Journal of Thermal Analysis and Calorimetry

Rajamony, Reji Kumar; Suraparaju, Subbarama Kousik; Kalidasan, B; Hasanuzzaman, M.; Selvaraj, Jeyraj; Bakthavatchalam, Balaji; Sofiah, A. G. N.; Samykano, Mahendran

doi: 10.1007/s10973-026-15625-xpmid: N/A

Transparent covered slope solar stills have gained significant attention for clean water production; however, their widespread adoption is limited by low productivity, high heat losses, and operation restricted to daylight hours. To address these challenges, this study proposes an innovative integration of silver-enhanced phase change materials (AgePCM) into a solar still (SS) system. The thermophysical properties of AgePCM at varying nanoparticle concentrations (0.2, 0.4, 0.6, 0.8, and 1.0 mass%) were systematically characterized, including morphology, chemical stability, optical performance, thermal conductivity, energy storage capacity, and thermal reliability. A dimensionless figure of merit (FOM) was introduced to enable standardized comparison of nanoenhanced PCMs. Although AgePCM-5 exhibited the highest FOM, AgePCM-4 was identified as the optimal formulation due to its superior thermal conductivity and balanced thermophysical performance. Experimental results revealed that the optimized AgePCM-4 sample achieved a 73.82% increase in thermal conductivity, a 6.02% enhancement in melting enthalpy, and a 62.85% reduction in light transmittance compared to the base PCM. A three-criterion parametric sensitivity analysis identified thermal conductivity as the dominant factor governing productivity enhancement, contributing 49.81% of the total logarithmic gain, followed by optical absorbance (44.93%) and melting enthalpy (5.27%). The AgePCM-integrated solar still (SS-AgePCM) system demonstrated significant improvements, with water temperature and distillate production increasing by 5.0% and 89.7%, respectively. Economic analysis indicated a reduced freshwater production cost of ₹2.4 per liter and a payback period of 6.9 months. These findings demonstrate the effectiveness, scalability, and economic viability of the proposed system for sustainable water production in water-scarce regions.Graphical abstract[graphic not available: see fulltext]

Chen, Y. K.; Sun, Y.

doi: 10.1007/s10973-026-15750-7pmid: N/A

Calcium-silicate-hydrate (C-S-H) seeds, recognized as an efficient accelerator for enhancing early-age hydration and facilitating rapid construction, have attracted considerable attention in cement-based materials. However, their synthesis typically relies on analytical-grade reagents, leading to high production costs. To address this limitation, this study investigated the feasibility of economically synthesizing C-S-H seeds from two agricultural wastes: silicon-rich palm oil fuel ash (POFA) and calcium-rich eggshell powder (ESP). Silicate and calcium species were extracted from POFA and ESP via strong alkaline and acid dissolution, respectively, followed by co-precipitation of C-S-H seeds through controlled mixing of the resulting leachates. The particle size distribution, morphology, phase composition, and microstructure of the synthesized C-S-H seeds were systematically characterized. Besides, the accelerating performance of the seeds was also evaluated by examining setting time, isothermal hydration heat, strength development, phase assemblage, and water absorption of cement pastes with and without seed incorporation. The results demonstrated that microscale C-S-H seeds with an average particle size of 14.2 μm were successfully synthesized. Despite their relatively larger particle size compared with commonly reported nanoscale seeds, the synthesized products significantly shortened the setting time and enhanced both early- and late-age compressive strength. Furthermore, the production cost of the agricultural waste-derived C-S-H seeds was reduced by approximately 75%, reaching only 183.30 US$/ton. This substantial reduction ensures economic feasibility for large-scale application of C-S-H seeds without significantly increasing the overall cost of cement-based systems. In summary, this work presents a facile and cost-effective strategy for producing C-S-H seeds from agricultural wastes and provides new insights into their role in enhancing the early-age performance of cementitious materials.

