Papers by Keyword: Energy

Abstract: Aerodynamics contributed directly on the energy efficiency and fuel consumption reduction of heavy vehicles in addition to its stability. The present study examines numerically the aerodynamics of heavy vehicles considering different drag-reduction devices using SolidWorks programme. Four different drag-reduction devices such as Base flaps, filled boat tail, Deflector and Rear offset plate in order to compare them with the baseline model. the results showed that the reflector contribute in more drag formation while Rear offset plate leads to lower drag.

Abstract: The operational integrity of supercritical steam power units necessitates comprehensive understanding of welded joint behaviour under high-temperature service conditions. Advanced steam cycle technology requires meticulous periodic evaluation of pressure-bearing components to ensure structural integrity throughout extended service periods. This requirement is particularly critical for components subjected to the most severe operational parameters, including superheater tubes, main steam pipelines, and steam collectors operating above critical temperature. For pressure components not directly exposed to exhaust gases, microstructural degradation represents the primary degradation mechanism governing component lifespan.P92 (X10CrWMoVNb9-2) steel, characterized by a tempered martensitic microstructure with 9% chromium content, has been extensively utilized for high-pressure applications in supercritical steam power generation systems. This advanced creep-resistant steel demonstrates superior mechanical properties, including exceptional high-temperature strength retention, oxidation resistance, and creep rupture strength under prolonged thermal exposure.Welded joints of pressure elements in steam boilers are potentially the weakest points when assessing their service life. These joints exhibit enhanced susceptibility to microstructural degradation and mechanical properties deterioration, particularly within the heat-affected zone (HAZ), during extended high-temperature operation. Therefore, systematic material characterization of welded joints relative to base material performance is essential for understanding long-term degradation mechanisms.This investigation presents systematic creep testing methodology and experimental results for P92 welded joint specimens subjected to annealing at temperatures of 600°C and 650°C for durations up to 10,000 hours. Both abridged and long-term creep tests were performed with the results of determination of creep strength and creep speed in steady state.

Abstract: This paper presents the relationship between crack width and acoustic emission (AE) energy in reinforced concrete (RC) beams subjected to cyclic loading. Two types of RC beams were tested, each reinforced with different tensile bar diameters: 12 mm (Y12) and 16 mm (Y16). The average ultimate loads (P_ult) for beams with Y12 and Y16 were 31 kN and 51 kN respectively. Beams tested under cyclic loading using Y12 and Y16 were labelled FT12 and FT16. Cyclic loading was applied at 80% of the P_ult and tests were continued until failure. A three-point bending test was performed under a sinusoidal load frequency of 1 Hz. AE monitoring was performed with six sensors installed at selected locations on the beams. The results showed that the crack width increased with the number of cycles, with correlation coefficients (R²) of 0.95 for FT12 and 0.93 for FT16, indicating a stronger linear relationship for both beams. Based on the trends in AE energy and crack width, three crack propagation stages were identified, with high AE energy found in both the initial microcrack formation and the final unstable failure stage. The results confirm that AE is an effective tool for early damage detection and fatigue monitoring in RC structures.

Abstract: This study compares the performance of a vapor compression refrigeration system (VCRS) with an integrated mechanical subcooled vapor compression refrigeration system (IMS-VCRS) in water-cooled centrifugal chillers. Specifically, this study uses four different refrigerants R134a, R450a, R513a, and R515a. A mathematical model of IMS-VCRS is developed to determine the performance parameters at a fixed cooling capacity of 1750 kW. This study investigates that the energy consumption of an IMS-VCRS is reduced by 11.36% for R134a, 11.98% for R450a, 13.36% for R513a, and 11.89% for R515a. The mechanical subcooled system's COP is increased by 12.84% for R134a, 13.59% for R450a, 15.40% for R513a, and 13.48% for R515a due to the low power requirement. In addition, exergetic analysis is also used to determine the system's second law efficiencies, which in this study improved by 11.25%, 11.84%, 13.41%, and 11.77% for R134a, R450a, R513a, and R515a respectively. Furthermore, parametric analyses were performed to investigate the effects of various system parameters such as evaporator and condenser temperatures.

Abstract: The forecast for electrical energy demands in the South Sulawesi area in 2060 is 198,353 GWh, so the electricity generation capacity required under the Business As Usual scenario is 38.68 GW in that year. If this demand is connected to the scenario of limiting the construction and operation of coal-fired power plants, then the capacity required is 41.02 GW. This article provides an overview of the value of electrical energy demand and generating capacity in South Sulawesi where the method used to plan additional electricity generating capacity is based on the OSeMOSYS model. The generating capacity of the analysis results comes from various types of power plants, namely: conventional types (combine cycle power plant, gas turbine power plant, gas engine power plant, coal-fired power plant, and diesel power plant), and Renewable Energy types (hydropower plant, mini hydro power plant, biomass power plant, waste-to-energy power plant, geothermal power plant, wind turbine power plant, and photovoltaic power plant). The primary energy used by these power plants comes from the South Sulawesi area and from outside South Sulawesi. Specifically, renewable energy is the potential of the South Sulawesi region.

