For saline or wastewater, solar distillation is a suitable, environmentally friendly technique for purifying water. The problem is that there is no distillation process that produces salt water, and that salt water used on plants may cause plant death. The techniques described in this work aim to enhance the solar distillation process using solar stills with a steam generator and a condenser. The distilled water was heated between 11 am and 4 pm, with best output of 1200 ml at 80-90°C. One method used to achieve faster evaporation is to increase the heating rate so that the temperature changes rapidly, such as 100°C/min, which results in lower total yields due to overheating. The novelty of this work is that the heating rate to the steam generator is increased, thereby increasing the overall temperature and the surface water temperatures of the solar still and the water surface. The other advantage of the extended heating for three hours was that it also resulted in higher yields, and sunlight alone did not guarantee that high temperatures were equivalent to moisture-loss temperatures above 41°C.Various thermal enhancement techniques were used in the study, including sensible heat storage synthesis, warming in an aquatic basin, and altering surface absorptivity. Furthermore, external thermal support to increase heat supply and improve thermal conduction pathways to the basin was designed to keep high temperatures throughout the low-light availability period. This study examined the effect on system efficiency and the performance comparison of different approaches to increase the efficiency of the solar dehydration process under realistic operating conditions. This study provides a scalable, energy- efficient, and renewable-energy solution to locally produce freshwater for the benefit of global health and climate goals.
This study presents a platform that focuses on the improvement of the performance of trans-critical CO₂ refrigeration systems to face the big demand of economic and friendly cooling technologies, reduce environmental impact, and reduce operational costs. Four different refrigeration cycles were studied: abase cycle with 14 kW nominal capacity, a two-stage compression cycle, a cycle with R448a mechanical subcooling and a hybrid cycle that incorporates the two modifications. The Engineering Equation Solver (EES) software is used to analyze the different cycles under different operating parameters that includes gas cooling outlet temperature (35–50°C), evaporation temperatures (0–10 °C), compressor efficiencies (0.6–0.9), and gas cooler pressures (8,000–12,000 kPa). All modified cycles show more enhanced performance than base cycle. The hybrid cycle reached the highest coefficient of performance with an average enhancement of 55.3%, followed by mechanical sub-cooling cycle with (46.1%) average enhancement and two-stage compression cycle with (7%) average enhancement. The analysis showed that the hybrid cycle reduced power consumption by about 7.1% compared to mechanical sub-cooling cycle and by about 6% compared to the base cycle. Also, the mechanical sub-cooling showed an increase of power consumption of 13.2% over the base cycle. The increase in ambient temperature from 35 °C to 50 °C resulted in about 35.5% increase in power consumption and a 40.1% decrease in coefficient of performance (COP). This study is novel because it evaluates the combination of two-stage compression refrigeration system cycle and a mechanical sub-cooling cycle under the effect of Jordanian climate conditions, conditions, which resulted in achieving higher performance, lower environmental impact, shorter payback period, and higher return on investment (ROI).
This paper compares different studies to show how various fin shapes affect the thermal performance of heatsinks in both free and forced convection heat transfer modes, which are vital for heat dissipation in electronic and industrial systems. Numerical analysis was conducted to assess the cooling efficiency of various aluminum fin designs, including cylindrical, flat, trapezoidal, pin, annulus, elliptical, and tapered types. Some studies also explore the use of advanced materials, such as hybrid and quaternary nanomaterials, to improve thermal conductivity and reduce weight. Results show that elliptical fins with a side ratio between 2 and 2.65 offer the best heat transfer performance (exceeding 90%) under forced convection. Conversely, flat and cylindrical fins are most effective in natural convection. Importantly, the best fin shape and nanomaterial integration not only significantly enhances heat sink performance by decreasing thermal resistance compared to conventional designs but also promotes energy savings. These findings offer new insights into designing thermally efficient, compact, high-performance heat sinks, surpassing existing research and emphasizing the benefits of innovative shapes and materials for advanced cooling solutions.
