Day 2 :
- Renewable and Non Renewable Energy Sources | Energy Storage System and Technologies | Energy Economics and Energy Policy | Sustainability | Battery, Fuel Cells and Combustion Technologies | Advanced Energy Technologies | Solar Energy and Wind Power
Tokyo University of Science, Japan
Hubei University, P R China
Tokyo University of Science, Japan
Shunsuke Mori received Doctor of Engineering from Tokyo University in 1981. He is a Professor, Department of Industrial Administration, Tokyo University of Science since 1994. He is Dean of Graduate School of Science and Technology from 2012 to 2014. He was the Invited Researcher for Economic Planning Agency from 1981-1983; Science Researcher, International Institute for Applied Systems Analysis (Austria) from 1986-1987; the Chief Researcher, Research Institute of Innovative Technology for the Earth from 2002-2007. He joined the IPCC activities and is the lead Author of Special Report of Emission Scenarios and the Third Assessment Report of IPCC, WG-III, Chapter 9. His field is system engineering, energy and economic modeling, regional energy planning, assessment of global warming, model development of environmental technologies. He is a Senior Member of JIE, and Vice Chair of Japan Society of Energy and Resources.
It is well understood that the energy conservation of the commercial buildings in the metropolitan area is one of the key issue under the environmental constraints. In Tokyo, since Olympic is being held in 2020, distributed energy technologies including CGS, Photovoltaics, new heat-pumps, etc., are expected to meet large air-conditioning demand in the summer season. In order to evaluate the contribution of these energy technologies, we have developed several models focusing on the regional energy supply-demand systems as well as the power expansion planning model of the utility. Recently, the unused thermal sources such as underground heat and the energy source from river are reconsidered; thanks to the progresses in the heat pump technologies. In this study, we investigate the contribution of new energy technologies for the buildings from two views: First, we look into three commercial and office buildings in the Tokyo area. We evaluate the energy demand on room cooling, room heating, hot-water supply and general electricity demand. We then develop an energy technology flow model shown in Figure 1. We also employ new energy technologies as follows; DC-inverter controlled heat-pumps which have almost constant COP in the low capacity utilization duration and the utilization of the thermal energy of the river and the underground energy which provide higher COP around 5-6. In this model, COP is formulated as a function of capacity utilization rates. This model is thus formulated as non-linear optimization model. We also include the energy transportation among building. Double-skin walls for the heat insulation are also evaluated. Another view focuses on the thermal energy transportation among regions. We divide Koto-area in Tokyo into 151 sub-regions in around 250 m by 250 m meshes specifying the building types. Including the potentials of unused energy sources such as underground heat, river heat sources, waste incineration heat, the possible contributions of these technologies and energy transportations among regions as well as the CGS are evaluated. Our model with the unused energy sources and new technologies demonstrates the potential and the limit of these new sources.
1. Mori, S, et.al. , Two-Stage Approach for the Assessment of Photovoltaic and Cogeneration Systems: Integration of Regional Distributed Energy Systems and Power-Expansion Planning, J. of Energy Engineering (to appear)
2. Shiogama,H., Stone,D., Emori,S., Takahashi,K., Mori,S., Maeda,A., Ishizaki,S & Allen, M. R. (2016), Predicting future uncertainty constraints on global warming projections, Scientific Reports, | 6:18903 | DOI: 10.1038/srep18903, Jan.11, 2016
3.Mori,S. (2016), A new approach of carbon emission allocation among stakeholders: an expansion of Multiregional and Multisectoral Dynamic Energy‑Economic Model THERESIA, J. of Economic Structures, Vol.5, No.5, pp.1/22
4. Mori,S., et.al (2013), Data Center as a Key Player of a District Electric Power and Heat Network System: A Comparison in Urban and Suburb Regions, Computer Technology and Application 4 (2013) 548-555.
5.Mori,S. et.al. (2013), Minimum Regret Climate Policy with Act-Then-Learn Decision - A New Model Framework under Long-term Uncertainties, J. of Energy and Power Engineering, Vol.7, No.6, pp.1106-1115
Indian Institute of Technology, Varanasi, India
Bhupendra Singh has expertise in synthesis and characterization of materials for energy conversion & storage, study of defect structure and transport properties of solid state ionic conductors, intermediate-temperature fuel cells. Currently, he is a Ramanujan Fellow at Department of Ceramic Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi, India. He has coauthored more than 50 research publications in the form of peer-reviewed research papers, conference proceedings, book chapters and patents.
