Journal of Thermal Analysis and Calorimetry最新文献

The purpose of this study is to present a comprehensive and updated review of solar dryer technologies for food drying processes, with emphasis on recent advancements achieved between 2016 and 2023. The study evaluates the design evolution, thermal performance, material selection, drying mechanisms, and economic viability of direct, indirect, natural convection, forced convection, hybrid photovoltaic–thermal (PV/T), and PCM-integrated solar dryers. A systematic review methodology was adopted, combining technical performance assessment, experimental outcomes, thermal modeling insights, and market forecasting. The findings reveal that indirect and mixed-mode dryers, particularly those integrated with phase change materials and hybrid PV/T systems, demonstrate significantly improved drying rates, higher thermal efficiency, and better product quality compared to traditional open sun drying. Case studies show notable reductions in drying time, with moisture reduction efficiencies improving by up to 40–60% depending on product type and dryer configuration. The global solar dryer market, valued at USD 3.5 billion in 2023, is projected to grow at a CAGR of 10.6% through 2031, indicating strong industrial and agricultural relevance. A novel feature of this review is its integration of emerging thermal research—including nanofluid-enhanced collectors, magnetohydrodynamic heat transfer concepts, artificial neural network-based predictive models, and bio-inspired hybrid fluid systems—highlighting their potential applicability to future solar drying technologies. The study also identifies critical research gaps such as the need for smart control systems, real-time monitoring, AI-assisted optimization, and cost-effective designs for rural deployment. Overall, this review provides a multidimensional understanding of solar dryer performance and future development pathways, offering valuable insights for researchers, engineers, and policymakers aiming to improve sustainable food preservation technologies.

For sustainability reasons, starch hydrolysis by (alpha)-amylase is becoming increasingly important in various industries. This study focused on potato starch hydrolysis catalyzed by porcine pancreatic (alpha)-amylase. The effect of potato starch hydrolysis time—3 min, 5 min, 10 min, 15 min, 30 min and 60 min—on the (alpha)-amylase activity was examined. The optimum (alpha)-amylase temperatures (T_{text {opt}}) and deactivation energies (E_{text {d}}) were determined for various starch hydrolysis times and variable hydrolysis temperatures with simultaneous deactivation of (alpha)-amylase. The study revealed that the optimum temperatures (T_{text {opt}}) for (alpha)-amylase activity ranged from ({313.88 pm 0.75}) to ({326.22 pm 0.79}) K. Additionally, the average activation energy E and deactivation energy (E_{text {d}}) were calculated as ({66.05 pm 14.17}) kJ mol(^{-1}) and ({161.02 pm 12.57}) kJ mol(^{-1}), respectively. These results allow for a better understanding of the effect of starch hydrolysis duration on (alpha)-amylase activity. These results have potential application in modeling and research in industrial processes such as starch saccharification. Furthermore, the findings may be useful in the development of pharmaceutical treatments for pancreatic cancer diagnosis.

Fluid dynamics research in the context of Hiemenz stagnation point flow on a stretched surface is critical owing to its widespread applicability in numerous industrial and technical industries. The proposed research aims to investigate the stagnation point nanofluid flow on a stretched surface. The formation of nanofluid composites involves dissolving single-wall and multi-wall carbon nanotubes as nanoparticles in base fluid water. The consideration of these nanoparticles to the base fluid will have a significant influence on the heat transfer rate of the emergent nanofluid. The assumption of boundary layer nanofluid flow simplifies the emergent mass, energy, and momentum conservation mathematical equations. A dimensionless system has been obtained from the governing partial differential equations and their related boundary conditions by using similarity transformations. In this case, the highly nonlinear transformed system is resolved using the built-in MATLAB function bvp4c. The physical consequences of developing dimensionless parameters on the velocity and thermal profiles of the nanofluids under consideration are thoroughly investigated and explored. The skin friction coefficient and Nusselt number are additionally computed on the stretching surface. The Nusselt number is augmented by rising the concentration of nanoparticles and thermal radiation parameters. The nanofluid thermal profile exhibits enhancement with rising nanoparticle concentration and radiation parameters. Moreover, fluid velocity decreases with an increase in Hartmann number. The present research is also compared to prior published research in order to corroborate the reported results. An outstanding agreement has been obtained in this regard. Researchers examining nanofluid flows under various assumptions should find this work to be a useful resource for crucial information on the deployment of revolutionary heat transfer devices in future.

