Heat Transfer Rate Research Articles

Integration of artificial intelligence (AI) to predict the behavior of milk enhanced with silver and zinc oxide nanoparticles when subjected to rapid heating in a movable electromagnetic channel

The implementation of artificial intelligence (AI) to predict and control the behavior of milk enhanced with silver and zinc oxide nanoparticles during electromagnetic heating enhances the precision and energy efficiency of pasteurization and sterilization processes. This approach ensures precise temperature management, reducing the risk of overheating and maintaining the milk’s nutritional and sensory integrity. The research examines milk flow dynamics (Ag-ZnO/milk) in a suddenly heated movable electromagnetic channel under sudden pressure variations. It incorporates significant physical phenomena such as radiant heat emission and Darcy drag forces, with Darcy’s model addressing drag within the porous medium. The dynamics of milk flow are thoroughly defined mathematically and physically, with solutions succinctly derived using the Laplace transform (LT) method. The findings, including analyses of shear stress (SS) and rate of heat transfer (RHT), are presented tabularly and graphically. The study indicates an annex in milk momentum with higher modified Hartmann numbers and an enfeeblement with wider electrode widths. Both hybrid nano-milk (HNM) and nano-milk (NM) exhibit thermal degradation, where rising Casson parameters amplify SS, whereas elevated radiation parameters lead to a reduction in RHT. Additionally, the AI-driven artificial neural network (ANN) model demonstrates remarkable predictive precision, achieving 95.175% accuracy during testing and 99.64% during cross-validation for SS predictions, while attaining a perfect 100% accuracy for RHT predictions across both testing and cross-validation phases. This model could lead to the development of advanced pasteurization equipment that utilizes electromagnetic technology for more consistent heating and better preservation of milk’s nutritional and sensory qualities.

Thermal analysis on the impact of different velocity calculation methods for microchannel liquid cooling system in GPUs

Abstract Recently, computational tasks are carried out by GPUs which consists of hundreds of cores that compute at higher speeds to provide systematic results. The computational power of GPUs suffers significant disadvantage in the form of heat emission. Traditional liquid cooling methods circulate the working fluid at constant velocity irrespective of the temperature raised. To mitigate the effects of improper cooling, the research focuses on analysing liquid cooling system for GPUs where Ethylene Glycol 40 was circulated through 20 microchannels at different velocities and thermal behaviour was analysed using a CFD analysis software. The paper aims to provide a clarity on the methods to calculate velocity for simulation approach. The velocity was calculated using two distinct approaches, the first approach uses the mass flow rate equation and second approach uses Reynolds number equation considering laminar flow. On assuming three different values for mass flow rate and Reynolds number, the velocity of the fluid is calculated. For Mass Flow rate of 0.1 g/s, 0.2 g/s and 0.3 g/s, the obtained velocities were 0.01886 m/s, 0.03773 m/s and 0.05659 m/s respectively. For Reynolds number of 10, 20 and 30, the obtained velocities were 0.04 m/s, 0.09 m/s and 0.1422 m/s respectively. The analysis proved that at lower velocities, the working fluid was not effective in carrying the heat but at higher velocities the temperature reduction was higher; displaying the ability of the coolant to absorb heat depending on the velocity. With the temperature data from the simulation, the heat transfer rates were calculated as 10352.4049 J, 7948.3535 J, 7711.2185 J, 6719.9088 J, 5318.3105 J, 3976.2213 J for 0.01886 m/s, 0.03773 m/s, 0.04 m/s, 0.05659 m/s, 0.09 m/s and 0.1422 m/s respectively. The analysis concludes that by changing the velocity of the working fluid, the thermal management system can work effectively under different scenarios.

Advances in Radiative Heat Transfer: Bridging Far‐Field Fundamentals and Emerging Near‐Field Innovations

AbstractRadiative heat transfer plays a pivotal role in many applications across various length scales, with its behavior significantly altering as systems change from the far‐field to the near‐field regime. In the far‐field, radiative heat transfer is governed by traditional laws such as Planck's and Stefan–Boltzmann's laws, which assume that the gap between objects involved in radiative exchange is larger than the thermal wavelength (λth), limiting the energy transfer to propagating electromagnetic waves. However, in the near‐field, where distances are smaller than the λth, evanescent wave coupling enables heat transfer rates that exceed the blackbody limit by several orders of magnitude. This near‐field enhancement opens new avenues for nanoscale thermal management, energy harvesting, and radiative cooling applications. This review synthesizes the key developments in radiative heat transfer theories, experimental advancements, and practical applications, spanning from early traditional studies to modern innovations leveraging fluctuational electrodynamics. Material‐specific mechanisms, such as surface phonon polaritons, and their role in enhancing radiative heat transfer are also explored while integrating machine learning techniques to optimize near‐field systems. By highlighting these mechanisms and exploring emerging research directions, this work aims to inspire new researchers to enter this dynamic field and provide a roadmap for advancing next‐generation technologies in energy efficiency and nanoscale thermal management.