Acceptor-doped tetravalent metal pyrophosphates (MP2O7: M=Sn, Zr, Ce, Ti, etc.) have shown significant proton conductivity of >10-2 S cm-1 in 100-300oC range and are being considered promising electrolytes in proton-conducting ceramic electrolyte fuel cells (PCFCs). But, poor sintering-ability of the tetravalent metal pyrophosphate (TMP) has posed one of the major challenges in their application in PCFCs. In an attempt to utilize the potential of these materials in PCFCs, a number of ways ranging from enhancing sintering behavior to the fabrication of composites have been proposed. Herein, we systematically address some of these aspects and present an overview of developments, and present a report on synthesis and characterization of novel TMP and alkali carbonate (A2CO3; A = Li and/or Na) composites. The TMP-carbonate composites are prepared by mixing indium-doped tin pyrophosphate or yttrium-doped zirconium pyrophosphate with Li2CO3 or an eutectic mixture of Li2CO3-Na2CO3 in different wt.% ratios. The phase composition, microstructure and electrical conductivity of the sintered specimen are analyzed. In addition, the effect of different TMP and A2CO3 phases is investigated. A maximum ionic conductivity of 5.5 × 10−2 S cm−1 at 630°C is observed in this study with a Sn0.9In0.1P2O7-Li2CO3 composite. Based on the literature data, TMP-carbonate composites can be considered to be primarily a proton and oxygen-ion co-ionic conductor and, therefore, have strong potential as electrolytes in fuel cells in 500-700°C range.
1. Singh B, Bhardwaj A, Gautam SK, Kumar D, Parkash O, Kim IH, Song SJ (2017) Fast ionic conduction in tetravalent metal-pyrophosphate-alkali carbonate composites: New Potential electrolytes for intermediate-temperature fuel cells. Journal of p[ower Sources 345:176-181.
2. Singh B, Bhardwaj A, Gautam SK, Parkash O, Kumar D, Jadhav HS, Song SJ (2017) Synthesis and characterization of MnO-doped titanium pyrophosphates, (Ti1-xMnxP2O7; x=0-0.2), for intermediate-temperature proton-conducting ceramic-electrolyte fuel cells. Ionics DOI: 10.1007/s11581-017-2024-y.
3. Singh B, Duong NMH, Henkensmeier D, Jang JH, Kim HJ, Han J, Nam SW (2017) Influence of different side-groups and cross-links on phosphoric acid doped Radel-based polysulfone membranes for high temperature polymer electrolyte fuel cells. Electrochimica Acta 224:306-313.
4. Im HN, Kim IH, Singh B, Jeon SY, Yoo YS, Song SJ (2017) Isothermal Charge Transport Properties of La0.1Sr0.9Co0.8Fe0.2O3-δ by Blocking Cell Method. Journal of The Electrochemical Society 164:F400-F404.
5. Im HN, Singh B, Hong JW, Kim IH, Lee KT, Song SJ (2017) Pd-YSZ cermet membranes with self-repairing capability in extreme H2S conditions. Ceramics International 43:2291-2296.
6.Singh B, Kim JH, Parkash O, Song SJ (2016) Effect of MnO-doping in tetravalent metal pyrophosphate (MP2O7; M=Ce, Sn, Zr) electrolytes. Ceramics International 42:2983-2989.
7. Kim JH, Singh B, Hong JW, Im HN, Song SJ (2016) Electrical behavior and stability of K2HPO4-KH5(PO4)2-Ce0.9Gd0.1P2O7 composite electrolytes for intermediate temperature proton-conducting fuel cells. Journal of The Electrochemical Society 163:225-229.
8.Im HN, Singh B, Hong JW, Kim IH, Lee KT, Song SJ, (2016) Defect chemistry of highly defective La0.1Sr0.9Co0.8Fe0.2O3-δ by considering oxygen interstitials. Journal of The Electrochemical Society 163:F1588-F1595.
9.Jeon SY, Yoo YS, Singh B, Im HN, Song SJ (2016) Investigation of effect of Al-doping on mass/charge transport properties of La2NiO4+δ by blocking cell method. Journal of The Electrochemical Society 163:F1302-F1307.
10. Lee TR, Lim DK, Singh B, Song SJ (2016) Study of mass transport kinetics in co-doped Ba0.9Sr0.1Ce0.85Y0.15O3-d by electrical conductivity relaxation. Solid State Ionics 289:9-16.
