Assam Engineering College

This study provides a detailed assessment of an innovative solar drying system developed for Terminalia chebula, evaluating its performance across energy, exergy, economic, and quality dimensions. The dryer incorporates a canned solar air collector (CSAC) integrated with sensible heat storage to maintain stable drying conditions under variable solar radiation. Experimental results showed a 41.51 % reduction in drying time compared to open sun drying (OSD), achieving a final moisture content of 12.5 % (w.b.) within 31 h. The CSAC exhibited average energy and exergy efficiencies of 74.4 ± 1.41 % and 26.9 ± 2.50 %, respectively, while the dryer demonstrated energy and exergy efficiencies of 21.15 ± 2.04 % and 12.77 ± 3.01 %, respectively. Exergy-based sustainability indicators were evaluated to assess the environmental impact and thermodynamic performance of the system, confirming its suitability for sustainable operation. A comprehensive techno-economic evaluation highlighted the system's economic viability, with a short payback period of 0.94 years. Quality analysis revealed improved retention of polyphenols, flavonoids, and favorable color attributes compared to OSD. This design, integrating sensible heat storage with solar drying technology, demonstrates substantial improvements in both operational efficiency and product quality, positioning it as a sustainable and practical solution for agricultural drying needs in resource-limited regions.

Abstract This work reports a TCAD-based investigation and comparative analysis of HfO2, SiO2 and hetero-dielectric (HfO2-SiO2) TFET-based photosensor in visible light region of the spectrum. The study examines the effects of dielectric material and demonstrates that superior photosensor parameters are obtained when a combination of HfO2 and SiO2 (hetero-dielectric) is employed as dielectric materials. Therefore, the hetero-dielectric TFET photosensor is considered for further analyses in this work. The photosensor induces two dielectric pockets each at source/channel (vacuum) and channel/drain interface (SiO2) whose impacts on optical performance are analyzed too. The vacuum pocket aids in diminishing trap effect while the SiO2 pocket suppresses ambipolar effect. The TFET-based photosensor is put under test in both illuminated and dark conditions to investigate their optical characteristics. The efficacy of the photosensor is determined by measuring its performance for varying wavelengths (λ) across the visible spectrum. The photosensor operates on the phenomenon of band-to-band tunneling, which, we validate, is able to detect visible light wavelength at a low incident intensity of 0.5 W/cm2. The sensor can obtain a maximum photosensitivity and signal to noise ratio (SNR) of 4.7×102 and 53.5 dB for an intensity of 0.5 W/cm2 and wavelength of 0.4 µm for the proposed photosensor with heterodielectric gate. The performance of the proposed photodetector is also investigated under the effect of uniform and gaussian interface traps. It is observed that Gaussian trap has larger effect on the performance of the photodetectorin respect of drain current, spectral sensitivity and SNR. Moreover, considering Gaussian trap, the impact of acceptor/donor traps are also analysed for optical metrics. Additionally, we investigate the impact of temperature on photosensor’s response. It has been perceived that increased temperature results in enhanced performance parameters indicating the suitability of the proposed photo TFET at elevated temperature. A status map comparing this work with state-of-the-art literature is also presented which indicates the proficiency of the proposed work.

Understanding the dynamics of wind-driven natural ventilation is essential for developing effective strategies to enhance indoor environmental quality and reduce energy consumption in buildings. The natural ventilation in buildings is influenced by multiple factors, making the study of wind-driven natural ventilation complicated. This work investigates the influence of roof pitch angle on natural ventilation effectiveness in pitched roof buildings. Computational fluid dynamics simulations were performed on building models with roof pitch angles of 16.6°, 26.5°, and 36.8°, incorporating various diagonally located opening configurations. Ventilation efficiency was assessed using indoor air distribution and indoor air quality metrics, including normalized mean velocity (NMV), velocity homogeneity index (H), and air change per hour (ACPH). The highest values of NMV, H, and ACPH were obtained with a lower roof pitch angle of 16.6°. However, for NMV and H, the windward opening was located at the bottom, while the leeward opening was at the top. In contrast, for ACPH, the windward opening was situated in the middle, and the leeward opening was at the bottom. The findings demonstrated that the natural ventilation efficiency is strongly linked to both the roof pitch angle and the opening configurations. The outcomes of this study would be useful for planning and designing a sustainable built environment.

Polymer chemistry has become a virgin in contemporary biomedical science because of its flexibility, adjustable nature and wide range of application within healthcare technology. Polymers are central in enhancing the therapeutic efficacy and patient outcome with applications in drug delivery systems, tissue engineering scaffolds, diagnostic devices, and implantable medical devices. This review represents a useful report overlay of polymer chemical during biomedical application, the classifications of biomedical polymers, the synthesis process, correlation between the structure and property, and functionality in the living environment. The critical areas of application covered in this review include in the controlled delivery of drugs, regenerative medicine, wound, healing, biosensors and medical implants. Amid the numerous advantages, biocompatibility, biodegradability, and controlled functioning, polymer systems still have several solid constraints in their practice, such as chronic intoxication, immune responseAbnormalities, scaling problems, and regulatory obstacles. The review concludes with determining the future research directions that are focused on smart polymers, bio-inspired materials, personalized medicine and sustainable production of polymers. Overall, this paper demonstrates that polymer chemistry plays a crucial role in enabling the sphere of biomedical innovation, and can be applied in the present impediments that it has to overcome in order to achieve greater clinical acceptance.

This work presents the fabrication and experimental evaluation of a zinc oxide nanoparticle-based chemiresistive sensor for ethanol vapor detection aimed at breath analysis applications. Zinc oxide (ZnO) nanoparticles were synthesized using a controlled co-precipitation method to achieve stable and uniform nanostructures and subsequently deposited onto patterned copper electrodes. Further nanostructure growth was achieved through a hydrothermal process followed by thermal annealing to improve crystallinity and surface reactivity. Optical characterization using UV-visible spectroscopy confirmed the characteristic absorption behavior of zinc oxide and yielded an estimated optical bandgap of approximately 3.0 eV. To establish a rigorous quantitative framework, injected liquid volumes were converted into calibrated parts per million concentrations using the ideal gas law, allowing for standardized performance comparisons. Sensing experiments demonstrated a repeatable and measurable change in electrical response upon exposure to ethanol vapors under airflow-assisted conditions. The results indicate that undoped zinc oxide nanostructures, when combined with optimized electrode geometry, can deliver reliable alcohol sensing performance at room temperature. This study highlights a simple, low-cost, and scalable nanomaterial-based approach for alcohol sensing applications.