Thermal Conductivity Properties Research Articles

Experimental study on the effect of filament-extrusion rate on the structural, mechanical and thermal properties of material extrusion 3D-printed polylactic acid (PLA) products

AbstractMaterial extrusion (MEX), also commonly referred to as fused deposition modeling (FDM) or fused filament fabrication (FFF) is currently one of the most commonly used additive manufacturing techniques. The quality of the 3D-printed objects fabricated by MEX methods highly relies on various printing parameters, one of which is the so-called filament extrusion multiplier (k). In this study, 3D-printed parts were prepared by MEX technique during which the material feeding rate was adjusted by varying the extrusion multiplier in the range of 97–105% (k = 0.97–1.05). The fabricated parts were tested for their geometrical, structural, mechanical, and thermal conductivity properties. Based on computed tomographic analysis and scanning electron microscopic images, increasing the k parameter resulted in smaller voids, along with gradually decreasing porosity (from 5.82 to 0.05%). Parallel to the decreasing defects, the thermal conductivity of the parts improved from 0.157 to 0.188 W/mK as determined by light-flash analysis technique. On the other hand, when k was set to ≥ 1.03 the geometrical accuracy declined, the size of the specimens considerably increased relative to the nominal values, especially in the X–Y directions due to excess material getting “squeezed” on the sides of the specimens. This latter phenomenon also resulted in the formation of a number of stress concentration sites, which manifested in the decrease of mechanical properties. Accordingly, the tensile, flexural, and impact strength of the samples improved up to k = 1.03; however, above that it dropped considerably.

Effect of Cu addition on the thermal conductivity and mechanical properties of Mg–Zn-xCu-Ce alloys

Thermal conductivity and mechanical properties of Mg–Zn-xCu-Ce alloys with different Cu contents under low extrusion temperature were systematically investigated in this work. The results shows that MgZnCu and Ce-rich (Mg, Zn, Cu, Ce) phase were formed in Mg–Zn-xCu-Ce alloys with high Cu content, which have significantly effect on the thermal conductivity and dynamic recrystallization (DRX). The distribution of grain morphology and LAGBs indicates that CDRX is the main mechanism. The addition of Cu element has an inhibitory effect on the DRX behavior, greatly refining the DRXed grains. After extrusion, a large amount of nano-phase is dispersed in the MZEC alloy, which has a strong pinning effect on dislocations. The formation of MgZnCu phase with high thermal conductivity sacrifices the solute atoms of Zn and Cu in α-Mg matrix, which leads to reduction of lattice distortion of Mg matrix, thereby ensuring high thermal conductivity of Mg–Zn–Cu–Ce ternary magnesium alloys. With the increase of Cu content, the strength and thermal conductivity of the alloy gradually increases. When the Cu content is 3.6 wt%, UTS (ultimate tensile strength), YS (yield strength), EL (elongation) and thermal conductivity are 350 MPa, 317 MPa,15.8% and 135 W/m∙K, respectively.

Preparation of PANI modified hollow microspheres and its application in anti-static buffer foam of OLED under-display

The polyaniline (PANI) modified hollow microspheres (HMs@PANI) was prepared by in-situ polymerization and then applied as both foaming agent and conductive fillers. The coating of PANI on the surface of hollow microspheres (HMs) was studied, and a dense conductive layer was obtained. Moreover, HMs@PANI was co-doped with acrylic acid and hydrochloric acid in order to improve the dispersion. Finally, the as-obtained HMs@PANI-CO was added into the polyacrylate matrix, then the multi-functional syntactic foam with both better anti-static property and buffer property was obtained. When the addition of HMs@PANI was 20 wt%, the surface resistivity of the foam reached 2.32×106 Ω. Furthermore, the better buffer property, lightweight, compression resistance, and thermal conductive property were also presented, which would be important in the practical application of organic light-emitting diode (OLED) under-display.

