison is done. From the outcomes, it is noticed that velocity and temperature profiles are enhanced with melting heat transfer at the boundary. The porosity parameter reduces the velocity of the tangent hyperbolic fluid. Moreover, the Eckert number demonstrates the dual nature of temperature profiles.

Comparison of water and benzene as probe liquids in thermoporometry of mesoporous carbons

Water and benzene were compared as probe liquids for thermoporometric characterization of mesoporous carbons. For testing, four different carbonaceous materials were prepared by soft- or hard-templating procedures with mesopore diameters in the range 3–12 nm. In addition, all materials were tested in hydrophobic (pristine, carbonized at 900 °C) and hydrophilic (moderate oxidation by persulphate) form. The results show that both tested liquids express a good linear correlation between heat of melting in pores (measured as DSC peak area) and volume of mesopores. Melting point depression of probe liquid confined in pores related to mesopore size was found out to be steeper for benzene confirming a higher value of Gibbs-Thomson constant of benzene compared to water. Neither heat of melting in pores nor melting point depression were affected by carbon surface oxidation. Contrary, the non-freezing layer (δ layer) of a liquid in pores was considerably wider for most of hydrophilic samples than hydrophobic ones when water was employed, while it stayed nearly constant when benzene was applied. Nevertheless, both tested probe liquids generally enable to obtain similar pore size distributions if appropriate values of δ layers are used. Benzene as a probe liquid in thermoporometry of carbons have some advantages compared to water but only in limited cases. Benzene can be recommended for characterisation of large mesopores and its usage can be beneficial for comparison of analogous samples with different surface chemistry.

НАПРЯМКИ ПОКРАЩЕННЯ ОСНОВНИХ ХАРАКТЕРИСТИК ТЕПЛОВИХ АКУМУЛЯТОРІВ ТА ТЕПЛОАКУМУЛЯЦІЙНИХ МАТЕРІАЛІВ

The article is devoted to the study of heat storage technologies as the main energy saving measure. The paper conducts a patent search and analyzes scientific papers that cover the issue and present the main material of existing technologies for thermal energy storage. The classification of the main types of heat accumulators (HA) and heat storage materials (HSM) is presented. Heat accumulators are classified: by the nature of accumulation; by the level of operating temperatures; by the duration of the charge-discharge period. The differences and design features of TAMs, advantages and disadvantages are analyzed. The main heat storage materials that are actually used or can be used in the future are identified. The thermophysical properties of heat storage materials, such as specific heat capacity, melting point, density, and density, are described.&#x0D; The methodology for calculating the volume of capacitive and phase-transition heat accumulators is determined based on the following initial data: the type of heat storage material, the type and thermal characteristics of the heat carrier, and the temperature drop of the heat storage material. Examples of the practical use of capacitive batteries are given, in particular, a tank battery in a solar heating system, as well as a gravel battery in a solar vegetable garden. The use of crystalline hydrates and organic low-melting compounds (fatty acids and paraffins) as phase-transition heat storage materials is described. The characteristics of thermochemical thermal accumulators, their principle of operation, and their advantages over capacitive and phase-transition accumulation units are presented. The reactions of enrichment of traditional carbon fuels are described, and examples of reactions that can be used as heat storage processes are given. Prospects for further research are identified.

Development of hybrid MgO/GO modified microencapsulated phase change material for thermal energy management: An experimental approach

The microencapsulation technique addresses the concerns of phase change material (PCM) leakage, transportation challenges, and limited efficacy in thermal energy management applications. Nevertheless, the organic shell material has lower thermal conductivity, and significant leakage issues. To improve the ability of heat transfer as well as leakage prevention, a novel form of microencapsulated phase change material (MEPCM) with paraffin core, and melamine formaldehyde (MF) shell modified by hybrid magnesium oxide (MgO), and graphene oxide (GO) thermal conductivity enhancer (TCE) interface is fabricated through the process of in-situ polymerization. The results revealed a well-developed TCE interface layer in between the core, and the shell of the modified spherical microcapsules. The modified MEPCMs exhibited a maximum encapsulation rate of 88.0 %, and 177.84 J/g latent heat of melting. The thermal stability of the MEPCMs is increased by 50 °C to 70 °C, and the thermal conductivity is remarkably elevated to 0.44 W/mK. The leakage rate is significantly reduced by 98.58%. The excellent thermal energy storage/release performance of the modified MEPCMs is attributed to the TCE interface, which serves as an efficient medium for thermal conduction. The modified MEPCMs endure exceptional physical, and thermo-chemical properties, that are relevant for thermal energy management applications.

Significance of Melting Heat Transfer, Inclined Magnetic Field, and Thermal Radiation on the Dynamics of Williamson Nanofluid Above a Stretching Sheet

This study investigates the melting heat transfer in MHD flow that occurs when the flow is past a stretched sheet. With the use of the boundary layer concept, a set of non-linear ODEs is derived from a system of PDEs of motion and energy. After transforming the non-linear ODEs and their boundary conditions into dimensionless form with the use of appropriate similarity conversions, the equations are then numerically solved by employing the MATLAB inbuilt solver bvp4c method in conjunction with the shooting methodology. Through the use of a variety of charts and tables, the authors analyze and describe in depth the effects that relevant factors have on a variety of flow fields. As melting factor (Me) increases, it is discovered that the effect of Me on fluid temperature and velocity distributions decreases. Williamson parameter and inclined magnetic profile are shown to have decreasing impact on velocity and momentum parameter. After that, the findings are compared with the earlier published findings in limited situations of the issue, and it is discovered that they are in exceptional specify with those findings.

