Journal of Thermal Analysis and Calorimetry最新文献

In response to the increasing demand for energy efficiency and sustainability in marine applications, this study presents the design and thermodynamic analysis of a combined-cogeneration power plant integrated with an LM2500 gas turbine-powered naval ship. The proposed system aims to enhance operational efficiency, minimize fuel consumption, and reduce carbon emissions by leveraging waste heat recovery from the gas turbine exhaust. A comprehensive energy analysis is conducted to evaluate system performance under varying compressor pressure ratios (11.4–18.1) and steam extraction ratios. The results indicate that as the compressor pressure ratio increases, both net power output and overall system efficiency improve significantly, reaching a maximum of 23,233 kW and 60.28%, respectively. In addition, exergy analysis was conducted, revealing that the overall exergy efficiency of the proposed system is up to 0.419 with rising compressor pressure ratios, indicating reduced irreversibility and improved utilization of the fuel’s available energy potential. However, fuel savings and emission reductions exhibit a decreasing trend at higher pressure ratios, highlighting the diminishing returns in energy conservation. The system achieves a maximum fuel savings of 552.009 kg h^–1, a cost reduction of 684.492 USD h^–1, and a CO₂ emission reduction of 1749.871 kg h^–1 at an optimal pressure ratio of 11.4. Furthermore, the obtained results are compared with data taken from naval surface ships, demonstrating strong agreement and validating the effectiveness of the proposed system. These findings underscore the effectiveness of combined-cogeneration cycles in naval propulsion systems, offering a promising pathway for enhancing sustainability, fuel economy, and mission endurance in marine operations.

In this article, both local non-similarity and global non-similarity solutions of the governing equations for momentum and thermal transport of Williamson nanofluid over a curved surface are reported. Effects of magnetic field, Joule heating, Brownian motion, and thermophoresis are taken into account. The problem is model using conservation laws of mass, momentum, energy, and nanoparticle concentration. The boundary layer approach, along with suitable dimensionless variables, simplifies the governing partial differential equations. The resulting equations for local non-similar and non-similar solutions are solved numerically. The flow features are presented and discussed for both curved and flat surfaces. The obtained velocity, temperature profiles, skin friction, local Nusselt number, and Sherwood number for different values of parameter are presented and discussed. Numerical values of skin friction, the Nusselt number, and Sherwood number are presented in tabular form. The results are validated with existing literature. A comparative analysis between local non-similarity solutions and global non-similarity solutions shows that flow and heat transfer features are strongly influenced with streamwise coordinate.

Pool boiling is a fundamental heat transfer process with wide-ranging applications in electronics cooling, energy conversion, and power systems. However, its performance is often constrained by the inherent limitations of the heat transfer coefficient (HTC) and critical heat flux (CHF). To address these challenges, extensive research has focused on tailoring surface characteristics through advanced microstructural modifications. This review consolidates and critically evaluates recent progress in chemical treatments, mechanical patterning, nanostructuring, and laser-based fabrication methods designed to improve pool boiling efficiency. The discussion encompasses surface modifications across macro-, micro-, and nanoscales, highlighting structural configurations such as cavities, grooves, channels, fins, and hybrid architectures that integrate multiple geometries. By comparing modified surfaces with conventional smooth counterparts, the review identifies key mechanisms responsible for performance enhancement, including increased density of nucleation sites, capillary-assisted liquid replenishment, vapor bubble departure control, and improved wettability. Notably, laser surface texturing and hybrid micro/nanostructured surfaces consistently demonstrate superior outcomes, with reported HTC enhancements of up to threefold and CHF improvements exceeding 100% under optimized conditions. Beyond summarizing experimental findings, the review emphasizes critical considerations for practical deployment. Scalability of fabrication methods, compatibility with diverse materials such as metals and ceramics, and long-term durability under repeated thermal cycling are assessed as essential factors for industrial integration. Furthermore, attention is given to the potential trade-offs between fabrication complexity, cost, and achievable thermal gains. Overall, this review highlights the transformative potential of microstructural surface engineering in advancing pool boiling performance. Bridging fundamental mechanisms with technological applications provides a comprehensive framework to guide future research and innovation. The findings suggest that next-generation boiling heat exchangers, enabled by tailored surface designs, could deliver compact, energy-efficient, and high-reliability thermal management solutions for emerging fields ranging from microelectronics to renewable energy systems.

