The present study investigated the enhancement of convective heat transfer in horizontal tubes using twisted tape inserts, particularly emphasizing the influence of modifications to their geometrical configurations. Three twisted tape models were designed using SolidWorks: a plain tape, a tape with curved edges, and a tape with curved edges and holes. Two twist ratios were considered, namely TR1 = 6.666 and TR2 = 5. Computational Fluid Dynamics (CFD) simulations were performed to evaluate the velocity and temperature fields, Nusselt number, and friction factor over a Reynolds number range of 15,000–25,000. The results indicate that employing twisted tape with curved edges and perforations leads to the greatest enhancement in heat transfer. Specifically, the Nusselt number increases from 410 for curved edges without perforations to 460, whereas the plain tape achieves 380 at Re = 25,000 and TR2. The tape with curved edges (without holes) demonstrated the most favorable improvement in friction factor, attaining a value of 0.024 versus 0.029 for the plain tape, corresponding to a 20.8% reduction. As a result, the performance evaluation factor achieved a peak value of 1.24, indicating a 30.5% improvement. These findings demonstrated that optimized twisted tape geometries significantly enhanced heat transfer performance while maintaining reasonable pressure drop penalties. This highlights their potential applicability in thermal system design, particularly in compact and energy-efficient heat exchangers.

Enhancement of heat transfer and flow boiling stability in an interrupted coaxial pin-fin microchannel based on a dynamic correction method

Use of a controlled microgap for suppression of flow boiling instabilities and heat transfer enhancement in a minichannel

Experimental research on heat transfer enhancement and pressure drop in tube fitted with foam copper on the shape of twisted tape

Enhancing heat transfer across metal/diamond interfaces with a graphene interlayer

Enhancing heat transfer in porous media with nanosolutions: A comprehensive review of mechanisms, models, and applications

Heat transfer enhancement to transcritical hydrocarbons due to wall roughness within microtube heat exchangers

Boiling heat transfer enhancement using deformable composite surfaces integrated with shape memory alloys

Numerical study on heat transfer enhancement of LBE flow in semicircular-fin fuel bundles

Study on the heat transfer enhancement of hydro-turbine thrust bearing with nano-oil

Enhancing heat transfer performance in heated corrugated channels has become a main focus of investigation because of its crucial role in an extensive range of thermal systems. In the current study, a numerical investigation is carried out to examine the influence of laminar pulsating flow and SWCNT-water nanofluids on the flow behavior and heat transfer characteristics in a heat channel with nonequilateral triangle corrugations. Two different approaches are applied for nanoparticles motion such as homogenous single-phase model (HPM) and two-phase Eulerian–Lagrangian model (ELM). Governing equations are solved using the finite volume method. The computational fluid dynamics (CFD) simulations include Reynolds number, pulsation frequency and amplitude, volume concentration of SWCNT nanoparticles within the range of 250≤ Re≤1250, 1 ≤ f ≤ 4, 0.5≤ A ≤ 1, 0% ≤φ≤ 4% respectively. According to results, it can be said that while increasing pulsation amplitude, A always yields higher mean Nusselt number, Numean and heat transfer enhancement ratio, η pulsating flow is more effective at lower pulsation frequencies, such as f=0.5 and Numean and η deteriorates with subsequent increment in f. For instance, at Re=500, the mean Nusselt number increases from Numean=13.519 to Numean=15.282 when the pulsation amplitude is changed from A=0.5 to A=0.75 at f=0.5. This corresponds to a 13.04% enhancement in Numean. But this proportion is only observed as 0.378% increment in Numean for the change in pulsation amplitude from A=0.5 to A=0.75 at Re=500 and f=2. Furthermore, it was observed that Numean increases when the nanofluid model is changed from HPM to ELM especially at higher φ. At the optimal condition (Re = 1250, f = 0.5, A = 1, φ = 4%), Numean augmented by approximately 88% with HPM and 91% with ELM compared to the steady flow case, f=0. The outcomes provide design insights for compact heat exchangers in applications such as microchannel coolers, automotive radiators, and electronic thermal management systems demonstrating that low pulsation frequencies and high pulsation amplitudes can remarkably improve heat transfer performance without changing exchanger dimensions.

Investigation on enhanced heat transfer characteristics of hybrid convective cooling-phase change material composite systems for battery thermal management

Processing iridium foil targets for the production of radioplatinum isotopes.

