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Comparative study of energy consumption and CO2 emissions between Beijing and London
Zhihua CAI, Xunmin OU, Xu ZHANG, Xiliang ZHANG, Jiankun HE, Yangang XING
Front Energ. 2013, 7 (1): 1-5.
https://doi.org/10.1007/s11708-012-0227-5
From the view of geographic location, climate and population status, this paper makes a comparative study of the economy structure, transport system, energy supply and carbon emissions among a few cities, especially between Beijing and London, two mega-cities in the world. The developed tertiary industry, consummate transport system and low-carbon energy supply system in London can be referenced to assist Beijing in establishing a low-carbon development pathway. The difference in the statistical coverage of population between these two cities also brings about the divergence of energy consumption per capita and CO? emissions per capita between them.
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Application of nanotechnologies in the energy sector: A brief and short review
Ferric CHRISTIAN, EDITH, SELLY, Dendy ADITYAWARMAN, Antonius INDARTO
Front Energ. 2013, 7 (1): 6-18.
https://doi.org/10.1007/s11708-012-0219-5
Energy is of great importance in human life because of its benefits as the main resource for human activity. According to International Energy Agency (IEA), energy demands are expected to continue increasing until 2030. Because energy demand will never decrease, it is necessary to develop modern technology, such as nano-based technology, in order to obtain a more effective and efficient process to produce more energy. The application of nano technology or nano material in the field of energy, which involves lithium-ion battery, fuel cell, light emitting diode (LED), ultra-capacitor, and solar cell (including Gr?tzel cell), is a hot topic in many scientific researches. Unfortunately, its current development is hampered by the expensive cost of production compared to conventional technologies. Therefore, priority should be given to nano technology in the energy sector order to obtain higher efficiency, lower production cost, and easier in its application.
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Structural dynamic analysis of the orbiting scroll wrap in the scroll compressor
Yicai LIU, Yubo XIA, Peng YAN, Yinbin LI, Haibo XIE
Front Energ. 2013, 7 (1): 19-25.
https://doi.org/10.1007/s11708-012-0223-9
A deep analysis of orbiting scroll wraps was conducted in this paper by using ANSYS and SolidWorks. Through the modal analysis, the involute of the circle profile orbiting scroll wrap demonstrated a large span in natural frequencies, which led to more superiority in avoiding structural resonances. Based on the dynamic harmonic analysis, loads of frequency changes were gained and the stress and strain distribution of the orbiting scroll wrap in the most dangerous working conditions were obtained, which determined the segments with maximum stress and strain-displacement properties. Two paths defined to elucidate further the structural characteristics of the exhaust chamber provided evidence for the initial correction of orbiting wraps. The results of the present study offer a theoretical basis for the design and manufacture of scroll wraps, and providing a new way to evaluate different scroll wraps.
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Wearable thermal energy harvester powered by human foot
Guodong XU, Yang YANG, Yixin ZHOU, Jing LIU
Front Energ. 2013, 7 (1): 26-38.
https://doi.org/10.1007/s11708-012-0215-9
With explosive applications of many advanced mobile electronic devices, a pervasive energy system with long term sustainability becomes increasingly important. Among the many efforts ever tried, human power is rather unique due to its independence of weather or geographical conditions and is therefore becoming a research focus. This paper is dedicated to demonstrate the possibility and feasibility of harvesting thermal energy from human body by sandwiching a thermoelectric generator (TEG) between human shoe bottom and ground, aiming to power a portable electronic device. Through the conceptual experiments conducted on adults, a maximum 3.99 mW steady state power output at a ground temperature with 273 K is obtained, which is sufficient enough to drive a lot of micro-electronic devices. Also, parametric simulations are performed to systematically clarify the factors influencing the TEG working performance. To further reveal the mechanism of this power generation modality, analytical solutions to the coupled temperature distributions for human foot and TEG module are obtained and the correlation between TEG characteristics and the output power are studied. It was demonstrated that, the TEG working as a wearable power resource by utilizing thermal energy of human foot shows enormous potential and practical values either under normal or extreme conditions.