The increasing global demand for high-quality greenhouse products, coupled with the heavy reliance on fossil fuels for climate control, has created an urgent need for sustainable, renewable-based solutions in agriculture. Conventional systems not only consume large amounts of energy but also contribute significantly to environmental pollution and greenhouse gas emissions. This study experimentally investigates a novel hybrid renewable energy system that integrates a windcatcher, photovoltaic-thermal chimney, and earth-to-air heat exchanger to provide passive heating and cooling for greenhouses. Experiments were conducted at Shahid Bahonar University of Kerman, Iran, using a lean-to greenhouse structure during peak summer (July-September 2024) and winter (January-March 2025) conditions. Vector linear regression was employed to develop robust predictive equations with broader applicability across different climates. Key performance parameters, including greenhouse temperature, ventilation rate, generated electricity, and the ratio of supplied electricity to consumed electricity (SECE), were measured and analyzed. Results proved a maximum temperature reduction of 21 °C in summer and successful maintenance of internal temperature between 19.5 °C and 22 °C in winter when outdoor temperature dropped to as low as 4.5 °C. The system achieved a ratio of supplied to consumed electricity exceeding 1, showing full self-sufficiency in meeting electricity demand, and delivered a higher coefficient of performance than most previously reported single- or dual-renewable systems. Energy and exergy analyses confirmed an energy-balance closure below 5% and second-law efficiencies of 0.32 in summer and 0.45 in winter. This study presents the first experimental demonstration of the configuration comprising a triple-hybrid windcatcher, a photovoltaic-thermal chimney, and an earth-to-air heat exchanger for greenhouse applications, addressing a critical research gap in integrated passive renewable systems and offering a practical pathway toward sustainable greenhouse thermal management in regions with high solar potential and extreme temperature variations.
The use of sustainable energy is of great importance in today’s world due to environmental issues and the lack of fossil fuels. Proton-exchange membrane fuel cells are a potential solution. The catalyst‐to‐ionomer ratio and the hot-press load are two important parameters that substantially affect the performance of the membrane electrode assembly. If the catalyst-to-ion-ion-ion-ion-ionomer ratio is too high, it can impair material bonding and cause uneven catalyst distribution; if it is too low, it can result in poor performance due to an insufficient catalyst amount. Likewise, too high a hot-press load can damage the porous catalyst layer, while too low a hot-press load increases the contact resistance between the catalyst-coated membrane and the gas diffusion layer. Optimization studies were performed on a 6.25 cm2 proton exchange membrane fuel cell with catalyst coated membrane-membrane electrode assembly at a loading of 0.15 mgPt cm-2. The best performance was achieved at a catalyst-ionomer ratio of 3:1 and a hot-press load of 160 kg. The statistical analysis with interaction plots and derived equations confirmed the correlation between the deviation value of 710 W m-2 (summed individual impact and integrated effect) and the traditional interaction effect value of 355 W m-2 (ratio of 2) and confirmed by the experimental results. The typical interaction effects are theoretically straightforward, and the deviation value provided here better depicts the influence of parameter interactions and provides a more reliable tool for performance measurement. The optimized catalyst-coated membrane electrode assembly showed a 5.8% improvement compared with a commercial membrane electrode assembly, mainly due to the optimized catalyst-to-ionomer ratio and hot-press load parameters. This work improves quantification and introduces a new evaluation metric, the deviation value, which can be extended to larger proton-exchange membrane fuel cell stacks, enabling a significant advance in the fundamental understanding of membrane electrode assembly design and in its practical application to sustainable energy systems.
