Abstract

This study involves the application of artificial neural network (ANN) as an intelligent approach to predict the output power of one alpha-type Stirling engine under some operating conditions. One ANN model had been developed based on experimental data from published literature. Output power as one of the performance indicators, was chosen as a response to input parameters, heat source temperature, engine speed and charging pressure. A multi-layer feed-forward network with a back-propagation algorithm had been proposed for such a prediction. The ANN model had been proven to be desirable in accuracy for predicting the output power by comparing the model results with experimental ones under the same operating conditions. This work would provide an effective approach based on ANN technique for solving complex design problems either with linear or nonlinear nature.

Abstract

Internal short circuit (ISC) plays an important role in lithium-ion battery safety accidents. However, the mechanism of how ISC triggers thermal runaway is still unclear yet. We implant the shape memory alloy device into jelly-roll to trigger ISC and analyze the thermal and electrical behaviors under different ISC types and SOC variance conditions. The ISC resistance is identified by using the no-salt battery based on the electrochemical impedance spectroscopy tests. The proposed resistance identification method benefits further ISC mechanism and modelling research.

Abstract

Many studies have been conducted to illustrate the production of formic acid (FA) utilizing carbon dioxide (CO2) in an economically viable manner, but the environmental impact has not received much attention. When CO2 is used to produce FA, greenhouse gas including CO2 will be reduced although the economics of FA production utilizing CO2 is lower than that of conventional production using fossil fuel. To achieve a sophisticated understanding of CO2 utilization, this study focuses on life cycle assessment (LCA) for analyzing the environmental impacts of FA production. Based on new process simulation data for CO2-based FA production, we compare the environmental impact results of CO2-based FA to fossil-based FA. LCA has been conducted in consideration of five petrochemical companies located in the industrial complex of Korea to ensure the potential availability of sources.

Abstract

Source reduction or process control of fuel-N conversion into reactive NOx precursors (NH3 and HCN) during pyrolysis process was fundamental and essential for clean thermal utilization of straw wastes. In this study, three typical straw wastes (bean, rice and wheat) were employed to probe formation characteristics and regulatory mechanisms of two target NOx precursors via stage pyrolysis method with the help of XPS and chemical absorption-spectrophotometry analytic techniques. Results demonstrated that consistent formation pathways of NOx precursors were elucidated by direct and indirect conversion of similar fuel-N types – amide-N/amine-N/amino-N (N-A) in straw wastes. Specifically, two NOx precursors were hardly linked with primary pyrolysis of N-A types (direct conversion) while dominantly determined by secondary reactions of subsequent nitrogen intermediates in chars and tars (indirect conversion); secondary reactions referring to hydrogenation of heterocyclic-N in chars and dehydrogenation of amine-N in tars were more responsible for NH3-N and HCN-N, respectively, leading to a maximal total yield of 45-50 wt.%. Consequently, compared to single-stage pyrolysis uniformly, two-stage pyrolysis could manipulate intensities of formation pathways at different pyrolysis stages through employing differential intermediate feedstocks for re-pyrolysis, minimizing the ratio of total yield by about 60 % with a greater effect on HCN-N yield (76-83 %) than NH3-N yield (44-50 %), which exhibited an excellent regulatory capacity on NOx precursors formation for straw wastes. These findings were favorable for developing some insights into emission control of N-containing gaseous pollutants during their thermo-chemical conversion processes.

Abstract

Contactless slip-ring provide a safe, non-contact, high efficiency, wear-free and reliable power transfer solution with low maintenance for rotary applications. In this paper, a novel magnetic coupler of wireless power transfer (WPT) system is designed. Compared with the traditional slip ring power supply, it can be applied to the rotating condition. To realize light-weight and small-volume of the WPT, the magnetic coupler and circuit have been optimized from both compensation topology and coil configuration. Experimental results are demonstrating that transfer power is 280W at efficiency of 91.7%.