Rising international power requirements has enabled a sudden need of renewable energy-waste heat recovery solutions demand efficient thermodynamic models competent of binding solar and thermal energy successfully. This study proposes a novel integrated heliostat-based solar thermal power generation system coupled with an absorption refrigeration cycle, employing high initial heat source temperature to enhance overall performance. A comprehensive thermodynamic assessment is implemented to assess system behavior under varying irradiation levels, evaporator temperatures, pump work, and absorption characteristics. A priority-weighted machine learning method is employed to identify the dominant contributors to system losses and to highlight critical operating parameters. Results show that the central receiver and heliostat account for 31.37 and 27.40% of total irreversibility’s, respectively, while energy and exergy efficiencies hold the highest decision weightage (30% each). The optimal condition (dataset 5), defined by DNI of 800 W m^–2, absorber efficiency of 0.91, evaporator temperature of 9 °C, and pump work of 52.01 kW, yields 24.18% energy efficiency and 33.11% exergy efficiency with stable molten salt (11.74 kg s^–1) and steam (1.80 kg s^–1) flow rates. The results confirm that the proposed solar–thermal–cooling configuration offers enhanced thermodynamic performance and improved sustainability compared to conventional systems, making it a promising candidate for future renewable energy applications. The findings validate the hybrid model, proving to have better thermodynamic performance and superior sustainability than standard systems, enabling it to be a viable candidate in future applications of renewable energy.

Passive thermal management of electronic devices employing circular fin–pin heat sinks embedded with phase-change materials (PCMs) that enhance thermal conductivity via mono-/hybrid nanoparticles is the focus of the present investigation. Two categories of nano-enhanced PCM were fabricated [mono-nano-PCM (MPCM) and hybrid nano-PCM (HPCM)] by combining paraffin wax (PFW) with 0.5 and 1.0 mass% of silver (Ag) and titanium dioxide (TiO₂) nanoparticles. The effect of nanoparticles on the thermophysical properties of paraffin wax was studied using differential scanning calorimetry, thermogravimetric analysis, and thermal conductivity measurement. Experimental investigations were conducted with unfinned heat sink (UHS) and circular finned heat sink (FHS) incorporating MPCM and HPCM with three power levels of 5 W, 10 W, and 15 W. The results demonstrated a maximum relative improvement of around 96.65% in thermal conductivity. The performance study of the circular finned heat sinks (CFHS) with PCM, HPCM, and MPCM shows peak temperature reduction of 12.5–28.6%. In particular, at 5 W, 10 W, and 15 W, MPCM_CFHS offers the greatest reduction (28.6%, 22.7%, and 22.5%, respectively). Comparatively performance study of unfinned heat sink with PCM, HPCM, and MPCM shows reductions between 7.1% and 20.6%, where HPCM routinely achieved the lowest temperatures, with drops of 20.6%,17.9%, and 14.3%. at different power levels. These percentages highlight the superior effectiveness, specifically MPCM and HPCM, incorporating into heat sinks to enhance thermal management. Also, maximum enhancement ratios of 1.28 and 1.8 were achieved at 55 °C and 60 °C set point temperatures (SPTs) which are highly suggested for electronic cooling systems and thermal management application.

This study examines the thermal and hydrodynamic behavior of Williamson non-Newtonian mucus in a two-dimensional divergent wavy microchannel, simulating ciliated surfaces with an eighth-order waveform. The flow is modeled as laminar, incompressible, and governed by low Reynolds number hydrodynamics, with equations transformed into a cilia-attached moving frame. Employing a long-wavelength approximation, inertia effects are neglected, and a perturbation method analyzes deviations from rheological and geometric nonlinearities. The interplay between shear-thinning effects, channel divergence, and undulation-driven periodicity is explored, with temperature distribution incorporating viscous dissipation and heat transfer. Graphical results illustrate velocity profiles, pressure gradients, streamline patterns, and thermal performance, highlighting how cilia motion enhances mixing and heat transfer in microfluidic systems. Crucially, divergence angle and Williamson rheology are shown to significantly alter flow structure, as evidenced by velocity vector fields. These findings provide critical insights for the design of bio-inspired microfluidic devices, particularly those requiring optimized thermal management and mixing.

