ABSTRACT. The present lecture reviews the analytic-based methodology known as the Generalized Integral Transform Technique (GITT) for convection-diffusion problems, focusing on recent progresses on fundamentals, such as the single domain formulation and the nonlinear eigenvalue problem base, which are more closely reviewed. Also, its recent application in direct-inverse analysis in petroleum reservoir simulation is illustrated.

ABSTRACT. The nature of the heat transfer enhancement seen in the boiling of thin falling liquid films is still a matter of some debate. This paper is a preliminary experimental investigation into the role bubble dynamics play, focusing on the bubble departure diameters and bubble growth after departure while sliding in the falling films. The bubble departure diameter did appear to be materially affected by the falling film conditions in comparison to pool boiling, while the bubble sliding growth was less clear.

ABSTRACT. We investigated hydrodynamic behaviour of a volatile drop (FC-72) impinging onto a heated substrate and accompanying heat transfer in the vicinity of the Leidenfrost point, the temperature above which liquid drops are lifted by their own vapour due to instant evaporation. A combination of temperature sensitive paint (TSP) and high-speed cameras allowed us to capture drop impact and local surface temperature distributions simultaneously. We have successfully captured temperature variations which indicated wetting/ drying regions over a range of temperatures across the Leidenfrost point.

ABSTRACT. This study investigates pool boiling and bubble behaviour of Novec7000, Novec649, and their binary mixtures. Utilizing a paired artificial cavity coated with superhydrophobic Glaco, bubbles horizontal coalescence sequences reveal a dependence on the mole fraction of the binary mixture. As the mole fraction (X_i) increases, bubble horizontal coalescence transitions from dual pinning onto the surface to depinning. The evaporative heat flux was calculated across varying mole fractions of the binary mixture. Detailed analysis indicates that binary mixtures significantly impact bubble coalescence compared to isolated bubble dynamics.

ABSTRACT. The global attempt to decarbonise the transport sector, combined with our dependency on vehicles, created research opportunities for new technologies and developments and thermal management is a vital focus area. Nucleate pool boiling is known for high heat transfer coefficients and is an attractive direct cooling method. The purpose of this study was to investigate single bubble dynamics R1336mzz(Z) and R245fa for different saturation temperatures and heat fluxes. It was found that the bubble growth rate significantly increased with an increase in heat flux and decrease in pressure, while there was only a slight increase in the departure diameter. The higher surface tension of R1336mzz(Z) led to an increased bubble departure diameter compared with R245fa, while the bubble growth rate also increased and the bubble growth time decreased.

ABSTRACT. This study investigates the plausible growth mechanism(s) and dynamical parameters of single vapor bubble during nucleate boiling regime of high volatile fluids under varying subcooling conditions. Dichloromethane (DCM) has been chosen as the high volatile　fluid　in the boiling experiments. The plausible bubble base growth mechanism(s), microlayer and/or contact line evaporation and the dynamical parameters of the vapor bubbles have been mapped through simultaneous application of thin film interferometry and high-speed rainbow schlieren deflectometry. The experimental observations reveal that unlike conventional fluids, like water, DCM displays a bubble base growth mechanism that is primarily dominated by contact line evaporation and thermal diffusion effects across the superheated thermal layer enveloping the growing vapor bubble. Irrespective of the surface wettability, no distinct microlayer could be observed beneath the growing DCM vapor bubble through thin film interferometry observations. Detailed force balance analysis shows a transition from downward to upward forces facilitating bubble departure beyond 0.9 departure time (td).

ABSTRACT. Natural convection loops are used in passive heat exchange systems in many applications, such as nuclear reactor cooling and photovoltaic cells. The fluid flow patterns observed in loops exhibit complex nature in certain geometric configurations even for moderate values of the Rayleigh number. We report the results obtained from 2D unsteady laminar numerical simulations on the impact of bend curvatures on fluid flow patterns in convective loops with the horizontal heater and horizontal cooler (HHHC) configuration

ABSTRACT. Wall-resolved Large-Eddy Simulation (WRLES) is carried-out to investigate the turbulent mixed convection in the upward flow within tube bundles, a configuration representative of a real scenario in a nuclear reactor. A database of first and second-order turbulence statistics is set-up. Interesting physical phenomena triggered by the buoyancy forces in the spatially developing flow are also highlighted.

