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In order to predict the evolution of the vulcanization process of cork-rubber slabs, a numerical approach was developed combining heat transfer by conduction and kinetics models. A one-dimensional model was applied to predict the evolution of temperature and degree of cure at different stages of the vulcanization of a cork-rubber composite. Also, due to the degradation verified by the compound, an existent reversion model was added to the problem. Based on rheometer data, cure and reversion parameters were determined. Experimental data were used to determine the thermal properties of the compound, assuming a constant value or according to its degree of cure and temperature. The results obtained by simulation showed a good correspondence with experimental results, even when assuming constant thermal properties. The application of the proposed methodology provides information about the optimum process parameters for each thickness slab, without compromising the homogeneity and characteristics of the final product, which can be a valuable tool during the development and product stages of cork-rubber composites. [ABSTRACT FROM AUTHOR]

This paper aimed to improve the thermal and waterproof properties of foamed concrete through the synergic work of nano SiO2 aerogel powder (NSAP) and organosilicon waterproofing agent (OWA). Hence, several series of foamed concrete with a 0–3.0% of OWA and with 1–4% of NSAP addition were developed. The results show that OWA can decrease the dry bulk density, compressive strength, water absorption rate, and thermal conductivity. With the addition of NSAP, the water absorption rate reached a minimum value of 9.2% at 3.0% NSAP, while the thermal conductivity continued decreasing. Through the microscopic pore size distribution, XRD, and SEM, it was found that the addition of NSAP had no effect on the type of hydration product, but it can increase the average pore size and the amount of macropore and weaken the interfacial adhesion between hydration products. Comparing the heat transmission model, the presence of NSAP increased the heat transmission pathway and resistance, resulting in lower thermal conductivity. [ABSTRACT FROM AUTHOR]

Ideal thermal interface materials (TIMs) can completely fill the interfaces among components to enhance heat transfer between devices and they have emerged as a major strategy to solve heat dissipation problems. However, some micro-scale voids and cavities existing at a device interface can hardly be adequately filled by externally squeezing in the highly elastic thermal interface material, which badly hinders heat transfer. Therefore, the light curing method is a very good path to obtain pre-filled TIMs, which can adequately fill micro-scale voids and cavities and perfectly replicate textures from the interfaces of components. Herein, a kind of polyurethane acrylate (PUA) resin with UV curability and conformal contact flexibility was chosen as a matrix, and an added photoinitiator was excited by UV irradiation to produce active species to trigger polymerization of the active group in the liquid material, thus curing it. By adding copper nanowires (Cu NWs) to bridge the modified hBN, a three-dimensional (3D) heat transfer network is formed to improve the thermal conductivity of the PUA resin. The thermal conductivity of the hBN@PEI-Cu NWs/PUA composites can reach 1.535 W m-1 K-1 at 20 wt% addition of total fillers. Meanwhile, the composites show excellent electrical insulation and good flexibility, and can be stretched, twisted and knotted arbitrarily when used directly, indicating their strong potential in practical applications. [ABSTRACT FROM AUTHOR]

Heat transfer enhancement by suspending nano-sized particles in a liquid, called nanofluid, has attracted considerable attention over the past few decades. The underlying mechanisms are an area of active research. The present study focused on the inhomogeneous and non-isotropic aspects of the thermophysical properties of nanofluids. A non-equilibrium molecular dynamics simulation was conducted, such that the temperature gradient was applied directly to the simulation domain where various particles were located, and local and directional characteristics of the heat transfer were investigated. The ordered structure in the liquid region next to the liquid-solid atomic interface played a critical negative role in altering the thermal properties that could not be predicted through the simple composite model of Maxwell. The formed liquid structure was sensitive to the surroundings, and the size, shape, and multi-particle arrangement affected the performance accordingly. Two nano-particles oscillating in the temperature-gradient direction were significantly effective in enhancing heat transfer. [ABSTRACT FROM AUTHOR]

The motorized spindle will produce a lot of heat at high speed, thereby making the physical structures deformed and changing the bearing performances. However, the interaction between thermal and mechanical characteristics has not been deeply studied. This paper aimed to consider the coupling of interference fit, centrifugal effect, and thermal effect in these components to build a comprehensive and optimized spindle model. Firstly, the displacements related to contact angles under the thermo-mechanical coupling effect were analyzed, and the oil film factor was added to the bearing static model to be studied together with centrifugal force and gyroscopic moment of the ball. Next, based on thermal network method, a quasi-3D model of cooling water pipe was established by considering its structural characteristics. Meanwhile, for the discussion of the number of balls and their thermal resistances, the heat transfer between the bearing ring and the ball was investigated and improved. Lastly, the influences of thermal characteristics on bearings parameters and spindle temperature rise were investigated under different speed, cooling water, and oil-air variables, which provide a reference for regulating and controlling motorized spindle. [ABSTRACT FROM AUTHOR]

In this work, effects of sealing temperature, time, pressure, as well as sealant thickness and viscosity on squeeze out flow (SOF) in heat sealing were examined. A new image analysis approach is presented to quantify SOF in heat sealing. It was found that increasing temperature or pressure could improve SOF but only in thick 130 μm sealants and reducing the sealant thickness to 50 μm suppressed SOF. Reducing viscosity in 50 μm sealant films was also found to improve SOF only at high‐sealing pressure and long sealing times. Three approaches were used to model SOF: analytical one‐dimensional model, numerical one‐dimensional model using finite difference method (FDM), (iii) Numerical two‐dimensional model using finite element analysis. Heat transfer was modeled, and it was shown that heat transfer induces a delay in SOF. When the FDM and the heat transfer models were combined, a good agreement between experimental and model prediction could be obtained. In addition, modeling results showed that SOF occurred in shear rates within the transition region between the Newtonian and Power‐law regions. This indicates the importance of considering the Carreau‐Yasuda fluid behavior in modeling of SOF. [ABSTRACT FROM AUTHOR]

A common calculation error of thermal processes in injection molding simulation programs is caused by the inadequate description of the heat transfer between the polymer melt and the wall of the mold. No correct description of the effect of pressure on the heat transfer coefficient is available for the numerical calculations of injection molding yet. During the injection molding cycle, the pressure of the melt can vary from atmospheric pressure to thousands of bars. When such a high pressure is applied, the heat transfer coefficient can change several orders of magnitude. To calculate heat removal accurately, we developed a novel measuring method and based on the measurement data, we created a model that describes the heat transfer coefficient as a function of pressure and temperature. Calculated maximal heat transfer coefficients vary between 250 and 800 W/(mK) at the pressure of 500 bar. The pressure dependence of the heat transfer coefficient can be described with a sigmoid function. The heat transfer coefficient increases as the temperature difference between mold and melt increases and as pressure increases. We determined measurement error and found it to be less than 5%. [ABSTRACT FROM AUTHOR]