Abdullah Gul University, Turkey
Irfan Alan received his BSc and MSc degrees from the Istanbul Technical University, Electrical and Electronic Engineering Department in 1983 and 1986 respectively. He won a PhD scholarship to study abroad in the field of Electrical Machines offered by Ministry of National Education, Turkey in 1986. He received his PhD degree from the University of Wisconsin-Madison, Electrical and Computer Engineering Department. He worked as a Faculty Member at Ege University at various capacities for sixteen years. He was and still is Thesis Advisor for many graduate students. He completed many projects including NASA funded, Government Planning Organization funded, Ege University funded, and TUBITAK (Turkish Scientific Technology Research Institute) funded projects. He has many SCI articles. He has refereed many articles published in National and International journals and conferences. He became a Vice Rector at Abdullah Gul University since 2011. He served as an Interim Rector in 2012. He served and still serves as a Dean and Director for different faculties and schools and General Secretary for AGU. His research interests are in the fields of electrical machines, power electronics and drives, energy efficiency, induction heating, wind power electric generation, and energy storage systems.
Here in this study, a revolutionary inverter technique will be discussed. The goal of this revolutionary technique is to obtain a DC-AC inverter which removes the need for use of known PWM modulation techniques such as multiple PWM, sinusoidal PWM, modified sinusoidal PWM, staircase, stepped, harmonic injected PWM and delta modulated PWM used in the inverter blocks to remove the dominant harmonics and obtain almost harmonic free AC voltage waveforms at the output of the inverters. In the novel technique presented here, the revolutionary inverter is composed of two back-to-back cascaded blocks; one of which is a DC/DC converter and the other is a classical DC/AC inverter. DC/DC converter block is used to obtain the rectified version of the sinusoidal AC voltage waveform desired to be obtained at the output of the inverter and the DC/AC block is used to obtain the desired sinusoidal output voltage waveform from the rectified version of itself formed at the output of the DC/DC converter with only a single loss free switching action in every half cycle of the sinusoidal AC output voltage waveform. In this way, the switching losses associated with the high switching frequencies of classical PWM techniques are eliminated. Besides, the need for classical high valued capacitor utilized in the DC bus to remove the ripples is eliminated because the DC bus voltage waveform is not a ripple free DC bus voltage anymore. In fact, it should be in the form of a rectified sinusoid voltage waveform desired to be obtained at the output of the inverter. Just because of this reason, the DC bus capacitor should actually be valued in small sizes so that it could discharge to zero voltage levels required to form the rectified sinusoid waveform at the output of the DC/DC converter. This means a cost reduction in capacitor sizing. A dynamic duty cycle adjustment is necessary for the control of DC/DC converter to achieve this goal. This dynamic duty cycle control is the most critical part of the revolutionary control, and the second part of the revolutionary control is its requirement for only one loss free switching action due to its zero voltage switching at every half cycle of the desired sinusoidal voltage waveform.
1.Celebi M, Alan I (2010) “A novel approach for a sinusoidal output inverter”, ELECTRICAL ENGINEERING, Vol. 92, Issue: 7-8, pp. 239-244, December 2010.
2. Akin O, Alan I (2010) “The use of FPGA in Field-Oriented Control of an Induction Machine”, Turk J Elec Eng & Comp Sci, Vol.18, No.6, pp. 943-962, TÜBİTAK, doi:10.3906/elk-0905-40, November 2010.
3. Gokalan R, Alan I (2010) “Control of Variable Speed Permanent Magnet Synchronuous Generator for Wind Turbine Application”, International Symposium on Computing in Science and Engineering, ISCSE’2010, Conference Proceedings, Proceeding Number: 206, June 3-5, 2010.
4. Alan I, Lipo TA (2003) "Induction Machine Based Flywheel Energy Storage System", IEEE Transactions on Aerospace and Electronic Systems, Vol.39, No.1, January 2003, pp.151-163.
5.Goksu S, Alan I (2003), "250W Flyback SMPS Design for a Big Size Color TV", IEEE Transactions on Consumer Electronics, Vol.49, No:4, November 2003, pp. 911-916.
6. Alan I, Lıpo TA (2000) "Starter/Generator Employing Resonant Converter Fed Induction Machine, Part I: Analysis", IEEE Transactions on Aerospace and Electronic Systems, Vol.36, No.4, pp. 1309-1318, October 2000.
7. Alan I, Lıpo TA (2000) "Starter/Generator Employing Resonant Converter Fed Induction Machine, Part II: Hardware Prototype", IEEE Transactions on Aerospace and Electronic Systems, Vol.36, No.4, pp. 1319-1329, October 2000.
