Effect of series and parallel combination of photovoltaic thermal collectors on the performances of integrated active solar still

In this paper, an analytical expression for hourly yield, electrical energy and overall exergy of self-sustained solar still integrated with series and parallel combination of photovoltaic thermal-compound parabolic concentrator (PVT-CPC) collectors have been derived. Based on numerical computations, it has been observed that the yield is maximum for all self-sustained PVT-CPC collectors are connected in series [case (i)]. Further, the daily yield and exergy increase with the increase of water depth unlike passive solar still for all collectors connected in series. However, overall exergy decreases with an increase of water depth for all collectors connected in parallel [case (iv)]. For numerical simulations, the total numbers of self-sustained PVT-CPC collectors has been considered as constant. Further, an effect of series and parallel combination of PVT-CPC collectors on daily yield, electrical energy and overall exergy have also been carried out. Following additional conclusions have also been drawn: (i) The daily yield of the proposed active solar still decreases with the increase of packing factor of semi-transparent PV module for a given water depth and electrical energy and overall exergy increase with water depth for case (i) as expected due to low operating temperature range at higher water depth in the basin. (i) The daily yield, electrical energy and overall exergy increase with the increase of water depth for all combination of series and parallel arrangement of PVT-CPC collectors for a packing factor of 0.22 as per our expectation.

Designs for Reliability and Failure Mode Prevention of Electrical Feedthroughs in Integrated Downhole Logging Tools

To enable an electrical feedthrough integrated down-hole logging tool to maintain high reliability during its logging service in any hostile wellbores, it is critical to apply some guidelines for the electrical feedthrough designs. This paper introduces a safety factor-based design guideline to ensure an integrated electrical feedthrough has sufficient compression or thermomechanical stress amplitude in the stress well against potential logging failures. It is preferred to have a safety actor of 1.5–2.0 for an electrical feedthrough at lowest temperature, such as −60°C, and a safety actor of 2.5–5.0 at operating temperature range of 200–260°C. Moreover, the designed ambient pressure capability should be 1.5–2.0 times higher than the maximum downhole pressure, such as 25,000–30,000 PSI. To validate this thermomechanical stress model, several electrical feedthrough prototypes have been tested under simulated 200–260°C and 31,000–34,000 PSI downhole conditions. The observed testing data have demonstrated that there is a maximum allowable operating pressure for an electrical feedthrough operating at a specific downhole temperature. It is clearly demonstrated that an electrical feed-through may operate up to 60,000 PSI at ambient temperature in a real-life application, but it may actually operate up to 30,000–35,000 PSI at 200–260°C downhole temperatures.

Immobilized Crosslinked Pectinase Preparation on Porous ZSM-5 Zeolites as Reusable Biocatalysts for Ultra-Efficient Hydrolysis of β-Glycosidic Bonds

In this study, we immobilized pectinase preparation on porous zeolite ZSM-5 as an enzyme carrier. We realized this immobilized enzyme catalyst, pectinase preparation@ZSM-5, via a simple combined strategy involving the van der Waals adsorption of pectinase preparation followed by crosslinking of the adsorbed pectinase preparation with glutaraldehyde over ZSM-5. Conformal pectinase preparation coverage of various ZSM-5 supports was achieved for the as-prepared pectinase preparation@ZSM-5. The porous pectinase preparation@ZSM-5 catalyst exhibited ultra-efficient biocatalytic activity for hydrolyzing the β-glycosidic bonds in the model substrate 4-nitrophenyl β-D-glucopyranoside, with a broad operating temperature range, high thermal stability, and excellent reusability. The relative activity of pectinase preparation@ZSM-5 at a high temperature (70 °C) was nine times higher than that of free pectinase preparation. Using thermal inactivation kinetic analysis based on the Arrhenius law, pectinase preparation@ZSM-5 showed higher activation energy for denaturation (315 kJ mol−1) and a longer half-life (62 min−1) than free pectinase preparation. Moreover, a Michaelis–Menten enzyme kinetic analysis indicated a higher maximal reaction velocity for pectinase preparation@ZSM-5 (0.22 µmol mg−1 min−1). This enhanced reactivity was attributed to the microstructure of the immobilized pectinase preparation@ZSM-5, which offered a heterogeneous reaction system that decreased the substrate–pectinase preparation binding affinity and modulated the kinetic characteristics of the enzyme. Additionally, pectinase preparation@ZSM-5 showed the best ethanol tolerance among all the reported pectinase preparation-immobilized catalysts, and an activity 247% higher than that of free pectinase preparation at a 10% (v/v) ethanol concentration was measured. Furthermore, pectinase preparation@ZSM-5 exhibited potential for practical engineering applications, promoting the hydrolysis of β-glycosidic bonds in baicalin to convert it into baicalein. This was achieved with a 98% conversion rate, i.e., 320% higher than that of the free enzyme.