Benettayeb, Youcef; Benouali, Abderrahmen; Tahri, Toufik; Cuce, Erdem; Bicer, Yusuf; Benali, Alouache

doi: 10.1007/s10973-026-15783-ypmid: N/A

In this study, an experimental solar chimney power plant (SCPP) is designed, built, and tested at the University of Chlef, Algeria. The prototype consists of a chimney height (CH) measuring 6 m as well as a chimney diameter (CD) of 0.40 m, with a solar collector of 5 m in diameter, 0.40 m in inlet height, and 5° inclination. This study describes the geometric configuration, material selection, and detailed construction procedure of the SCPP prototype. The experimental investigation aims to examine the effect of air inlet design parameters on the aerodynamic and thermal performance of the system. Measurements are taken under local climatic conditions, with the ambient temperature (AT) averaging 312 K and solar radiation intensity peaking at 817 W m−2. Key parameters, including airflow velocity through the chimney as well as the temperature distribution within the collector, are continuously recorded throughout the experiments. To enhance the airflow distribution beneath the collector, the traditional open-air inlet is modified into a circular configuration. The experimental setup considers air inlet diameters of 10, 20, and 30 cm. In addition, three inlet arrangements comprising 2, 4, and 6 openings are systematically investigated. The findings indicate that the best system performance is achieved using a 20 cm inlet diameter with a four-inlet circular configuration, resulting in an airflow velocity of 3.2 m s−1, a corresponding collector-beneath air temperature of 332 K, and an output power (PO) of 2.72 W. These outcomes confirm that optimising air inlet geometry, particularly through circular air inlet design, significantly enhances airflow distribution and overall system performance.

Sharma, Chandra Shekhar; Ranganayakulu, Chennu; Vishwakarma, Devendra Kumar

doi: 10.1007/s10973-026-15831-7pmid: N/A

The environment control system (ECS) of an aircraft is essential for regulating the temperature and pressure and providing the ventilation for the cabin and avionics with respect to altitude and Mach number based on an air-cycle-based bleed or bleed-less system. However, various studies have been conducted on the thermodynamic analysis of the ECS, comparing bleed and bleed-less configurations for the high-pressure water-separation-based ECS. A comparative thermodynamic performance analysis of bleed and bleed-less membrane-based dehumidifier (MAD) ECS has not been explored in the existing open literature. To address this research gap, a steady-state thermodynamic model was developed to estimate the temperature and pressure profiles for both configurations of the MAD ECS at altitudes of 0–11 km and Mach numbers of 0–0.85 by utilizing MATLAB. The credibility of the MATLAB code is validated against the existing literature on the bleed MAD ECS by comparing the temperature profiles of the main airflow path at critical points. The performance of both systems is evaluated in terms of the coefficient of performance (COP) parameter, and the effect of heat exchanger effectiveness and compression pressure ratio, altitude, and Mach number on COP is also carefully analysed in the study. The study concludes that the MAD ECS with a bleed-less air-cycle system (ACS) achieves a higher COP at the cruise phase of the aircraft compared to the traditional bleed ACS, and the COP is increased from 0.22 to 0.52 for the cruise phase of the aircraft. The findings of this research provide a detailed thermodynamic platform useful for advanced ECS architecture and demonstrate the potential of bleed-less MAD ECS to increase aircraft efficiency and contribute to energy-efficient next-generation aircraft applications.

Liu, Jianhui; Han, Zhongxuan; Yang, Zhanjun; Zhao, Shuna; Li, Mi; Xu, Qiang

doi: 10.1007/s10973-026-15622-0pmid: N/A

Nanocomposite thermite materials show great application potential in high-energy-consuming applications. However, significant challenges remain in precisely controlling their nanoscale microstructure and synergistically optimizing their combustion performance. Building upon the high oxidative potential of metal fluorides, using electrostatic spray technology, composite thermite particles were prepared with metal fluoride (CuF2) and metal oxide (CuO) as oxidizers and polyvinylidene fluoride (PVDF) as a binder. Comparative samples were prepared by physical mixing. With the help of transmission electron microscope (TEM), scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), X-ray diffractometer (XRD), simultaneous thermogravimetry–differential scanning calorimeter (TG-DSC), and combustion performance test system, the microstructure, thermal reaction kinetic traits, combustion performance parameters, energy release law, as well as the morphological traits and component structure of combustion products of the prepared composite materials were systematically characterized and analyzed. The research results show that, compared with physically mixed samples, the composite materials prepared by electrostatic spray form submicron-scale (nano-aluminum powder) and micron-scale structures (micron-aluminum powder) with uniformly dispersed reactants in a nearly spherical shape. This structure enhances interfacial contact, suppresses nanoparticle agglomeration, and promotes more efficient energy release and combustion heat utilization. These samples exhibit larger flame height and area, higher combustion temperature and produce condensed-phase products with a fragmented, porous morphology and fewer metallic residues, indicating more complete reactions. Notably, CuF2-containing thermites demonstrate significantly higher combustion intensity than conventional thermite formulations. In conclusion, developing high-performance fluorine-containing thermite materials holds considerable academic and practical value for advancing thermite technology.