This paper presents a comprehensive analysis of magnetohydrodynamic (MHD) flow, radiative heat transfer, and mass transport in nanofluids interacting with an incompressible, electrically conducting fluid. The study accounts for the combined effects of Joule heating, viscous dissipation, and a first-order chemical reaction over a porous plate embedded in a porous medium subjected to a prescribed heat flux. A numerical investigation is performed on the boundary-layer flow model involving three distinct nanoparticle types Cu , A l 2 O 3 and Ag . The governing equations for momentum, energy, and species concentration are formulated under the boundary-layer approximation. By employing similarity transformations, the coupled nonlinear partial differential equations with associated boundary conditions are reduced to a system of ordinary differential equations (ODEs) defined over a semi-infinite domain. This system is solved numerically using a hybrid scheme that integrates the Shooting technique with the fourth-order Adams–Moulton method. The accuracy of the results is confirmed through comparison with previously published data, demonstrating excellent agreement. The effects of key physical parameters on the velocity, temperature, and concentration fields are examined and illustrated through graphical and tabular analyses. Furthermore, thermophysical property correlations are provided. The findings indicate that an increase in nanoparticle volume fraction leads to elevated temperature profiles, thereby enhancing the Schmidt number. Thus, the results provide a clear understanding of fluid flow behaviour in applications such as nuclear reactor cooling systems, polymer extrusion processes, and electromagnetic magnetohydrodynamic generators.

This study experimentally investigates the thermal–hydraulic performance of heat exchanger tubes fitted with wired twisted tapes, with particular emphasis on the effects of the hole spacing-to-width ratio (s/W) and edge margin-to-width ratio (e/W). Experiments were conducted over a Reynolds number range of 6000–20,000, and the results were compared with those of plain tubes and tubes equipped with conventional twisted tapes. The findings revealed that the incorporation of wires significantly enhanced heat transfer due to the combined action of longitudinal eddies generated by wire protrusions and swirling flow induced by the twisted tape. At identical Reynolds numbers, tubes with a smaller hole spacing (s/W = 0.16) exhibited superior heat transfer performance, achieving Nusselt number enhancements of up to 107.7% relative to plain tubes and 51.6% relative to conventional twisted tapes. Similarly, reducing the edge margin ratio intensified near-wall eddies and further disrupted the boundary layer. The friction factor was found to increase with decreasing hole spacing and edge margin, primarily due to additional flow obstructions and enhanced near-wall shear stresses. For wired twisted tapes with s/W = 0.16, the friction factor reached nearly six times that of a plain tube. Despite this penalty, the thermal performance factor (TPF) remained favorable, with values of up to 1.2, indicating that the heat transfer benefits outweighed the corresponding pressure losses.

Efficient ortho–para hydrogen conversion is essential to suppress spontaneous heat release and boil-off losses during cryogenic liquid hydrogen storage and pre-liquefaction processes. In this study, a novel catalyst-filled wavy plate-fin heat exchanger (CFHE) is proposed to simultaneously enhance heat transfer and ortho–para hydrogen conversion under cryogenic conditions. Compared with conventional straight-fin configurations, the wavy-fin structure introduces controlled flow perturbations and increased specific surface area, thereby intensifying transport processes. Three-dimensional computational fluid dynamics (CFD) simulations, using the SST k–ω turbulence model, coupled with an ortho–para hydrogen conversion kinetic model were performed to quantitatively investigate the effects of key geometric parameters and catalyst loading on hydrogen conversion, heat transfer, and pressure drop within a Reynolds number range of 941–1577 and a temperature range of 35–20 K. Within the same CFHE configuration, the para-hydrogen fraction remains nearly unchanged without catalyst but increases significantly with catalyst loading. However, the catalyst reduces the global average Colburn j-factor by about 25%. Despite higher friction losses, the outlet–inlet temperature difference decreases to about 0.866 times that of the non-catalyst case, indicating improved temperature uniformity. A comprehensive performance index e, integrating heat transfer enhancement, flow resistance, and conversion efficiency, was introduced and optimized using a genetic algorithm. The optimized CFHE achieves an outlet para-hydrogen fraction exceeding 95% of the thermodynamic equilibrium value while maintaining hydrogen entirely in the gaseous phase to avoid catalyst deactivation. Overall, the catalyst-packed wavy channel configuration demonstrates superior conversion efficiency, enhanced thermal uniformity, and improved overall performance compared with straight-fin structures, providing quantitative design guidance for high-performance heat exchangers in cryogenic hydrogen liquefaction systems.

