Phase change materials (PCMs), an innovative class of functional materials, exhibit the ability to store or release thermal energy through reversible transformations at specific phase transition temperatures, which have been extensively employed in aerospace, military, construction, and refrigeration industries. As oil and gas exploration and development word-widely advance into deeper formations, extremely high-temperature and high-pressure conditions in these environments impose significant challenges on drilling fluids and down-hole instruments, limiting the progress of deep hydrocarbon exploration. To address the technical challenges related to the high-temperature resistant stability of drilling fluids in deep formations, this study investigates the integration of PCMs into drilling fluids. Through theoretical analysis and experimental simulations, the feasibility of utilizing the "phase change heat storage principle" of PCMs to reduce circulating drilling fluid temperatures in boreholes was demonstrated. The results indicate that three selected PCMs exhibit phase transition temperatures in the range of 120–145℃ and phase change latent heat of 90.3–280.6 J/g, showcasing excellent phase change heat storage properties. The materials were found to be compatible with drilling fluids. At a PCM concentration of 12%, the rheological and filtration properties of the drilling fluids still met operational requirements. Incorporating PCMs into drilling fluids effectively reduced the circulating temperature in boreholes, with a more pronounced cooling effect observed at higher PCM concentrations. At a concentration of 12%, the circulating temperature of drilling fluids was reduced by up to 20℃. Additionally, the PCMs demonstrated good reusability, consistently undergoing the "heat storage and release" phase change process, thereby satisfying the circulating cooling demands of drilling fluids. The findings provide a robust reference for PCM integration in high-temperature drilling fluids, particularly in ultra-deep wells with extreme thermal conditions.

The thermal performance and energy efficiency of Photovoltaic Thermal (PVT) systems were investigated through the integration of Phase Change Materials (PCMs) combined with distinct container configurations. Two types of PCMs—paraffin wax, an organic material, and Polyethylene Glycol 1000 (PEG-1000), a polymer-based alternative—were embedded within two container designs: a plain container and a baffled container. To evaluate the impact of PCM selection and container geometry on system performance, a series of numerical simulations were conducted using Computational Fluid Dynamics (CFD) in ANSYS Fluent under varying solar irradiance levels of 300, 600, 900, and 1200 W/m². The results revealed that PCM integration significantly mitigates the operating temperature of PV cells, contributing to enhanced thermal stability and electrical conversion efficiency. At the highest irradiance of 1200 W/m², the plain paraffin configuration attained a minimum cell temperature of 27.4℃ and achieved the highest electrical efficiency of 11.7%. Conversely, the baffled PEG-1000 configuration exhibited a slightly higher peak temperature of 28.1℃ with a corresponding efficiency of 11.18%. Although the baffled container promoted improved internal heat distribution, the plain configuration demonstrated superior overall thermal regulation. These findings underscore the critical influence of PCM thermal properties and container geometry on the operational sustainability of PVT systems. This study provides new insights into PCM-container coupling strategies, offering a valuable framework for the development of high-efficiency, sustainable solar energy systems.

The transition from outdated biomass boiler systems to modern, efficient district heating technologies represents a critical pathway toward sustainable energy production. In this study, the replacement of obsolete solid biomass-fueled boilers with a new wood chip-based heating system in the district heating plant of Pale, Bosnia and Herzegovina, was analyzed under real-world operational conditions. Historical operational data, including annual fuel consumption, were obtained directly from the facility. The degree-day method was applied to evaluate the thermal efficiency of the former heating system and to estimate the annual fuel demand for the newly installed wood chip-based infrastructure. A key component of this transition involves the reliability and efficiency of the wood chip supply chain. Therefore, the logistical feasibility of securing a continuous, local, and renewable wood chip fuel source was examined, including the assessment of storage capacity and supply chain resilience. Furthermore, a scenario-based simulation was conducted to project the cost of heat production under varying fuel price conditions and market dynamics. Through this integrated approach, a replicable methodology was proposed for replacing legacy biomass heating systems with environmentally sustainable, economically viable district heating technologies based on locally sourced wood chips. The findings offer a practical roadmap for municipalities aiming to achieve energy transition targets through the adoption of locally available renewable energy sources, with particular emphasis on operational feasibility, fuel logistics, and cost-effectiveness.

