A Comprehensive Review Of The Influence Of Heat Exchange Tubes On Hydrodynamic, Heat, And Mass Transfer In Bubble And Slurry Bubble Columns

Bubble and slurry bubble column reactors (BCRs/SBCRs) are used for various chemical, biochemical, and petrochemical applications. They have several operational and maintenance advantages, including excellent heat and mass transfer rates, simplicity, and low operating and maintenance cost. Typically, a catalyst is present in addition to biochemical processes where microorganisms are used to produce industrially valuable bio-products. Since most applications involve complicated gas-liquid, gas-liquid-solid, and exothermic processes, the BCR/SBCR must be equipped with heat-exchanging tubes to dissipate heat and control the reactor\u27s overall performance. In this review, past and very recent experimental and numerical investigations on such systems are critically discussed. Furthermore, gaps to be filled and critical aspects still requiring investigation are identified

Groundwater Hydrogeochemical and Quality Appraisal for Agriculture Irrigation in Greenbelt Area, Iraq

This study highlights the groundwater hydrogeochemical characteristics and processes (hydrochemistry characteristics, ion exchange, and salinization) and quality suitability assessment for irrigation purposes from five wells in the Greenbelt area located in northwestern Al‐Najaf Gov-ernorate, Iraq. The suitability of groundwater for irrigation was assessed based on the irrigation water quality index (IWQI) for thirteen parameters and groundwater quality indices such as total dissolved solids (TDS), electrical conductivity (EC), sodium adsorption ratio (SAR), soluble sodium percent (SSP), residual sodium carbonate (RSC), total hardness (TH), permeability index (PI), potential salinity (PS), Kelley’s ratio (KR), and magnesium hazard ratio (MHR). The IWQI’s average values ranged between 76–139. The results of IWQI for the first and second sampling sites showed values of 139 and 104, respectively, indicating that the groundwater was unsuitable and unsafe for irrigation. In contrast, the IWQI for the third, fourth, and fifth sites were 83, 97, and 76, respectively, indicating that the groundwater was safe and possibly used for irrigation. The EC, TDS, PS, and MHR indices were all found to be unsuitable for irrigation in all five sites, and the KR index was also found to be unsuitable for agricultural irrigation in about 80% of the sites, while it was found that the indices of SAR, SSP, RSC, PI, and TH for all sites were suitable and safe for irrigation. As a result of this study, it has been determined that groundwater in the study area is unsuitable for agricultural irrigation. For sustainable groundwater exploitation, it is advised that a continuous water‐quality‐monitoring program should be implemented, as well as the development of suitable management practices. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Evaluation of T-Shaped Fins With a Novel Layout for Improved Melting in a Triple-Tube Heat Storage System

The effects of T-shaped fins on the improvement of phase change materials (PCM) melting are numerically investigated in vertical triple-tube storage containment. The PCM is held in the middle pipe of a triple-pipe heat exchanger while the heat transfer fluid flows through the internal and external pipes. The dimension effects of the T-shaped fins on the melting process of the PCM are investigated to determine the optimum case. Results indicate that while using T-shaped fins improves the melting performance of the PCM, the improvement potential is mainly governed by the fin’s body rather than the head. Hence, the proposed T-shaped fin did not noticeably improve melting at the bottom of the PCM domain; additionally, a flat fin is added to the optimal case (Added-Fin case) and compared to the No-Fin, Uniform-Fin, and Optimum T-shaped Fin cases (no added fin). The analysis shows that the total heat storage rate of the Added-Fin case increased by 141.7%, 58.8%, and 47.6% compared with the No-Fin, Uniform-Fin, and the Optimum T-shaped Fin cases, respectively. Furthermore, the total melting time for the Added-Fin case was 1882 s and decreased by 59.6%, 38.4%, and 33.6% compared with those of the No-Fin, Uniform-Fin, and the Optimum T-shaped Fin (Optimum) cases, respectively

D-galactose-induced brain ageing model:A systematic review and meta-analysis on cognitive outcomes and oxidative stress indices