Performance of the SRI radial design evaporator in the final-effect position at Victoria Mill

Victoria Mill installed a 4000 m2 SRI-designed Robert evaporator in the final-effect position for the 2021 season. This evaporator is the first installation of this design in the final effect of the set. The design differs from the conventional Robert evaporators in the industry as it provides a radial flow of both vapour and juice and has a large central downtake for the outflow of juice/syrup. Previous installations of the design have been in the early evaporation stages, and these have provided improved separation of the inlet and outlet juice and increased heat-transfer efficiency. Evaluation trials demonstrated favourable heat-transfer performance, with the temperature difference across the evaporator being 3 to 4 °C lower than that typically required by the conventional Robert evaporators for the same heat-transfer rate. Modelling has shown that a conventional Robert evaporator would require one of the following changes to maintain the same crushing rate: (1) a 7% increase in installed heating surface area for the set; (2) an increase in exhaust pressure of 13 to 15 kPa and an increase in the process steam on cane by 0.6%; or (3) a reduction in added water to the milling train and the mud filters of 19%. Increased sugar losses in bagasse and mud cake would reduce sugar yield from the cane supply for the factory. The test program has determined that minor modifications to the juice outlet arrangements should be incorporated in future installations of the design.

Optimising heat transfer efficiency in unsteady Maxwell hybrid nanofluid flow for solar energy

ABSTRACT In solar thermal applications, hybrid nanofluids revolutionise heat transfer by pushing the boundaries of sustainable energy innovation. Incorporating unsteady parameters enhances the understanding of dynamic thermal processes. The novelty of the current investigation is to scrutinise the impact of unsteady flow dynamics on radiative Maxwell hybrid nanofluid flow (Fe3O4-Graphene/Ethylene Glycol) across an inclined surface at a slope pi/4. Relationship between physical parameters and heat transmission are assessed by Pearson correlation coefficients. The similarity transformation technique lowers the governing nonlinear equation's order, and the ODE Analyzer is subsequently employed to solve the problem numerically. Flow patterns for stable and unsteady cases are evaluated using streamlines to strengthen the novelty of the current work. In the case of suction, the unsteady parameter heat transfer rate for hybrid nanofluid is 18.78%, while 28.48% for injection. This study paves the way for sustainable energy through advancements in hybrid solar technology.

Performance Optimization of Double U‐Tube Borehole Heat Exchanger for Thermal Energy Storage

ABSTRACTThis paper presents an optimization study of the thermal performance of a double U‐tube borehole heat exchanger (BHE) with two independent circuits that can be used in borehole thermal energy storage. The study applies the Taguchi method and utility concept to obtain the optimum parameters for two objective functions: maximum heat transfer rate and thermal effectiveness of the BHE. A validated numerical heat transfer model with a fully implicit method is applied to compute the transient heat transfer in the BHE. The Taguchi optimization results revealed that the optimal factors (denoted with letters and numbers showing their levels) for achieving the maximum heat transfer rate and thermal effectiveness are A1B3C2D1E3F3G3H3 and A3B3C2D3E3F3G1H1, respectively. This resulted in an optimal heat transfer rate of 120 W/m and a thermal effectiveness of 69.3%. Using the utility concept method, a single set of optimal parameters (denoted by their levels as A3B3C3D2E3F3G2H3) is obtained to maximize the performance of the BHE. These parameters yielded an optimum heat transfer rate of 87.3 W/m and thermal effectiveness of 54.6%. Finally, analysis of variance (ANOVA) showed that ground thermal conductivity, the inlet temperature of the working fluid, and borehole depth are the most influential parameters affecting the performance of the BHE. The study provides crucial information for performance improvement, enhanced energy savings, reduced environmental impact, and optimization of a hybrid ground source heat pump system that can be integrated with borehole thermal energy storage.