Enhancing the thermal performance of the Trombe Wall is crucial for improving the energy efficiency of passive solar heating systems. This study presents a three-dimensional numerical analysis to investigate the combined effects of internal rib density and geometrical configuration on the thermo-hydrodynamic behavior of a Trombe wall. Using a finite-volume method with laminar flow assumptions based on the Reynolds number, the research is conducted in two sections. First, four rib densities (Nr = 3, 5, 7, and 9) are evaluated using a rectangular rib geometry to identify the best rib number. Subsequently, four innovative designs are compared: rectangular (Model A), semi-circular (Model B), crossed semi-circular (Model C), and spaced semi-circular (Model D) ribs. The findings indicate that while increasing rib count enhances heat transfer through secondary-flow intensification, improvements become marginal beyond Nr = 5 due to excessive flow resistance. At Re = 1600, the Nr = 5 configuration achieves a 68% increase in the average Nusselt number over a smooth channel while maintaining acceptable friction levels. The thermal enhancement factor of case Nr = 5 is the highest in all evaluated Re numbers. Regarding geometry, the model with crossed semi-circular ribs (Model C) provides the maximum thermal enhancement at Re = 1600, with nearly a twofold increase in heat transfer (compared to the smooth channel), albeit at the cost of higher pressure losses. Conversely, the spaced semi-circular ribs case (Model D) achieves the best thermal enhancement factor of 1.51, a 12.7% increase in heat flux, and a lower Poiseuille number. Overall, this study demonstrates that enhanced ribbed configurations can significantly improve Trombe Wall efficiency, with the spaced semi-circular design and five ribs.

Extensive efforts have enhanced flat plate solar collectors through active and passive strategies to advance clean energy adoption aligned with SDG7. In this context, a compact domestic solar hot water system was developed using a rifled riser tube flat plate collector and CuO/La2O3 nanofluids under forced circulation. A 1 m2 collector coupled with a 50 L day − 1 storage tank was experimentally evaluated using deionized water, CuO, La2O3 mono nanofluids, and an 80:20 CuO/La2O3 hybrid nanofluid at 0.5 wt% concentration and flow rates of 1, 2, and 3 LPM. At 3 LPM, maximum thermal efficiencies of 70.24%, 75.73%, 79.95%, and 81.96% were achieved for deionized water, La2O3, hybrid, and CuO nanofluids, respectively. The rifled tube produced heat transfer coefficients of 8836 W m − 2 K − 1 for the hybrid and 9027 W m − 2 K − 1 for CuO nanofluids. La2O3 improved colloidal stability, while CuO enhanced thermal conductivity, yielding synergistic performance. Compared with a plain tube collector using deionized water, average efficiency improved by 30.56% and 32.36% for hybrid and CuO nanofluids. Enhanced heat transfer increased exergy efficiency to 22.54% and 25.45% for hybrid and CuO nanofluids, respectively. The combined use of rifled tubes and hybrid nanofluid enabled a 24.86% reduction in collector area domestically.

Ink-based fabrication of copper (Cu) interconnects and electrical pads has attracted increasing attention for a wide range of applications. In this study, we investigate the use of copper oxide (CuO) nanoparticle ink combined with laser sintering to produce conductive Cu pads on various substrates with different thermal conductivities, including glass, polyimide (PI), and poly(ethylene terephthalate) (PET) films. A 532 nm continuous-wave (CW) laser was employed in both CW and modulated-power (dot-mode) configurations to reduce CuO to metallic Cu. Our findings reveal that the degree of laser irradiation overlap plays a critical role in selective-area sintering, affecting both line- and dot-based processing. Optimal overlap conditions depend on several factors, such as ink layer thickness, laser scanning speed, substrate thermal conductivity, and glass transition temperature. For CuO layers with a thickness of more than 5.02 μm, slight overlap of laser irradiation is necessary for effective pad formation. In contrast, thinner layers (≤3.24 μm) typically do not require overlap due to the enhanced heat transfer efficiency. The resulting Cu patterns exhibited a resistivity of approximately 3.50 μΩ·cm, which is about twice that of bulk Cu on both glass and PI substrates. However, achieving conductivity on PET proved difficult due to substrate damage caused by its low thermal conductivity and glass transition temperature. This challenge was addressed by predepositing a thin silver (Ag) interlayer prior to CuO ink deposition. While both line- and dot-based sintering methods showed comparable electrical performance, dot-based irradiation offered advantages in reducing surface porosity and preserving edge integrity during sintering.

Enhancement of Thermohydraulic Performance in 3D Annulus Based on Different Configurations of Copper Metal Foam