Development of a new vacuum-based photovoltaic/thermal collector, thermal and exergy analyses

Photovoltaic-thermal (PV/T) solar collectors convert solar radiation into electrical power and heat. A considerable amount of received solar energy can be lost to the ambient from the top surface of the PV/T module, especially in windy regions. Thus, in this study, a new vacuum based photovoltaic thermal (VPV/T) collector is designed and comparatively analyzed with the conventional PV/T collector. The new design differs from the conventional PV/T design by including vacuum layer above the silicon wafer. Besides, to enhance the heat dissipation from the silicon wafer in the VPV/T design to the thermal absorber, the thicknesses of ethylene-vinyl acetate and tedlar polyester tedlar layers underneath the silicon wafer are decreased. A comprehensive 3D conjugate thermal model is developed and validated. The comparison is conducted at steady and transient conditions. The effect of Reynolds number (Re), wind speed, glass emissivity, and vacuum pressure are investigated. And finally, the exergy analysis for both designs are compared. The results showed that the new VPV/T collector has accomplished a 26.6% increase in the thermal power without changing the electrical power gain at Re of 50 and solar irradiance of 1000Wm-2. In addition, the vacuum pressure degradation from 0.01 Pa to 10 Pa slightly decreases the gained thermal power of the new VPV/T. A further increase in the vacuum pressure from 10 Pa to 1.013×105 Pa significantly decreases the gained thermal power with a slight increase in the electrical power. Furthermore, the total predicted VPV/T and the conventional PV/T exergy efficiency are 40% and 32%, respectively

Performance Evaluation and Kinetic Analysis of Photocatalytic Membrane Reactor in Wastewater Treatment

The objectives of the current study are to assess and compare the performance of a developed photocatalytic membrane reactor (PMR) in treating industrial waste (e.g., organic dye waste) against membrane distillation. The current PMR is composed of a feed tank, which is a continuous stirred photocatalytic reactor containing slurry Titanium dioxide (TiO2) particles that are activated by using ultraviolet lamp irradiation at a wavelength of 365 nm, and a poly-vinylidene flouride (PVDF) membrane cell. The experimental setup was designed in a flexible way to enable both separate and integrated investigations of the photocatalytic reactor and the membrane, separately and simultaneously. The experimental work was divided into two phases. Firstly, the PVDF membrane was fabricated and characterized to examine its morphology, surface charge, and hydrophobicity by using a scanning electron microscope, surface zeta potential, and contact angle tests, respectively. Secondly, the effects of using different concentrations of the TiO2 photocatalyst and feed (e.g., dye concentration) were examined. It is found that the PMR can achieve almost 100% dye removal and pure permeate is obtained at certain conditions. Additionally, a kinetic analysis was performed and revealed that the photocatalytic degradation of dye follows a pseudo-first-order reaction

Synthesis, X-ray structure, Hirshfeld analysis, and DFT studies of a new Pd(II) complex with an anionic s-triazine NNO donor ligand

A new Pd(II) complex, [Pd(Triaz)Cl], with the hydrazono-s-triazine ligand, 2,4-di-tert-butyl-6-((2-(4-morpholino-6-(phenylamino)-1,3,5-triazin-2-yl)hydrazono)methyl)phenol, was synthesized by the reaction of PdCl2 with the organic ligand (1:1) in acetone under isothermal conditions. The molecular structure of the [Pd(Triaz)Cl] complex was determined using FTIR and 1H NMR spectroscopic techniques, and single-crystal X-ray diffraction. Moreover, using Hirshfeld surface analysis, the percentages of the intermolecular interactions were determined. The obtained values were 60.6%, 11.6%, 8.1%, 3.6%, and 5.0% for the H⋯H, C⋯H, O⋯H, N⋯H, and Cl⋯H interactions, respectively. Among them, the O⋯H, C⋯H and C⋯N interactions are considered extremely important. Natural bond orbital calculations have been used to calculate the amount of electron transfer from the ligand to the metal ion and to evaluate the Pd–N, Pd–O, and Pd–Cl coordination bonding interactions.peerReviewe

A Micro-Metal Inserts Based Microchannel Heat Sink for Thermal Management of Densely Packed Semiconductor Systems

The thermal management of high-heat-density devices is essential for reliable operation. In this work, a novel procedure is proposed and investigated for the efficient thermal management of such devices. The proposed procedure introduces different arrangements of metal inserts within a cooling channel heat sink. The objective of those inserts is to form boundary layers to prevent any hot spots from appearing within the flow and increase temperature uniformity. Five different arrangements are introduced and numerically investigated using the commercial software package ANSYS FLUENT 2021R1. The model was validated against previous findings and showed a good agreement with errors of less than 5.5%. The model was then used to study the heat transfer characteristics of the proposed cases compared to traditional straight channels under the same operating conditions. All the proposed arrangements displayed better heat transfer characteristics than the traditional configuration within the studied range. They also exhibited lower temperature nonuniformities, implying better temperature distribution. The temperature contours over the heat source top surface and the flow streamlines are also introduced. Among all the proposed arrangements cases, a microchannel with micro metal insert located at the top wall along with a second row of inserts covering two-thirds of the bottom wall is studied. This case achieved the best heat transfer characteristics and highest temperature uniformity, making it a viable candidate for high power density devices’ thermal management

Surgical hip dislocation in treatment of slipped capital femoral epiphysis

Background: Most surgeons advocate in situ fixation of the slipped epiphysis with acceptance of any persistent deformity in the proximal femur [Aronsson DD, Loder RT, Breur GJ, Weinstein SL (2006) Slipped capital femoral epiphysis: current concepts. J Am Acad Orthop Surg 14, 666–679]. This residual deformity can lead to osteoarthritis due to femoroacetabular cam impingement (FAI) [Leunig M, Slongo T, Ganz R (2008) Subcapital realignment in slipped capital femoral epiphysis: surgical hip dislocation and trimming of the stable trochanter to protect the perfusion of the epiphysis. Instr Course Lect 57, 499–507]. Objective: The primary aim of our study was to report the results of the technique of capital realignment with Ganz surgical hip dislocation and its reproducibility to restore hip anatomy and function. Patients and methods: This prospective case series study included 30 patients (32 hips, 13 left (Lt) hips, 19 right (Rt) hips) with stable chronic slipped capital femoral epiphysis (SCFE) after surgical correction with a modified Dunn procedure. This study included 22 males and eight females. The mean age of our patients was 14 years (10–18 years). The mean follow-up period was 14.5 months (6–36 months). Results: Thirty hips had excellent and good clinical and radiographic outcomes with respect to hip function and radiographic parameters. Two patients had fair to poor clinical outcome including three patients who developed Avascular Necrosis (AVN). The difference between those who developed AVN and those who did not develop AVN was statistically significant in postoperative clinical scores (p = 0.0000). The mean slip angle of the femoral head was 52.5° ± 14.6 preoperatively and was corrected to a mean value of 5.6° ± 8.2° with mean correction of 46.85° ± 14.9° (p = 0.0000). The mean postoperative alpha angle was 51.15° ± 4.2° with mean correction of 46.70 ± 14.20 (p = 0.0000). In our series, the mean postoperative Harris hip score (HHS) was (96.16 ± 9.7) and the mean improvement was (29.6 ± 9.6) (p = 0.0000). Conclusions: The modified Dunn procedure allows to restore the normal proximal femoral anatomy by complete correction of the slip angle. This technique may reduce the probability of secondary osteoarthritis and femoroacetabular cam impingement