A Case Study on the Corrosion of an Aging Jack-Up Drilling Rig

Data Availability Statement: Data is contained within the article.Corrosion costs the Oil & Gas Industry billions of pounds annually, primarily due to environmental factors such as high salinity, temperature fluctuations, and humidity in marine environments. Mobile Offshore Drilling Units (MODUs), especially jack-up rigs, are particularly susceptible to these dangers. This paper examines the impact of cold stacking on aging jack-up rigs and highlights how the absence of an adequate corrosion control system can accelerate structural deterioration. Our findings show that repair costs following cold stacking can far exceed the costs associated with maintaining rigs in a warm-stacked state. Preload tanks are critical areas prone to degradation due to microbiologically influenced corrosion (MIC) and inadequate preservation practices. Furthermore, although high-strength steels are frequently utilized in the construction of jack-up rigs due to their durability, we illustrate that, in the absence of meticulously devised preventative measures, these steels are susceptible to considerable corrosion, resulting in substantial repair expenses and diminished operational lifespans. This study highlights the significance of proactive corrosion control measures in maintaining the long-term structural integrity and cost-effectiveness of offshore drilling units.This research received no external funding

Solidification Enhancement in a Triple-Tube Latent Heat Energy Storage System Using Twisted Fins

Copyright: © 2021 by the authors. This work evaluates the influence of combining twisted fins in a triple-tube heat exchanger utilised for latent heat thermal energy storage (LHTES) in three-dimensional numerical simulation and comparing the outcome with the cases of the straight fins and no fins. The phase change material (PCM) is in the annulus between the inner and the outer tube, these tubes include a cold fluid that flows in the counter current path, to solidify the PCM and release the heat storage energy. The performance of the unit was assessed based on the liquid fraction and temperature profiles as well as solidification and the energy storage rate. This study aims to find suitable and efficient fins number and the optimum values of the Re and the inlet temperature of the heat transfer fluid. The outcomes stated the benefits of using twisted fins related to those cases of straight fins and the no-fins. The impact of multi-twisted fins was also considered to detect their influences on the solidification process. The outcomes reveal that the operation of four twisted fins decreased the solidification time by 12.7% and 22.9% compared with four straight fins and the no-fins cases, respectively. Four twisted fins improved the discharging rate by 12.4% and 22.8% compared with the cases of four straight fins and no-fins, respectively. Besides, by reducing the fins’ number from six to four and two, the solidification time reduces by 11.9% and 25.6%, respectively. The current work shows the impacts of innovative designs of fins in the LHTES to produce novel inventions for commercialisation, besides saving the power grid.Jiangsu Provincial Basic Research Program (Natural Science Fund); Natural Science Research Project of Jiangsu Province Colleges and Universities; Philosophy and Social Science Project of Jiangsu Province Colleges and Universitie

Performance analysis of a solar cooling system with equal and unequal adsorption/desorption operating time

Copyright: © 2021 by the authors. In solar-thermal adsorption/desorption processes, it is not always possible to preserve equal operating times for the adsorption/desorption modes due to the fluctuating supply nature of the source which largely affects the system’s operating conditions. This paper seeks to examine the impact of adopting unequal adsorption/desorption times on the entire cooling performance of solar adsorption systems. A cooling system with silica gel–water as adsorbent-adsorbate pair has been built and tested under the climatic condition of Iraq. A mathematical model has been established to predict the system performance, and the results are successfully validated via the experimental findings. The results show that, the system can be operational at the unequal adsorption/desorption times. The performance of the system with equal time is almost twice that of the unequal one. The roles of adsorption velocity, adsorption capacity, overall heat transfer coefficient, and the performance of the cooling system are also evaluated.Iraqi Ministry of Higher Education and Scientific Research / Research and Development Department / Program of Renewable and Sustainable Energy Projects, grant number 1613

Numerical study of nanocomposite phase change material-based heat sink for the passive cooling of electronic components

University of Nottingham Faculty of Engineering Research Excellence PhD Scholarshi

Consecutive charging and discharging of a PCM-based plate heat exchanger with zigzag configuration

Due to the remarkable energy savings, isothermal nature of the operation and low costs, energy storage with phase-change materials (PCMs) is a reliable technology for filling the gap between energy supply and demand. In this paper, an attempt has been made to modify the storage functionality of PCM in a plate type heat exchanger with zigzag configuration. A two-dimensional, time-dependent simulation model for the PCM phase transition during the charging and discharging modes has been developed and validated via earlier related findings. The effects of zigzag angle orientation, inlet flowrate and mean temperature of the heat transfer fluid (HTF) are thoroughly studied and revealed. Results show that increasing the angle of zigzag orientation has no noticeable impact on the development of phase transition during the early stages of operation. However, this effect becomes more noticeable and almost leads to faster storage/retrieval rates as time further elapses. It is found that the system with the zigzag angle of 60° augments the storage rate by 32.6% compared with the system of 30° zigzag angle. Also, higher HTF temperature and/or higher Reynold number result in faster phase-transition rates during both parts of the energy charging-discharging cycle

Artificial intelligence and numerical study of the heat transfer and entropy generation analysis of NEPCM-MWCNTs-Water Hybrid Nanofluids inside a quadrilateral enclosure