Enhanced thermal conductivity and mechanical property via improvement of hydrogen bonding between hexagonal boron nitride and aramid copolymer

This study focuses on enhancing thermal properties of aramid copolymer nanocomposites by integrating hexagonal boron nitride (hBN). Pristine hBN (P-hBN) is first subjected to oxidative heat treatment at 900 °C, producing thermally treated hBN (T-hBN), which significantly improves thermal conductivity while also increasing the tensile properties of composites. The study further explores the effect of different diamine co-monomers, 3,4′- and 4,4′-oxydianiline (ODA), on the nanocomposite properties. Both types of ODA-based composite films show improvement in various properties containing T-hBN. With 20 wt% of T-hBN, the 3,4′-ODA and 4,4′-ODA-based films exhibit 33.2 % and 290 % increase in tensile strength and thermal conductivity, respectively. The functionalization of hBN by heat treatment enhances the interaction between aramid copolymer and hBN and prevents the aggregation of hBN. The rough interface was shown in fractured images for films with T-hBN, suggesting that the composite films with T-hBN withstand higher external forces. In addition, it was observed that T-hBN exhibits better dispersion compared to P-hBN. This is supported by molecular dynamics (MD) simulation, and, in addition, it also provides the underlying mechanism for the property differences between both types of co-monomers.

High throughput screening of thermal interface materials by machine learning

Till now, it remains a challenge for effective prediction and screening of novel materials with high thermal conductivity, as well as further optimization of the interface thermal resistance. Normally, people have to spend long time on tedious calculations when predicting and screening these materials. In this paper, I combined machine learning with molecular dynamics simulations to investigate the thermal conductive properties of materials with the aim of significantly reducing computational consumption. I first applied molecular dynamics simulations to obtain the relevant properties of materials, then generated models for predicting physical properties by machine learning, and finally made predictions of thermophysical properties of materials. The use of machine learning significantly reduces the prediction time compared to direct molecular dynamics simulations. Especially when the XGBoost and the neural network models are employed, the prediction efficiency is significantly improved. This work guides a new way for the future screening of high-performance thermal interface materials.

Boron Nitride/Carbon Fiber High-Oriented Thermal Conductivity Material with Leaves-Branches Structure.

In the realm of thermal interface materials (TIMs), high thermal conductivity and low density are key for effective thermal management and are particularly vital due to the growing compactness and lightweight nature of electronic devices. Efficient directional arrangement is a key control strategy to significantly improve thermal conductivity and comprehensive properties of thermal interface materials. In the present work, drawing inspiration from natural leaf and branch structures, a simple-to-implement approach for fabricating oriented thermal conductivity composites is introduced. Utilizing carbon fibers (CFs), known for their ultra-high thermal conductivity, as branches, this design ensures robust thermal conduction channels. Concurrently, boron nitride (BN) platelets, characterized by their substantial in-plane thermal conductivity, act as leaves. These components not only support the branches but also serve as junctions in the thermal conduction network. Remarkably, the composite achieves a thermal conductivity of 11.08 W/(m·K) with just an 11.1 wt% CF content and a 1.86 g/cm3 density. This study expands the methodologies for achieving highly oriented configurations of fibrous and flake materials, which provides a new design idea for preparing high-thermal conductivity and low-density thermal interface materials.

Effects of Superheating Treatment on the Microstructure, Tensile and Thermal Conductivity Properties of Fe-Bearing Al-10Si-Mg Casting Alloy

