Experimental and numerical analysis of the thermal performance of pebble solar thermal collector.

In this work, pebbles of higher specific heat than the conventional absorber materials like aluminium or copper are proposed as a absorber in the solar flat plate collector. The proposed collector are integrated into the building design and constructed with masonry. Tests were conducted by varying the operating parameters which influence its performance, like the flow rate of the heat-absorbing medium, and the tilt of the collector using both coated and uncoated pebbles. The maximum temperature difference that could be measured for a conventional absorber was approximately 8 °C for a flow rate of 0.6 L/min. While for a coated and uncoated absorber, it was 7 °C and 5.5 °C respectively. This difference decreased with an increase in flow rates from 0.6 L/min to 1.2 L/min. For all the flow rates, it was observed that the average difference in efficiency between the coated and the conventional absorber collector is 5.82 %, while the difference between the coated and uncoated absorber collector is 15.68 %. Thus, it is very much evident that by replacing the conventional absorber with the proposed coated pebble absorber, the overall loss in efficiency is just 5.82 %, but the advantages are enormous. Along with the experimental study, numerical analysis was also carried out with CFD modeling. The numerical results agreed well with experimental results with the least error. Therefore, CFD simulation can be further used to optimize the design of the collector.

Biodegradable Green Composites: Effects of Potassium Permanganate (KMnO4) Treatment on Thermal, Mechanical, and Morphological Behavior of Butea Parviflora (BP) Fibers.

This study emphasizes the importance of utilizing biodegradable material Butea parviflora (BP) fiber for sustainable solutions. BP fiber offers numerous ecological benefits, such as being lightweight, biodegradable, and affordable to recycle. The study examines the effects of potassium permanganate (KMnO4) treatment on BP fiber and analyzes its physical and chemical behavior using various methods, including X-ray Diffraction (XRD) analysis, tensile testing, thermogravimetric analysis, thermal conductivity, Scanning Electron Microscopy (SEM), and Fourier Transform Infrared spectroscopic (FTIR) analysis. The results demonstrate that BP fiber possesses low density (1.40 g/cc) and high cellulose content (59.4%), which fosters compatibility between the matrix and resin. XRD analysis indicates a high crystallinity index (83.47%) and crystallite size (6.4 nm), showcasing exceptional crystalline behavior. Treated fibers exhibit improved tensile strength (198 MPa) and Young's modulus (4.40 GPa) compared to untreated fibers (tensile strength-92 MPa, tensile modulus-2.16 GPa). The Tg-DTA thermograms reveal the fiber's thermal resistance up to 240 °C with a kinetic activation energy between 62.80-63.46 KJ/mol. Additionally, the lowered thermal conductivity (K) from Lee's disc experiment suggests that BP fiber could be used in insulation applications. SEM photographic results display effective surface roughness for composite making, and FTIR studies reveal vibrational variations of cellulosic functional groups, which correlates with increased cellulosic behavior. Overall, the study affirms the potential of BP fiber as a reinforcing material for composite-making while emphasizing the importance of utilizing biodegradable materials for sustainability.

Investigation on Properties of Raw and Alkali Treated Novel Cellulosic Root Fibres of Zea Mays for Polymeric Composites.

Today, new materials based on natural fibres have been emerging day by day to completely eradicate plastics to favour our environmental nature. In this view, the present work is based on the extraction and characterisation of the novel root fibres of the Zea mays (Zm) plant, grown by the hydroponic method. Both the dried untreated and alkali treated root fibres are investigated using a variety of structural, morphological, thermal, elemental and mechanical tests by subjecting both the samples to p-XRD, FT-IR, SEM-EDAX, TGA-DTA, CHNS and tensile strength analyses. Thermal conductivity of the untreated and treated fibres is found using Lee's disc experiment. From p-XRD analysis, the Crystallinity Index, Percentage Crystallinity and Crystallite size of the samples are found. FT-IR studies clarify the different vibrational groups associated with the fibre samples. SEM images show that the surface roughness increases for the chemically treated samples, such that it may be effectively utilised as reinforcement for polymeric composites. The diameter of the fibre samples is found using SEM analysis. According to the EDAX spectrum, Zm fibres in both their raw and processed forms have high levels of Carbon (C) and Oxygen (O). The TGA-DTA tests revealed that the samples of natural fibre have good thermal characteristics. CHNS studies show that Carbon content is high for these samples, which is the characteristic of many natural fibres. Chemical analysis is used to ascertain the prepared samples' chemical makeup. It reveals that both samples have significant amounts of cellulose. The density of the fibres is found to be in the range 0.3-0.6 g/cc, which is much less than any other natural fibre. Therefore, it can be used in light weight applications. From the tensile strength analysis, physical properties such as Young's modulus and micro-fibril angle are determined. The fibres in the roots exhibit a lower tensile strength. Thus, these fibres can be used in powdered form as reinforcement for natural rubber or epoxy composites. After examining all of its properties, it could be reasonably speculated that Zea mays root fibres can be considered as an efficient reinforcement for various matrices to produce attractive bio-composites.

The Effect of Polymers on Drug Release Kinetics in Nanoemulsion In Situ Gel Formulation.

Glaucoma is an ocular condition characterized by elevated intraocular pressure (IOP). Conventional treatments of glaucoma face poor corneal permeability and bioavailability. To address these issues, a nanoemulsion in situ gel of Timolol maleate was developed in this study by adding the polymer Carbopol 934p. Using Carbopol 934p, a novel ophthalmic pH-induced nanoemulsion in situ gel was formulated. The formulation was liquid at pH 4 and quickly gelled when the pH was raised to 7.4 (Lacrimal pH). The pH-triggered in situ gelling mechanism demonstrated continuous drug release over a 24 h cycle. A total of nine trial formulations were prepared (NEI1-NEI9) and subjected to various physicochemical and in vitro evaluations. According to the in vitro release kinetics, the drug release of Timolol maleate nanoemulsion in situ gel NEI5 followed zero-order kinetics, with a release exponent value of 0.902, indicating that the mechanism of release was non-Fickian diffusion regulated. In vivo results showed that Timolol maleate nanoemulsion in situ gel NEI5 provided a better-sustained release of the drug, compared with the Timolet OD eye drops. The formulation is stable in storage, with no distinguishable change in appearance, physical properties, quality, and percentage drug release. NEI5 also reduces drug administration frequency, which improves patient compliance. Timolol maleate nanoemulsion in situ gel NEI5 achieved the goal of controlled drug delivery with extended-release and cost-effectiveness, lowering the dosage and frequency of drug administration, and thus may improve patient compliance. In conclusion, the stable nanoemulsion in situ gel of Timolol maleate NEI5 decreases intraocular pressure (IOP) over a prolonged period.