Melting heat effect in MHD flow of maxwell fluid with zero mass flux

This study delves into the investigation of Maxwell fluid flow across a sheet with a particular effort on the melting heat and zero mass flux at the boundary. A Maxwell fluid, characterized by both viscous and elastic responses, plays a pivotal role in various industrial and biological applications. The mathematical model describing Maxwell fluid flow is represented using non-linear momentum and energy equations, incorporating MHD. Similarity transformation is used to change from partial differential equation to ordinary differential equation. The introduction of a phase change term in the energy equation accounts for the melting heat effect at the boundary. The BVP4C solver using MATLAB is hired to numerically answer the system of equations, enabling the determination of the steady-state solution. The solution of this investigation offers valuable insights into the interplay between viscoelasticity and melting heat effects on various flow characteristics, including velocity and temperature profiles. The practical significance of this research is evident in polymer processing, food processing, and materials engineering, where the understanding of Maxwell fluids and their interaction with melting boundaries is essential for process optimization and product quality. So far in the literature survey no one have considered Melting heat effect along with Maxwell fluid. The conclusion for this study is that Melting heat effect increases velocity profile and decreases the temperature profile. This is the main conclusion of this research.

Passive cooling of two phase change materials installed in series

Portable transport passive-type refrigeration systems keep products in specific temperature ranges for several days without electricity. Phase change material (PCM) is often combined with insulation panels to form an insulated box.This paper presents the effect of utilizing multiple PCMs with different melting temperatures and heat capacities on product storage and product temperature abuse. Two PCMs with different transition temperatures were thermally coupled, forming a cascade passive refrigeration system. The primary PCM (water) had the largest storage capacity. At the same time, the secondary PCM acted as a thermal buffer to prevent the temperature abuse, namely freezing, of the product carried inside the box.Modifications were made to an existing state-of-the-art refrigerated transport box to install PCM-based passive refrigeration systems that extended the refrigeration performance while maintaining the same envelope and interior volume. Experiments were conducted at ambient temperatures of 20 °C, 35 °C, and 42 °C while the temperature inside the container remained below 6 ℃ for several days. Effective thermal resistance values for the insulated refrigerated transport box and between the PCMs and the product inside the box were determined experimentally. A semiempirical numerical thermal model was developed to predict the duration, and the average error between the predicted duration and the data was 9.7 %. Correlations from the literature were also compared to estimate the transport box performance for various configurations, and the results indicated that such correlations estimated the storage duration satisfactorily only for simple configurations of the insulated box.

A new generation of metal chillers to control the solidification structure of Al-4.5 wt%Cu alloy

This paper introduces and examines a new generation of chillers for judicious control of the solidification structure of cast metals and alloys. This innovative chiller makes use of the absorption of the latent heat of melting of a Phase Change Material (PCM) incorporated in the chiller. In this work, Al-4.5 wt%Cu melt was cast in sand molds fitted with a traditional solid steel chiller as well as this new type of chiller consisted of a steel container filled with a given amount of pure zinc as PCM. Effects of the PCM fitted chiller on the thermal history, solidification and structure of the castings were studied by experimental and computer simulation investigations. The optimum casting parameters and mold and chillers dimensions were selected using ProCast simulation software. Use of the PCM fitted chiller resulted in faster columnar-equiaxed transition, 27 %, 54 % and 40 % reduction in the length of the columnar zone and the primary and the secondary dendrite arm spacings, respectively, and about 30 % improvement in the hardness. Thermal gradients and cooling rates at different points of the PCM fitted casting were generally more than those in the traditionally chilled casting. Use of the PCM fitted chiller eliminated the formation of the feathery grains and reduced the formation of the undesired Fe-rich phases close to the chiller due to different thermal history of the castings. Segregation pattern and change of Growth Restriction Factor (GRF) along the castings were studied and related to the cooling and growth conditions experienced by each casting.

Synthesis, characterization and application of a magnetic nanoencapsulated PCM in enhancing the natural convection in a cube cavity

Encapsulation of phase change materials (PCMs) is an intelligently effective way to overcome the challenges of PCMs usage in heat storage and transfer applications. At the first stage of the current study, a novel magnetic nanoencapsulated PCM (M−NEnPCM) consisting of n-Octadecane (n-C18) coated with a poly methyl methacrylate (PMMA) shell was synthesized through the miniemulsion ultrasonic-assistant polymerization technique. The magnetic property was introduced to the nanocapsules by adding surface-modified Fe3O4 nanoparticles into the core during the formation step. The dynamic light scattering (DLS) results showed an average nanocapsule size of 78 nm. The scanning electron microscope (SEM) along with transmission electron microscope (TEM) images confirmed the spherical shape with a core/shell structure of the M−NEnPCM. According to the differential scanning calorimetry (DSC), M−NEnPCM had melting and crystallization latent heats of 116.47 and 124.71 J/g, respectively. Moreover, based on vibrating sample magnetometry (VSM) results, the superparamagnetic property of M−NEnPCM is proved. At the second stage, the performance of water suspensions containing different amounts of the as-prepared nanocapsules in enhancing the natural convection in a cube cavity was investigated under various heat fluxes and magnetic field flux densities. The results illustrated that the use of nanocapsules leads to enhance the natural convection up to 2 times higher than that of pure water; while there are optimum levels of M−NEnPCM concentration and magnetic field flux density at which the heat transfer coefficient is maximized.