In this study, we designed and manufactured a new Fe-bearing Al-10Si-Mg casting alloy (F alloy) and investigated its microstructure, mechanical properties, and thermal conductivity. Two types of Fe-bearing Al-10Si-Mg alloys were used: the Conventional-F alloy, injected at 720 ℃ and cooled by water quenching, and the Superheated-F alloy, heated to 820 ℃ and maintained at that temperature for 1 hour. Subsequently, it underwent a degassing process at 720 ℃ before being cooled by water quenching. Both the Conventional-F alloy and the Superheated-F alloy exhibited dendritic microstructures and Fe-intermetallic compounds. The Secondary Dendrite Arm Spacing (SDAS) of the Conventional-F alloy measured 32.4 μm, whereas the Superheated-F alloy measured 28.6 μm. Additionally, the average eutectic Si sizes were 10.3 μm for the Conventional-F alloy and 7.7 μm for the Superheated-F alloy. Fe-rich IMCs were observed in the eutectic region, with their size decreasing due to the superheating treatment. Tensile tests at room temperature were conducted at a strain rate of 10<sup>-3</sup>/s. The Conventional-F alloy exhibited a yield strength (YS) of 93.4 MPa, ultimate tensile strength (UTS) of 183 MPa, and an elongation (El.) of 6.4%. Conversely, the Superheated-F alloy displayed a YS of 115.4 MPa, UTS of 218.2 MPa, and an El. of 5.1%. The mechanical properties notably improved with the superheating treatment. Regarding thermal conductivity, the Conventional-F alloy exhibited 114.9 W/m·K, while the Superheated-F alloy displayed 153.7 W/m·K. This represents a roughly 14% increase compared to the thermal conductivity of the commercial Al-10Si-Mg material (Silafont36: 135.1 W/m·K). The effects of the Superheating Treatment on microstructural characteristics, deformation behavior, and thermal conductivity of the Fe-bearing Al-10Si-Mg casting alloys were discussed.

Microstructure modification in Ba-doped SnO2-based ceramics with promising thermal conductivity and electrical properties

In this paper, the thermal conductivity of Ba-doped SnO2 varistors was tested using the heat flow method, and it was found that the thermal conductivity is related to the grain boundary barrier of the samples. Introducing the reduction of impurity phases and point defects is an effective method to enhance the thermal conductivity of SnO2-based varistors. Energy dispersive spectrograms indicate that the content of spinel Co2SnO4 doped with 1 mol% Ba is the least when the arrester is operated at 40 °C. The positive and negative charge defects are fully compensated, thereby reducing phonon scattering and improving the thermal conductivity of the samples. Spinel Co2SnO4 occupies the position of the effective grain boundary, so the reduction of Co2SnO4 and the compensation of positive and negative defects also effectively increase the grain boundary barrier. When the doping amount of Ba is 1 mol%, the optimal potential barrier height is 1.48eV, the nonlinear coefficient is 45, the leakage current is 0.8 μA/cm2 and the voltage gradient is 418 V/mm.

Study the Effect of Hybrid Nanofillers Content on the X-ray Diffraction and Thermal Conductivity Properties of Epoxy-Based Nanocomposites

High-performance polymer nanocomposites utilizing different-sized nanofillers had a lot of interest recently. Due to their distinct structural, and thermal characteristics. Multi-wall carbon nanotubes (MWCNT) and nanoclay (NC) have the most interest among the numerous types of reinforcing as filler elements for a polymer. The formation of hybrid from MWCNT and NC at various loadings (0.5%, 1%, and 2wt%) on the characteristics of epoxy polymer have been assessed in this work. The specimens have been created using solution blending procedures with the addition of solvent ethanol at a ratio of 1:1 for dispersed nanofillers, and then they have been re-mixed with epoxy. Tests like X-Ray diffraction (XRD), and thermal conductivity were used to identify properties of epoxy. According to the test results, the thermal conductivity rise as the filler content rises at 1wt%, then start to decrease after 1wt%. The sample with the hybrid filler loading of 1 wt% produced the best performance. Since hybrid epoxy exhibits the best result of the thermal conductivity 135% over MWNT and NC nanocomposites of 1 wt.% reached 0.3568 W/m.K in the increased thermal conductivity property. By examining the EP nanocomposites XRD pattern. The hybrid of epoxy nanocomposites exhibits all of the NC and MWCNT characteristic peaks. Since interactions between the filler and the epoxy cause a shift in the peak location of 1wt%. Due to the homogeneity of the nanofillers entire epoxy matrix, there may be changes in the intensity or location of the peaks at 1% for 2θ= 20.13°, which corresponds to an interlayer distance of d=0.461nm.