Military Institute of Engineer Technology, Poland
Agnieszka Iwan is an Associate Professor and Scientific Secretary, formerly working at the Electrotechnical Institute (Wroclaw) as Head of the New Technologies Lab, moved to Military Institute of Engineer Technology (WITI, Wroclaw) in October 2016 to start R&D activities devoted to practical application of solar cells. She is an expert in organic (polymer) solar cells on glass and flexible substrate, nanomaterials, graphene, polymers, oligomers, fuel cells, liquid crystals. She is author and co-author of more than 260 articles.
A photovoltaic (PV) technology on the elastic substrates is considered presently as more cost-effective than traditional crystalline silicon based PV, which is heavier and more fragile. Flexible photovoltaic technologies can be divided into: Si based solar cells and organic (polymer) solar cells. Both of the mention types of solar cells are investigated at the Military Institute of Engineer Technology (WITI) for civil and military applications. It is known that the preparation of thin film c-Si still remains a challenge. Several methods as epitaxial layer transfer, etch-release method and exfoliating from bulk silicon wafer are investigated to fabricate flexible silicon solar cells. We proposed in our work new smart strategies to incorporate commercial silicon solar cells into various textiles, without any change of the electrical and mechanical parameters of devices. We propose various constructions of devices connected with battery or supercapacitors as is schematically presented in Fig. 1. Depending on the lamination process and compatibility of textile with solar cell an efficiency of investigated flexible Si solar cells was 9.44-16.64%. Multi folding and unfolding of flexible device has no impact on its efficiency. Moreover, we investigated organic solar cells on the polyethylene terephthalate (PET/ITO), graphene (PET/G) substrate or substrate with special optical elements. Taking into consideration brittleness of ITO, more perspective is PET/G substrate, however in this case, improvement of electrical parameters of graphene is required. We study photovoltaic properties of various devices with graphene, taking into consideration different placement of graphene in solar cell. Finally, electrical properties of devices are observed by thermographic camera to define heat energy before and after mechanical destruction. Presented flexible silicon and organic devices can be widely used on a large scale, e.g., in flexible solar cells integrated with textiles, different equipment or buildings for both military and civil applications (dual use).
1. Lin Q. et al. (2014) Flexible photovoltaic technologies. J. Mat. Chem. C 2:1233-1247.
2.Krebs F. C. et al. (2006) Strategies for incorporation of polymer photovoltaics into garments and textiles. Solar Energy Mat.&Solar Cells 90:1058-1067.
3. Singh M. K. (2011) Flexible photovoltaics textiles for smart applications. Solar Cells – New Aspects and Solutions 43-68.
4. Iwan A., Chuchmała A. (2012) Perspectives of Applied Graphene: Polymer Solar Cells. Progress in Polymer Science 37:1805-1828.
5. Iwan A. (2015) An overview of LC polyazomethines with aliphatic-aromatic moieties: Thermal, optical, electrical and photovoltaic properties. Renewable and Sustainable Energy Reviews 52:65-79.
6.Iwan A. et al. (2017) Electrochemical and photocurrent characterization of polymer solar cells with improved performance after GO addition to the PEDOT:PSS hole transporting layer. Solar Energy 146:230-242.
7.Iwan A. et al. (2016) Polymer devices with graphene: solar cells and ultracapacitors. Graphene Science Handbook. 14:193-209. CRC Press/Taylor & Francis, Florida.
8.Iwan A. (2015) Polymer Solar Cells: An Overview. Energy Science & Technology, Studium Press LLC, Houston, USA. 12:321-347.
9.Januszko A., Przybył W., Krajewska A., Pasternak I., Przewloka A., Strupinski W. (2015) Patent application P.413693.
R Anand serves as an Assistant Professor of Mechanical Engineering at National Institute of Technology, Trichy from May, 2007. His area of specialization is Internal Combustion Engines and it expands to the field of Waste to Energy, Alternative Fuels, Emission Control and Fuel Cells. His research oriented scholarship has facilitated him to publish 25 SCI international journals and presented papers in several international conferences besides presenting paper in ASME and SAE international conferences. He received Endeavour Fellowship from Australian Government. He has received the N K Iyengar Award from Institute of Engineers, India. Currently, he is undertaking projects received from DST-SERB, DST-UKERI and Institution of Engineers, India. Currently, he is undertaking Consultancy for Industry and Academics to support their research activities in the area of production of new alternative fuels, emission control strategies, fuel property determination and engine study. He is a Reviewer of many Elsevier, ACS, ASME and SAE journals.