This study focuses on perfecting greenhouse solar drying conditions for banana slices using Response Surface Methodology (RSM). Experiments were conducted across a temperature range of 40-60 °C and a drying period of 20-40 hours, employing a Central Composite Design to investigate their effects on three critical quality parameters: moisture content, color change (ΔE), and vitamin C retention. The developed quadratic regression models showed excellent prediction power with R² values from 95.2% to 97.8%. The moisture content was found to be in the range of 12.50% to 16.83%, color change 22.0 to 35.8 and vitamin C content 3.25 to 8.85 mg/100 g. Optimal drying conditions were determined to be 52.15 °C for 31.66 hours, which yielded balanced product quality with moisture content of 14.45%, color change of 29.55 and vitamin C content of 5.41 mg/100 g. The results presented here show that the optimized solar drying process is capable of high-quality production of dehydrated banana slices with retention of the nutritional contents and efficient energy use. Designed to be compatible with commercial scale drying equipment, the developed predictive models can help to lower the post-harvest losses and ease food processing in rural and industrial settings in a more sustainable manner.
This experiment investigates enhancing evacuated-tube solar collectors by combining carbon nanotube coatings with reflective mirrors. The study focuses on improving the heat absorption and retention capacity of solar collectors, thereby increasing the efficiency of solar thermal structures used for hot water production. This research investigates diverse configurations — black-painted plates, carbon nanotube-painted plates, and inclined mirrors — under extreme climatic conditions to assess their effects on water temperature and heat conservation. All enhancement techniques produced significant improvements in performance. Among the configurations examined, the carbon nanotube-painted plates produced the largest temperature increase, with temperatures reaching up to 70.88 °C. Moreover, reflective mirrors, strategically placed to maximize solar storage, produced a desirable temperature rise of up to 77.68 °C. The combined use of carbon nanotube coatings and mirrors yielded the most promising results, perfecting the temperature of hot water supplied across diverse weather conditions. This study provides strong evidence that the combination of carbon nanotube coatings and reflective mirrors can significantly improve the overall performance of evacuated tube solar collectors. These findings suggest that such advanced materials and configurations have a substantial capacity to enhance the efficiency of solar thermal storage systems, providing a promising and sustainable solution for water-heating applications in diverse environmental settings.
In this work, as a model for manufacturing coating processes, the thermal and solutal magnetohydrodynamic (MHD) flow of a Sisko hybrid nanofluid (AA7072 and AA7075 nanoparticles dispersed in methanol) over a bilinear stretching sheet next to a porous medium is investigated. The model includes Forchheimer inertial drag effects, heat source, chemical reaction, and thermal radiation. The study also considers boundary conditions for convective heating. Using similarity transformations, a system of nonlinear ordinary differential equations is derived from the original nonlinear partial differential conservation equations. This system is solved with transformed boundary conditions using the MATLAB bvp4c solver, and the results are verified for consistency and reliability. Graphical representations are used to examine the effects of several control parameters, such as the Sisko fluid parameter, radiation parameter, magnetic field parameter, Forchheimer parameter, and Schmidt number, on the transport characteristics. Using response surface method (RSM), we calculated the Nusselt and Sherwood numbers and the skin-friction components on the stretching surface. The results are confirmed using specific cases from previously published studies. According to the results, an increase in the Sisko fluid parameter increases the velocity profile, while it decreases the temperature and concentration profiles. Furthermore, increasing the magnetic-field parameter increases the velocity boundary-layer thickness. R2 value using Sherwood number and adjusted R2 were equal to 100%. This study sheds light on the dynamics of nanofluids in MHD systems, which have significant consequences for energy generation, electronic cooling, processing of magnetic materials, and other areas of chemical and biomedical engineering that rely on enhanced heat transfer.