ABSTRACT. In the present work, Numerical investigation is performed to analyse the influence of the aspect ratio of a rectangular enclosure on flow and heat transfer with Cu-H2O as a nanofluid using the Eulerian-Eulerian model. The enclosure considered is differentially heated, with top and bottom walls insulated. The aspect ratios (AR=H/W) of the enclosure considered in this study are 0.5, 1.0 and 2.0. All the governing equations are discretised with the help of finite difference methods. The flow and heat transfer study is conducted at three different aspect ratios for various Grashof numbers (Gr =1000 to 1000000) and nanoparticle volume fractions (Фs=1% to 3%). The enhancement in heat transfer performance is observed as the aspect ratio increased from 0.5 to 2.0 at a specific Grashof number. The heat transfer augmentation is also observed by increasing the Grashof number and volume fraction at a particular aspect ratio.

ABSTRACT. Rectangular fins play a crucial role in many cooling applications, particularly in the realm of electronics, mechanical, and solar applications. This study focuses on the conjugate heat transfer analysis of natural convection over arrays of parallel fins attached to either vertical or inclined heated surfaces. This arrangement is relevant to the passive cooling of PV cells. The objective is to first validate the numerical method using experimental data for vertical arrays and then to apply the resulting methodology to the investigation of the effect of the angle of inclination.

ABSTRACT. This study aims to investigate viscoelastic natural convection flow using the general pressure equation, considering Rayleigh (Ra) numbers ranging from 104 to 107, Weissenberg (Wi) numbers ranging from 1 to 100, and a maximum elongation length (L2max) equal to 10 and 500. The results indicate that at low elasticity effects (Wi=10), there is a slight increase in both maximum horizontal and vertical velocities, resulting in higher heat transfer. Conversely, high elasticity effects (Wi=100, L2max=500) led to a decrease in heat transfer compared to its Newtonian counterpart. The presence of polymer generated opposing stress near the wall, resulting in a decrease in vertical velocity and, consequently, heat transfer.

ABSTRACT. As part of a flow accelerated corrosion project, a qualitative validation of 4 RANS models for mass and heat transfer coefficients (Sherwood and Nusselt numbers) is conducted, by reference to a recent experiment (Re_H=16-24,000, Pr = 0.707, Sc = 2.28). The friction coefficient and velocity profiles, missing in the mass transfer study, are compared with data from DNS and experimental studies at higher and lower Re values.

ABSTRACT. Boiling is a perfect example of a multiscale process where molecular-level physics giving rise to bubble nucleation interact with larger-scale boundary layers determined by the outer system boundary conditions. We present a novel multiscale simulation method which merges Molecular Dynamics (MD) and Computational Fluid Dynamics (CFD) descriptions into a single modelling framework, where MD resolves the near-wall region where molecular interactions are important, and a CFD solver resolves the bulk flow. We model the progressive heating of a Lennard-Jones fluid via contact with a solid wall until a vapour bubble nucleates in the MD region of the domain and grows by entering in the CFD domain. Our results show that an incompressible CFD flow model based on the Volume Of Fluid (VOF) method with interphase mass transfer calculated via the Hertz-Knudsen-Schrage equation is sufficient to obtain seamless coupling of phase fraction, velocity and temperature fields, with the hybrid MD-CFD framework yielding bubble dynamics closely matching those of MD alone.

ABSTRACT. Limited data exists for thermal contact conductance h_c between surfaces which may contact lightly, such as differential thermal expansion at sealing faces. This paper describes a transient experimental technique to measure h_c between rough surfaces contacting at low pressures, allowing data to be gathered quickly and effectively using standard apparatus. It produces comparable results to the bulk steady-state method several orders of magnitude faster, whilst being simple to implement, both physically and computationally. Overall measurement uncertainty is estimated in the range 0.40%-6.88% for h_c = 100-100,000 W m-2 K-1.