Many efforts have recently concentrated on constructing and developing nanoparticles (NPs) as promising thermal agent for optical hyperthermia and photothermal therapy. However, thermal energy transfer in biological tissue is a complex process involving different mechanisms such as conduction, convection, radiation. Therefore, having information about thermal properties of tissue especially when NPs are embedded in is a necessity for predicting the heat transfer during hyperthermia. In this work, the thermal properties of solid phantom based on agar in the presence of three different nanoparticles (BPSi, tNAs, GNRs) and alone were measured and reported as a function of temperature (ranging from 22 to 62 °C). The thermal response of these NPs to an 808 nm laser beam with three different powers were studied in the water comparatively. Agar and tNAs have almost constant thermal properties in the considered range. Among the three NPs, gold has the highest conductivity and diffusivity. At 62 °C BPSi NPs have the similar amount of increase for the diffusivity. The thermal parameters reported in this paper can be useful for the mathematical modeling. Irradiation of the NPs-loaded water phantom displayed the highest radiosensitivity of gold among the three mentioned NPs. However, for the higher power of irradiation, BPSi and tNAs NPs showed the increased absorption of heat during shorter time and the increased temperature gradient slope for the initial 15 s after the irradiation started. The three NPs showed different thermal and irradiation response behavior; however, this comparison study notes the worth of having information about thermal parameters of NPs-loaded tissue for pre-clinical planning. [ABSTRACT FROM AUTHOR]

The ground thermal properties are the basic parameters for the design of borehole heat exchanger (BHE) in ground–coupled heat pump system (GCHPs), and their accuracy directly affects the economy and reliability of the heat pump system. In traditional design, ground is usually regarded as an isotropic homogeneous medium, and its thermal properties are obtained by solving the inverse heat transfer problem in BHE through in-situ thermal response test (TRT). In fact, different geological layers can be observed along the depth of BHE, and thermal physical properties of each layer are different based on the ground geological conditions. In order to investigate the effect of geological stratification on estimated accuracy of ground thermal parameters in TRT, a validated numerical layered BHE model (NLBM) is presented to simulated TRT, and the fluid temperature response is used to estimate effective ground thermal conductivity and borehole thermal resistance based on line source model (LSM). Secondly, the distributions of fluid temperature in U-pipe and heat flux of BHE along the depth are compared and analyzed based on the NLBM and the numerical homogeneous BHE model (NHBM). At last, borehole thermal resistance from the NLBM and estimated borehole thermal resistance from LSM are compared. The results show the maximum heat flux in the 3rd layer of the NLBM is 21.1% higher than that of NHBM, and the minimum heat flux in the 1st layer is reduced by 46.9% in the 100 h duration. The estimated λ LSM using the fluid temperature responses in the NLBM is 1.3% higher than the thickness-weighted thermal conductivity in the NLBM. The minimum relative error between R LSM and R b is still up to 10.45% in the duration of 100 h even though extending the duration is helpful to improve the estimated accuracy of R LSM. • A numerical layered BHE model is proposed and validated by the experiment. • The distributions of fluid temperatures are compared from the two models. • The differences of heat flux are illustrated in the two models. • Effect of geological stratification on estimated accuracy is investigated in TRT. [ABSTRACT FROM AUTHOR]

The study of flow and convective heat transfer from a rotary sphere in fluid mechanics, astrophysics, and astronaut subjects is important. Today, use of porous media has become widespread because of heat transfer characteristics as well as their lightweight and low volume. Many numerical studies on heat transfer and fluid mechanics in the rotary sphere have been done. The present project studies the phenomena of flow and heat transfer due to the rotation of the sphere at a constant temperature around itself in a porous medium, assuming a laminar, steady and incompressible flow. Analytical solution of the equations used is based on power series and the porosity coefficient is assumed to be between 0 and 1 in this problem. In the spherical coordinate system used here, changes in the azimuthal angle direction are ignored and the body force and pressure gradient for the problem are considered zero. The presence of the porous medium is expected to increase the value of thermal parameters. [ABSTRACT FROM AUTHOR]

This paper models the thermal transport properties and performance of a water-based CuO nanofluid (with varying volume fractions of CuO) in a laboratory-sized double pipe heat exchanger (DPHE). Copper oxide (CuO) nanoparticles were used and their quantity was varied from a volume fraction of 0% to 0.1% with an incremental step size of 0.025%. The mass flow rates of the hot and cold fluids were maintained at 0.87 kg/s and 0.9 kg/s, respectively. Simulation results revealed that temperatures of 410 and 306.75 K, respectively, were attained at the hot and cold fluid outlets. Analysis of the DPHE showed that for cold fluids, thermophysical properties such as viscosity, thermal conductivity, specific heat capacity (SHC) and density were enhanced by the addition of nanoparticles. The temperature distribution, effectiveness and the heat transfer in the DPHE were observed to linearly increase with increment increases of the nanoparticle volume fraction.

Interfacial heat transfer across curved surfaces has not been understood sufficiently well. The present study reports a significant decrease in heat transfer at a convex fluid-solid interface. Effects of curvature on the Kapitza length and the thermal accommodation coefficient are investigated for both gas and liquid phases to understand the occurrence of large temperature jumps. The study also examines the penetration depth of non-equilibrium effects into gas from the convex surface theoretically and reveals the expansion of the Knudsen layer at convex surfaces. [ABSTRACT FROM AUTHOR]

As dimensions of nanoelectronic devices become smaller, reaching a few nanometers in modern processors, CPU hot spots become increasingly more difficult to manage. Applying mechanical strain in nanostructures provides an additional tuning mechanism for both electronic band structures and phonon dispersions that is independent of other methods such as alloying and dimensional confinement. By breaking crystal symmetry, strain increases anisotropy. We present thermal conductivity calculations, performed in thin Si and Ge strained films, using first principles calculations of vibrational frequencies under biaxial strain, along with a phonon Boltzmann transport equation within the relaxation time approximation. We find that, while in-plane transport is not strongly dependent on strain, the cross-plane component of the thermal conductivity tensor shows a clear strain dependence, with up to 20% increase (decrease) at 4% compressive (tensile) strain in both Si and Ge. We also uncover that strain emphasizes the anisotropy between in-plane and cross-plane thermal conductivity across several orders of magnitude in film thickness. [ABSTRACT FROM AUTHOR]

