Authors:Sulaiman AL HASHMİ; Mingjie CHEN Abstract: Thermal analysis of high-temperature phase change materials (PCM) is conducted with the consideration of a 20% void and buoyancy-driven convection in a stainless-steel capsule. The effects of the thermal expansion and the volume expansion due to phase change on the energy storage and retrieval process are explored. The used water to fill the void between two different wax paraffin and stearic acid spheres is considered as a potential PCM for concentrated solar power. The charging/discharging process into and from the capsule wall is simulated under different boundary conditions for laminar and turbulent flows. Computational models are conducted by applying an enthalpy-porosity method and volume of fluid method to calculate the transport phenomena within the PCM capsule, including an internal air void. A simplified two-dimensional model of the PCM contained within the spheres is constructed and thermal analyses are performed for the transition from solid to liquid states. Simulated charging process modes are compared with the theory. According to experiments, the temperature distributions from 40-60 mm without and with 60 mm with copper fin have different behavior. The paraffin takes less time than stearic acid for total transformation at a rate of 0.5. The size of the sphere increases over the amount of time and the phase of the sphere to complete changes as stearic acid expands more than paraffin during the transition. Inserting a rectangular fin, that is made from copper into the ball reduces the cycle time and increases output. PubDate: Sat, 30 Sep 2023 00:00:00 +030
Authors:Mehmet SARIKAHYA; Nihan Merve SARIKAHYA, Erol KURT Abstract: In the present work, some tests on the electromagnetic interference issues of a new designed and constructed axial flux permanent magnet generator have been presented. The machine itself has multiple special laminated cores (i.e., 12) and 24 windings in the stator component with two active sides. Machine operates in 3 phases and uses disc type permanent magnets on two rotors at two sides in a sandwiched formation. Rotors have 32 magnets and freely rotates at the vicinity of stable stator within a certain air gap. The electromagnetic interference measurements have been realized for different distances and directions from the machine. Besides, the effects of different frequencies are also evaluated following the tests. It has been concluded that the shielding material shape is very important for the optimum shielding results. PubDate: Sat, 30 Sep 2023 00:00:00 +030
Authors:Denis CHİKURTEV; Veneta YOSİFOVA, Milena HARALAMPİEVA, Rosen PETROV Abstract: Energy efficiency is a global problem that has become a top priority for all developed countries in recent years. Limited energy resources and high pollution worldwide have led to an increase in research and development in terms of energy efficiency. In the present work, one of the energy-efficient methods for heating by using infrared sources is focused. The advantages of infrared heaters compared to standard heating sources are underlined. A comparative study of the energy consumed during heating by the most frequently used by the heating systems has been made, and the results of the theoretically calculated power costs are presented. An intelligent system has been developed for the management of the infrared heaters to reduce the consumption of electricity better. The intelligent control system is based on a fuzzy-logic control and an internet of things. Results of simulation experiments of the intelligent system are presented as well as of the application of the system in a real environment. During the experiments, the system successes to control the heaters and to reduce power consumption. The achieved results prove that signal processing and control can improve the performance by using modern sensor systems, thereby additional efficiency can be achieved by using the infrared heating. It is possible to develop different optimization systems and algorithms for increasing the energy efficiency of different heating systems. PubDate: Sat, 30 Sep 2023 00:00:00 +030
Authors:Froilan DESTREZA Abstract: Energy plays an important role globally. Industrial growth, coupled with high system losses, has resulted in a major demand-supply imbalance resulting in an energy shortage with a devastating effect on the economies of countries. The pollution brought by the combusting energy source and the price-increasing-motion of fuel tends people to explore and use greener and cheaper alternatives. Combining solar sources with Thermoelectric Generators (TEGs), and Piezo-Electric Generators (PEGs), and the concept of using a prime mover and secondary mover of the electric generator, in which, the idea of a self-sustaining electric generator with an automatic control system has come to exist. The self-sustaining electric generator with an automatic control system is compact based on the positioning of the components. The system is acceptable for households used. The noise level of the project passed the Class 1 noise level standard of the Philippines stated in NPCC Memorandum Circular No. 002, Series of 1980, vibration level is concluded to be better with enclosure, and the temperature rise is of normal temperature. The generated power yielded an above-average efficiency. The produced mathematical model validated the Seebeck effect theory, showing the proportional relationship between electrical power and temperature difference. PubDate: Sat, 30 Sep 2023 00:00:00 +030
Authors:Festus Oluwadare FAMESO; Dawood DESAİ, Schalk KOK, Dylan ARMFİELD, Mark NEWBY Abstract: The energy and power industry conventionally depends on large-scale turbomachinery to meet the ever-growing global energy demands. However, unplanned in-service failures remain a threat to sustainability with safety and economic consequences. The laser shock surface treatment technique is being considered a competitive alternative in mitigating crack initiation and growth, wear and fatigue of industrial components such as turbine blades. This paper presents the modelling and optimization of laser shock treatment parameters using numerical methods and commercial codes such as ABAQUS® and MATLAB®. Model-based process optimization parameters for the induction of global optimum compressive residual stress distribution in laser-worked Chromium-12 based high strength steel alloy (X12Cr) turbine blade is established, showing parametric combinations of inputs variables within the domain under investigation, yielding maximized CRS outputs. A hierarchy of significance of the input parameters to the laser shock peening process for stress induction has also been put forward as an outcome of this study. The capacity to predict and analyze outcomes before actual treatment of the components is beneficial and imperative to cutting costs, downtimes and other economic losses associated with unplanned failure of these components. PubDate: Sat, 30 Sep 2023 00:00:00 +030
Authors:Abdul-basset A. AL-HUSSEİN; Fadhil RAHMA TAHİR Abstract: The aim of this paper is to study the unwanted chaotic oscillation that can severely affect the reliable and safe operation of electrical power systems. The dynamical behavior of a benchmark three-bus nonlinear electrical power system model is explored using modern nonlinear analysis methods, where the Lyapunov exponents spectrum, bifurcation diagram, power spectral density and bicoherence are used to investigate the chaotic oscillation in the power system. The analysis shows the existence of critical parameter values that may drive the power system to an unstable region and can expose the system to bus voltage collapse and angle divergence or blackout. To eliminate the chaotic oscillation, a fractional-order fixed time sliding mode controller has been used to control the power system in a finite time that can be predetermined by the designer. The Lyapunov theorem has been used to prove the stability of the controlled power system. The results confirm the superiority, robustness, and effectiveness of the suggested control algorithm. PubDate: Sat, 30 Sep 2023 00:00:00 +030
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