ABSTRACT. This research addresses the exploration of additive manufacturing for an aerospike breadboard engine, utilizing laser powder bed fusion (PBF-LB/M) with INCONEL®718 powder. The process was assessed through material characterization and non-destructive testing such as computed tomography. Geometric features were also studied to determine overhang and accuracy, shaping the design of the aerospike breadboard engine. The study also discusses general results on surface roughness reduction and shape accuracy, which was found to cause notable reductions in propellant mass flow rates in prior tests in 2019.

ABSTRACT. An extended thermal model for jacketed batch stirred tank reactors (STRs) has been expanded for applications to both non-reactive and reactive systems. It is not only able to replicate the predicted process temperature profile by the reduced thermal model, but also provides information about how the jacket outlet temperature and the heat flows vary with time. It is revealed that values of the overall heat transfer coefficient obtained from experimental data and the reduced thermal model inherently include several thermal effects not covered in the model equations and thus should not be used to predict other experimental equipment, process and ambient conditions.

ABSTRACT. The performance of advanced RANS turbulence models using different near-wall treatments is assessed in the computation of a natural convection flow occurring in a cubic cavity with a partially heated inner obstacle. The flow field has a Rayleigh number of 1.4× 10^9 at which recent experimental data have been published. The time dependent 3D computations apply eddy-viscosity (k-ε,k-ω based) and advanced Reynolds stress transport models (EB-RSM). The predictions returned from a recently developed variant of the analytical wall function combined with either high-Re or low-Re k-ε formulation are assessed. The low-Re k-ε AWF combination leads to substantial predictive improvements of the Nusselt number levels on the active walls despite the coarse grid resolution adopted.

ABSTRACT. A methodology is presented for the investigation of the hydrodynamic and heat transfer effects of subcooled flow boiling phenomena. We employ interface capturing simulation with mechanistic calculation of the local rate of phase change. The numerical accuracy of the methodology is demonstrated for the modelling of condensation, by considering the case of heat-controlled collapse of a spherical vapour bubble surrounded by subcooled water. Our results demonstrate excellent agreement with the analytical solution.

ABSTRACT. Direct numerical simulation of incompressible, inductionless magnetohydrodynamic Rayleigh-Bénard convection is conducted for Rayleigh numbers up to 10^6, a Prandtl number of 1 and for a range of Hartmann numbers in the interval 0<Ha<64. First- and second- order statistics are collected for the velocity, temperature and electrical current, forming a high-resolution DNS database. The resolution of these results is ensured post-simulation by comparing the mesh-spacing and time-step with Kolmogorov length- and time- scales respectively. The Nusselt number is computed as a function of the Hartmann number, quantifying the heat transfer performance of this flow. A negative trend is observed between the Nusselt and Hartmann numbers.

ABSTRACT. This paper presents a coarse-grid Computational Fluid Dynamics approach, initially developed for light-water reactors and now extended to prismatic High-Temperature Gas-cooled Reactor fuel assemblies. This method, known as Subchannel CFD, combines the strengths of traditional subchannel codes and CFD. It offers CFD-like 3-D predictions at a substantially reduced computational cost, potentially allowing for cost-effective simulations at the reactor core scale.

ABSTRACT. Motivated by the current development of the Westinghouse Lead-cooled Fast Reactor, this study presents transient CFD simulations of solidification within a pool type vessel cooled externally by the forced convection of air using STAR-CCM+. Results indicate the melting-solidification model within STAR-CCM+ can reproduce the solidification front as it moves past a mock-up LFR fuel bundle included within the vessel. However, comparisons with experimental data reveal that the CFD under-predicts the solidification rate and thus further work is required to address these discrepancies.

ABSTRACT. In this contribution, low-Prandtl number fluids are investigated for the use as heat transfer fluid in packed-bed heat storage systems. At the Karlsruhe Liquid Metal Laboratory (KALLA), liquid metals, mostly heavy metals such as lead-bismuth or tin, are used. They are excellent heat transfer fluids and are used in concentrating solar power plants or in nuclear power plants, where high heat loads are supposed to quickly and efficiently be cooled. Above that, KALLA is looking into using liquid metals as heat transfer fluids in packed-bed heat storage systems, making use of their excellent heat transport capabilities and the wide liquid phase temperature range. This work highlights the ongoing work with regard to experimental demonstration of the technology and related fundamental heat transfer investigations.