Dielectric, electrical and thermal properties of Sodium Molybdate-hexagonal Boron Nitride composites enabled by cold sintering

Advances in 5G and 6G communication technologies and their applications are in part limited by the capabilities of current electronic packaging materials, as expanded bandwidth is a pressing need for novel dielectric substrates capable of co-firing into packages and devices, characterized by low dielectric loss and enhanced thermal conductivity. This investigation provides further characterization in the dielectric, electrical and thermal conductivity properties over previously reported cold sintered composite of Sodium Molybdate Na2Mo2O7 (NMO) with hexagonal Boron Nitride (hBN), such as relative permittivity (εr) and dielectric loss (tan δ) values at high frequencies of 75–110 GHz, electrical resistivity (ρ) fitting to percolation theory, Weibull statistical analysis of electrical breakdown strength (Eb) and its anisotropic thermal conductivity (κ) influenced by the filler's crystal structure. The cold sintered composites were systematically characterized with respect to filler volume fraction, temperature, and frequency. The findings in this analysis position engineered composites as a promising alternative for microwave substrate materials, with using a densification method that limits interactions and maximizes densification, hence the demonstration with cold sintering.

Thermal conductivity and mechanical properties of polymeric aerogels for cryogenic insulation applications

Non-vacuum insulation systems are frequently applied in the thermal management of low temperature systems as well as for the use and storage of cryogens. Aerogels are known for their low density, high mesoporosity, high surface areas, low thermal conductivity and high acoustic impedance. This study focuses on polymeric aerogels that can be mass produced as large monoliths while maintaining the low thermal conductivity over a wide temperature range. The manufacturing flexibility of polymeric aerogels allows fabrication of monolithic blocks and sheets that can be applied in various configurations to insulate cryogenic and superconducting devices. To measure the thermal conductivity, an immersion calorimeter was developed and has been operated at different cold boundary temperatures. The calorimeter heats a hollow cylinder of insulating material on the inside surface and the surrounding bath maintains a cold boundary. This calorimeter was used to measure the thermal conductivity of commercially available FoamGlass and a hollow cylinder of a polymeric aerogel machined from a cast cylinder. The thermal conductivity of the FoamGlass and the polymeric aerogel are compared at room temperature (290 K), ice bath (273 K), and at liquid nitrogen (80 K) cold boundary temperatures. Room temperature measurements of the modulus of elasticity and yield strength using an optical technique are also reported for flat specimens of the aerogel made from the same stock as the cylindrical specimens tested for thermal conductivity. Mechanical properties of aerogels are also reported under compression and both at room temperature and at cryogenic temperature (Liquid nitrogen).

Experimental investigation of the cooling performance of an additively manufactured prototype for nuclear fusion energy application

Metal Additive Manufacturing (MAM) is a non-traditional technology recently introduced to manufacture multifunctional mechanical components. In fact, recent developments in Laser Powder Bed Fusion (LPBF) process have enabled the production of materials characterized by high density and high thermal conductivity properties, such as copper alloys and pure copper, making the technology attractive for thermal science. In nuclear fusion energy applications, mechanical components often encounter extremely high heat fluxes. An innovative solution using unconventional integrated cooling channels is therefore required to safely manage the components. However, the high surface roughness in 3D-printed parts represents an intrinsic limitation of the LPBF technology: the cooling channels show high-pressure drops due to the high viscous dissipation generated by the rough surface. To address this challenge, a lab-scale prototype of an e-beam extraction grid for a fusion experiment with an original integrated cooling system was designed and manufactured. Additionally, a novel heating mask was designed and manufactured to reproduce the realistic heat load distribution on the grid during the experimental tests. The prototype was built using additive manufacturing with a CuCrZr copper alloy. The grid underwent heat treatment via solution annealing and age hardening, to increase thermal conductivity from about 100 W m−1 K−1 to almost 300 W m−1 K−1. The prototype was tested at three different constant heat fluxes by varying the water flow rate while measuring the pressure and the maximum temperatures of the grid. A CFD numerical model was also calibrated to estimate the thermo-hydraulic performance of the prototype under test conditions. The experimental and numerical results are presented in terms of overall thermal performance, maximum temperature, and pressure drop.