Drug-excipient compatibility assessment is a prerequisite for solid dosage formulation of active pharmaceutical ingredients (API) but has not yet been regularly practiced in phytotherapeutics. Traditionally, Withania somnifera (WS) root is used as powder, fermented preparation (Asava and Arishta), or tablet (Vati- edible gums as a binder). However, pharmaceutical excipients are also increasingly used in solid dosage forms. Often, such Withania root extract (WS-Ext) derived solid dosage formulations have technological complications related to the stability, bioavailability, and bioequivalence of its key bioactives and other phytochemicals of complex multi-component systems. Therefore, the present study aims to characterize and assess the compatibility of standardized WS-Ext with pharmaceutical excipients viz., sodium propylparaben (SPP), sodium methylparaben (SMP), magnesium stearate (MS), talc, microcrystalline cellulose (MCC), and lactose. The binary mixtures (BM) of WS-Ext and excipients were stored at 37 ± 2 °C, 30 °C/65% RH, and 40 °C/75% RH, respectively, in open and closed containers for the stability evaluation. The effect on WS-Ext bioactives (withanolide-A and withanone) and change in the overall phytochemical profile of the binary mixture of WS-Ext and excipient blended at a 1:1 (w/w) ratio were evaluated through HPLC–PDA analysis. The WS-Ext: excipient BMs showed no significant change in the key bioactives and the overall phytochemical profile at 37 ± 2 °C one-month screening study. SPP, SMP, and MS have significantly distressed the withanone content but not withanolide-A in 30 days under stress conditions storage in a closed container. The characterization of WS extract and excipient binary mixtures was performed using thermogravimetry (TG), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. The results of the TGA and FTIR were also consistent with the HPLC analysis. However, XRD analysis confirmed that all the excipients contributed to improving the crystallinity of the binary mixture (CrI = 0.51–0.91%) of WS-Ext (CrI = 0.21). Lactose followed by SMP were more effective than other excipients in improving the amorphous characteristic, flow-ability, crystallinity of WS-Ext powder, and stability of its bioactives. The present study reveals that thermo-analytical techniques can ensure excipient compatibility with improved pharmaceutical characteristics at the pre-formulation stage of solid dosage products.

Graphical abstract

With the growing demand for efficient thermal management in electric motors, spiral water jackets have become widely used to enhance cooling performance. However, achieving a balance between effective cooling, uniform temperature distribution, and energy-efficient pump power remains a significant challenge. This study proposes a multi-objective optimization design for spiral liquid jackets, aiming to improve cooling efficiency, temperature uniformity, and minimize pump power consumption. The optimization process considers geometric parameters and boundary conditions as design variables. A radial basis function surrogate model, developed using the Latin hypercube sampling method, is employed to filter geometric constraints and create a database for training and testing. The model’s accuracy is enhanced through k-fold cross-validation. Non-dominated Sorting Genetic Algorithm-II (NSGA-II) is used to search for the Pareto front, providing a set of optimal trade-offs. Two selection strategies are applied: one based on multi-criteria decision-making and another tailored to system design requirements. Results show that the optimized designs reduce the maximum temperature by at least 5.49%, the static pressure by at least 24.72%, and increase temperature uniformity by up to 1.27%, demonstrating improved cooling performance and reduced pump power consumption. The proposed optimization procedure effectively addresses the challenges in spiral water jacket design, providing a more efficient and reliable solution for electric motor cooling.

A significant amount of research focuses with constant or variable thermophysical properties of the phase change materials. However, limited models address spatially varying functionally graded (FG) thermal conductivity and mass diffusivity with generalized boundary conditions. The study employs generalized boundary conditions on freezing surface, whereas Dirichlet boundary conditions are applied for heat and mass transmission in other scenarios. The similarity transformation technique is highly effective at offering simulated analytical solutions. To justify and analyze our results, we have considered 5% copper–95% aluminum alloy. Higher heat flux reduces the temperature profile, whereas interfaces are expanding, so freezing rate increases according to Newton’s cooling law. In contrast, higher conductive heat transfer coefficients raise the boundary temperature, which slows down the freezing process. We examine the impact of FGthermal conductivity and mass diffusivity over different Peclet numbers. Results indicate that alloy solidification decelerates as the slope of (f(xi )=1+bxi) increases. With a rise in FG thermal conductivity, the mushy and solid zones reduce under Dirichlet and Neumann situations but expand in Robin conditions. A higher Peclet number increases the freezing process, but a lower slope of FG mass diffusivity accelerates the alloy concentration. Consequently, the combined effects of thermal and concentration gradients accelerate the alloy’s solidification, enhancing overall efficiency and enabling practical applications such as thermal management, alloy casting, and metallurgical processes.

Improving energy efficiency through the integration of micro-channel designs with thermal storage systems offers a promising approach for advanced heat transfer applications. Despite their advantages, micro-channels are often challenged by fouling and clogging, which can reduce thermal performance over time. This review highlights strategies to enhance system efficiency by combining optimized micro-channel structures with advanced thermal storage materials. Recent progress in materials and fabrication techniques such as the use of metals, polymers, ceramics, and precision methods like photolithography and soft lithography has enabled more durable and effective designs. Integrating micro-channels with phase change materials (PCMs) and sensible heat storage media improves both charging and discharging processes, leading to higher heat transfer rates and reduced energy loss. Reported studies show that such integrated systems can enhance heat transfer rates by 25–60% and reduce energy losses by up to 35% compared to conventional micro-channel configurations. This synergistic approach shows strong potential for creating compact, efficient, and sustainable thermal systems that support the global shift towards cleaner and more energy-resilient technologies.