ABSTRACT. Traditional food storage methods often lead to problems such as energy waste and the inability to maintain food quality over the long term. Phase change materials (PCM) have the advantages of high energy storage density, energy saving, and environmental protection. This article provides a recent overview on the use of PCMs in indirect solar drying. This study details the working principles, materials, equipment, and main findings of ITSD. Paraffin wax became the most prevalent PCM, and PCM demonstrated a remarkable ability to significantly extend drying duration.

ABSTRACT. Integration of concentrating solar collectors with thermal energy storage systems, can enhance the performance of solar thermal adsorption refrigeration systems. In this research, soils sourced from the central rift valley of Ethiopia were investigated for thermal energy storage. Therefore, emphasis was on heat capacity and thermal diffusivity to assess thermal storage capacity and charging/discharging agility. The study analyses soil samples from representative locations (Koka, Bote, and Meki) and examines their thermophysical attributes across varying grain sizes. The results reveal associations between porosity, heat capacity, and thermal diffusivity, providing valuable insights for energy-efficient systems. The specific heat capacity ranges from 0.86 to 1.44 J/g°C, while thermal diffusivity varies between 0.38 and 0.54 mm²/s. These findings contribute to sustainable energy practices and inform soil-based thermal management strategies. It is observed that utilising soil as a low-cost sensible heat storage and integrating it with solar thermal collectors and photovoltaic panels to power adsorption refrigeration system, high solar fractions can be achieved. Soil appears to be a technically viable heat storage medium, facilitating extended operating periods and efficient early starts of the system.

ABSTRACT. This paper examines Phase Change Materials (PCM) in UK residential buildings to improve energy efficiency, focusing on a detached house in Nottingham. It assesses three PCM types on external walls' inside and outside, considering energy consumption impacts. The research uniquely simulates different housing forms—detached, semi-detached, and flats. By adjusting external wall boundary conditions to mirror varied thermal environments. It explores how these conditions affect heat dissipation in each building type. The research shows that the application of PCMs to the inner and outer walls of the building can effectively reduce the heat loss of the building and thus reduce the building energy consumption. PCM RT22 HC has the best performance among the three selected PCMS. In addition, for detached building, Semi-detached building and Flat building, adding PCM to the outer wall of the building has the best effect, which can achieve 8.21%, 6.22% and 4.51% of building energy consumption reduction, respectively.

ABSTRACT. Encapsulated Phase Change Materials (EPCM) offer a promising solution to the escalating demand for sustainable energy storage solutions. However, challenges persist in ensuring the structural integrity of EPCM during operational cycles, particularly regarding thermal distribution and the accumulation of localized stresses. This study presents an innovative simulation model based on Large Eddy Simulation (LES) to address these challenges. By integrating advanced thermodynamic principles into the OpenFOAM platform, a hybrid solver is developed, allowing for a comprehensive analysis of EPCM behaviors. Preliminary results highlight stress hotspots in conventional EPCM designs, providing insights for design optimizations aimed at enhancing structural resilience. These findings contribute to the broader objective of advancing EPCM technologies for efficient and reliable energy storage applications.

ABSTRACT. The present work discusses the use of polymer materials in the fabrication of two-phase passive thermal management systems such as pulsating heat pipes, with an analysis of their limitations and technical challenges. Although heat transfer systems are usually built with metals due to their excellent thermal properties, there is an increasing interest in replacing metallic materials with polymers and composites that can offer cost-effectiveness, light weight and high mechanical flexibility. On the other hand, polymer materials suffer from poor thermal conductivity, poor wettability, viscoelasticity, selective permeability to moisture and incondensable gases, as well as ageing.