Enhancement of Heat Transfer in Double‐Pipe Heat Exchangers Using Wavy Edge Twisted Tape With Varying Twist Ratios and Perforated Diameters

ABSTRACTA computational simulation of an enhanced double‐pipe heat exchanger equipped with inserted twisted tape. The Navier–Stokes, energy, and turbulence equations were employed to represent fluid flow and heat transmission, utilizing a k–ε model for turbulence. ANSYS Fluent 22 is used to solve the governing equations and investigate how the perforated wavy edge tape, along with the diameter of its holes (5, 15, and 30 mm), twisting ratio of a wavy edge twisted tape ratio (0.5, 1, 1.5, 2, 2.5, and 3), affects heat transfer and pressure drop at ranging Reynolds numbers (6957–187,837), compared to a plain tube. Hot air is utilized in the inner tube, which incorporates twisted tapes to enhance turbulence and heat transfer and cold oil in the outer tube to establish a counter‐flow system and experience the improved flow's effects. Results demonstrate significant improvements in oil outlet temperature. The Nusselt number (Nu) increases with increasing Reynolds numbers and twist ratios; the enhanced tubes increase Nu and friction factor by about 41% and 2.6 times greater than the smooth tube. Increasing the Reynolds number and twisted tape ratio generally leads to higher heat transfer rates and pressure drop. Optimal configurations of PWETT with Tr = 2 and WET with a hole diameter of 30 mm gave the best thermal performance index (1.11 and 1.24) when balancing heat transfer and pressure drop. The findings provide valuable insights for designing and optimizing heat exchangers in applications demanding efficient heat transfer.

Surface Wettability Effects on Droplet Dynamics and Heat Transfer on Heated Stainless-Steel Foils

Abstract We report the dynamics and heat transfer characteristics of water droplets impacting a thin stainless-steel foil maintained at different temperatures. The hydrophobic characteristics are imparted to the surface through polysiloxane coating, and water droplets impact the uncoated and coated heated surfaces at different velocities. High-speed videography is utilized to capture the dynamics of the droplet upon impact, while the temperature field of the substrate, during the phenomenon, is simultaneously recorded using high-speed infrared thermography. Heat transfer to the droplet over different surfaces is determined through energy balance on the foil using the captured thermographs. The results reveal that the spreading phase duration is independent of droplet impact velocity, irrespective of surface wettability, whereas surface wettability primarily affects the receding phase. The coated hydrophobic surfaces exhibited lower resistance to motion at the three-phase contact line, resulting in reduced spread ratios during the receding phase. It is noted that the majority of heat transfer occurred during the initial spreading and receding phases, driven primarily by forced convection. The maximum heat fluxes were observed along the three-phase contact line, particularly at the onset of the receding phase. The coated surface demonstrated lower overall heat transfer rates compared to non-coated surfaces, with the difference increasing at higher surface temperatures. Additionally, an increase in surface temperature to 75 °C enhanced the hydrophobicity of the coated surface, leading to prolonged receding phases and extended time to reach the sessile state.

Utilisation of steel slag aggregates to propose novel asphalt pavement structures alleviating urban heat islands

Asphalt pavements release their absorbed heat, exacerbating an urban issue called urban heat island (UHI). In this study, the base course and the interface of the asphalt mixture and the base course were modified with steel slag aggregates (33, 66, and 100%) and a conductive prime coat (40% steel slag powder) to mitigate this issue. The heat transfer rates of developed specimens were then investigated using a solar simulation setup. The thermal properties of these specimens were also measured using a C-Therm device, developing a numerical model using ANSYS Fluent software and computational fluid dynamics (CFD) algorithms. The base courses containing 66% steel slag aggregates and the conductive prime coat showed the best performance. These structures decreased the pavement surface temperature by 13% and nighttime outgoing heat by 38% and 33%, respectively. The air temperature near the surface of these pavement structures was also reduced by 14%.

Thermo-mechanical analysis of free convection in an octagonal cavity with adjustable active walls and flexible separator

This study investigates free convective within an octagonal cavity, which is partitioned into two compartments by a flexible separator. One of the left walls is maintained at a high temperature, while a lower temperature is applied to one of the right walls. The position of these active walls is adjustable, and the separator can be oriented vertically or inclined with either a positive or negative slope. The deformation of the flexible separator is modeled using the Arbitrary Lagrangian–Eulerian method. The outcomes indicate that locating the hotter wall near the top and moving the colder wall downwards hinders free convection and reduces the stress in the separator. Moreover, upward movement of both active walls leads to a decrease in the average temperature. An inclined separator with a positive slope enhances the heat transfer rate and experiences the lowest stress levels compared to vertical and negatively sloped separators. Raising Rayleigh number enhances the flow intensity and the stress in the flexible separator. Furthermore, it is found that a decrease in the elasticity modules of the separator from 1014 to 5 × 1011 results in a 5% increase in the average Nusselt number.