Abstract: A new viscoelastic design known as auxetic sheet is proposed for the protection of GFRP planing hull vessels. The study of specimens made with auxetic sheets with different configurations in their geometry is presented to determine which one will be capable of absorbing the greatest amount of energy. For this, uniaxial compression tests were carried out using Hooke's 3D law on the designed specimens. The execution showed that the auxetic specimen in the "M" shape was the one capable of absorbing the greatest amount of energy from the applied force, obtaining the greatest capacity to absorb energy. The compression was considered quasistatic with the purpose of simulating an instantaneous slamming impact and being able to process the uniaxial test curve for the calculation of the elastic energy according to the level of damage in the specimen.

Abstract: The integration of photovoltaic systems into energy grids has been very common in recent times since more renewable forms of energy are sought after. Reliability and safety are among the most essential concerns that have to be considered for the deployment and operation of such systems. There have been some very conspicuous failures of protective devices in recent installations, leading to huge damage to solar equipment and an estimation of millions of Naira in repair and maintenance costs. The said incidents further underscore the need for technical competency in PV system installations as well as good-quality protective component acquisition. This study examines the critical role of protective devices in photovoltaic (PV) systems, focusing on their impact on system reliability, operational safety, and financial implications. A survey of industry professionals revealed that the major causes of device failures are overvoltage and poor-quality devices. Similarly, Circuit Breakers and Surge Protectors top the list of devices affected by failures. Critical system shutdowns take up 50% of the resultant consequences of failures, deteriorated performance, and safety hazards. Surprisingly, 65% of those who responded reported financial losses due to the failures, estimated at 45% between N100,000 and N500,000, while 15% had losses above N500,000. The study recommends high-quality protective devices be installed, installation and maintenance be standardized, and predictive maintenance/remote monitoring technologies be adopted to improve reliability and early fault detection. The long-term performance of devices in varying environmental conditions and the economic benefit of using durable, high-quality components are to be focused on further for research. These findings also put forward actionable suggestions to better ensure the PV system resilience for all stakeholders, thereby reducing their financial risks and ensuring the continued growth of the solar energy infrastructure in a reliable manner.

Abstract: Ukraine has accumulated a large amount of industrial waste. The paper presents the results of the behavior of a mixture of waste dolomite and waste coal during heating. During the operation of enterprises a large amount of “waste” - small fractions of dolomite, which are in the dumps, has been accumulated. Waste is a valuable raw material for production of dolomite binders - lime and cement. Dolomite waste is used for comparison. Comparative analysis showed: energy consumption decreases. Reduction of energy costs indicates reduced fuel consumption for the process. The analysis of reduction of operational costs as a result of replacement of high-calorie fuel by coal preparation waste is carried out. Reduction of operational costs is shown when using dolomite waste instead of dolomite. The economic calculation of reduction of operational costs as a result of replacement of high-calorie fuel by coal preparation wastes is carried out.

Abstract: Pollution problems caused by industrial production of leather tanneries are an important environmental issue. In the present paper we propose to study effects of tannery sludge (TS) addition in manufactured clay bricks applying a mixture design formed by different proportions of four components: Clay, two types of sand and TS. The analysis leads to an optimal practical mixture of around 10% of TS, 20% of sand and 70% of clay and this to remain with an acceptable aspect, an admissible water absorption below 15%, an admissible total shrinkage (drying and after fire) lower than 8%, a tensile strength higher than 5MPa and a thermal conductivity of 0.93 Wm^-1K^-1, 15% lower than the reference mixture with 0% of TS. Experimental results indicate that a temperature cycle firing up to 950°C can lead to higher tensile strength and lower water absorption compared to a cycle that reaches only 850°C. Furthermore, incorporating (TS) in the fired brick manufacturing process can lead to significant energy saving. Additionally, it was observed that a moderate inclusion of TS can enhance evaporation process. Keywords : Mixture design, Tannery Sludge (TS); Clay bricks ; Evaporation ; Strength; Water absorption; Shrinkage; Leaching; Energy.

Abstract: Thermoelectric technology is one of the fast-developing technologies in the present days due to its excellent heat transfer and heat conversion capabalities. This uses the electromotive force produced by the temperature difference at each end of the device to produce electricity and vice versa. There are various applications developed based on this thermoelectric technology which includes thermoelectric coolers, thermoelectric generators, and thermoelectric air conditioners. This paper provides a comprehensive analysis of thermoelectric (TE) technologies, starting with a complete summary of their working principles explaining the effects like Seebeck, Peltier, and Thomson effects, as well as optimization techniques, applications, semi-conductor materials used, and potential future developments.