Ever increasing energy demand, continued exploitation of fossil fuel sources, uncertainty in the cost of petroleum-based fuels and the detrimental effects related to the use of fossil fuels on the environment have encouraged to search new and alternate sources of fuel for automobiles. In recent years the quantity of waste has increased significantly all over the world. Most of the wastes are inorganic, non-biodegradable nature and affects the landfill, so waste disposal has been a major problem in most of the countries. The conversion of useful energy from wastes can be divided into thermo-chemical and biological conversion. Thermo-chemical conversions are more suitable for converting the inorganic wastes into useful energy. There are several thermo-chemical conversion routes available for converting the waste into energy, such as pyrolysis, gasification, and combustion. The fast pyrolysis has added advantage compared to gasification and incineration and promising way to obtain diesel like fuel from the wastes. Most of the research works reveal that the pyrolysis fuel has best replacement for the fossil fuel but it has slightly higher engine out emissions compared to fossil fuel. These emissions are major threat to human health and living organisms and it has been minimized by the advanced technologies. Common rail direct injection (CRDI) is one of the appropriate methods to reduction in the engine out emissions by and enhances the engine efficiency. The thermal efficiency increased upto 36 to 40% and unburnt hydrocarbons, particulate matters, and carbon monoxide emissions are reduced by 55%, 50%, and 60% respectively at rated power, but NO emission is increased by 20%. The quantity of EGR and mode of Split Injection are predominant methods for controlling the NOx emission. The high-pressure injection enhances the turbulence and homogeneity in the air-fuel mixture to obtain the better thermal efficiency as well as lower emissions.
1.Gong, Yichao; Wang, Dan Ping; Wu, Renbing; Gazi, Sarifuddin; Soo, Han Sen; Sritharan, Thirumany; Chen, Zhong, "New Insights into the Photocatalytic Activity Of 3-D Core-Shell P25@Silica Nanocomposites: Impact of Mesoporous Coating", Dalton Transactions, Vol 46, 2017, pp 4994 – 5002.
2. Danping Wang, Prince Saurabh Bassi , Huan Qi, Xin Zhao, Gurudayal, Lydia Helena Wong *, Rong Xu, Thirumany Sritharan, Zhong Chen, “Improved charge separation in WO3/CuWO4 composite photoanodes for photoelectrochemical water oxidation”, Materials, Vol 9(5), paper no 348, May 2016.
3.Chao Wei, Zhenxing Feng, Murat Baisariyev, Linghui Yu, Li Zeng, Tianpin Wu, Haiyan Zhao, Yaqin Huang, Michael J Bedzyk, Thirumany Sritharan, Zhichuan J Xu, “Valence Change Ability and Geometrical Occupation of Substitution Cations Determine the Pseudocapacitance of Spinel Ferrite XFe2O4 (X = Mn, Co, Ni, Fe)”, Chemistry of Materials, Vol 28(12), June 28 2016, pp 4129-4133
4. Shukla, Sudhanshu; Xing, Guichuan; Ge, Hu; Prabhakar , Rajiv Ramanujam ; Mathew, Sinu ; Su, Zhenghua; Nalla, Venkatram; Venkatesan, Thirumalai; Mathews, Nripan; Sritharan, Thirumany; Sum, Tze Chien; Xiong, Qihua, "Origin of Photocarrier Losses in Iron Pyrite (FeS2) Nanocubes", ACS Nano, Vol 10(4), 26 April 2016, pp 4431 - 4440
5. Chao Wei, Linghui Yu, Chenlong Cui, Jiadan Lin, Chen Wei, Nripan Mathews, Fengwei Huo, Thirumany Sritharan, Zhichuan Xu, “Ultrathin MnO2 Nanoflakes as Efficient Catalysts for Oxygen Reduction Reaction” ChemComm, Vol 50(58), 25 July 2014, pp 7885-7888.
Stuttgart Technology University of Applied Sciences, Germany
Rafal Strzalka has been working at the Stuttgart University of Applied Sciences since 2002. As part of his work, he was involved in numerous national and European projects. Since 2013, he has been coordinating the research activities of the university in the field of energetic use of biomass as a Project Manager. The core competences include the optimization of energy production processes, the comprehensive analysis of biomass energy infrastructure and specialized, simulation-based efficiency enhancement measures for biomass-fired energy generation systems.