In the present investigation, the primary objective is to assess the synergistic impact of a novel hybrid nanofluid composed of nano-enhanced phase change material, multi-walled carbon nanotubes, and water. The governing equations are transformed into dimensionless forms for a more generalized analysis. To solve the problem, the Galerkin finite element method is employed, offering a robust numerical approach. A dataset of 1000 records was created by numerically solving the model for various combinations of control parameters. Using the dataset, a neural network was trained to learn the relationship between control parameters and heat transfer rate. The evaluation outcomes are comprehensively illustrated through key parameters, including local and average Nusselt numbers, total entropy generation, contours, and streamlines in the range of 103<Rayleigh number<105, 0<nanotube concentration<0.025, 0<nano capsule concentration <0.025, and 0.1<non-dimensional fusion temperature <0.7. Remarkably, the results indicate a substantial improvement in the heat transfer rate of the suspension for a hybrid concentration of 5 %, showcasing an impressive 13 % enhancement in contrast to the water host fluid's performance. Notably, the observed rise in entropy generation is relatively moderate, only a 5 % increase

Effect of the quasi-petal heat transfer tube on the melting process of the nano-enhanced phase change substance in a thermal energy storage unit

Data Availability Statement: The data will be available on request.Copyright: © 2021 by the authors. The melting heat transfer of nano-enhanced phase change materials was addressed in a thermal energy storage unit. A heated U-shape tube was placed in a cylindrical shell. The cross-section of the tube is a petal-shape, which can have different amplitudes and wave numbers. The shell is filled with capric acid with a fusion temperature of 32 °C. The copper (Cu)/graphene oxide (GO) type nanoparticles were added to capric acid to improve its heat transfer properties. The enthalpy-porosity approach was used to model the phase change heat transfer in the presence of natural convection heat transfer effects. A novel mesh adaptation method was used to track the phase change melting front and produce high-quality mesh at the phase change region. The impacts of the volume fraction of nanoparticles, the amplitude and number of petals, the distance between tubes, and the angle of tube placements were investigated on the thermal energy rate and melting-time in the thermal energy storage unit. An average charging power can be raised by up to 45% by using petal shape tubes compared to a plain tube. The nanoadditives could improve the heat transfer by 7% for Cu and 11% for GO nanoparticles compared to the pure phase change material.Funding: This research received no external funding

Twisted-fin parametric study to enhance the solidification performance of phase-change material in a shell-and-tube latent heat thermal energy storage system

Copyright © The Author(s) 2022. Phase change material (PCM) is considered as one of the most effective thermal energy storage (TES) systems to balance energy supply and demand. A key challenge in designing efficient PCM-based TES systems lies in the enhancement of heat transmission during phase transition. This study numerically examines the privilege of employing twisted-fin arrays inside a shell-and-tube latent heat storage unit to improve the solidification performance. The presence of twisted fins contributes to the dominating role of heat conduction by their curved shapes, which restricts the role of natural convection but largely aids the overall heat-transfer process during solidification. The heat-discharge rate of twisted-fin configuration is increased by ∼14 and ∼55% compared to straight fin and no fin configurations—leading to a reduction in the solidification duration by ∼13 and ∼35%, respectively. The solidification front at various times has also been assessed through a detailed parametric study over the fin height, fin pitch number, and fin thickness. Over the range of values assumed, the fin height is the most dominant parameter – increasing the heat-retrieval rate from 10.0 to 11.4 W and decreasing the discharge time from above 3600 to 2880 s by varying the fin height from 2.5 to 7.5 mm.National Science Foundation of China (Grant No. 51904233); the National Science Foundation of China (Grant No.52074218 ); Innovation Capability Support Program of Shannxi Province (Grant No. 2020TD- 021)

Natural Convection Effect on Solidification Enhancement in a Multi-Tube Latent Heat Storage System: Effect of Tubes’ Arrangement

Copyright: © 2021 by the authors. The solidification process in a multi-tube latent heat energy system is affected by the natural convection and the arrangement of heat exchanger tubes, which changes the buoyancy effect as well. In the current work, the effect of the arrangement of the tubes in a multi-tube heat exchanger was examined during the solidification process with the focus on the natural convection effects inside the phase change material (PCM). The behavior of the system was numerically analyzed using liquid fraction and energy released, as well as temperature, velocity and streamline profiles for different studied cases. The arrangement of the tubes, considering seven pipes in the symmetrical condition, are assumed at different positions in the system, including uniform distribution of the tubes as well as non-uniform distribution, i.e., tubes concentrated at the bottom, middle and the top of the PCM shell. The model was first validated compared with previous experimental work from the literature. The results show that the heat rate removal from the PCM after 16 h was 52.89 W (max) and 14.85 W (min) for the cases of uniform tube distribution and tubes concentrated at the bottom, respectively, for the proposed dimensions of the heat exchanger. The heat rate removal of the system with uniform tube distribution increases when the distance between the tubes and top of the shell reduces, and increased equal to 68.75 W due to natural convection effect. The heat release rate also reduces by increasing the temperature the tubes. The heat removal rate increases by 7.5%, and 23.7% when the temperature increases from 10 °C to 15 °C and 20 °C, respectively. This paper reveals that specific consideration to the arrangement of the tubes should be made to enhance the heat recovery process attending natural convection effects in phase change heat storage systems

Latent heat thermal storage of nano-enhanced phase change material filled by copper foam with linear porosity variation in vertical direction

Data Availability Statement: Data is contained within the article.Copyright: © 2021 by the authors. The melting flow and heat transfer of copper-oxide coconut oil in thermal energy storage filled with a nonlinear copper metal foam are addressed. The porosity of the copper foam changes linearly from bottom to top. The phase change material (PCM) is filled into the metal foam pores, which form a composite PCM. The natural convection effect is also taken into account. The effect of average porosity; porosity distribution; pore size density; the inclination angle of enclosure; and nanoparticles’ concentration on the isotherms, melting maps, and the melting rate are investigated. The results show that the average porosity is the most important parameter on the melting behavior. The variation in porosity from 0.825 to 0.9 changes the melting time by about 116%. The natural convection flows are weak in the metal foam, and hence, the impact of each of the other parameters on the melting time is insignificant (less than 5%).Funding: This research received no external funding