Palm Oil as a Heat Transfer Medium

Palm oil plants are abundantly available in Malaysia and are harvested commercially to either be exported in their crude form or used as a base for products such as soap and cooking oil. However, palm oil has also invoked interest in being used as a coolant. As opposed to conventional coolants, vegetable-based coolants such as palm oil offer several advantages, such as being more environmentally friendly upon disposal and safer for users as they are less chemically reactive. It is an accepted hypothesis that the inclusion of nanoparticles would generally increase the heat transfer rate of most fluids as these nanoparticles contribute to a rise in the heat transfer area. This paper presents a numerical study on using palm oil as a medium for heat transfer in machining operations, with and without the use of nanoparticles. It presents heat transfer comparisons between palm oil, conventional water and mineral oil coolants. It was found that the inclusion of nanoparticles increases the heat transfer capability of mineral oil and palm oil with palm oil being more positively affected. However, there is no apparent trend or correlation that can be made between concentration and heat transfer as the percentage increase of the surface heat flux and heat transfer coefficient are inconsistent with the 2% concentration showing a higher percentage increase compared to the 1% and 3% concentrations. Considering the results of this preliminary study, it can be concluded that palm oil together with nanoparticles does present a promising prospect as a coolant.

Energy saving and corrosion control by heat recycling in re-baking process of graphite electrode manufacturing

In the graphite electrode manufacturing industry, the re-baking process is energy-intensive and poses significant challenges due to heat loss and corrosion of equipment. The current work focuses on developing an innovative approach to enhance energy efficiency and control corrosion through heat recycling. The proposed method, heat recycling and corrosion control, involves capturing waste heat generated during the re-baking process and redirecting it to preheat the electrodes, thereby reducing overall energy consumption. Key parameters investigated include the temperature profile, heat transfer rate, and the rate of corrosion in the furnace components. This approach explores potential methods to enhance the energy efficiency of an operational oil-fired re-baking furnace. The findings indicate a notable 19.56% improvement in heat transfer rates based on data collection and analysis. Additionally, the combustion air volume increased by 25.49%, while the temperature rose by 66.67%. The study also identified opportunities for energy savings, with a reduction of 26.08% in power consumption and 40% in oil usage per hour. The study demonstrates that the HRCC method not only conserves energy but also mitigates corrosion-related damages, leading to lower operational costs. Future work will focus on optimizing the heat recovery system, scaling the method for industrial applications, and exploring the integration of advanced materials to further enhance corrosion resistance. The HRCC approach holds promise for widespread application in the graphite electrode manufacturing industry, contributing to sustainable production practices and reduced environmental impact.

Effects of Heat Source and Thermal Radiation on MHD Casson and Williamson Nanofluid Flow in a Porous Media

A non-Newtonian Casson-Williamson nanofluid flow's mass and heat transport characteristics were examined in this study. We investigate how the velocity boundary condition and viscous dissipation impact the mass and heat transfer mechanism in the presence of a stretching sheet immersed in a porous material that generates heat in response to thermal radiation and a uniform magnetic field. Casson-Williamson nanofluid is assumed to have constant physicochemical properties. As the nanofluid particles flow through the system, their concentration is studied in relation to the chemical consequences. This physical problem is quantitatively modelled using a series of boundary-conditioned nonlinear partial differential equations. By combining the Runge-Kutta method with the shooting methodology, we were able to numerically solve the differential equations with the associated boundary conditions. Next, the numerical analysis is shown graphically to demonstrate how different controlling parameters affect concentration, temperature, and velocity. Without a magnetic field, the non-Newtonian nanofluid moves more quickly than with one, while the temperature field shows the reverse tendency. The rate of heat transfer decreased while the skin-friction coefficient rose with an increase in the porosity parameter.

Enhancing the thermal properties of foam concrete with pumice-encapsulated soy wax phase change material: a novel approach.