Bioenergy is so far the most important renewable energy source in Germany. This can be explained above all by the availability of numerous proven technologies and processes developed for energy generation from biomass. Furthermore the advantage of biomass lies in the possibility of direct substitution of fossil fuels which creates numerous perspectives for the implementation of new bioenergy project within the existing energy infrastructure. Above all biomass also represents a form of stored solar energy, which can be used efficiently according to the current energy demand. The results summarized in the proposed study provide an overview of the role of biomass in the German energy mix, with a particular focus on the renewable energy sector. Furthermore, the technologies for energy generation from biomass, their main indicators and properties are presented. The main focus is placed on the technologies for decentralized generation of power and heat, since these technologies achieve relatively high conversion efficiency, can be characterized by low transport loses and fulfill the criteria of economically feasible operation. In addition, the perspectives and barriers for the successful implementation of new bioenergy projects will also be described and presented in the paper. These analyses will provide particularly important results in view of the changed energy policy system conditions within the framework of the last EEG amendment. In particular the influence of the energy policy issues and their influence on the bioenergy sector will be discussed on the basis of the two most important technologies: Biogas plants and combustion-based CHP plants. The publication also analyses and describes the success factors which determine the increasing application of bioenergy technologies. Subsequently, the aspects of the integration of biomass into energy systems and its various facets will be discussed. Concerning this matter, the main challenge is the achievement of the energy policy objectives and the maintenance of the positive sector growth despite the worsening of the general economic conditions and system-technical requirements. Finally, as a result of these considerations the final part of the study is devoted to questions of efficiency enhancement, system optimization and infrastructure adaptation, which are crucial for the efficient implementation of bioenergy within innovative energy supply systems.
1. Strzalka, R., Erhart, T., & Eicker, U.: Analysis and optimization of a cogeneration system based on biomass combustion. Applied Thermal Engineering (50) 2013 , pp. 1418-1426.
2. Strzalka R., Aly A., Schneider D., Eicker U.: Exergetic analysis and optimisation of a decentralised woodchip-fired cogeneration plant. Proceedings of the 23rd European Biomass Conference, 1- 4.06.2015, Vienna, Austria, pp. 760-768.
3. Strzalka R., Schneider D., Eicker U.: Current status of bioenergy technologies in Germany. Renewable and Sustainable Energy Reviews 72:801-820 May 2017.
4. Swaaij, W., Kersten, S., & Palz, W. Biomass power for the world. Vienna: Pan Stanford Publishing Pte. Ltd.: 2015.
5.Kaltschmitt, M., Hartmann, H., & Hofbauer, H. Bioenergy – fundamentals, technology and process engienering (in German). Berlin-Heidelberg: Springer 2016
Nanyang Technological University, Singapore
Thirumany Sritharan is a Professor at the School of Materials Science and Engineering, NTU Singapore. His expertise is in multiferroic materials, thin films and solar energy harvesting. He is currently the main PI in NTU for the multi-million $ CREATE program between NTU-Singapore, University of California – Berkeley and NUS, Singapore. This program is fully funded by the National Research Foundation of Singapore under their CREATE umbrella funding program. It is on the topic of Sustainable Energy and has a total of about 60 researchers from both Singapore and Berkeley. Prior to this, he worked on multiferroic materials with special attention BiFeO3 epitaxial thin films and also on various thin film and interfacial problems in microelectronic circuits. He obtained his PhD from The University of Sheffield, UK and worked at The University of Melbourne and Comalco Research Centre, Melbourne before joining NTU Singapore.
One of the important practical issues in solar energy harvesting is energy storage as solar radiation varies hourly and seasonally. The common practice is to store energy in batteries. An alternative possibility is to store them in the form chemicals from which the energy could be regained subsequently. This is called solar fuels and there is keen interest in them now. Hydrogen is a simple form of chemical energy which could be readily converted to thermal energy. Obtaining hydrogen by electrolytic splitting of water is an established process. However, this uses significant electrical energy. In solar fuel production we intend to use photons to aid the water splitting in an electrochemical device to reduce the energy requirement for splitting water. The photoelectrochemical (PEC) cell is one such device that is being examined for this purpose. This work deals with the development of large anodes of active area about 25 cm2 for water splitting in a PEC cell. Oxides responsive to visible light such as Fe2O3, BiVO4 were investigated as photoactive anodes. Such investigations have previously concentrated on small area anodes such as 2 to 5 cm2. In this work we designed and built a large PEC cell to take anodes of typical size 5x5 cm. We produced and tested BiVO4, samples for their performance. The practical problems encountered in translating small scale anodes to large areas will be highlighted and discusses. Increasing the illumination area generally resulted in loss of photo current density. This loss is caused by several factors which must be understood to take corrective actions to improve the current. The stability and degradation mechanism of BiVO4 is of particular interest as it is known to be less stable than Fe2O3. The mechanistic insights into the degradation will be analyzed with experimental data as direct evidence.
