Monitoring and Control on Impressed Current Cathodic Protection for Oil Pipelines

This research is devoted to design and implement a Supervisory Control and Data Acquisition system (SCADA) for monitoring and controlling the corrosion of a carbon steel pipe buried in soil. A smart technique equipped with a microcontroller, a collection of sensors and a communication system was applied to monitor and control the operation of an ICCP process for a carbon steel pipe. The integration of the built hardware, LabVIEW graphical programming and PC interface produces an effective SCADA system for two types of control namely: a Proportional Integral Derivative (PID) that supports a closed loop, and a traditional open loop control. Through this work, under environmental temperature of 30°C, an evaluation and comparison were done for two types of controls tested at low soil moisture (48%) and high soil moisture (80 %) to study the value of current, anode voltage, pipe to soil potential (PSP) and consumed power. The results show an decrease of 59.1% in consumed power when the moisture changes from the low to high level. It was reached that the closed loop controller PID is the best solution in terms of efficiency, reliability, fast response and power consumption

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

Analytical and Numerical Solutions for the Thermal Problem in a Friction Clutch System

The dry friction clutch is an important part in vehicles, which has more than one function, but the most important function is to connect and disconnect the engine (driving part) with driven parts. This work presents a developed numerical solution applying a finite element technique in order to obtain results with high precision. A new three-dimensional model of a single-disc clutch operating in dry conditions was built from scratch. As the new model represents the real friction clutch including all details, the complexity in the geometry of the clutch is considered one of the difficulties that the researchers faced using the numerical solution. The thermal behaviour of the friction clutch during the slip phase was studied. Meanwhile, in the second part of this work, the transient thermal equations were derived from scratch to find the analytical solution for the thermal problem of a clutch disc in order to verify the numerical results. It was found, after comparison of the numerical results with analytical results, that the results of the numerical model are very accurate and the difference between them does not exceed 1%

The temperatures distributions of a single-disc clutches using heat partitioning and total heat generated approaches

An accurate estimation of temperature distribution is considered necessary to avoid the premature failure of friction clutches. In this work, different approaches were used to compute the surface temperatures of the friction clutch disc. The results presented the maximum surface temperature when the contact occurs between the rubbing surfaces during a single engagement and repeated engagements. Two approaches were used to simulate the thermal models of the automotive clutches to obtain the temperature field are heat partitioning approach and total heat generated approach. The analysis was conducted using developed axisymmetric finite element models to study the thermal behavior of the friction clutches during multi-engagements. The comparison was made between the temperature distributions based on the proposed approaches to show the accuracy of each approach. It was found that the heat partitioning approach was not accurate to investigate the thermal problem of the friction clutch during the multi-engagements

Effect of Sliding Speed on the Thermal Stresses of Single-Disk Friction Clutches

The friction clutch is considered an essential machine element in the power transmission system, whereas the friction clutches are used widely in many applications of mechanical engineering, especially in the automotive vehicles. Most of failures happen in the elements surfaces of the clutch system due to the excessive heat generated through the early stage of the engagement period. In this paper, the finite element technique is applied to compute the variation of the heat generated due to friction, temperature and thermal stresses through the heating stage of the friction clutch. The simulation of working of the friction clutch has been accomplished using developed axisymmetric finite element models. The results present the distributions of frictional heat generated and thermal stress during the sliding period. The results proved that the non-uniformity of the pressure distribution is responsible for generating the high local frictional heat generated in some zones of nominal contact area through the heating stage and this will lead to a high increase in the thermal stresses

Experimental Investigation and Computational Fluid Dynamic Simulation of Hydrodynamics of Liquid–Solid Fluidized Beds

The present study provides and examines an experimental and CFD simulation to predict and accurately quantify the individual phase holdup. The experimental findings demonstrated that the increase of solid beads has a significant influence on the (Umf), as comparatively small glass beads particles require a low (Umf) value, which tends to increase as the diameter of the beads increases. Besides that, the expansion ratio is proportional to the velocity of the liquid. Even though, the relationship becomes inversely proportional to the diameter of the beads. The liquid holdup was found to increase with increasing liquid velocity, however, the solid holdup decreased. The Eulerian–Eulerian granular multiphase flow technique was used to predict the overall performance of the liquid–solid fluidized beds (LSFBs). There was a good agreement between the experimental results and the dynamic properties of liquid–solid flows obtained from the CFD simulation, which will facilitate future simulation studies of liquid–solid fluidized beds. This work has further improved the understanding and knowledge of CFD simulation of such a system at different parameters. Furthermore, understanding the hydrodynamics features within the two-phase fluidization bed, as well as knowing the specific features, is essential for good system design, enabling the systems to perform more effectively

Experimental Investigation and Computational Fluid Dynamic Simulation of Hydrodynamics of Liquid–Solid Fluidized Beds

The present study provides and examines an experimental and CFD simulation to predict and accurately quantify the individual phase holdup. The experimental findings demonstrated that the increase of solid beads has a significant influence on the (Umf), as comparatively small glass beads particles require a low (Umf) value, which tends to increase as the diameter of the beads increases. Besides that, the expansion ratio is proportional to the velocity of the liquid. Even though, the relationship becomes inversely proportional to the diameter of the beads. The liquid holdup was found to increase with increasing liquid velocity, however, the solid holdup decreased. The Eulerian–Eulerian granular multiphase flow technique was used to predict the overall performance of the liquid–solid fluidized beds (LSFBs). There was a good agreement between the experimental results and the dynamic properties of liquid–solid flows obtained from the CFD simulation, which will facilitate future simulation studies of liquid–solid fluidized beds. This work has further improved the understanding and knowledge of CFD simulation of such a system at different parameters. Furthermore, understanding the hydrodynamics features within the two-phase fluidization bed, as well as knowing the specific features, is essential for good system design, enabling the systems to perform more effectively

Recent progress in performance improvement strategies for quantum dot sensitization methods: Challenges, achievements, and future prospects

In the recent past, there has been an increase in the use of semiconductor nanostructures that convert solar energy to electrical energy. This has encouraged the development of better and more efficient solar cells (SCs). Numerous investigations have been conducted into synthesizing novel semiconductor materials and tuning the electronic properties based on the shape, size, composition, and assembly of the quantum dots to improve hybrid assemblies. Recent studies that are determining the prospects of quantum dot SCs can form the basis for improving photovoltaic efficiency. Here, we have reviewed studies that investigated the sensitization methods for fabricating highly efficient SCs. We also discussed some examples that would help other researchers who want to sensitize quantum dot (QD) SCs. Thereafter, we analyzed the main and popular strategies that can be used for sensitizing the QD SCs within the limitations, advantages, and prospects of fabricating high-efficiency and stable QDs. During this work, we offered strong technical support and a theoretical basis for improving the industrial applications of QD. In addition, we provide a reference that can inspire other researchers who aim to improve the performance of SCs