Jet mixing ventilation using air is a well-known technology for providing thermal comfort in indoor environments. Jet diffusers are designed to maximize the effective dispersion of clean air and thermal energy for air conditioning or heating in an inhabited room. Jet diffusers are designed to improve mixing between jets and surrounding air and take aspects of aesthetic into account. However, the existing studies mainly focus on single jets or conventional multi-jet diffusers, and few studies have examined how central jet shape affects heat comfort and dynamic homogeneity. This paper presents a novel comparison of two multi-jet diffuser configurations. Both configurations consist of six peripheral jets of similar geometry, but the central jet is designed differently, one with a lobed central jet and the other with a swirling central jet. The originality of this work lies in the systematic evaluation of these diffuser designs from experimental and numerical points of view, concerning their influence on dynamic homogenization and thermal comfort. This work is different from earlier studies in that it uses multiple turbulence models, such as the RNG k-ε, the standard k-ω, the (k-ω) SST and the RSM models to decide the best predictive method for jet interactions. It was found that the swirling diffuser improves thermal comfort and dynamic homogenization significantly without any increase in the pressure drop and sound pressure level as compared to the lobed diffuser. Quantitative results show that the swirling central jet improves the axial dynamic and thermal homogenization by about 20% and the radial dynamic and thermal homogenization by about 10% with respect to the lobed configuration. Furthermore, the present study shows that the Shear Stress Transport k-ω SST model can accurately predict the complex flow structures and thermal characteristics of multi-jet diffusers, which can be a useful tool to optimize the geometric parameters of lobed and swirling perforated panels in heating, ventilation, and air conditioning systems. Also, the k-ω SST model showed better agreement with experimental data with root mean square error values of 0.0368 for axial velocity and 0.0384 for axial temperature. The results offer new insights into diffuser design strategies for better indoor air distribution and energy efficiency.
High-heat-flux dissipation technology has become a key bottleneck restricting development in fields such as electronic information, new energy vehicles, aerospace, high-power semiconductor devices, and data centers. The heat transfer performance of heat pipes and vapor chambers mainly depends on the structural characteristics of their core part—the wick. Therefore, in-depth research on wick structures is of great practical significance for addressing the thermal management challenges in the fields. Focusing on metal-based wicks, this study combines a literature review with quantitative analysis and systematically classifies them into 4 major categories (with 13 subcategories). These four categories are homogeneous porous structures, biporous structures, composite structures, and other structures. The key influencing factors (such as particle size, pore size, thickness, and preparation process) and best parameter ranges of various wicks are systematically discussed, their heat transfer performance and application adaptability are compared, and a “scenario-parameter-performance” matching framework is set up. The results show that biporous metal powder wicks exhibit the best performance with respect to critical heat flux and superheat temperature; composite wicks possess both high capillary force and high permeability; homogeneous porous wicks are simple to prepare but have relatively limited performance. Notably, discrepancies between actual test results and theoretical predictions are mainly attributable to inconsistencies in test components (single-wick, assembled heat pipe or vapor chamber), dimensions, heating power, and cooling conditions. Based on the above findings, it can be inferred that the core of wick performance optimization lies in achieving a synergistic balance between capillary force and permeability, and in customizing parameters for specific application scenarios. This study proposes a refined classification system and conducts cross-type comparisons of their heat transfer performance, thereby providing a reliable reference for engineering applications. Future research should incorporate actual operating conditions, improve wick performance, perfect long-term reliability, standardize test methods, and promote the transformation of composite wicks from laboratory research to large-scale engineering applications.
Combustion of wood logs continues to improve despite the diversification and standardization of wood-derived fuels. Gasification boilers— featuring separate gasification and combustion chambers—are widely used to meet stringent environmental requirements, yet they remain underrepresented in the engineering and scientific literature. To bridge this gap, 146 simulations were conducted to assess how refractory size, position, inclination angle, producer gas quality, and gas-inlet location affect flue-gas residence time, temperature fields, and heat transfer to boiler water. An 18-kW boiler is experimentally characterized with respect to producer-gas composition and temperature under varying gasification conditions. These data are used as boundary conditions for a CFD model that features non-premixed combustion and is described using the standard k–ε turbulence model, the Discrete Ordinates radiation model, and a domain-based weighted-sum-of-gray-gases model for radiative properties. Refractories not only protect metal surfaces, enable complete combustion, and aid particulate removal, but also enhance heat transfer. In total, 8 different combustion chamber designs are analyzed. Compared to the best refractory-free case, a combustion chamber with a U-shaped flue-gas flow path and two additional refractory-coated surfaces achieves 22% higher heat transfer despite a 17% smaller heat-exchange area. Refractories that create a U-shaped flow path extend flue-gas residence time, span at least half the chamber length, and feature an asymmetric channel height that favors a smaller flue-gas cross-section at the exit. Finally, combustion chamber design depends on upstream gasification performance—specifically, producer-gas composition and temperature, and air-preheating temperature.