Thermo-mechanical behaviours investigation of Nano-Sized Al2O3, TiO2, and Graphene Nanoplatelet Reinforced Epoxy Composites

Composite materials find extensive applications in various industries, thanks to their remarkable properties. These sectors include energy, maritime, motor sports, aviation, space and defense. The materials commonly used in these sectors are fiber reinforced plastic (FRP) composite materials. Epoxy materials are commonly used as matrix in the production of FRP materials. This study delves into the enhancement of epoxy-based nanocomposites by using graphene nanoplatelets (GNP-5nm), TiO2 (13nm), and Al2O3 (8nm) nanoparticles. These nanoparticles were added at varying mass ratios into a commercial epoxy to investigate their effects on some chemical, thermal and mechanical properties. Meticulous mixing methodologies were used to reduce clumping effects and ensure even distribution during the process. The curing process was carried out in a PLC (Programmable Logic Controller) controlled hot air oven under isothermal conditions under the influence of 100 °C for 30 minutes. Tensile strength, elongation at break, toughness, resilience modulus, elasticity modulus, hardness, FTIR analysis and thermal conductivity properties were characterized to assess the nanoparticle influence on the epoxy matrix. The results showed that there were remarkable improvements in mechanical properties with nanoparticle reinforcement. Especially, 1.25% Al2O3 inclusion exhibited a substantial increase of 140.32% in tensile strength and a 7% rise in shore D hardness compared to pure epoxy. This enhancement was attributed to enhanced O-H bonding between 'O' atoms in Al2O3 nanoparticles and epoxy polymer chains, enhancing matrix-filler interactions. Additionally, the effect of 1.0% TiO2 led to plasticity, displaying a 32% rise in elongation at break, signifying improved deformation energy absorption compared to neat epoxy. In thermal conductivity measurements, the highest thermal conductivity was observed in the sample with 1.25% GNP added and it increased by 123.5% compared to neat epoxy. In TiO2 and Al2O3 added samples, an increase of 69% and 47%, respectively, was observed at 1.25% additive rates compared to neat epoxy. According to the results, thanks to the nanoparticle reinforcement added into the epoxy matrix, composite structures can be given new and superior properties specific to the applications.

A comparative study on the effects of multi-walled carbon nanotubes and graphene nanoplates incorporated for improved thermal conductivity and dielectric properties of polyvinyl chloride

In the present work, the improvement in the thermal conductivity and dielectric behavior in the frequency range of 0.025–5 MHz of polyvinyl chloride (PVC) films incorporated with graphene nanoplates (GNs) and multi-walled carbon nanotubes (CNTs) were investigated. The neat PVC and PVC composites consisting of different filler ratios of 0.25, 0.5, 0.75, and 1 wt% were synthesized using the casting technique. The increase in the concentration of GNs or CNTs up to 0.75 wt% enhanced the dielectric constant, ac conductivity, q-factor, F-factor, thermal conductivity, and total impedance of PVC composites. The values of the investigated parameters are slightly higher for PVC-CNTs composites compared to PVC-GNs composites. A further increase in concentration to 1 wt% reduces these parameters, but still more than PVC consisting of 0.5 wt% fillers. The mechanism of correlated barrier hopping (CBH) could be successfully used to describe the AC electrical conductivity of both PVC-GNs and PVC-CNTs composites thin films. Furthermore, the glass transition and decomposition temperatures were determined and found to be dependent on the filler ratio and type, and the thermal stability was increased after adding the GNs or CNTs nanofillers. These findings have drawn special attention to developing PVC composites that can be used in various industrial fields including flexible and wearable technologies, power devices, supercapacitors, electric vehicle battery systems, and aerospace components.

