The oil and gas industry is looking for ways to accurately identify and prioritize the failure modes (FMs) of the equipment. Failure mode and effect analysis (FMEA) is the most important tool used in the maintenance approach for the prevention of malfunctioning of the equipment. Current developments in the FMEA technique are mainly focused on addressing the drawbacks of the conventional risk priority number calculations, but the group effects and interrelationships of FMs on other measurements are neglected. In the present study, a hybrid distribution risk assessment framework was proposed to fill these gaps based on the combination of modified linguistic FMEA (LFMEA), Analytic Network Process (ANP), and Decision Making Trial and Evaluation Laboratory (DEMATEL) techniques. The hybrid framework of FMEA was conducted in a hazardous environment at a power generation unit in an oil and gas plant located in Yemen. The results show that mechanical and gas leakage FM in electrical generators posed a greater risk, which critically affects other FMs within the plant. It was observed that the suggested framework produced a precise ranking of FMs, with a clear relationship among FMs. Also, the comparisons of the proposed framework with previous studies demonstrated the multidisciplinary applications of the present framework.
In the present study, a simulation and response surface methodology (RSM) combined approach has been applied to investigate the thermal and thermo-hydraulic performance parameter (THPP) of solar air heater (SAH) with inclined fins. CFD based software (ANSYS Fluent v16.1) is used to simulate the SAH. RNG k-Ɛ turbulence model was selected to carry out a two-dimensional simulation modeling. Moreover, RSM is applied to analyze the results of finite volume method and to optimize the process parameters of SAH. A numerical model describing the heat transfer characteristics of SAH having inclined fins has been developed and employed to study the effects of various design of fins on the average Nusselt number, fiction factor as well as THPP. The study covered different length of fin in the range of 1.5-2.5 mm, different slant angle (α) of fin in the range of 30°-60°, different pitch (P) of fin in the range of 15-25 mm, and a range of 4000-24,000 for the Reynolds numbers. Based on results of the model, the optimized values of design parameters for the optimal operation of SAH to provide the optimal THPP of 1.928 were found to be; length of fin = 1.52 mm, the pitch of fin = 19.04 mm, slant angle = 49° and Reynolds number at 18243.5. According to the optimized values of design parameters, the enhancement ratio of Nusselt number and friction factor were found to be 2.53 and 2.22, respectively. Finally, the thermal performance of the proposed inclined fin in terms of THPP was compared to other roughness geometries, such as circle (THPP = 1.65), square-sectioned (THPP = 1.80) and L-shaped (THPP = 1.90). Accordingly, a better THPP of 1.928 was observed for the current study.
This paper demonstrates the applicability of artificial neural networks (ANNs) that use multiple bck-propagation networks (MBP) and a non-linear autoregressive exogenous model (NARX) for predicting the deflection of a smart wind turbine blade specimen. A neural network model has been developed to perform the deflection with respect to the number of wires required as the output parameter, and parameters such as load, current, time taken and deflection as the input parameters. The network has been trained with experimental data obtained from experimental work. The various stages involved in the development of a genetic algorithm based neural network model are addressed in detail in this paper.
The world today is going through a phase of uncertainty in terms of provision of power and energy because of shortages of fossil fuels, and these issues are increasing the costs as well as developing uncertain economic conditions worldwide. Hence, there is a dire necessity to find a solution to this problem by finding sustainable alternative power and energy solutions. However, the thermal performance of the conventional SAH is found to be poor due to low convective heat transfer coefficient between the heat collecting surface and working fluid. Therefore, increasing the convection heat transfer coefficient is essential so that thermal system performance can also be increased. In the present research, a numerical evaluation was carried out on the heat transfer and the flow friction processes in a SAH coupled with inclined fins underneath the absorber plate. With a constant heat flux application (1000 W/m2), the average Nusselt number (Nu) and friction factor, as well as the thermo-hydraulic performance parameter (THPP), were comprehensively investigated. The research covered different slant angle (α) of fins in the range of 30°-75°, different pitch (P) of fin in the range of 15-25 mm and a range of 4000-24000 for the Reynolds numbers (Re). For the current CFD evaluation, ANSYS FLUENT (v16.1) with renormalization group turbulence model is selected for computational domain analysis. In general, a significant improvement of the heat transfer in a SAH having inclined fins has been achieved. Moreover, with a view to analyzing the total effect of the slant angle and pitch of fin, the THPP subjected to similar pumping power constraint was calculated. From the investigated range, a maximum THPP of 1.916 was achieved by utilizing fins with α = 45° and P = 20 mm at Re = 20,000. Finally, the proposed inclined fin's THPP was compared to other geometries such as, L-shaped (THPP = 1.90), square (THPP = 1.80), and circle (THPP = 1.65). As a result, a better THPP of 1.916 was observed for this study.
In the present study, a rotational piezoelectric (PZT) energy harvester has been designed, fabricated and tested. The design can enhance output power by frequency up-conversion and provide the desired output power range from a fixed input rotational speed by increasing the interchangeable planet cover numbers which is the novelty of this work. The prototype ability to harvest energy has been evaluated with four experiments, which determine the effect of rotational speed, interchangeable planet cover numbers, the distance between PZTs, and PZTs numbers. Increasing rotational speed shows that it can increase output power. However, increasing planet cover numbers can increase the output power without the need to increase speed or any excitation element. With the usage of one, two, and four planet cover numbers, the prototype is able to harvest output power of 0.414 mW, 0.672 mW, and 1.566 mW, respectively, at 50 kΩ with 1500 rpm, and 6.25 Hz bending frequency of the PZT. Moreover, when three cantilevers are used with 35 kΩ loads, the output power is 6.007 mW, and the power density of piezoelectric material is 9.59 mW/cm3. It was concluded that the model could work for frequency up-conversion and provide the desired output power range from a fixed input rotational speed and may result in a longer lifetime of the PZT.
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