Sule Erten Ela received Assistant Professor position in 2005 and Associate Professor position in 2009 and Full Professor position in 2015 in Ege University-Solar Energy Institute. She is a specialist in Dye Sensitized Solar Cells (DSSC), Solid State Dye Sensitized Solar Cells (SDSC), Heterojunction Solar Cells (BHJ/IBHJ), Flexible Solar Cells, Organic Field Effect Transistors (OFET), Organic Light Emitting Diodes (OLED), and she conducted high level studies on organic electronic technologies. She received prestigious award of Alexander von Humboldt in 2011. She was selected Testimonial of Alexander von Humboldt Foundation in 2012. She received Turkish Academy of Sciences-Outstanding Young Scientist Award (TUBA-GEBIP) in 2013. She received UNESCO-LOREAL Young Woman Scientist Award in 2014. In 2015, she received Young Scientist Award from The Science Academy (BAGEP). And she received a Research & Incentive Science Award from Middle East Technical University in 2016.
Among fullerene derivatives, PCBM offers the advantages of good solubility in organic solvents (chloroform, chlorobenzene, dichlorobenzene, etc.), higher electron mobility and higher electron affinity. However, weak absorption in the visible region and low lying LUMO level are the weak points. Weak absorption of PCBM limits the light harvesting in photovoltaic conversion and low LUMO level of the acceptor result in lower open circuit voltage (Voc) in PSCs, since Voc is strongly related to the difference between the LUMO level of acceptor and the HOMO of the donor material. Therefore, it is very important to design and synthesize new soluble fullerene derivatives with stronger visible absorption and higher LUMO energy levels than PCBM. It is crucial to control the lowest unoccupied molecular orbital (LUMO) of electron accepting materials for producing efficient charge transfer in bulk heterojunction (BHJ) solar cells. Due to their high LUMO level, soluble bis-adducts of C60 are of high interest for improving the Voc in BHJ solar cells. In this work, we have developed novel fullerene derivatives for organic solar cells and perovskite solar cells. A novel bis-4-propylpentyl [6,6] methanofullerene bis-adduct, using an alkyl solubilizing group. The optoelectronic, electrochemical and photovoltaic properties of this bis-product are investigated. Perovskite heterojunction solar cells have attracted considerable attention because of their unique efficiencies. Novel fullerene bis-adduct dicarboxylic material showed good performance in perovskite solar cells. Novel benzoic acid fullerene bis-adducts pays significantly more attention for engineering perovskite heterojunction solar cells to passivate the defects on surface and grain boundaries of perovskite films. Our photovoltaic results show that benzoic acid fullerene bis-adduct compound is highly promising for the application in heterojunction perovskite solar cells because of its close solar cell efficiency to PCBM material. The carboxylic group may form hydrogen bond with I- ion in the perovskite and passivate the surface of perovskite, thus reducing the recombination. Our results show that the efficiency of reference perovskite bulk heterojunction solar cell using PCBM is higher than 1.066 times that of perovskite heterojunction solar cells using benzoic acid fullerene bis adducts. Our successful preliminary results suggested that further optimization of this novel fullerene bis- adduct can yield higher efficiencies with chemical modifications to fine tune the electronic properties.
1. Erten Ela S, Villegas C, Delgado JL, Martin N (2015) Pyrrolidino  and  Fullerene Homo and Heterodimers as Electron Acceptors for OPV New Journal of Chemistry (RSC), 39:1477-1482; doi: 10.1039/C4NJ01709A.
2. Cakmak Y. Kolemen S, Buyuktemiz M, Dede Y, Erten Ela S (2015) Synthesis and dye sensitized solar cell applications of Bodipy derivatives with bis-dimethylfluorenyl amine donor groups, New Journal of Chemistry (RSC) 39:4086-4092; 2015, Doi: 10.1039/C4NJ02393E.
3. Poluektov O.G., Niklas J, Mardis KL, Beaupré S, Leclerc M, Villegas C, Erten-Ela S, Delgado JL, Martín N, Sperlich A, Dyakonov V (2014) Electronic Structure of Fullerene Heterodimer in Bulk-Heterojunction Blends, Advanced Energy Materials, 4:1031517 (1-7).