JSW Steel’s Salem plant has committed to achieving Net Zero emissions by 2050, with a specific focus on reducing greenhouse gas emissions from its coal-based steam generation systems. Biomass, including briquettes, spent coffee grounds, wood chips, rice husk, and cattle dung logs, has been identified as a key component in reducing these emissions, particularly through its incorporation as a supplementary fuel in coal-fired boilers. This paper presents a comprehensive analysis of the challenges and solutions related to biomass fuel preparation, including briquette sizing, feed optimization, and contamination control. We propose an innovative action plan aimed at enhancing biomass fuel efficiency through optimized fuel size control, expanding biomass supply, and fostering deeper collaboration with suppliers. This action plan has resulted in a significant reduction in CO₂ emissions, with approximately 8,000 tons of CO₂ reduced annually a 5-10% improvement in boiler efficiency, and substantial cost savings due to reduced coal consumption through biomass blending. The novelty of this work lies in its comprehensive approach to biomass utilization, addressing challenges across the entire process from fuel preparation to combustion, and its focus on a real-world industrial setting using an AFBC boiler. In addition, we assess the plant’s current biomass fuel mix and compare it to India’s national strategies for sustainable energy utilization. The technical measures discussed herein for improving biomass feed systems contribute to improved boiler efficiency, higher fuel blending ratios, and substantial reductions in greenhouse gas emissions. these findings support broader sustainability goals and offer valuable insights for industries in India aiming to reduce their carbon footprints.
This study investigates TIG welding current variations effects on 4 mm thickness AISI 304 stainless steel joint welded using Argon gas, and this process impacts on ferrite composition, structural properties and joint strength. Ferrite content control must be managed properly to prevent hot cracking while ensuring both material strength and corrosion resistance because improper management leads to deficits during welding operations. A set of welding currents starting at 100 A progressed to 150 A and ending at 190 A created welds which delivered heat inputs of 6 J/mm, 9 J/mm and 11.4 J/mm. Welds under each condition received full inspection using metal structure analysis, scanning electron microscopy (SEM) along with Ferritoscope ferrite measurement, Vickers hardness analysis and mechanical strength testing. Data showed that a rise in heat intensity led to more ferrite formation starting from 4% at 100 A up to 9% at 190 A. The welds with 150 A heat application produced the optimal combination of mechanical properties since they contained 6% ferrite and displayed peak tensile strength at 689 MPa and mid-range hardness from 160–170 HV along with increased resistance to hot cracking. The welding current at 100 A produced a high hardness level of 170–181 HV in the weld but lost strength because of excessive ferrite content. Meanwhile the weld at 190 A exhibited lower strength and reduced hardness (150–157 HV) due to its excessive ferrite formation. Because of its ability to achieve superior microstructure with desirable austenite-to-ferrite ratio the weld using 150A heat input delivers optimal weld quality. The current investigation establishes quantitative assessments about heat treatment effects on AISI 304 TIG welds which distinguishes itself from previous research. The integration of Schaeffler diagram modeling with direct ferrite evaluations paired with SEM verification leads to a superior method for welding process prediction and enhancement.