ABSTRACT. This paper presents the results of a series of investigations aimed to aid the implementation of a battery thermal management system for electric vehicles based on loop heat pipes. The LHPs can passively transfer heat from the battery pack to a remote chiller, without consuming parasitic power. Experiments demonstrate that the proposed solution can enable fast 3C charging and maintain satisfactory battery temperatures from -20°C to 50°C ambient. Compared to passive air cooling, the system reduces peak temperatures during fast charging by 7.9°C and more than doubles battery lifetime. The results highlight the potential of passive two-phase heat transfer for automotive thermal management.

ABSTRACT. This paper presents an overview of recent research on flexible polymeric pulsating heat pipes (PPHPs). Two promising fabrication techniques are explored - selective transmission laser welding and stereolithography (SLA) 3D printing. The thermal performance of PPHPs manufactured using these methods is experimentally investigated, including the impact of microgravity conditions and bending on the laser-welded design. Key findings show that the SLA technique enables precise control over complex geometries, while the laser-welded PPHPs demonstrate effective thermal performance even in microgravity. Non-uniform channel configurations are found to promote fluid circulation and enhance heat transfer. This work highlights the potential of polymeric PHPs for flexible electronics cooling and disposable applications.

ABSTRACT. Foil And Slot Thermal Transfer (FASTT) uses precision, solid foils to transport heat from high flux sources to low flux sinks such as ambient air. Earlier research utilised simple lumped parameter models to determine system performance. This paper describes recent three dimensional time transient finite element analyses, which have been used to examine system behaviour in more detail. The results support the earlier findings that FASTT can provide high thermal flux throughput, but over much wider temperature ranges than existing technologies, such as those based upon microchannels or heatpipes.

ABSTRACT. This paper presents the development of a novel copper-water flat evaporator loop heat pipe (fLHP) model with compact evaporator dimensions of 60x40x5 mm for electric car batteries thermal management. The fLHP can operate both with and against gravity, transporting up to 250 W (25.6 W/cm2 ¬) when aided by gravity and 120 W (12.3 W/cm2) when operating against gravity. The maximum transport distance tested was 1.5 m. An optimised filling ratio of 4.5ml was determined which minimised the overall thermal resistance of the fLHP (0.116 K/W at X W power input).

ABSTRACT. The use of thermal gradients to self-assemble colloidal particles into ordered structures, also known as ice templating, is well understood. Freezing colloidal droplets leads to complex shapes which is of both scientific and technological significance. While frozen pure water droplets show a sharp tip at their apex, colloidal droplets show a flat top morphology. Preliminary experiments with colloidal suspensions of alumina show an array of morphological features, based on initial particle concentration. The present work attempts a parametric investigation with implications in droplet based ice templating.

ABSTRACT. Development of passive icephobic surfaces are highly desirable due to their energy, economic and safety implications in various sectors such as aircrafts, wind turbines, power lines and infrastructure. Among few, inhibiting ice nucleation is one of the most primitive strategy in designing effective icephobic surfaces. In this work, we show that surface-grown covalent organic frameworks (COFs) with pore size approx. 1.8 nm can effectively inhibit the nucleation of ice due to nanoconfinement effect. The effectiveness in delaying ice nucleation is further enhanced by post-functionalisation with flexible alkyl chains. It is observed that the flexibility and molecular chain length can also affect the ice nucleation on such surface and this work can help in advancing the design for practical solution against undesirable icing on surfaces.

ABSTRACT. Film cooling plays a crucial role in creating effective cooling systems for gas turbine blades, which are ‎necessary to meet thermal protection standards to achieve high thermal efficiency. This study was ‎conducted to experimentally evaluate detailed heat transfer coefficients within a representative ‎geometry, provide contours of internal surface Nusselt number, and circumferentially average Nusselt ‎number along the entry length of the channels. The Transient Liquid Crystal technique has been ‎implemented to study the heat transfer distributions over the wall of the film hole. The test section ‎representing the film cooling hole was a cylindrical channel and it had a length of 5 jet diameters. The ‎experimental tests have been conducted at a wide range of Reynolds numbers (30,000–60,000), inclination ‎angle (0o -135o ) and rotation angle (0o -135o ). The effect of channel entry configuration was also varied ‎between sharp, filleted, and chamfered. Results showed that the sharpness of the nozzle was directly ‎related to the magnitude of the entry length separation and reattachment heat transfer enhancement. ‎When the inclination angle was introduced, it was discovered that there was a reduction of the reattachment ‎heat transfer enhancement, but an overall increase in heat transfer could be achieved, with most ‎enhancement shown for an inclination angle of 45°. While varying the rotation angle illustrated that the most ‎significant impact was within one diameter in length from the channel entry, with overall reductions in ‎heat transfer when varied by more than 90°.‎