Enhancement in heat transfer can be realized by adding nanoparticles to boost the thermal properties of the base fluid, increase the tube surface area, and modify the flow trajectory of the fluid. In the present investigation, the convective heat transfer and pressure loss characteristics of Al₂O₃-Ethylene glycol and Al₂O₃-Water-based nanofluid in the vertically positioned helically coiled tube with micro-fin are studied by ANSYS FLUENT 19.2 through numerical methods. The effects of nanofluid mass fraction (1–4%), Reynolds number changing (10,000–30,000), micro-fin number (4–12), and the coil diameter (100–200 mm) on the heat transfer coefficient and pressure drop characteristics are carried out. The heat transfer and pressure drop characteristics are found to be highly sensitive to changes in Reynolds number and nanoparticle volume concentration. Furthermore, an increase in micro-fin density contributes to elevated heat transfer coefficients and higher pressure losses in nanofluid. The study confirms that the thermal performance index of Al₂O₃-Ethylene glycol nanofluid is universally lower than that of Al₂O₃-Water nanofluid across all nanofluid mass fraction.

Enhancing the heat transfer efficiency of solar air heaters (SAHs) remains a critical challenge in renewable energy applications due to the inherently poor convective characteristics of air. Improving the absorber plate design through optimized roughness geometry is therefore essential for achieving higher energy conversion efficiency. Despite numerous studies on conventional rib geometries, limited attention has been paid to the comparative thermo-hydraulic behaviour of fixed and variable arc rib configurations under identical boundary conditions. This study numerically investigates the thermal and fluid flow performance of SAHs equipped with three arc rib geometries: Fixed Arc Rib (FAR), Fixed Arc Rib with Diameter variation (FARD), and Variable Arc Rib (VAR) over two duct lengths (1 m and 2 m). Simulations were performed using the RNG k–ε turbulence model under a uniform heat flux of 1000 W m⁻² and Reynolds numbers ranging from 3000 to 21000. The results reveal that the VAR(1 m) configuration achieves the highest thermal efficiency (93.2%) and exergy efficiency (2.65), while FARD(1 m) exhibits the best thermo-hydraulic performance parameter (THPP ≈ 6.1). Velocity contour analysis further confirms enhanced mixing and turbulence intensity for variable rib geometries. The findings offer practical design guidance for developing compact and energy-efficient solar air heaters suitable for sustainable heat recovery systems.

The study is concerned with the optimization of performance of solar drying to be carried out on ivy gourd (Coccinia grandis) making use of indirect convection-based technologies. The results of three systems of dryer such as indirect solar dryer (ISD), mixed-type solar dryer (MSD) and greenhouse solar dryer (GSD) were compared based on drying kinetics, product quality, nutrient retention and energy consumption. The effect of four important parameters such as drying temperature, drying time, air velocity and type of dryer used was studied using response surface methodology (RSM). The experimental analysis indicated that the rate of drying was very much enhanced with variation of temperature and the air velocity, the value being high (19.7 g h^–1) in the mixed-type dryer. A maximum of nutrient retention (86.2) was achieved at the moderate temperatures and low drying times, more so when the application of energy efficiency with consideration of designs in dryers was adopted. Nonetheless, the increased temperature of drying and an increased time had significant knock-off effects on the heat-sensitive nutrients. The difference in energy consumption across conditions was quite large with a high of 15.7 kWh attained at the maximum parameter level. The paper presents essential trade-offs between the consumption of energy and the quality of products. The indirect dryer exhibited a high degree of energy efficiency, and the mixed-type dryer provided relatively high rates of drying with tolerable loss of quality. The greenhouse dryer demonstrated a well-balanced ratio in the quality and sustainability indicators. RSM integrations enabled determination of the best drying conditions, which at the same time consumed minimal energy and preserved maximum nutrients. The study has added a strong framework in the designing and operation of solar drying systems that address various agro-processing requirements, a sustainable, energy-efficient and quality food preservation at post-harvesting.