The arsenic (As) to selenium (Se) ratio in AsxSe1-x glasses ranging from x=0.2 to 0.5 was varied in order to examine the effect of chemical and topological ordering on the glass' thermal transport behavior. The fundamental thermal properties of glass transition temperature (Tg), thermal conductivity (k), and heat capacity (cp) were experimentally measured using differential scanning calorimetry, transient plane source method, and ultrasonic testing. Based on topological constraint theory, inflections in Tg and k were found at the structural coordination number of 2.4, whereas a slight increase in heat capacity (cp) with increasing was observed. A maximum in total thermal conductivity of 0.232 W/m.K was measured for the composition with x=0.4, which corresponds to the stoichiometric As2Se3. Gas kinetic theory was used to derive an expression for the photon (kp) portion of thermal conductivity, which was calculated by measurements of the glass' absorption coefficient (α) and refractive index (n). Models based on Debye theory were used to derive expressions for specific heat (cv) and the lattice (kl) portion of thermal conductivity. The maximum value for kp was 0.173 W/m.K for the composition with x=0.2, and a minimum value of 0.144W/m.K was measured for the composition with x=0.4. Photonic conduction was found to be the dominant carrier mechanisms in all compositions, comprising 60% to 95% of the measured total thermal conductivity. [ABSTRACT FROM AUTHOR]

• Measured through-thickness thermal conductivity of 2 × 2 twill carbon fabric using C-Therm Trident system with MTPS sensor. • Thermal conductivity is reduced by 38% under vacuum, attributed to presence of air in the porous structure of the fabric. • Layup thickness/configuration have negligible impact on thermal conductivity due to limited heat penetration. • Higher fabric compaction increases thermal conductivity owing to improved fibre nesting and contact. For high-fidelity simulation of heat transfer responses during various composite manufacturing processes involving heat, thermal conductivity (TC) of dry carbon weaves is essential. In this paper, the through-thickness TC properties of a 2 × 2 carbon twill weave are presented, employing a state-of-the-art C-Therm Trident module equipped with a Modified Transient Plane Source (MTPS) sensor. The effects of air presence, layup thickness, layup configuration, and fabric compaction on TC are investigated. Results reveal negligible impacts of layer number and configuration on TC. However, TC is significantly influenced by air presence and stack compaction. These findings provide improved comprehension of heat transfer in textile composites for more accurate process modelling and simulation using homogenized models. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) nanosheets, such as graphene and hexagonal boron nitride, are considered as the most promising fillers for enhancing thermal conductivity of polymers and phase-change materials. Nevertheless, the effect of various 2D nanosheets on the effective thermal conductivity of composites is not fully understood, and the corresponding prediction model is still lacking, since numerous influence factors and complex thermal transfer networks are involved. This paper aims to study the macroscopically effective thermal conductivity of the nanosheets-reinforced composites in a systematical way, and develop a robust machine learning based prediction model. To this end, a series of representative volume elements are reconstructed based on the SEM observations of experimental samples, and high-throughput simulations are performed via the updated lattice Boltzmann scheme proposed in our recent work. The effects of shape, size, orientation, intrinsic thermal conductivity, interface thermal resistance, surface coating, and hybrid filling of the 2D nanosheets are clarified. This work could provide a deep insight into the effective thermal conductivity of the nanosheets-reinforced composites, and may offer important guidelines for the custom-design of polymer and phase-change composites with targeted thermal performances. [Display omitted] [ABSTRACT FROM AUTHOR]

The prediction of the prevailing self-heat transfer parameters of a glass/epoxy composite coupon during fatigue testing in general and the distinction between viscoelastic- and frictional crack growth-related energy dissipation in particular, are not trivial problems. This work investigates the feasibility of predicting the convective film coefficient, the total work loss as well as the ratio between viscoelastic and fracture-induced damping from thermal images using Bayesian optimization in conjunction with 3D FE thermal analysis. To this end, glass fiber/epoxy biax coupons are pre-damaged by means of a drop weight impact machine and subsequently tested under uniaxial tension-tension high cycle fatigue conditions. IR images are taken of the self-heating thermal profile at steady-state conditions. Synthetic surface thermal images are generated by numerical thermal analysis of the damage distribution obtained by μ -CT scanning prior to testing. Bayesian optimization of the aforementioned parameters is conducted by minimizing the loss function between the as-measured and the synthetic IR image. The predicted work-loss is consequently validated against the measured hysteretic response, from which a very good agreement is found. [Display omitted] • Thermal heat transfer parameters are predicted via Bayesian optimization (BO). • FEM and BO are combined to find physically meaningful parameters. • The method efficiently handles 3D parameters compared to other approaches. [ABSTRACT FROM AUTHOR]

The electronics in logging tools are susceptible to thermal failure due to the extreme thermal environment. Passive thermal management system (PTMS) has been proven to protect the electronics for several hours. In this paper, a numerical model based on the equivalent thermal conductivity method was developed to determine the transient temperature of downhole electronics. Compared with the traditional analytical model or numerical model considering only one single heat transfer process, the complex heat transfer in the logging tool were comprehensively considered through the proposed model. Briefly, the heat transfer processes in the vacuum bottle were theoretically calculated rather than empirically acquired, and the convective and radiative heat transfer inside the vacuum bottle was equated to the temperature-dependent thermal conductivity of air. In addition, the proposed numerical model was compared with experiments and previous numerical models to verify the accuracy of the model, and the temperature deviation of the electronics was within 5 °C. Moreover, the computational time was greatly reduced compared with the traditional three-dimensional numerical simulation process while ensuring the accuracy of calculation. Therefore, the proposed numerical model achieved both computational accuracy and efficiency, which was expected to be widely used in the development of PTMS for logging tools. • A numerical model based on equivalent thermal conductivity method was proposed. • The complex heat transfer processes in PTMS were comprehensively considered. • The proposed model possessed high computational accuracy and efficiency. [ABSTRACT FROM AUTHOR]