Abstract

Polygeneration technology is an important way to realize clean and efficient coal utilization. Coal-steam gasification technology with thermochemical regenerative process is effective to enhance cold gas efficiency of coal gasification. In this paper, a novel methanol-electricity polygeneration system based on coal-steam gasification is proposed. In this novel polygeneration system, the component adjustment is cancelled and unreacted syngas partially recycled is adopted. The Aspen Plus software is selected to simulate the polygeneration systems. As a result, the energy efficiency of the novel polygeneration system based on coal-steam gasification is 53.5% when chemical to power output ratio is 1.1, while energy efficiency of polygeneration system based on traditional gasification is 47.3%. Furthermore, the energy saving effects of system integration method and gasification process improvement are distinguished.

Abstract

In this paper, a data-driven approach is explored to evaluate the impact of weather conditions on the reliability of urban distribution system. The severity of power outages is divided into two levels according to the number of days with outages in one week. The actual outage records from the local utility are used for the analysis in this study. First, the difference of weather conditions under the two outage levels are intuitively described with the Kernel Density Estimation (KDE). Then, an extreme gradient boosting algorithm is applied to build a classification model for evaluating the outage levels of the local distribution system under given weather conditions. The importance of weather features on the outage level is discussed with the built model. Finally, the performance of the proposed data-driven model is assessed with the Receiver Operating Characteristic (ROC) curve.

Abstract

Extreme ice disasters may lead to a rapid degradation of power system performance. By using a fault probability model of transmission lines with respect to ice-wind loads, the impacts of ice disasters on power systems can be regarded as transmission line outages. To quantify these consequences, a quantitative resilience index is developed in this paper. Finally, the proposed index is testified on the IEEE RTS-79 test system. Results indicate that different enhancement measures can be evaluated based on the obtained resilience indices.

Abstract

Electric power plays an important role in the development of a nation’s economy, and it improves human life. Therefore, understanding the driving forces behind the growth and consumption of electricity will help leaders plan energy savings and create economic policies. Using the LMDI that is based on the Kaya identity, this paper decomposes the factors driving the growth of electric power consumption in the Chinese production sector into the effects of population size, economic development, regional economic structure, regional industrial structure, and electricity consumption intensity. The study finds that the national electricity consumption for production increased by 2,143 TWh from 2007 to 2016. The increasing power consumption intensity inhibits the growth of electric power consumption for production, which has led it to decrease by 1,408.2 TWh, and the suppression effect is more significant in the secondary industry. Economic growth is the main driving force behind the growth of electricity consumption for production, which has led it to increase by 3,770.6 TWh, most obviously in the eastern region. Population growth promotes electricity consumption; however, the impact of this has been relatively small. The regional economic structure has a negative effect on power consumption growth; however, there is a big difference among provinces. To delay the growth of electric power consumption, it is necessary to strengthen technological innovation and management, as well as to pay attention to industrial structure adjustment and energy conservation technology promotion in the central and western regions. Furthermore, we should improve the consumption efficiency of the secondary industries.

Abstract

Undersize the capacity of a solar inverter is a common practice in the industry to reduce capital expense. However, the optimal inverter sizing ratio (ISR) is a site- and system-dependent value. It can vary from 1.0 to 2.2, globally. So far, there is no study on the optimal ISR for photovoltaic (PV) power plants in Malaysia. The industrial practice assumes that the ISR is either the inverse of the performance ratio of the system or value of experience design from other countries, which do not share the same climate. In this paper, a generalised method, which separates the system-dependent and non-system-dependent values, is used to find the optimal ISR for eight different geographic locations in Malaysia. The chosen sites are distantly distributed and have different annual solar irradiation. Hourly solar irradiance data is used to find out the power clipped by the undersized inverter during high solar irradiance period. In addition, the simulation also considers the inverter can be overloaded to 110% of its rated capacity, which is a common specification of an inverter nowadays. This feature was not considered in other research articles. The optimal ISR for the eight sites, which was obtained based on the lowest the levelised cost of electricity (LCOE), falls within 1.475 to 1.525. The optimal ISRs show a strong linear correlation with the annual solar irradiation of the sites. The information is useful for the local industry to optimise the LCOE for their project quickly.