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Application of fuzzy logic control algorithm as stator power controller of a grid-connected doubly-fed induction generator
Ridha CHEIKH, Arezki MENACER, Said DRID, Mourad TIAR
Front Energ. 2013, 7 (1): 49-55.
https://doi.org/10.1007/s11708-012-0217-7
This paper discusses the power outputs control of a grid-connected doubly-fed induction generator (DFIG) for a wind power generation systems. The DFIG structure control has a six diode rectifier and a PWM IGBT converter in order to control the power outputs of the DFIG driven by wind turbine. So, to supply commercially the electrical power to the grid without any problems related to power quality, the active and reactive powers (Ps, Qs) at the stator side of the DFIG are strictly controlled at a required level, which, in this paper, is realized with an optimized fuzzy logic controller based on the grid flux oriented control, which gives an optimal operation of the DFIG in sub-synchronous region, and the control of the stator power flow with the possibility of keeping stator power factor at a unity.
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Performance prediction of switched reluctance generator with time average and small signal models
Jyoti KOUJALAGI, B. UMAMAHESWARI, R. ARUMUGAM
Front Energ. 2013, 7 (1): 56-68.
https://doi.org/10.1007/s11708-012-0216-8
This paper presents the complete mathematical model and predicts the performance of switched reluctance generator with time average and small signal models. The complete mathematical model is developed in three stages. First, a switching model is developed based on quasi-linear inductance profile. Next, based on the switching behaviour, a time average model is obtained to measure the difference between the excitation and generation time in each switching cycle. Finally, to track control voltage and current wave shapes, a small signal model is designed. The effectiveness of the complete multilevel model combining electrical machine, power converter, load and control with programming language is demonstrated through simulations. A PI controller is used for controlling the voltage of the generator. The results presented show that the controller exhibits accurate tracking control of load voltage under different operating conditions. This demonstrates that the proposed model is able to perform an accurate control of the generated output voltage even in transient situations. The simulation is performed to choose the control parameters and study the performance of switched reluctance generator prior to its actual implementation. Initial experimental results are presented using NI-Data acquisition card to control the output power according to load requirements.
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Hydrogen production from water splitting on CdS-based photocatalysts using solar light
Xiaoping CHEN, Wenfeng SHANGGUAN
Front Energ. 2013, 7 (1): 111-118.
https://doi.org/10.1007/s11708-012-0228-4
Hydrogen energy has been regarded as the most promising energy resource in the near future due to that it is a clean and sustainable energy. And the heterogeneous photocatalytic hydrogen production is increasingly becoming a research hotspot around the world today. As visible light response photocatalysts for hydrogen production, cadmium sulfide (CdS) is the most representative material, the research of which is of continuing popularity. In the past several years, there has been significant progress in water splitting on CdS-based photocatalysts using solar light, especially in the development of co-catalysts. In this paper, recent researches into photocatalytic water splitting on CdS-based photocatalysts are reviewed, including controllable synthesis of CdS, modifications with different kinds of cocatalysts, solid solution, intercalated with layered nanocomposites and metal oxides, and hybrids with graphenes etc. Finally, the problems and future challenges in photocatalytic water splitting on CdS-based photocatalysts are described.
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A combined experimental and theoretical study of micronized coal reburning
Hai ZHANG, Jiaxun LIU, Jun SHEN, Xiumin JIANG
Front Energ. 2013, 7 (1): 119-126.
https://doi.org/10.1007/s11708-012-0226-6
Micronized coal reburning (MCR) can not only reduce carbon in fly ash but also reduce NOx emissions as compared to the conventional coal reburning. However, it has two major kinetic barriers in minimizing NOx emission. The first is the conversion of NO into hydrogen cyanide (HCN) by conjunction with various hydrocarbon fragments. The second is the oxidation of HCN by association with oxygen-containing groups. To elucidate the advantages of MCR, a combination of Diffuse Reflection Fourier Transform Infrared (FTIR) experimental studies with Density Functional Theory (DFT) theoretical calculations is conducted in terms of the second kinetic barrier. FTIR studies based on Chinese Tiefa coal show that there are five hydroxide groups such as OH-π, OH-N, OH-OR2, self-associated OH and free OH. The hydroxide groups increase as the mean particle size decreases expect for free OH. DFT calculations at the B3LYP/6-31 G(d) level indicate that HCN can be oxidized by hydroxide groups in three paths, HCN+OH→HOCN+H (path 1), HCN+OH→HNCO+H (path 2), and HCN+OH→CN+H2O (path 3). The rate limiting steps for path 1, path 2 and path 3 are IM2→P1+H (170.66 kJ/mol activated energy), IM1→IM3 (231.04 kJ/mol activated energy), and R1+OH→P3+H2O (97.14 kJ/mol activated energy), respectively. The present study of MCR will provide insight into its lower NOx emission and guidance for further studies.
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