This study explored an innovative technique for improving the thermal characteristics of foam concrete by incorporating soy wax phase change material (PCM) encapsulated within pumice. The core of this research is the development of PCM-pumice aggregates through the macro encapsulation of soy wax. This process involves direct impregnation, where melted soy wax is uniformly distributed within the porous structure of lightweight pumice aggregates. The thermal properties of the resulting foam concrete, notably its thermal conductivity, were rigorously evaluated. This evaluation entailed measuring the conductivity using a heat flow meter and subjecting the concrete samples to controlled temperature cycles, with a focus on the 25°C and 55°C marks. These specific temperatures were chosen to assess the impact of the PCM phase change on the thermal behavior of the concrete. Key findings indicate that the incorporation of PCM-pumice aggregates markedly improves thermal conductivity and heat retention in the solid state while simultaneously reducing fluidity, density, and compressive strength as a result of increased cohesion and porosity. Thermal conductivity significantly increased by up to 37% in the solid state relative to the control mix, due to the phase change material occupying air gaps within the concrete. Conversely, the thermal conductivity decreased in the liquid state, utilizing the PCM's latent heat capacity to lower heat transfer rates.

AI-led study of dynamic changes in milk containing hybrid nanoparticles in an electromagnetically vibrated channel subjected to thermal oscillations and rapid pressure changes: Implications for dairy industry

AI-led study of dynamic changes in milk containing hybrid nanoparticles in an electromagnetically vibrated channel subjected to thermal oscillations and rapid pressure changes: Implications for dairy industry

The matching effect of the cold-to-hot fluid on the thermohydraulic characteristics of heat exchangers using gyroid-typed triply periodic minimal surfaces

The triply periodic minimal surface (TPMS) is a potential candidate for constructing the next-generation heat exchanger (HEX) due to its considerably high specific area and flexible topology. Considering the flow rate and volume ratio of the cold-to-hot fluid domain, this work aims to probe the matching effect of the cold-to-hot fluid on the thermohydraulic features of cross-flow HEXs using gyroid TPMS structures. The results indicate that owing to the contiguous and intertwined path, TPMS structures induce a three-dimensional spiral flow with three typical flow characteristics (“merge-split,” parallel, and circulation) from different perspectives, dominating the fluid mixing and heat exchanger. The flow rate and volume ratio have a negligible influence on the thermohydraulic features but with different intensities. Increasing the cold-side velocity with a constant hot-side velocity can remarkably enhance convection heat transfer of the cold side with an increased pressure drop, while the hot side is influenced negligibly. Finally, the total heat transfer rate is gradually raised but reaches stability due to the limited hot-side heat transfer. A slightly higher flow rate ratio is recommended for improving HEXs. In comparison, the volume ratio simultaneously affects the fluid–solid interface area and internal fluid velocity under the mutual restriction between cold and hot fluids with an optimum volume ratio of Rvol = 1.0. With Rvol from 0.42 to 1.0, the heat transfer rate is increased by 7.7%, and the outlet temperature decreases by 1.5 K. Compared with the traditional structures, the gyroid structure offers a 100% higher specific surface area and 150%–225% higher volume-based power density.

Rectal temperature and heat transfer dynamics in the eye, face, and breast of broiler chickens exposed to moderate heat stress.

Rectal temperature and heat transfer dynamics in the eye, face, and breast of broiler chickens exposed to moderate heat stress.

Sensitivity along with statistical response for optimizing shear and heat transfer rate on the flow over power-law deformable plate considering bi-hybrid nanofluid

Sensitivity along with statistical response for optimizing shear and heat transfer rate on the flow over power-law deformable plate considering bi-hybrid nanofluid

Thermodynamics of an oblique droplet impinging on stationary water film

The flow and heat transfer of the oblique impact of a droplet on a stationary liquid film with various dimensionless thicknesses (01.0–0.5) are investigated experimentally and numerically. A superhydrophobic guideway is used to create the oblique impact of a droplet, which causes subsequent asymmetric crown structure and splashing. The thermal level set method is employed to capture the deformation and heat transfer of warm droplets' oblique impact on a cold liquid film. A parameter study of the effect of Weber number, oblique angle, and liquid film thickness on geometrical characteristics and wall heat flux is carried out. The results show that in the downstream direction, during the crown rising period, the radius is independent of the normal Weber number but increases for a larger tangential Weber number and a thinner liquid film. The maximum downstream crown height increases with an increase in the Weber number and exhibits a non-monotonic trend with the liquid film thickness. The heat transfer rate between the liquid film and surface decreases with larger oblique angles and thicker liquid films while having a poor dependence on the Weber number. In addition, the critical oblique angles for prompting splashing at different liquid film thicknesses are presented. Finally, modified thermodynamics models and splashing thresholds for the liquid film are developed to further enhance the understanding of aircraft icing.

Non-intrusive experiments on coupled bubble dynamics and heat transfer during nucleate boiling under varying pressure conditions

Non-intrusive experiments on coupled bubble dynamics and heat transfer during nucleate boiling under varying pressure conditions