Forest fires mainly come from the surface fuel layer, and the key to reducing the risk of forest fires is to block the spread of surface fires. Due to the complexity of the terrain environment, it is difficult to achieve efficient and rapid fire prevention by conventional physical means, which increases the difficulty and cost of forest fire prevention and control. Therefore, it is imperative to find a suitable, effective and clean extinguishing agent. In this paper, the inhibition test of fire extinguishing agent isolation zone in indoor environment was carried out on the spread of surface litter fire in the area with frequent forest fires in Southwest China. Three different fire extinguishing media, water, foam fire extinguishing agent and hydrogel fire extinguishing agent, are used. The results show that the different extinguishing media are able to suppress flame spread of mixed leaf litter combustion and the phenomenon of flying fire. However, as the slope increases, water and foam extinguishing agents cannot completely inhibit the spread of foliage litter flames, and during the period of inhibition by these two extinguishing media, when fuel flames are prone to spreading and burning across the containment zone, hydrogel is effective in inhibiting the spread of foliage litter flames. Comparing the peak temperature of TC1 before isolation zone and the peak temperature of TC5 after isolation zone, the reduction is about 70 °C, 176 °C and 208 °C in the three extinguishing media conditions, respectively. And the cooling effect of hydrogel is the best compared with water and foam extinguishing agent. Based on the results of different widths of hydrogel barrier inhibiting the spread of leaf litter at different slopes, the relationship model between the intensity of surface fire spread at different slopes and the width of hydrogel barrier is constructed, and the boundary conditions of the hydrogel barrier inhibiting the spread of surface fire in leaf litter are determined, which is of great significance for the design of forest fire fighting systems.

Scholars are interested in the significance of this study, which looks at a transportation phenomenon where the host fluid is fully mixed with three different types of nanoparticles (ternary hybrid nanofluid). Tri-hybrid nanofluid's (THNF) special capacity to enhance thermal performance is the main driver of its growing popularity, as it is highly beneficial in a variety of heat exchangers. In order to observe the fluid heat presentation, the primary goal of this research is to analyze the Incompressible, unsteady, laminar 3D magnetohydrodynamics (MHD) ternary hybrid flow with the model of heat flux and viscous dissipation of nanofluid between two surfaces. This method for succeeding a well heat conductor than hybrid nanofluid (HNF), and mono nanofluid is described by this model. Three different kinds of nanoparticles with unique chemical and physical bonds are added to water as a base liquid to create the ternary nanofluid. This mixture aids in environmental cleaning, the breakdown of harmful materials, and the cooling of other devices. At z = 0, the lower disk remains fixed the top disk moves axially, while causing the liquid to squeeze. A homogenous suction or injection is applied at the lower surface. At the fixed bottom disk, the effects of energy and velocity slip are also taken into account. The governing equations are transformed into nonlinear ordinary differential equations (ODEs) by applying the proper similarity functions, and the bvp4c approach is then used to solve them numerically in the MATLAB environment. The results are then graphically shown to examine the velocity, temperature and concentration profiles. Finally, we determine that the thermal conductivity of tri-hybrid nanoparticles is well as compare to hybrid and nanofluids particles since the temperature profile reduced against the tri-hybrid case in the bottom disk case and subsequently increased near the top disk in the tri-hybrid case. For a small number of examples, the current findings are shown to be in good agreement with existing literature.

To improve the slow crystallization and difficult processing issues of polyethylene terephthalate (PET) and enhance its mechanical properties, we prepared a nucleating agent composed of sodium linoleate and talc, studied the synergistic effects of both individual and composite components on properties of PET, and established that the optimal talc to sodium linoleate ratio is 1:1. The sodium carboxylate component serves as the primary active agent governing PET crystallization. The synergistic action of both can lower the crystal grain size during PET crystallization, resulting in a 13–23% enhancement in flexural modulus. Based on the findings, we prepared five alternative compound nucleating agents (CNAs) made from sodium carboxylate and talc. Among them, the crystallization performance and mechanical properties of PET nucleated with the CNA in which the mass ratio of sodium linoleate to talc is 1:1 exhibited the most significant enhancement compared with pure PET, surpassing the performance improvement observed in PET nucleated with the commercial nucleating agent P250. The findings indicate that the nucleating agents developed in this work demonstrate significant potential to substitute commercial nucleating agents, reducing production costs, enhancing PET characteristics, and facilitating industrial manufacturing.