Hole shrinkage is a common phenomenon in drilling difficult-to-cut materials like Ti6Al4V due to their poor thermal properties and high elasticity, which can lead to increase in tool wear and decrease in surface integrity. In this study, an in-depth analysis of hole shrinkage mechanism is carried out through a hybrid modelling approach for both dry and cryogenic cutting conditions. The plastic deformation induced by chip formation and tool-workpiece interaction is treated as equivalent thermomechanical loads, and heat convection conditions are described along tool path in order to perform details in heat transfer process for both cases. Quantitative analysis is presented through numerical simulation and experimental data of temperature and deformation along hole contour to analyze deformation components in order to reveal the hole shrinkage mechanism. Additional interactions between cutting tool and workpiece material are induced by recovery of elastoplastic deformation, and plastic portion is a more devastating factor in tool wear and surface damage induced by hole shrinkage. This study presents an in-depth and fundamental understanding of the hole shrinkage mechanism through a hybrid modelling approach, which can characterize heat transfer process during machining for both dry and cryogenic conditions, and simulation of this fully coupled thermomechanical cutting process with supply of coolants was rarely reported in previous research. The results show that plastic deformation induced hole shrinkage can enhance the interaction between workpiece material and cutting tool, and cryogenic assistance presents a good performance in restricting this kind of phenomenon. The related results could be used to optimize strategies of eliminating hole shrinkage with cryogenic assistance in industrial applications. [ABSTRACT FROM AUTHOR]

In this review work, the recent progress made in the use of nanofluids (NFs) applied in three specific areas will be presented: machining, solar energy, and biomedical engineering. Within this context, the discussions will be guided by emphasizing the thermal and stability properties of these fluids. In machining, NFs play a prominent role in the processes of turning, milling, drilling, and grinding, being responsible for their optimization as well as improving the useful life of the tools and reducing costs. In the solar energy field, NFs have been used in the thermal management of the panels, controlling and homogenizing the operating temperature of these systems. In the biomedical area, the advantages of using NFs come from the treatment of cancer cells, the development of vaccines before the improvement of diagnostic imaging, and many others. In all lines of research mentioned in this study, the main parameters that have limited or encouraged the use of these fluids are also identified and debated. Finally, the discussions presented in this review will inspire and guide researchers in developing new techniques to improve the applications of NFs in several fields. [ABSTRACT FROM AUTHOR]

In this work, composite samples were fabricated through melt blending with mesocarbon microbeads (MCMBs) and polyamide‐66 (PA66). Noteworthily, the thermal conductivity (TC) of the composites reached 1.51 W/m K with 60 wt% MCMBs, and the mechanical properties and heat resistance of PA66/MCMB composite were significantly improved. It was mainly due to the formation of heat transfer network at high filler content and their good dispersion in the matrix. The present work provided a new selection of thermally conductive fillers and expanded the application of MCMB in thermal management materials. [ABSTRACT FROM AUTHOR]

In this study, thermal insulation and solar properties of polyester woven fabrics which were coated with micronized perlite having three different particle sizes (10–38, 50–63, and 100–150 μm) at four different concentrations (20, 40, 60, and 80 g/kg) were investigated. The coating process was performed according to the knife‐over‐roll method. Thermal measurements were carried out with two different principles to evaluate contact and radiant heat transfer according to JIS R 2618 (testing method for thermal conductivity of insulating fire bricks by hot wire) and EN ISO 6942 (protective clothing‐protection against heat and fire‐method of test: evaluation of materials and material assemblies when exposed to a source of radiant heat), respectively. Perlite coating enhanced the thermal insulation property of fabrics. The lowest thermal conductivity coefficient and heat transmission factor (0.088 W/mK and 26.83%) values were obtained at the maximum concentration with the biggest size perlite. With the increasing perlite concentration, solar transmittance values decreased for all particle sizes while solar reflectance values increased. [ABSTRACT FROM AUTHOR]

Controlling thermal energy transfer at the nanoscale and thermal properties has become critically important in many applications since it often limits device performance. In this study, the effects on thermal conductivity arising from the nanoscale structure of free‐standing nanocrystalline silicon films and the increasing surface‐to‐volume ratio when fabricated into suspended optomechanical nanobeams are studied. Thermal transport and elucidate the relative impact of different grain size distributions and geometrical dimensions on thermal conductivity are characterized. A micro time‐domain thermoreflectance method to study free‐standing nanocrystalline silicon films and find a drastic reduction in the thermal conductivity, down to values below 10 W m–1 K–1 is used, with a stronger decrease for smaller grains. In optomechanical nanostructures, this effect is smaller than in membranes due to the competition of surface scattering in decreasing thermal conductivity. Finally, a novel versatile contactless characterization technique that can be adapted to any structure supporting a thermally shifted optical resonance is introduced. The thermal conductivity data agrees quantitatively with the thermoreflectance measurements. This study opens the way to a more generalized thermal characterization of optomechanical cavities and to create hot‐spots with engineered shapes at the desired position in the structures as a means to study thermal transport in coupled photon‐phonon structures. [ABSTRACT FROM AUTHOR]

The thermal properties of nanofluids are variable with working temperature and pressure and ignored by the existing empirical formula. In the present work, based on the application of nanofluids in pressurized water reactor (PWR) nuclear power plants, different concentrations of Al2O3/H2O nanofluids are prepared for measuring its thermal properties and then modifying empirical formulas at high temperature and high pressure (HTHP). In addition, the primary heat transfer process of PWR nuclear power plants is simulated by numerical method. The results show that, when volume fraction φ within 2.0%, the heat transfer performance of Al2O3 nanofluid increases with the increase of concentrations; however, it is on the contrary when the volume fraction of nanoparticles is larger than 2%. Comparing with water as the coolant, Al2O3 nanofluids with 2% volume fraction give the largest heat transfer enhancement of 103%. Therefore, Al2O3 nanofluids as the coolant can achieve the goals of heat transfer enhancement and safety limit improvement. [ABSTRACT FROM AUTHOR]

The present paper describes an approach for evaluating the thermal and mechanical behavior of a small satellite aluminum frame. The study takes into account two types of hinge configurations: a torsional and a lamellar spring joint. An equivalent heat flux is derived from the scientific literature. The temperature gradients are used as input in a structural analysis for evaluating the displacements and stress that occurs in the assembly joint locations. [ABSTRACT FROM AUTHOR]