Maharana, Samaresh; Mishra, Sujata

doi: 10.1007/s10973-026-15813-9pmid: N/A

Hydrophobic deep eutectic solvents (HDESs) have emerged as promising alternatives to conventional solvents because of their tunable structures and ecologically benign nature. The present study focuses on a series of carboxylic acid-based HDESs synthesized using hexanoic acid (HA), octanoic acid (OA), and decanoic acid (DA), combined with di(2-ethylhexyl) phosphoric acid (DEHPA)/Citronellal. Their structural, thermal stability, and physicochemical properties were systematically investigated. 1H NMR and FTIR spectroscopy confirmed H bonding interactions between HBDs (hydrogen bond donors) and HBAs (hydrogen bond acceptors), as indicated by characteristic shifts and broadening in the -C=O, -O–H, and -P=O stretching regions. Thermogravimetric analysis (TGA) reveals that DA-based HDESs exhibit superior thermal stability relative to HA-based analogues, as reflected by significantly higher decomposition temperatures of 439.21 K for DEHPA:DA and 385.70 K for Citronellal:DA, compared to 350.64 K for DEHPA:HA and 375.18 K for Citronellal:HA. Physicochemical properties, including density (ρ), dielectric constant (ε), refractive index (nD), and viscosity(η), were estimated in a range of temperatures 298.15 K to 328.15 K. In all systems, density, dielectric constant, refractive index, and viscosity decreased with increasing temperature. The results highlight that DEHPA:HA and Citronellal:HA show the highest density and dielectric constant values among their respective systems. In the case of refractive index and viscosity, DEHPA:DA and Citronellal:DA exhibit the highest values with respect to their OA and HA combinations.

Cheng, Ruiqin; Wang, Jiaxing; Wan, Jiangyuan; Chen, Hongchu

doi: 10.1007/s10973-026-15531-2pmid: N/A

Temperature-dependent thermophysical properties lead to nonlinear transient heat conduction problems. This phenomenon is commonly observed in numerous engineering applications. Predicting surface heat flux and temperature variations under these conditions is challenging due to the mathematical and physical complexity of the nonlinear governing equation. To resolve this issue, this paper proposes a calibration integral equation based on the Laplace transform combined with a linearization approach. For one-dimensional nonlinear inverse heat conduction problems with insulated back surface condition, this method effectively achieves surface heat flux estimation with minimal input of system parameters. In the nonlinear heat conduction process, the thermal conductivity and heat capacity are temperature-dependent. However, in case the thermal diffusivity is not highly temperature-dependent, linearization technique can be adopted to simplify the nonlinear heat equation. Under such a condition, both numerical simulations and laser heating experimental results illustrate the accuracy and robustness of the proposed approach. This data-driven methodology offers valuable theoretical support for industrial design and thermal management.