Animal models are commonly used in brain ageing research. Amongst these, models where rodents are exposed to d-galactose are held to recapitulate a number of features of ageing including neurobehavioral and neurochemical changes. However, results from animal studies are often inconsistent. To better understand the characteristics of the model and effects of d-galactose on neurobehavioral and neurochemical outcomes in rodents we performed a systematic review and meta-analysis. We applied random-effects meta-analysis to evaluate the effect of study features. Our results give an overview of the characteristics of the d-galactose rodent ageing model, including neurobehavioral and neurochemical outcomes. We found that few studies took measures to reduce risks of bias, and substantial heterogeneity in the reported effects of d-galactose in included studies. This highlights the need for improvements in the use of the d-galactose rodent ageing model if it is to provide useful in the development of drugs to treat human ageing

Optimization of Graphene Oxide Mixed Matrix Membrane for AB-210 Dye Removal

This research aimed to find the best-operating conditions for incorporating the GO material into PES/GO membranes for the NF applications. Organic dye molecules may foul GO-NP/PES membranes. The improved model aimed to reduce the energy lost while maintaining a high system discharge throughout the treatment process in order to face the technical problems that the membranes are exposed to. To create a particular amount of flux above the intended values, an optimization approach was used to find the optimal values for several important parameters in the process. To enhance the process effectiveness on a broader scale, mathematical and statistical studies, such as response surface methodology and statistical analysis of the parameters (ANOVA), were applied. The impact of operational factors, like the pH values of the dye feeding (3–11), GO weight content (0–2 wt.%), dye concentration (10–100 ppm) of AB-210, and the interfaces for these factors with the PES/GO membrane permeability was examined. The PES membrane had the best performance, with a result of 131.2338 L·m-2·h-1·bar-1. The pH did not influence the AB-210 dye reaction, and the Pareto chart of the standardized effects on dye permeation flux using statistical comparison at the 5% significance level supports these findings

Nano-Iron Oxide Coating for Enhanced Heat Transfer in Gas–Solid Fluidized Bed Systems

This study explores using iron oxide coatings on glass beads to improve heat transfer efficiency in fluidized bed reactors. Techniques such as BET surface area analysis, SEM imaging, and X-ray diffraction were used to characterize the coated beads. Results showed the successful creation of a crystalline iron layer on the beads’ surface and increased thermal conductivity, especially at elevated temperatures. The study also quantified the impact of air surface velocity and heating power on the heat transfer coefficient, revealing substantial improvements, especially at higher velocities. It was found that the heat transfer coefficient for 600 µm glass beads increases significantly from 336.4 W/m2·K to 390.3 W/m2·K when the velocity is 0.27 m/s and the heating flux is 125 W. This demonstrates the effectiveness of the iron oxide coating in improving heat transfer. The results of this study emphasize the efficacy of iron oxide coatings in augmenting heat transmission characteristics, particularly in fluidized bed reactor

Experimental Investigation on the Impact of Tube Bundle Designs on Heat Transfer Coefficient in Gas-Solid Fluidized Bed Reactor for Fischer-Tropsch Synthesis

The impact of vertical heat exchanging tube bundle on heat transfer coefficient (HTC) has been investigated locally and instantaneously using a sophisticate heat transfer technique using glass beads solid particles of 210 μm average size and 2500 kg/m3 solid density (Geldart B particles), with a static bed height of 0.35 m as bed material. A mimicked Fischer-Tropsch fluidized bed with vertical heat exchanging tubes is designed and built in this study. Heat transfer performance is also investigated by using two different tubes arrangement (square-pitch and triangular-pitch tubes arrangement). To represent the heat exchanging tubes used in the Fischer-Tropsch process, stainless-steel heat exchanging tubes inserted vertically, each with a diameter of 0.012 m, were used in each tubes arrangement occupying 25% of the column cross-section area. The experiments were performed in a 0.13 m inner diameter Plexiglas fluidized bed reactor with varied gas flowrates (0.2-0.48) m/s at numerous radial positions along the diameter of the column (±0.58, ±0.33, and ± 0.03) and two axial locations (H/D = 1.153 and 1.923). It was found that HTCs significantly enhance with increasing the gas flowrates for all radial positions for square-pitch tubes arrangement. While different behavior can be noticed in the radial positions with triangular-pitch tube arrangement, especially near the wall region (±0.33). Also, the local heat transfer coefficient (LHTC) improved with increasing the axial positions by 12.06% at highest gas flowrates (0.48 m/s). Moreover, the square-pitch tubes arrangement showed a significant increase and uniformity in HTC when measured instantaneously comparing with other tubes arrangement. Furthermore, the findings of this study will improve awareness of vertical tubes\u27 effect on heat transfer in a fluidized bed reactor. Moreover, the data acquired from this investigation can be employed to validate reactor models, CFD codes, and simulations in order to support the design and scale-up processes of such reactors