Eco-friendly preparation of polyimide/boron nitride composite films with excellent thermal conductivity and mechanical properties

Polyimide/hexagonal boron nitride (PI/BN) composite films have attracted interest as heat dissipation materials for advanced microelectronic devices. However, conventional preparations of PI/BN composite films employ harmful and expensive high-boiling organic solvents. In this work, thermally conductive PI/BN composite films were, for the first time, prepared using a nontoxic, eco-friendly, and inexpensive aqueous solvent. BN was ultrasonically exfoliated in a mixed solvent of water and tert-butanol to obtain aqueous BN suspensions, in which a poly(amic acid) salt (PAAS) was synthesized. The PAAS/BN suspensions were then drop-casted, and thermally imidized into PI/BN composite films. The PI/BN films exhibited excellent in-plane and out-of-plane thermal conductivities (up to 15.043 W/mK and 1.142 W/mK, respectively), which is attributed to the effective exfoliation and dispersion of BN in the aqueous solvent. Furthermore, these films exhibited high tensile strength, flexibility, and thermal stability.

Layer-by-layer assembly of boron arsenide and copper nanoflake-based aramid nanofibers for thermoconductive electromagnetic interference shielding materials with superior mechanical flexibility and flame retardancy

Flexible and wearable electronics represent an emerging frontier, but realizing their potential requires addressing challenges like electromagnetic interference (EMI) shielding, electrical insulating thermal management, and mechanical flexibility. Layer-by-layer structure with alternating conductive and insulating layers offers a promising solution. In this work, we fabricated layer-by-layer structured papers combining boron arsenide (BA) as insulating layers and two-dimensional copper nanoflake (CuF) as conductive layers based on aramid nanofiber (ANF) film via alternating vacuum filtration. The resultant paper (BA4/CuF3) consists of 3 layers of CuF (50 wt%) based ANF (CuF@ANF) conductive layers sandwiched between 4 layers of BA (50 wt%) based ANF (BA/ANF) insulating layers providing exceptional EMI shielding effectiveness (SE) up to 52 dB in the X-band frequency, and in-plane thermal conductivity up to 32.8 W/mK. Meanwhile, the composite papers also demonstrate excellent mechanical flexibility, with the BA4/CuF3 papers exhibiting a tensile strength of 92.38 MPa and EMI SE above 50 dB. Moreover, the composites impart thermal stability up to 500 °C and reduce flammability. The concurrent enhancement of EMI shielding, thermal conductivity, and mechanical properties confirms the potential of layer-by-layer BA/CuF papers for next-generation flexible electronics demanding electromagnetic protection and thermal management.

Development of hBN/natural fibres reinforced polymer composites using grey relation grade analysis for thermal and electrical applications