Under the thermal action on wood when applying a protective screen made from fire-retardant fabric, the process of temperature transfer is natural. It has been proven that depending on the thermal properties of the coating of fire-proof fabric, this could lead to varying degrees of heat transfer. Therefore, it becomes necessary to study the conditions for establishing low thermal conductivity and establishing a mechanism that inhibits heat transfer to wood. Given this, a mathematical model has been built of the process of heat transfer to wood when it is protected by a screen made of fireproof fabric. According to the experimental data on determining the temperature on the non-heated surface of the fabric and the resulting dependences, the density of the heat flow transmitted to wood through fire-proof fabric was determined. Thus, with an increase in the temperature, the density of the heat flow to the surface of the wood through a protective screen made of fire-proof protected coating based on "Firewall-Attic" increases to a value above 16 kW/m², which is not sufficient for ignition of wood. Instead, the density of the heat flow through the protective screen of fire-proof fabric protected by the "Firewall-Wood"-based coating did not exceed 14 kW/m². This makes it possible to argue about the compliance of the detected mechanism of formation of heat-insulating properties in the protection of wood and the practical attractiveness of the proposed technological solutions. Thus, the peculiarities of inhibition of the process of heat transfer to wood through a protective screen made of fire-proof fabric under the action of a radiation panel imply the formation of a heat-insulating layer of coked cellular material when decomposing the coating. Thus, on the surface of the fire-proof fabric, a temperature above 280 °C was achieved and, on an untreated surface of the fabric, it did not exceed 220 °C, which is insufficient for the ignition of wood [ABSTRACT FROM AUTHOR]

Ho 2 O 3 was employed to improve the microstructural densification and performances of pressureless sintered corundum–mullite ceramic composites. This study investigated the influences of Ho 2 O 3 addition on the microstructure, physical properties and thermal shock resistances of the composites. The results indicated that sample AH5 (80 wt% Al 2 O 3 , 20 wt% coal series kaolin, and 5 wt% additional Ho 2 O 3), which was sintered at 1550 °C, showed the best comprehensive properties. In this Al 2 O 3 -rich and SiO 2 -poor system, a reaction between the Ho 2 O 3 and Al 2 O 3 –SiO 2 system produced an Ho 2 O 3 –Al 2 O 3 –SiO 2 liquid phase. This liquid phase increased the microstructural densification and resulted in a lower sintering temperature. The generation of mullite and holmium disilicate during thermal shocks improved the thermal shock resistance. The high bending strength and satisfactory thermal shock resistance of the as-prepared corundum–mullite ceramic composites showed their potential for use in heat transmission pipelines. [ABSTRACT FROM AUTHOR]

The impetus of the this study is to investigate flow and thermal field in rarefied gas flows inside a trapezoidal micro/nano-cavity using the direct simulation Monte Carlo (DSMC) technique. The investigation covers the hydrodynamic properties and thermal behavior of the flow. The selected Knudsen numbers for this study are arranged in the slip and transition regimes. The results show the center of the vortex location moves by variation in the Knudsen numbers. Also, as the Knudsen number increases, the non-dimensional shear stress increases, but the distribution deviates from a symmetrical profile. The cold to hot transfer, which is in contrast with the conventional Fourier law, is observed. We show that the heat transfer is affected by the second derivative of the velocity. By increasing the Knudsen number, the transferred heat through the walls decreases, but the contraction/expansion effects on the temperature in the corner of the cavity become higher. [ABSTRACT FROM AUTHOR]

Back in 2008, Panofsky gave an empirical formula, T = 1 1.5 W 2 / 3 , for turkey baking time, T, in hours vs turkey weight, W, in pounds, the so-called Panofsky formula or Panofsky constant. Compared to the previously existed recipes that are based on the simple linear relationship between turkey weight and baking time, the Panofsky formula provides a more accurate estimate for the baking time. For instance, a general guideline of 13–20 min/lb was widely recommended in all previous turkey baking recipes. In this work, we conduct a comprehensive study of the turkey baking process that leads to a mathematical derivation of the Panofsky formula under some approximations. We also generalize the Panofsky formula to define a general Panofsky formula, T = 1 P W 2 / 3 , where P is defined as the Panofsky constant. Under spherical approximations, we then apply an accurate physical solution of the heat transfer equation and use the rigorous solution with numerical methods to study the generalized Panofsky formula and the Panofsky constant. We found that the generalized Panofsky formula can be perfectly applied to all turkey baking scenarios for baking time calculations. Furthermore, we did a careful analysis of the Panofsky constant, which equals 1.5 in the original Panofsky formula. The dependency of the new Panofsky constant on thermal properties of the turkeys and other initial parameters of baking, e.g., initial and final center temperature of the turkeys, oven temperature, thermal conductivity, specific heat, and turkey's density, was carefully analyzed and mapped out. The Panofsky constant, P, could vary from 1.1 to 1.9 depending on these thermal parameters. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate a novel exploitation approach for a mass livestock byproduct, namely sheep wool fibres. In order to fulfil this aim, wool fibre toughened epoxy composites with an amount of 2.4, 4.1 and 5.7 phr were prepared via the hot press method. Initially, mechanical assessment of the composites was executed, in order to evaluate their mechanical integrity. The flexural and shear strength tests showed that the wool fibre-epoxy composites maintain their mechanical properties for up to 4.1 phr and no degradation is detected. Subsequently, the thermal properties were tested. Thermogravimetric analysis proved that adding wool fibres as toughening agent in epoxy matrix can prolong the endurance of the material while reaching high temperatures. The coefficient of thermal conductivity decreased by 30% compared to neat epoxy, something that is also confirmed through simulation, proving that wool fibre-epoxy composites can be considered as a promising insulating material, while exploiting a natural waste. [ABSTRACT FROM AUTHOR]

Purpose: To have a better understanding of the heat transfer mechanisms in a sleeping bag and to investigate the factors influencing thermal resistance of a down sleeping bag. Design/methodology/approach: The mechanism of heat transfer in a sleeping bag was discussed in this paper. The thermal resistances of 24 samples were investigated. Besides, the relation between fill weight and thermal resistance, and that between the air permeability of fabric and thermal resistance, as well as that between down filling rate and thermal resistance were analyzed. Findings: The results showed that thermal resistances of samples varied from 0.35 to 0.8 m2 K/W. The fill weight was the most important factor of thermal resistance of sleeping bag and the relation between fill weight and thermal resistance matched well with cubic function. A multiple regression formula was proposed, which with thermal resistance as a dependent variable and with air permeability of fabric, down filling rate, fill weight as independent variables. Originality/value: Thermal properties of a sleeping bag were analyzed through simplified basic unit under simplified environment conditions, which was necessary for building the first stage of systematic study of thermal performance of a sleeping bag. [ABSTRACT FROM AUTHOR]