The present paper emphasizes finding the solution for a fuzzy fractional heat conduction equation using the homotopy analysis transform method (HATM). The HATM combines two powerful, well-known methods: homotopy analysis method and the Laplace transform method. The approximate solution of the fuzzy fractional heat conduction equation is obtained by using HATM. Comparison with existing methods shows that the results obtained using the proposed method are in good agreement with the exact solutions available in the literature. All the numerical computations justify the proposed method is very efficient, effective, and simple for obtaining an approximate solution of the fuzzy time-fractional heat conduction equation.

A novel approach for analyzing fluid flow dynamics and static pressure distributions within a convergent-divergent nozzle was presented, integrating soft computing techniques with computational fluid dynamics (CFD) simulations performed using Ansys Fluent. The study differs from traditional CFD approaches by leveraging soft computing methods to optimize simulation parameters and enhance the accuracy of predictions. Four distinct fluids—air, hydrogen, nitrogen, and helium—were analyzed across a range of inlet velocities (1 m/s to 5 m/s). The study systematically evaluates the influence of boundary conditions and flow models, including both viscous and inviscid conditions, on the flow patterns and static pressure distributions. The results highlight the substantial impact of fluid density and viscosity on the flow dynamics, particularly for lighter gases such as hydrogen and helium. These gases exhibit higher velocities and less pronounced pressure gradients due to their lower density and viscosity compared to denser fluids like air and nitrogen. Soft computing techniques improve the reliability of these findings by enhancing the predictive capability of the CFD model, allowing for more precise insights into complex fluid behaviors. The implications of these findings are significant across multiple engineering domains, such as aerospace propulsion, chemical processing, and energy systems, where optimizing fluid flow characteristics is critical. The integration of soft computing with CFD provides a robust framework for more accurate modelling of low-density, high-velocity flows and offers valuable insights for the design of more efficient systems. This study underscores the potential of advanced computational techniques in advancing both fluid dynamics research and engineering applications.

The concept of heat commodification is proposed as a sustainable solution for global energy management, with heat being treated as a tradable commodity in an international market. In such a market, heat would be assigned a value based on factors such as available enthalpy, heat grade (temperature), and the time at which it is delivered. Heat, as the currency of this market, would allow for a decentralized and dynamic exchange system. A central heat market could be established, extending down to individual households where excess heat—such as waste heat from household appliances—could be stored and traded locally, potentially through a peer-to-peer model or a virtual marketplace. A key innovation in this system would be the development of modular heat storage solutions, analogous to gas bottles, that allow consumers to store excess heat and exchange it within the market. These “heat packets" would be rechargeable with heat, as opposed to gas, and could be traded both physically or digitally. To ensure inclusivity and sustainability, it is suggested that these heat packets be based on nature-inspired storage materials that can efficiently store renewable or waste heat with minimal environmental impact. Specifically, thermochemical storage media, such as salt, would be employed to facilitate charging and discharging processes using water as a trigger. Such solid-state storage systems would allow heat to be stored indefinitely with minimal heat loss to the environment, even in lower temperature conditions. This paradigm shift could enable the cross-continental transport of heat packets, revolutionizing the global energy market. The proposed system would also eliminate the need for electricity grids and reduce inefficiencies associated with energy conversion, as heat can be stored and utilized directly for both heating and cooling applications. Furthermore, the reliance on heat-driven refrigeration systems would obviate the need for electricity-driven heat pumps or chillers. This approach offers a potential solution to global energy challenges by facilitating a sustainable and efficient heat exchange network on a global scale.