Improving the thermal insulation of contemporary cement buildings is a significant challenge, particularly in desert environments subject to high temperatures. Adobe, a raw earth-based material, represents a practical solution due to its natural thermal properties. However, its low mechanical strength, particularly in bending, limits its integration into modern construction. This study demonstrates that a 13 cm layer of adobe reinforced with palm fibers, used as ceiling insulation, improves the thermal insulation of the building by approximately 133%, while reducing annual energy consumption by up to 53%. Furthermore, the impact of the length and dosage of palm fibers on the mechanical and thermal properties of adobe was examined through a series of tests. Four dosages (0.25%, 0.50%, 0.75% and 1% by weight) and four fiber lengths (25 mm, 50 mm, 75 mm and 100 mm) were tested. The results reveal that concentrations between 0.5% and 1% offer the best performance. In particular, the 50 mm fibers at 0.5% increased the compressive strength by about 20%, while the 75 mm fibers at 1% improved the flexural strength by up to 45%, reaching 1.70 MPa.
The main objective of this study is to optimize the geometry of a tension strip with opposite semicircular edge notches in order to reduce the stress concentration factor (h) by using computational techniques. An ABAQUS finite-element model was developed, and a full-factorial design of experiments was used to test the effects of four independent geometrical variables: width, notch radius, thickness, and length. The analytical workflow was automated through a MATLAB-ABAQUS interface, enabling a systematic parametric exploration of sixteen configurations. The inverse relationship between thickness and Kt was the strongest with the notch radius and width showing positive correlation. The lowest Kt was obtained with H=16mm, r=2mm, h=2mm and L=28mm, resulting Kt =1.73. This combined interface system is very effective and dependable process for notched components stress optimization.
As prospective alternative fuels for diesel engines, the current study examines two edible oils, namely sunflower and palm oil, and three non-edible oils namely jatropha, karanja, and waste cooking oil. The transesterification process was used to produce methyl esters from Karanja oil, Jatropha oil, Sunflower oil, Palm oil, and Waste cooking oil. The physical properties of these methyl esters met the specifications of IS biodiesel standards and were found to be similar to those of conventional diesel. An experimental setup used a single-cylinder, air-cooled, four-stroke direct injection diesel engine with a power output of 4.4 kW to assess the fuels performance, emission and combustion characteristics with varying blends of the methyl esters (20%, 40%, 60%, 80%, and 100%). Peak pressure, ignition delay and heat release rate were assessed in the combustion analysis. The performance metrics assessed included brake thermal efficiency, while the exhaust emissions analyzed were nitrogen oxides, hydrocarbons, smoke, and carbon monoxide. The experimental outcomes were compared to baseline data from diesel fuel. The findings indicated that the low blends of 20% biodiesel of Jatropha oil methyl esters (JTME), Karanja oil methyl esters (KME), Palm oil methyl esters (POME), Sunflower oil methyl esters (SFOME) and Waste cooking oil methyl esters (WCOME) served as the effective alternative fuel for performance and emissions under full load conditions among all fuels tested.
Dehumidification systems based on liquid desiccant have the potential to lower the latent cooling load of traditional vapour-compression airconditioning, especially in humid climates. This paper presents an experimental research on a liquid desiccant dehumidification system using calcium chloride that was run under controlled winter conditions. The effects of inlet air velocity and regeneration temperature on the outlet air relative humidity are evaluated. The results indicate that lower air velocities improve moisture removal because of increased air–desiccant contact time. The regeneration at about 58 C gave a relatively stable regeneration behaviour with a small range of outlet air relative humidity under the conditions of the experiment. The work gives experimentally determined operating trends applicable to real-world humidity-control applications and low-grade heat regeneration, and observes that the results are not to establish universal performance standards but to assist in optimising systems.