Knowledge about the thermal properties of human teeth is imperative for accurate understanding of heat transfer in dentistry. Despite the presence of specific heat in thermal conduction and heat transfer equations, and requiring this parameter for calculation of conductivity based on diffusivity, adequate attention has not been paid to experimental assessment of specific heat of the human enamel and dentin. Specific heat can be a temperature-dependent property. Thus, this study aimed to assess the specific heat of the human enamel, sound dentin, and carious dentin at 20 °C to 70 °C temperature (which is the realizable temperature range in dental procedures) using the differential scanning calorimetry (DSC). The results showed that the specific heat of the enamel, sound dentin and carious dentin increased with temperature rise. The specific heat of the enamel, sound dentin and carious dentin at 20 °C to 70 °C ranged from 709 J·kg−1·K−1 to 921 J·kg−1·K−1, 880 J·kg−1·K−1 to 1139 J·kg−1·K−1 and 951 J·kg−1·K−1 to 1311 J·kg−1·K−1, respectively. [ABSTRACT FROM AUTHOR]

A 12.3 inch FHD flexible AMOLED display module for vehicle application was produced and the heat dissipation was studied. Passive thermal management technology was investigated and a simplified steady heat transfer model was established to analysis the thermal properties of the vehicle AMOLED display module. The simulation results were good consistent with the measured data. By optimizing the structure and materials of heat dissipation, the surface temperature of the AMOLED display module with the luminance of 800 cd/m2 at full white pattern can be decreased to 42.5 °C which was 4.1 °C lower than that of without any dissipation films. [ABSTRACT FROM AUTHOR]

The present analysis describes the effect of dissipative heat energy transfer in Ethylene–Glycol (EG) based on conducting nanofluid over a heated semi-infinite vertical plate past through a porous medium. Uniform magnetic field, heat source/sink, and the effect of particle concentration also have been discussed by incorporating in the energy and solutal transfer equations, respectively. In addition to that, the thermal properties of the nanofluid are affected by the thermal slip boundary condition since; the temperature slip is favorable for the reduction in the heat transfer. Assuming self-similar transformations, the governing PDEs are transformed into non-linear coupled ODEs. These transformed equations are solved by using semi-analytical techniques such as Adomian Decomposition Method (ADM). The characteristics of different parameters on the flow phenomena are obtained and presented via graphs. The numerical values of the thermophysical properties of both the nanoparticles and the base fluid are shown in the table. Validation of the present work is obtained by comparing our result with the earlier established result and it is found that both the results are coinciding with each other. However, the main quantified results are the following: due to heavy density of the Cu nanoparticles, increasing volume fraction in ethylene–glycol base fluid resists the fluid motion and the inclusion of dissipative heat energy is favorable to enhance the nanofluid temperature. [ABSTRACT FROM AUTHOR]

Thermal properties are critical parameters to design and implement efficient thermal processes especially for food manufacturing. Current methods to measure temperature-dependent thermal properties are expensive, time consuming and labor intensive with certain methods requiring composition analysis of food. To solve those problems, a novel method and equipment, named TPCell, was developed to estimate temperature-dependent thermal conductivity in a single experiment. For simultaneous estimation of temperature-dependent thermal conductivity and volumetric heat capacity, a new generation of TPCell was designed with complementary experimental profile and parameters were estimated by analyzing the parameter sensitivity coefficients. For different heating profile, the scaled sensitivity coefficients (SSC) of multiple parameters and optimal values were compared to determine the number of parameters that can be estimated. The thermal properties of sweet potato puree were estimated using sequential parameter estimation. The temperature-dependent thermal conductivity was found as 0.516 ± 0.011 W/mK at 26 °C and 0.798 ± 0.030 W/mK at 135 °C. Also, the volumetric heat capacity in the same temperature range was 3.520 × 106 ± 0.124 × 106 J/m3K. Therefore, the complementary experiment was successful in simultaneous estimation of temperature-dependent thermal conductivity and volumetric heat capacity. [ABSTRACT FROM AUTHOR]

Featured Application: Microencapsulation of alkali metal nitrates for latent heat storage in concentrated solar power plants has the potential to reduce salt corrosion in storage tanks and installations. Microencapsulation of sodium nitrate (NaNO3) as phase change material for high temperature thermal energy storage aims to reduce costs related to metal corrosion in storage tanks. The goal of this work was to test in a prototype thermal energy storage tank (16.7 L internal volume) the thermal properties of NaNO3 microencapsulated in zinc oxide shells, and estimate the potential of NaNO3–ZnO microcapsules for thermal storage applications. A fast and scalable microencapsulation procedure was developed, a flow calorimetry method was adapted, and a template document created to perform tank thermal transfer simulation by the finite element method (FEM) was set in Microsoft Excel. Differential scanning calorimetry (DSC) and transient plane source (TPS) methods were used to measure, in small samples, the temperature dependency of melting/solidification heat, specific heat, and thermal conductivity of the NaNO3–ZnO microcapsules. Scanning electron microscopy (SEM) and chemical analysis demonstrated the stability of microcapsules over multiple tank charge–discharge cycles. The energy stored as latent heat is available for a temperature interval from 303 to 285 °C, corresponding to onset–offset for NaNO3 solidification. Charge–self-discharge experiments on the pilot tank showed that the amount of thermal energy stored in this interval largely corresponds to the NaNO3 content of the microcapsules; the high temperature energy density of microcapsules is estimated in the range from 145 to 179 MJ/m3. Comparison between real tank experiments and FEM simulations demonstrated that DSC and TPS laboratory measurements on microcapsule thermal properties may reliably be used to design applications for thermal energy storage. [ABSTRACT FROM AUTHOR]

Gas‐assisted injection molding is a polymer processing technology in which a penetrating gas bubble hollows out a plastic part as it cools and solidifies within a mold. In this study, non‐isothermal gas injection experiments at high capillary number illustrate the effects of delay time in gas injection, tube diameter, capillary number, and temperature‐sensitive fluid viscosity and flow activation energy on coating thickness. Experiments with polybutene H‐300 and Dow Corning silicon oil (DC‐200) in stainless steel tubing (1.27 and 0.635 cm) demonstrated fractional coverage increasing from 0.6 to a maximum in the range of 0.63–0.83 at short delay times, then decaying toward 0.6 at long delay times upon approaching the cooled isothermal state. Further analysis is drawn from simulations based on a simple theoretical model incorporating one‐dimensional heat transfer with convection at the outer surface of the mold, non‐isothermal behavior of the viscous fluid, and radial velocity profiles in the one‐phase fluid flow region. Quantitative agreement is found between experimental and simulated results. Two‐dimensional modeling and simulation methods extend the prior results to illustrate transient axial and radial heat transfer as well as flow behavior with respect to the penetrating gas bubble within the fluid flow region. [ABSTRACT FROM AUTHOR]