Experimental Investigation on the Impact of Tube Bundle Designs on Heat Transfer Coefficient in Gas-Solid Fluidized Bed Reactor for Fischer-Tropsch Synthesis

The impact of vertical heat exchanging tube bundle on heat transfer coefficient (HTC) has been investigated locally and instantaneously using a sophisticate heat transfer technique using glass beads solid particles of 210 μm average size and 2500 kg/m3 solid density (Geldart B particles), with a static bed height of 0.35 m as bed material. A mimicked Fischer-Tropsch fluidized bed with vertical heat exchanging tubes is designed and built in this study. Heat transfer performance is also investigated by using two different tubes arrangement (square-pitch and triangular-pitch tubes arrangement). To represent the heat exchanging tubes used in the Fischer–Tropsch process, stainless-steel heat exchanging tubes inserted vertically, each with a diameter of 0.012 m, were used in each tubes arrangement occupying 25% of the column cross-section area. The experiments were performed in a 0.13 m inner diameter Plexiglas fluidized bed reactor with varied gas flowrates (0.2–0.48) m/s at numerous radial positions along the diameter of the column (±0.58, ±0.33, and ± 0.03) and two axial locations (H/D = 1.153 and 1.923). It was found that HTCs significantly enhance with increasing the gas flowrates for all radial positions for square-pitch tubes arrangement. While different behavior can be noticed in the radial positions with triangular-pitch tube arrangement, especially near the wall region (±0.33). Also, the local heat transfer coefficient (LHTC) improved with increasing the axial positions by 12.06% at highest gas flowrates (0.48 m/s). Moreover, the square-pitch tubes arrangement showed a significant increase and uniformity in HTC when measured instantaneously comparing with other tubes arrangement. Furthermore, the findings of this study will improve awareness of vertical tubes\u27 effect on heat transfer in a fluidized bed reactor. Moreover, the data acquired from this investigation can be employed to validate reactor models, CFD codes, and simulations in order to support the design and scale-up processes of such reactors

Parameters Affecting the Efficiency of Solar Stills—Recent Review

Although water is the second most important fluid, after air, found on the Earth, there is a vital problem in the availability of water for many organisms, and this problem faces the whole world. As a result, scientists have developed many methods of purifying the saline/brackish water to be suitable for different uses in addition to the purpose of drinking. Fortunately, solar distillation is very rewarding in terms of operating costs and costs for a liter of freshwater distillated with using clean and environmentally friendly energy. Solar distiller is one of the solar distillation systems devices, which is simple in construction, cheap, and easy to use but it has the drawback of low productivity. This article aims to provide a summary of the different ideas and works on solar stills through different variables that affect the performance of distillers. In contrast to the review papers dealing with this topic, this paper contains comprehensive and complete details and careful reviews of all the variables that affect the performance of distillers. Therefore, it is like a ladder in front of the authors until they reach the recent of what has been studied on the distillers in a simplified way to save time and effort, which will help them to come up with different ideas that were not easily studied. Thus, this paper introduces an overview on the detailed parameters affecting the performance of solar stills. These parameters are climatic, design, and operating factors. Climatic factors consist of solar radiation, ambient temperature, air speed, and dusty and cloudy weather. While the design factors include the evaporative and exposure surface areas, glazing cover material, inclination, and thickness, distiller material, and of insulating material and thickness. Whist, the operating parameters consist of the water temperature, feed water temperature, applying vacuum, temperature difference between water and glass cover, and hybrid systems. From the extensive literature, it is concluded that the climatic, design, and operating factors significantly affect the performance of the solar still. Finally, some points are proposed for further investigation