Lu, Yongjie; Yang, Jialiang; Wu, Xilei; Ye, Gongran; Han, Xiaohong

doi: 10.1007/s10973-026-15757-0pmid: N/A

Liquid immersion cooling has emerged as a promising solution for battery thermal management field due to its high heat dissipation performance, excellent temperature uniformity, and potential to prevent thermal runaway. To optimize the performance of immersion cooling systems under automotive-grade battery module conditions, a numerical model of a 190-cell cylindrical 21,700 lithium-ion battery module was developed and validated. The effects of inlet/outlet configurations, flow rates, inlet temperatures, and battery spacings using electronic fluorinated liquid as the coolant were explored. Among the four inlet/outlet configurations tested, the double inlets and singleoutlet setup performed best. Enhancing the number of inlets improved heat dissipation in the automotive-grade module, whereas increasing the number of outlets showed no such effect. Higher flow rates proved more effective in improving heat dissipation performance than lowering inlet temperatures. Reducing the inlet temperature had a time lag in lowering maximum temperature (Tmax) of the module. Battery spacing along the x-axis significantly impacted heat dissipation performance and pressure drop, with an optimal spacing of 5 mm identified. In contrast, spacing along the z-axis had minimal effect on heat dissipation and pressure drop. Given the growing demand for fast charging in electric vehicles, the module’s heat dissipation performance was evaluated under 4C high-rate charging conditions. By optimizing coolant flow rates and inlet temperatures, both Tmax and maximum temperature difference (ΔTmax) were kept within acceptable limits, demonstrating the module’s robust heat dissipation performance. These results highlight the potential of liquid immersion cooling to meet the stringent thermal requirements of fast-charging applications.

Zhou, Yong; Dong, Qi; Qin, Guizhou; Zhang, Song; Yu, Hu; Zhang, Ji

doi: 10.1007/s10973-026-15526-zpmid: N/A

Superconducting motors, with their zero-resistance properties, can significantly improve energy efficiency and reduce energy loss. As key components in new energy systems, superconducting motors require effective thermal management to ensure their long-term stability and extend their service life. This study proposes three types of indirect oil-cooled reinforced structures to address the heat dissipation challenge of superconducting motor windings. The thermal performance of each structure is comprehensively evaluated through experimental tests. Results show that the average convective heat transfer coefficient of the gap-reinforced structure increases with flow velocity across all heating power levels. At 95 W heating power, the V-type-reinforced structure demonstrates a gradual increase in the convective heat transfer coefficient with rising flow rate. For the empty pipe, the convective heat transfer coefficient increases gradually at 85 and 105 W heating power. Simulation results confirm that the V-type-reinforced structure offers the best heat transfer performance, reducing the maximum tube wall temperature by 3.54% and the motor stator temperature by 3.46 °C compared with the empty pipe.

Momin, Modaser; Atofarati, Emmanuel O.; Oladipo, Stephen; Adogbeji, Victor O.; Ajuka, Luke; Giwa, Solomon O.; Sharifpur, Mohsen; Meyer, Josua P.

doi: 10.1007/s10973-026-15698-8pmid: N/A

The growing demand for efficient heat transfer and energy conversion systems require advanced working fluids with superior thermal and electrical transport properties. In this study, investigation on the thermophysical behaviour of Al2O3/MWCNT–DI water hybrid nanofluids through comprehensive experimental characterization and predictive modelling was carried out. Hybrid nanofluids of 0.05–0.25 vol% were synthesized via a two-step method, and viscosity, electrical conductivity, and thermal conductivity were measured over temperatures ranging from 15 to 60 °C. Results show that viscosity decreases with temperature but increases with nanoparticle concentration, while both electrical and thermal conductivities rise significantly with temperature and nanoparticle concentration. At 0.25 vol% and 60 °C, electrical conductivity exceeded 2400 μS cm−1, and thermal conductivity improved by ~ 35 to 50% relative to DI water, confirming strong synergistic enhancement mechanisms. Empirical correlations developed for relative viscosity, relative electrical conductivity, and relative thermal conductivity demonstrated high predictive accuracy, with R2 values between 0.938 and 0.991 and deviations within ± 2 to ± 5%. Advanced machine-learning models; Artificial Neural Network (ANN), Adaptive Neuro-Fuzzy Inference Systems- Fuzzy C-Means (ANFIS-FCM), and Particle Swarm Optimization (PSO)-ANFIS, were used to train the experimental datasets to model nonlinear interactions between temperature, concentration, and thermophysical responses. Among these, the ANFIS-FCM, yielded the highest accuracy coupled with the lowest error values across all the studied properties, e.g. Viscosity (ANFIS-FCM5: RMSE = 0.0140, MAE = 0.0114, MAPE = 1.3505%, U = 0.0153). Overall, the combined experimental and intelligent-modelling framework provides robust predictive capability for optimizing Al2O3/MWCNT hybrid nanofluids in thermal management, cooling systems, and electrohydrodynamic applications, supporting their integration into next-generation energy and process engineering technologies.Graphical abstract[graphic not available: see fulltext]