Solid oxide fuel cell/gas turbine (SOFC/GT) hybrid systems have been recognized as a promising solution in the pursuit of high-efficiency and low-emission power generation, offering electrical efficiencies exceeding 60% and notable fuel flexibility. However, the substantial amount of high-temperature exhaust gas (typically in the range of 700–800 K) released during operation has presented ongoing challenges in effective thermal energy recovery, thereby constraining further improvements in overall system efficiency. In recent years, various waste heat recovery technologies have been explored for their applicability to SOFC/GT systems. Among the most studied are the supercritical carbon dioxide (SCO₂) cycle, the transcritical carbon dioxide cycle (TRCC), the organic Rankine cycle (ORC), the Kalina cycle (KC), and the steam cycle (ST). In this review, the thermodynamic principles, performance metrics, and thermal integration compatibility associated with each technology were critically examined. In addition, a novel waste heat recovery configuration optimized for SOFC–GT hybrid systems was proposed and discussed. This approach was conceptually validated to enhance total system efficiency and to facilitate the development of advanced combined heat and power (CHP) systems. The results contribute to the broader efforts in clean energy system design and offer technical insights into the next generation of high-performance, low-emission power technologies.

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.