Natural Circulation Loop (NCL) which is also called as a thermosyphon system is the heat transfer loop which uses no pump or external device to drive the loop fluid. In the present paper, a comparative study on thermal characteristics of two loop fluids viz. water and Al2O3/water nanofluid is made. Experiments are conducted on in-house designed test rig. Thermo-hydraulic behaviour of loop fluid is presented. Two parameters such as heat input, nanofluid concentration are varied in order to study their individual and combined effects. It is concluded that Al2O3/water nanofluid as loop fluid results in higher mass flow rates as compared to the water. Different derived quantities such as Nusselt number and Grashof number are calculated. Quantitative comparison is made between water and Al2O3/water nanofluid. Time to reach steady state is reduced by 22 % using Al2O3/water nanofluid as loop fluid when compared with water. Mass flow rate and Grashof number of the Al2O3/water nanofluid based NCL are enhanced by 6.75% and 26% respectively, when compared with water-based NCL at 1000W heat input. At the heater, the temperature gradient is reduced by 30.2% due to the improved thermal and transport properties of Al2O3/water nanofluid when compared with water at 1000 W heat input. As particle concentration increases from 1% to 5%, Nusselt number increases from 10.1 to 20.1, for the heat input of 1000W. [ABSTRACT FROM AUTHOR]

Rare-earth barium copper oxide (REBCO) tape is used for resistive type superconducting fault current limiters (RSFCLs) owing to its quick response and simple structure. To shorten the recovery time, film boiling on the REBCO tape should be suppressed as it exhibits poor heat transfer performance. To address the aforementioned issue, this study utilized low thermal conductivity materials as the thermal/electrical interface material for porous-stabilized REBCO tape. The experimental results showed that the cooling and recovery performances were dramatically improved by utilizing an insulating epoxy, which has a thermal conductivity of 0.6 W/mK. Based on the visualization of the boiling behavior, the liquid-solid contact between liquid nitrogen and the REBCO tape was promoted by the insulating epoxy, in which the film boiling was easily broken. [ABSTRACT FROM AUTHOR]

Improved heat transfer efficiency with considering economic analysis in heating systems is an interesting topic for researchers and scientists in recent years. This research investigates the heat transfer rate (HTR) and flow of non-Newtonian water-Carboxyl methyl cellulose (CMC) based Al2O3 nanofluid in a helical heat exchanger equipped with common and novel turbulators using two-phase model. The requirements for dimensions and cost reduction and also energy saving in thermal systems are the main goal of this study. According to gained results usage of corrugated channel in helical heat exchanger has a considerable influence on thermal and hydraulic performance evaluation criteria (THPEC) index of helical heat exchanger and can improve the THPEC index. Thus, Re = 5000 is obtained as an optimum value, in which the maximum THPEC value is achieved. As it is found in this paper, in case of using novel heat exchanger instead of the basic smooth system, the thermal properties (by considering Nusselt number) increases about 210%, the hydraulic performance (friction factor) reduces about 28%, performance evaluation criteria index increases about 57% and the material consumption (in case of similar THPEC) decreases about 31%. In another word, with considering economic analysis for the basic and novel system which has same efficiencies, the novel one has lower length and consequently 31% lower material. [ABSTRACT FROM AUTHOR]

In the production of functional nonwovens with sustainable fibers, kapok, with unique qualities, becomes an excellent candidate for the production of thermal insulation textiles. However, the development of 100% raw kapok fiber structures is a challenge, since their mechanical resistance and interfiber cohesion is very low. In this work, the thermal behavior of new needle punched bi-layered nonwovens produced from 100% raw kapok fibers is studied. These innovative structures were obtained through dry heat-pressing of needle punched nonwovens, developed according to a novel method designed. The results obtained have shown that the heat-pressing conditions (temperature and number of cycles) affected the thermal properties of the nonwovens and the thermal performance profile of an insulating arrangement. The bi-layered nonwoven structures reinforced in one heat-pressing cycle at 100 °C showed the higher thermal resistance and the lower thermal conductivity and heat flux and led to the highest delay (decrement delay) of the heat transfer from the outside to the inside of the insulating assembly and vice-versa, acting as an effective thermal insulator. [ABSTRACT FROM AUTHOR]

The thermal distribution of granular media for heat assisted magnetic recording has been explored by the heat Fourier equation; particularly, the effect of the thermal conductivities in the grain boundary has been extensively investigated. When the thermal conductivity is sufficiently small, the grain boundary provides a natural constraint to heat dissipation: the effective in-plane thermal conductivity can be ten times smaller than that of FePt with the decrease limited only by the heat dissipation through the interlayer MgO. For low thermal conductivities in the grain boundary, the out of plane thermal gradient increases sharply owing to the inability of the heat to spread. Therefore, a compromise between power consumption and uniformity of the temperature distribution within grains should be taken into account when optimizing the media design. [ABSTRACT FROM AUTHOR]

With molecular dynamics simulations, we systematically investigate interfacial thermal resistance between suspended and encased single layer graphene. Combining with lattice dynamics analysis, we demonstrate that induced by substrate coupling which serves as perturbation, the long wavelength flexural phonon mode in the encased graphene is significantly suppressed when compared with that in the suspended graphene. Therefore, at the interface between suspended and encased graphene, in-plane phonon modes can transmit well, whereas low frequency flexural phonon modes are reflected, leading to this nontrivial interfacial thermal resistance. The impacts of coupling strength, temperature, and size of the system on this type of interfacial thermal resistance are explored. More interesting, we find that thermal rectification can be realized in this inhomogeneous encased graphene structures with a thermal rectification efficiency of 40% at 50K temperature difference. Our study provides insight to better understand thermal transport in two-dimensional materials and promising structures for practical thermal rectification devices. [ABSTRACT FROM AUTHOR]

Optimum ultrasonication time will lead to the better performance for heat transfer in addition to preparation methods and thermal properties of the nanofluids. Nano particles are dispersed in base fluids like water (water-based fluids), glycols (glycol base fluids) &oils at different mass or volume fraction by using different preparation techniques. Significant preparation technique can enhance the stability, effects various parameters & thermo-physical properties of fluids. Agglomeration of the dispersed nano particles will lead to declined thermal performance, thermal conductivity, and viscosity. For better dispersion and breaking down the clusters, Ultrasonication method is the highly influential approach. Sonication hour is unique for different nano fluids depending on their response to several considerations. In this review, systematic investigations showing effect on various physical and thermal properties based on ultrasonication/ sonication time are illustrated. In this analysis it is found that increased power or time of ideal sonication increases the dispersion, leading to higher stable fluids, decreased particle size, higher thermal conductivity, and lower viscosity values. Employing the ultrasonic probe is substantially more effective than ultrasonic bath devices. Low ultrasonication power and time provides best outcome. Various sonication time periods by various research are summarized with respect to the different thermophysical properties. This is first review explaining sonication period influence on thermophysical properties of graphene nanofluids.