The objective of this work is to enhance the thermal conductivity and electrical properties of polymer hybrid composites through a systematic novel grey relation grade analysis (GRGA) optimization approach. This involves reinforcing the hybrid composites with hexagonal boron nitride (hBN) and various kinds of natural fibers or fillers. The development of a unique technology to produce multiphase composites using 2% of natural fibers or fillers such as coir fiber, rice husk filler, wood filler (WF), banana fiber (BF) and sugarcane fiber along with hBN (1, 3, 5 wt.%) particulates as reinforcements in epoxy matrix. The Taguchi L15 matrix array is utilized to fabricate interlaced composite samples via hand layup molding. Ultrasonic waves are used to ensure the uniform distribution of hBN filler into the matrix. Analysis of variance and GRGA reveal the significant results. It shows that the multiphase hybrid composites exhibit good thermal conductivity when higher content of hBN (5 wt.%) particulate for all the micro particulate polymer (MPP) composites. Multi-response optimization shows that the micro BF (2 wt.%) interlaces with hBN (5 wt.%) composite exhibits the higher thermal conductivity and electrical resistance compared to all other natural fiber interlaced composites. The aforementioned MPP composite has thermal conductivity of 1.03 W (m·K)−1 and electrical resistance of 279.88 Giga Ohms. Besides, the WF interlaced hBN (5 wt.%) composite shows the minimum dielectric constant compared to all other natural fiber composites. This desirable result is caused by the proper dispersion of hBN with the matrix which encourages interlocking with the fiber and the matrix. Maximum electrical resistance is observed for composite containing 5 wt.% of h-BN and 2 wt.% of BF. The developed MPP composite could be used in heat shields, electrical insulation components, and interior automotive components like dashboards, luggage compartments and interior walls.

Vertically aligned carbon fiber/polydimethylsiloxane composites prepared by lyophilization with exceptional thermal conductivity and electromagnetic interference shielding performance

Composites with high thermal conductivity and exceptional electromagnetic interference (EMI) shielding properties are crucial for ensuring the long-term stability of electronic devices. One-dimensional carbon fibers (CFs) stand out as promising materials due to their excellent thermal and electrical conductivity. However, the anisotropic nature of CFs limits the overall electrical and thermal conductivity of the composite, thus impeding its practical application. To address this limitation, we investigated the effect of different freezing methods on CF orientation using the ice template method. Subsequently, CF-150/PDMS and CF-250/PDMS composites with varying average lengths of CFs were prepared using the unidirectional freezing technique. We studied the influence of CF content and average length on the anisotropic thermal conductivity and EMI shielding properties of the composites. The CF-250/PDMS composite, with a CF content of 15.71 vol%, exhibits a remarkable thermal conductivity of 9.07 W·m−1·K−1 and a low thermal resistance of 2.61 °C·cm2‧W−1. The thermal conductive mechanism of CF/PDMS composites was simulated by thermal conduction model and finite element analysis. Furthermore, it demonstrates longitudinal electromagnetic interference shielding effectiveness (EMI SE) reaches up to 39.66 dB, while the transverse EMI SE reaches up to 52.55 dB. The vertically aligned CF/PDMS composites exhibit significant potential for a range of applications in thermal management and EMI shielding.

Artificial neural network analysis of the flow of nanofluids in a variable porous gap between two inclined cylinders for solar applications

Copper (Cu) nanoparticles (NPs) and polyvinyl alcohol (PVA) are utilized to enhance heat transfer (HT) which is used in the efficiency of solar energy systems. Copper nanoparticles have excellent thermal conductivity (TC) properties that enable them to conduct heat efficiently. In this arrangement, the gap between the two cylindrical channels is settled for the hybrid nanofluids (HNFs) flow in an inclined position that is favourable to sunlight. The nanomaterials consist of a mixture of PVA and Cu nanoparticles (NPs), to execute HNFs. Solar radiation is present on the hot side of the system. The porous gap between the two channels is considered variable which plays a crucial role in enhancing heat transfer and energy conversion. The varying permeability of the gap is adjusted to control the flow resistance and improve the stability of the system. It is observed that higher porosity allows for better convective heat transfer and reduced pressure drop. The transformed equations are solved through an artificial neural network (ANN) while the control volume finite element method (CVFEM) is also used to handle the governing equations. The Cu and PVA (HNF) improves solar radiation absorption and protects components, ultimately increasing the performance and efficiency of the systems.

Simultaneous Enhancement of Thermal Conductivity and Mechanical Properties of EZ42 Magnesium Alloy by Ca Microalloying

Simultaneous Enhancement of Thermal Conductivity and Mechanical Properties of EZ42 Magnesium Alloy by Ca Microalloying