Prediction of Ni-based alloy microstructure in wire arc additive manufacturing from cellular automata model

Wire Arc Additive manufacturing (WAAM) process is a class of directed energy deposition processes with wire feedstock. The process enables a higher build rate than the powder-based additive process and integrates multiple custom wire feedstock to induce spatial variation of microstructure and composition. The lower speed employed in WAAM reduces the cooling rate and resultant residual stress compared to the powder bed fusion process. The systematic epitaxy across the layer creates a directional/columnar microstructure for Ni-superalloy. Here, we report cellular automata model development to predict the microstructure evolution with surface and bulk nuclei for single track and multiple layers. The cellular automata model was developed to account for secondary element addition, predict segregation, local melting, and latent heat release, as well as predict crystallographic texture/Euler angles from orientation information. We experimentally validated the layer-level microstructure and texture from SEM and EBSD, respectively, and found agreement with the CA model developed.

Exploring the thermal performance of a solar air heater with a V-corrugated and shot-blasted absorber plate comprising nano-enhanced phase change materials

This research aims to carry out an experimental investigation into the performance of a solar air heater using phase change materials in combination with V-corrugated absorber plates and shot blasting. This shot blasting approach is applied to interrupt the boundary layer thickness of the absorber plate material it will increase the absorbance of the material. This study incorporates the analysis of four distinct absorber plates namely (i) V-Corrugated Plate (ii) V-Corrugated with shot blasting, incorporating PCM (iii) V-Corrugated with shot blasting, including NEPCM (0.6 %) (iv) V-Corrugated with shot blasting, including NEPCM (0.9 %). In this study, Paraffin wax was selected as the base PCM, and MWCNT dispersed into base PCM with different weight fractions. The nano-enhanced phase change material with a concentration of 0.9 wt% examined that the latent heat of melting and solidification experienced a significant augmentation. This enhancement resulted in a maximum increase of 12.5 % for melting and 8.2 % solidification was attained at 0.9 % of MWCNTs compared with paraffin wax. The average exergy efficiencies of V-corrugated plate attains an efficiency of 1.023 %, V-corrugated with PCM records 1.357 %, V-corrugated with 0.6 % NEPCM attains 1.698 %, and V-corrugated with 0.9 % NEPCM attains the highest efficiency at 2.167 %. The significant enhancement in exergy efficiency observed in NEPCM configurations with volume fractions of 0.6 % and 0.9 % is primarily attributed to two key factors namely enhanced thermal conductivity and improved heat transfer properties. The maximum sustainability index for the V-corrugated design with 0.9 % NEPCM falls within the range of 1.014 to 1.037. The average “Nu” value of 27.5 was achieved under the conditions of a mass flow rate of 0.02 kg/s and the addition of 0.9 % MWCNTs dispersed in paraffin wax.

Fabrication and thermal properties of capric–stearic acid eutectic/nano-SiO2 phase change material with expanded graphite and CuO for thermal energy storage

With the booming development of energy storage technology, phase change materials (PCMs) provide more possibilities for building energy efficiency. In this paper, binary eutectic mixture of capric acid (CA) and stearic acid (SA) is PCM, nano silica (SiO2) is used as the nano-enhancer, and expanded graphite (EG) and nano CuO are used as the thermal conductivity enhancers. Different mass fractions of composite phase change materials (CPCMs) are prepared by melt impregnation method. The structure, thermal properties, stability, thermal conductivity properties, thermal storage/release properties and temperature response properties of the CPCMs are characterized. Results show the prepared CA-SA/SiO2/EG(CPCM5) melts at 30.62 °C and solidifies at 25.29 °C with latent heat of 156.50 J/g and 144.20 J/g, respectively, and CA-SA/SiO2/CuO(CPCM8) melts at 29.09 °C and solidifies at 25.30 °C with latent heat of 152.60 J/g and 140.70 J/g, respectively. The latent heats of melting are higher than the theoretical latent heat due to the enhancement of the nano SiO2. Good compatibility is observed between CA-SA, SiO2, CuO and EG. The thermal conductivity of CPCM8 and CPCM5 are 0.287 and 0.929 W/(m·K), respectively, and CPCM5 has better thermal storage/release and temperature response characteristics. Moreover, CPCM5 does not decompose at 100.00 °C, and shows good stability after 200 cycles of heating and cooling. Therefore, the composite has great potential for application in the field of building energy efficiency.