For suitable design of equipment and process optimization, the determination of thermophysical properties of the raw materials is necessary. Therefore, this work was aimed at determining and modeling the density, specific heat, thermal diffusivity, and thermal conductivity of acid slurries of cassava bagasse used during its conversion into bioethanol. Experimental measurements were carried out in slurries with different mass fractions of cassava bagasse (0.00 to 0.10) and phosphoric acid (0.00 to 0.10) at temperatures from 278.13 to 318.13 K. Results obtained show that density varied from 986.5 to 1,029.3 kg∙m−3, specific heat from 3,830.0 to 4,142.6 J∙kg−1∙K−1, thermal diffusivity from 0.9624 × 10−7 to 1.5249 × 10−7 m2∙s−1 and thermal conductivity from 0.3825 to 0.6212 W∙m−1∙K−1. While density increased with increasing solids and acid content at decreasing temperature, the thermal properties decreased at higher solids and acid content and increased when heating the slurries. The values were well‐fitted to polynomial models with good accuracy (R2 > 0.921 and MRE < 1.75%), allowing the application of the models to obtain reliable and ready‐to‐use data for cassava bagasse processing. Thus, the data reported in this study can be used for designing and managing momentum, heat and mass transfer processes for enhancing bioethanol production from cassava bagasse. [ABSTRACT FROM AUTHOR]

The anisotropic heat transfer properties of two-dimensional materials play an important role in controlled heat transfer and intelligent heat management. At present, there are many references on anisotropic heat transfer of two-dimensional materials, but less systematic review of their development status, problems, and future directions. In this paper, intrinsic anisotropic heat transfer of two-dimensional materials, influencing factors and control means are introduced. The preparation methods of thin film with two-dimensional material and the influence factors of macroscopic anisotropic thermal properties are summarized. The technology of two-dimensional material oriented arrangement in matrix and the influence factors of macroscopic anisotropic thermal properties of the composite are outlined. [ABSTRACT FROM AUTHOR]

In present work, semiconducting iron (III) oxide (Fe2O3) nanoparticles have been synthesized by sol–gel method. X-ray diffraction (XRD), UV–Visible (UV–Vis) absorption spectroscopy and transmission electron microscopy (TEM) have been used for the characterization of the synthesized nanoparticles. Two-step technique was used to formulate stable ethylene glycol (EG) based Fe2O3 nanofluids at room temperature. Thermal conductivity of nanofluids has been measured using hot disc thermal constants analyzer. Significant enhancement in the thermal conductivity is noted at very low nanoparticle loading (up to 1 wt%). Ultrasonic velocity and ultrasonic attenuation in the prepared nanofluids were investigated using an ultrasonic interferometer and acoustic particle sizer (APS-100), respectively. APS-100 was also used for the analysis of particle size distribution (PSD) of Fe2O3 nanoparticles in the prepared nanofluids. The PSD result of APS-100 has been found in good agreement with that of TEM. The characteristics behaviour of Fe2O3 nanofluid has been illustrated based on its ultrasonic and thermal properties. Our investigations advocate that Fe2O3 nanofluids have potential application for effective heat transfer management in various cooling industries. [ABSTRACT FROM AUTHOR]

Considering that SF6 is a potent greenhouse gas, SF6/N2 gas mixtures are preferred to serve as the insulating gas for its environmental friendliness and good insulation. Since heat transfer analysis is very useful for ascertaining the appropriate temperature rise range, which can ensure the safe operation and extension of remaining useful life of GIL, it is essential to study the thermal properties of SF6/N2 gas mixtures. Nevertheless, very few studies investigate on the temperature field of SF6/N2 gas mixtures under ideal conditions. To reflect the heat transfer characteristics accurately, in this paper, by using the finite-element method and multi-physics coupling, the heat transfer properties in the GIL is analyzed by using a three-dimensional (3-D) axisymmetric GIL model. By varying the SF6/N2 mixing ratio and observing the corresponding heat transfer characteristics, the mapping between SF6/N2 mixing ratio and the temperature rise is obtained by using the model. Furthermore, the mappings are studied under different gas pressures, line currents and ambient temperatures, which correspond to different real-life operating conditions. The proposed strategies can effectively give guidance of choosing proper SF6/N2 mixing ratio for desired temperature rise, and thus having great values of practical applications. [ABSTRACT FROM AUTHOR]

Establishing and optimizing a distributed parameter thermal path model for transformer windings is an important means to analyze the hot-spot temperature of the windings; furthermore, in the process of improving the thermal path model of transformers and improving the accuracy of their models, the thermal characteristics of the insulation paper are extremely important. A microscopic thermal contact resistance model was established for the contact interface of insulation paper and copper, according to the microscopic morphology parameters of copper and insulation paper observed by atomic force microscopy, the thermal contact resistance under different temperatures was calculated. A dual heat flow test platform was built to test the heat transfer behavior of four different thickness insulation papers under four temperatures, and the thermal contact resistance and thermal bulk resistance with temperature were analyzed. The results show that as the temperature increases, the thermal resistance of the insulation paper becomes larger and the thermal conductivity decreases. The average error between the experimental and theoretical values of the thermal contact resistance under four temperature points in the study is 6.6%. The results provide a data support for establishing and optimizing transformer heat generation and heat transfer models. [ABSTRACT FROM AUTHOR]

This paper models the thermal transport properties and performance of a water-based CuO nanofluid (with varying volume fractions of CuO) in a laboratory-sized double pipe heat exchanger (DPHE). Copper oxide (CuO) nanoparticles were used and their quantity was varied from a volume fraction of 0% to 0.1% with an incremental step size of 0.025%. The mass flow rates of the hot and cold fluids were maintained at 0.87 kg/s and 0.9 kg/s, respectively. Simulation results revealed that temperatures of 410 and 306.75 K, respectively, were attained at the hot and cold fluid outlets. Analysis of the DPHE showed that for cold fluids, thermophysical properties such as viscosity, thermal conductivity, specific heat capacity (SHC) and density were enhanced by the addition of nanoparticles. The temperature distribution, effectiveness and the heat transfer in the DPHE were observed to linearly increase with increment increases of the nanoparticle volume fraction. [ABSTRACT FROM AUTHOR]