Increasing automotive usage drives exploration of polymer matrix composite (PMC) materials rather than conventional metals, such as aluminum (Al), for engine pistons and valve plates, to reduce mass and fuel consumption. The PMC materials generally offer many advantages but have poor thermal properties. Since poly(ether ether ketone) (PEEK) offers superior mechanical properties and thermal stability among thermoplastics, it can be used as a matrix in combination with conventional Al. However, the PEEK-Al composite has not been studied yet, either by simulation or experiment, for these engine parts. In the present study, a novel PEEK-Al composite system was designed, with Al content varying from 10–40 vol%, to identify the composition that yields the optimal mechanical and thermal properties. A structural and thermal analysis was performed using finite element analysis (FEA) in ANSYS. The present results were compared to determine the optimal composite compositions based on their thermomechanical properties. From the entire present FEA results, it is concluded that the PEEK-40%Al has best overall optimum mechanical (i.e., up to 1.056×107 Pa shear stress for Plate and 8.815×107 Pa shear stress for piston) and heat transfer (i.e., up to 2590.3 W/m2 heat flux for Plate and 74.939 W/m2 for Piston) characteristics for plate and piston materials. Hence, PEEK-40%Al, which has the best heat-transfer characteristics, can be applied to both engine plates and piston components. Hence, these PEEK-Al composites will enhance engine efficiency and align with automotive sustainability goals.
The present work considers dual-solution behaviour of radiative hybrid nanofluid flow of sodium alginate containing aluminium alloys (AA7072 and AA7075) past a power-law stretching/shrinking sheet with suction. This understanding of such flow is important because of applications in thermal energy systems, biomedical devices, and aerospace cooling technology. The governing nonlinear boundary layer equations have been transformed using similarity variables and then solved numerically using the MATLAB bvp4c solver. The influence of the magnetic field, thermal radiation, suction, volume fractions of the nanoparticles, thermal slip, and chemical reactions on the velocity, temperature, and concentration profiles has been discussed in the analysis. It is found that the temperature profile increased by 15.6% due to the increase of the radiation parameter and heat source term. In comparison, the velocity approached the wall decreased by 12.3% due to the increase of the modifier parameter. The suction leads to better stability for the boundary layer, while increasing the values of the Prandtl and Schmidt numbers enhances the thermal and concentration boundary layer thickness. In certain ranges of both the suction rate and the stretching/shrinking rates, there exist dual solutions that indicate a bifurcation of the flow and a sensitivity of the stability. The new addition to existing models presented in this work is the mixture of sodium alginate with dual aluminium alloy nanoparticles under the influence of both radiative and MHD effects, allowing for new perspectives in hybrid nanofluid control mechanisms. These findings can be applied to increase the efficiency of heat and mass transfer in new, high-tech industrial and biomedical systems.
This work is about graphene-TiO₂ hybrid nanofluid used for cooling a diesel engine exhaust manifold via coupled CFD simulations and experimental validation. The authors of this paper confirmed grid independence at more than 800 mesh elements with the pressure converging within -6 to 4 Pa. At 4.102 m/s velocity, the hybrid nanofluid caused a 7.016 Pa pressure drop, whereas the same for the conventional coolants was only 4.620 Pa thereby, the 52% rise in the pressure differential that correlates with the convective mixing enhancement. Streamline visualization depicted flow regularity improvement with the use of nanofluids, whereas turbu-lent kinetic energy increased steadily from 0.05 to 0.25 m²/s² over the 0-4 m/s velocity range, thereby promoting heat transfer directly. The enhancements in thermal conductivity of 5% and the heat transfer coefficients of 6% (with respect to the baseline fluid) have made it possi-ble to reduce the peak manifold temperature by 340°C. The pressure gradient or the change in pressure remained very stable (within ±6 Pa) all over the domain, which is a clear indication that the hydrodynamic behavior was under control. The experimental data corroborated the CFD predictions with temperature and pressure drop accuracy percentages of 30% and 20%, respectively. These results confirm that graphene-TiO₂ nanofluids are capable of resulting in specific improvement metric of "15% faster heat dissipation" or "20°C lower operating temperatures" in automotive exhaust systems and establish a validated computational framework for nanofluid-based thermal management design in internal combustion engines.