ABSTRACT. The aim of this study is to investigate the flow boiling characteristics of butanol water mixture under different flow orientations. Here, a 5% v/v butanol-water mixture was chosen as a working fluid. Next, a one-sided coated rectangular channel for an aspect ratio of 20 and with a hydraulic diameter of 571 µm was used as the test section under three different flow orientations (horizontal flow, vertical upward flow and vertical downward flow). The results show that flow orientation influences the characteristics of the flow pattern and the wall temperature distribution with vertical downward flow being dominated by the vapour phase. This phenomenon in vertical downward flow will lead to the occurrence of dry out that increases the wall temperature along the channel.

ABSTRACT. The efficacy of surface treatment technology is highly dependent on the dimensional and operational parameters. UV-C is a commonly used surface treatment technology for semi-processed crops. This paper makes use of a simultaneous optimization approach for multi-objective function so as to obtain the best possible combination of variables in the irradiation process (UV-C dose, storage period, and distance from the light) that offer maintained properties of semi-finished potato tuber.

ABSTRACT. The heat dissipation of local hot spot with high heat flux is always a serious challenge, which will seriously threaten the service life and operation efficiency of high-performance electronic devices. In this work, we proposed that utilize the conceptual design of local variable density for micro-jet heat sink to achieve accurate and effective cooling of local hot spot areas. The hybrid of the local variable density design of jet nozzle and the micro pin fin arrays can significantly improve cooling performance of the local hot spot region. The research results show that the novel design can solve the heat dissipation of 700 W/cm2, the design concept exhibits excellent cooling characteristics in both thermal and hydraulic performance.

ABSTRACT. Single-phase flow of HFE-7100 in a micro-pin fin heat sink was investigated and the results described in this paper. Both adiabatic and diabatic experiments were carried out at a system pressure of 1 bar, inlet fluid temperature of 19 ⁰C and Reynolds number ranging from 86 to 850. Different existing correlations of friction factor and Nusselt number were evaluated and assessed. A good agreement between the present results and some correlations was found.

ABSTRACT. The rapid evolution of electronic devices has resulted in increased heat generation, highlighting the demand for polymer composites with high thermal conductivity. However, traditional polymer composites typically exhibit low thermal conductivity at room temperature. This study enhances thermal conductivity of silicone polymer composites by adding Boron Nitride (BN) and Silicon Carbide (SiC) fillers. BN and SiC were aligned first and infiltrated with silicone together with nano-BN to further improve thermal conductivity.

ABSTRACT. Fast charging of Lithium Ion Batteries in Electric Vehicles is important to reduce ‘range anxiety’ among motorists. However, fast charging generates considerable heat, which must be removed to avoid battery degradation at high temperatures. Direct thermal management, where the cells are in contact with a dielectric liquid to cool them, offers the potential for more efficient heat transfer. However, these fluids generally have less favourable physical properties compared to water. We present some a new experimental flow system to quantify the heat transfer performance of dielectric fluids and as part of a project to identify strategies for improvement.

ABSTRACT. Thermal metamaterials can effectively redistribute heat through simple designs, offering a cost-efficient solution for cooling flexible electronics, which often suffer from low thermal conductivity in their polymeric substrates like polyimide. A simple sensu-fan design can reduce a 350°C central heat source by nearly 250°C while maintaining a high temperature of ~90°C throughout the fan structure, with an optimal cooling effect achieved by varying the fan's thickness logarithmically. A linear thickness profile is however ideal for achieving a high temperature of 96°C at the fan blades. These findings suggest that using less material in specific thickness profiles can effectively distribute thermal energy across a polymer substrate. Additionally, a thermal cloaking shield made from the sensu fan can block heat conduction to sensitive areas, making the structure ideal for managing heat distribution without exceeding the limitations of flexible substrates.