Water-cooled heat sinks are efficient cooling solutions for high-heat dissipation applications in industrial and electronic systems. This study investigates water-cooled heat sinks' thermal and hydrodynamic performance through Computational Fluid Dynamics (CFD) simulations. The fluid flow distribution, heat transfer characteristics, and thermal efficiency of various cooling channel geometries were examined under controlled conditions, including a mass flow rate of 0.05 kg/s, an inlet fluid temperature of 22℃, and a convection film coefficient of 80 W/m²℃ between the fluid and heat sink. Additionally, the convection coefficient between the heat sink body and its fins to the environment was set at 10 W/m²℃, with an ambient temperature of 22℃ and a heat flux of 10,000 W/m² applied to the heat sink's base. The analysis reveals that the coolant channel geometry, flow velocity, and the materials' thermophysical properties strongly influence the system's thermal performance and pressure drop. The optimized channel configuration significantly enhanced the heat dissipation efficiency, achieving an increase of 49.1% and a temperature reduction of 59℃. Furthermore, a thermal efficiency of 40.97% and an overall system efficiency of 45.04% were attained. These findings highlight the substantial role of optimized channel geometries in enhancing the performance of water-cooled heat sinks, leading to more efficient and effective cooling systems. The study demonstrates that CFD simulations can be a powerful tool in identifying key design parameters that maximize heat transfer efficiency in water-cooled heat sinks.

To investigate the variation in the diffusion patterns of natural gas leaks in the Floating Production Storage and Offloading (FPSO) system, with the aim of formulating appropriate emergency response strategies and minimizing accident losses, a study was conducted on the gas leak issues of oil and gas processing equipment in the FPSO upper module. A consequence prediction and assessment model was established based on Computational Fluid Dynamics (CFD) methods. Sixteen working conditions and one control working condition were developed to simulate the diffusion characteristics of combustible gas leaks. The simulations provided insights into the gas leakage patterns under different conditions and identified the most hazardous scenario for gas leaks in the FPSO upper module. The results indicate that the density and shape of the equipment within the upper module significantly influence the diffusion outcome. After a leak, high concentrations of combustible gas were observed near the crude oil heat exchanger skid in Industrial Zone II. The effects of individual factors on gas diffusion were significant, and the interactions among multiple factors were complex. Wind speed had a more pronounced effect on longitudinal gas diffusion compared to wind direction and leak aperture, while wind direction significantly influenced lateral gas diffusion. The leak aperture, on the other hand, had a more substantial impact on vertical gas diffusion.

The thermal behavior and fluid dynamics of Nano-Enhanced Phase Change Materials (NEPCM) in enclosed systems have been investigated using numerical simulations, focusing on the effects of time-varying temperature profiles and nanoparticle concentration. The analysis reveals that the inclusion of nanoparticles significantly enhances the fluid flow velocity and streamlining within the enclosure, particularly for aluminium oxide (Al₂O₃), copper oxide (CuO), and zinc oxide (ZnO) nanoparticles. The results indicate that an increase in nanoparticle concentration leads to an acceleration in fluid flow and improved heat transfer efficiency, with distinct phase change dynamics observed across different concentrations. The study demonstrates that nanomaterials hold substantial potential for enhancing the thermal performance of NEPCM systems. These enhancements can contribute to greater efficiency in thermal energy storage (TES) and heat transfer processes, particularly in industrial applications requiring energy optimization. The findings align with previous research, emphasizing the positive correlation between nanoparticle concentration and velocity streamlining. This work provides valuable insights for the future exploration of different nanoparticle types and concentrations, paving the way for the development of more efficient NEPCM systems in advanced thermal systems.

The study aimed to compare the effects of thermal stratification ($S$), anisotropic parameters ($k^*$ and $\theta$), and buoyancy force distribution parameter ($m^*$) on natural convection in fluids characterized by high and low Prandtl numbers. The second-order coupled partial differential equations governing the problem were initially converted into ordinary differential equations through the Laplace transform technique. The D'Alembert method was then applied to systematically decouple these equations without altering their original order. Subsequently, the closed-form solutions in the Laplace domain were transformed into their respective time domains using a numerical scheme based on the Riemann sum algorithm. The research established that reverse flow is feasible under certain conditions, occurring more rapidly in fluids with lower Prandtl numbers. Additionally, it was observed that an increase in $k^*$ and $S$ reduces skin friction on the bounding plates, whereas an increase in $\theta$ enhances skin friction on both channel walls.