ABSTRACT. Floating photovoltaic panels have several advantages such as using the open water surface instead of large land areas. Exploiting the water body as a heat sink to cool the panels offers an additional advantage, leading to increased efficiency. This study focuses on the development of a numerical model for a hybrid system that combines a natural convection cooling loop with a solar filter feature. This added feature decreases the temperature of photovoltaic cells and optimises the spectral distribution of the incoming solar radiation. A conjugate heat transfer analysis shows that the cooling system is highly effective in dissipating heat and maximising the electrical output of floating photovoltaic panels. The study also optimises the thickness of the cooling channel to assess the effectiveness of nanofluids.

ABSTRACT. The thermal performance of a deep borehole coaxial heat exchanger with High-Density Polyethylene (HDPE) and vacuum-insulated central tubing (VIT) is presented in this paper. The analysis was performed for a wellbore equipped with a casing steel pipe of external diameter 198.52 mm and 10.36 mm thick. The central pipe consists of an HDPE tube 139.7 mm in outside diameter and 25.7 mm thick or two coaxial steel tubes, the first having an outside diameter of 139.7 mm and 10.5 mm thick, with the inner tube having an outside diameter of 101.6 mm and a thickness of 6.65 mm giving the same inner diameter of 88.3 mm as the HDPE tube. The gap between the steel pipes was maintained at different partial vacuum pressures. The depth was up to 5 km. Water was used as the working fluid. It was found that the VIT outperforms the HDPE for deep wells with the advantage diminishing for more shallow heat exchangers. A partial vacuum of 10 Pa does not demonstrate any relevant improvements over a gap maintained at normal atmospheric pressure, while the yield can be significantly improved when the pressure is reduced to 1 and 0.1 Pa.

ABSTRACT. Domestic-scale solar stills are designed, manufactured, and examined for comparison. This study explores the practical investigations of two distinct solar still designs, namely the inclined and pyramid solar stills. These configurations encompass the conventional passive solar still, the actual daily yield of the inclined solar still is 71.9 ml/h, and the 113 ml/h from the pyramid solar still. So, the pyramid solar still is better than inclined, and its productivity can be increased by incorporating active devices, ultrasonic fogger, thermoelectric devices, and heaters.

ABSTRACT. This paper validates experimentally two numerical models of solar-powered tube heater that uses air impingement jets to heat steel tubes in the powder-based coating process as they move axially. A test rig is built to evaluate the thermal performance of the tube heater and validate both, its ANSYS FLUENT Dynamic Mesh model which simulated a moving target and ANSYS FLUENT Transient Thermal model which simulated a moving heat source. Results showed the experimental results to agree with those of the numerical models with an R2-value of 0.983-0.997 and error fit of 3-10% for tube velocities of 0.033-0.1 m/s.

ABSTRACT. Heat transfer with liquid immersion represents a highly emphasized thermal solution to consider. In various technological and industrial applications, liquid immersion heat transfer can be applied without the need for additional equipment. The only consideration needed is to adjust the material specifications to our desired settings. In our case, we examined Lithium-Ion Batteries for heat generation with 1C discharge for the cooling system and investigated the optimal cooling method for the batteries. We conducted a series of tests to compare the effects of liquid immersion cooling on batteries. Additionally, we utilized air cooling to demonstrate the cooling potential compared to an air-cooled design. Due to its dielectric and thermal properties, we selected HFE-7000 for our thermal management system. A comprehensive analysis of the batteries' heating coefficients under different C-ratings was also essential, as it exponentially affects the batteries' heat rate. Our findings indicate that liquid immersion maintains battery temperature better than air cooling, resulting in a more uniform temperature distribution among batteries. The data obtained from charged and discharged batteries is valuable for designing under specified conditions.