4.Kolemen S, Cakmak Y, Ozdemir T, Erten Ela S, Buyuktemiz M,Dede Y, Akkaya EU, Design and characterization of Bodipy derivatives for bulk heterojunction solar cells (2014) Tetrahedron, 36: 6229-6234, doi:10.1016/j.tet.2014.03.049
5.Erten Ela S, Chen H, Kratzer A, Hirsch A, Brabec C(2016), Perovskite solar cells fabricated using dicarboxylic fullerene derivatives , New J. Chem., 40: 2829-2834.
University of Erlangen-Nuremberg, Germany
Title: Ternary sensitization of organic solar cells: A multifunctional concept to boost power conversion efficiency
Time : 12:40-13:05
Tayebeh Ameri is a Senior Researcher in the group of Prof. Brabec in the Institute of Materials for Electronics and Energy Technology (i-MEET) at the Friedrich Alexander University Erlangen-Nürnberg, where she leads the ternary sensitization team and carries out her Habilitation. She studied Physics and Solid State Physics at Isfahan University of Technology and Ferdowsi University of Mashhad in Iran, respectively. After her Master’s study, she joined Konarka GmbH Austria and received her PhD in Engineering Sciences from Johannes Kepler University Linz in 2010. Her main research interests include investigation and development of organic and hybrid optoelectronic device. She has published over 100 articles in this field in reputed journals.
During the last 10 years, organic photovoltaics (OPVs) have evolved from an early research effort to a major main stream research field and a tremendous progress has been made in the synthesis and production of organic solar cells. Compared to inorganic solar cells, organic photovoltaics offer many advantages, such as low cost, high throughput production, flexible devices, and lightweight products, as well as custom-designed colors. On the down side, OPVs still have significantly lower efficiency values and lifetime expectations as compared to their inorganic counterparts. To boost the efficiency, different strategies have to be developed in parallel. Recently, we have centered our research on an elegant alternative approach to overcome the photocurrent and the performance limitation of polymer: Fullerene solar cells in a simple single-junction structure by implementing a sensitizer with complementary absorption profile into the host matrix. To boost near infrared light harvesting, we investigate different semiconductor systems such as low bandgap polymers, small molecules, dye compounds as well as hybrid and inorganic nanoparticles/nanostructures. We carry out in-depth investigations on how the structural properties of the host system as well as the sensitizer will be influencing the microstructure formation and the functionality of ternary systems. To illuminate on the modified recombination mechanisms in ternary systems, we also investigate the charge or energy transfer and charge transport between the constituent components. Finally based on our understanding of these key issues, we engineer multi-composites such as to guarantee spectrally broad absorption, to maximize open circuit voltages and to reduce parasitic loss mechanisms like non-radiative recombination. In this presentation, we discuss our highlight achievements on the aforementioned topics with a central focus on the fundamentals of microstructure and charge transport.
1. X. Du, X. Jiao, S. Fladischer, J. Darío Perea, N. Kazerouni, E. Spiecker, M. Meyer, H. Ade, C. J. Brabec, R. H. Fink, T. Ameri, “Crystallization of sensitizer controls morphology and performance in C-/Si-PCPDTBT-sensitized P3HT:ICBA blends”, Macromolecules, 50, 2415, 2017.
2. N. Gasparini, L. Lucera, M. Salvador, M. Prosa, P. Kubis, G. D. Spyropoulos, H-J. Egelhaaf, C. J. Brabec and T. Ameri, “High-performance ternary organic solar cells with thick active layer exceeding 11% efficiency”, Energy Environ. Sci., 10, 885, 2017.
3. R. Soltani, A. A. Katbab, K. Schaumberger, N. Gasparini, C. J. Brabec, S. Fladischer, E. Spiecker, A. G. Alabau, A. Ruland, A. Saha, D. M. Guldi, V. Sgobba, T. Ameri, “Light harvesting enhancement upon incorporating alloy structured CdSeXTe1-X quantum dots in DPP:PC61BM bulk heterojunction solar cell”, J. Mater. Chem. C, 5, 654, 2017.
4. L. Ke, N. Gasparini, J. Min, H. Zhang, M. Adam, S. Fladischer, K. Forberich, C. Zhang, E. Spiecker, R. R. Tykwinski, C. J. Brabec, T. Ameri, “Panchromatic quaternary polymer/fullerene BHJ solar cells, based on the novel silicon naphthalocyanine and silicon phthalocyanine dye sensitizers”, J. Mater. Chem. A, 5, 2550, 2017.
5. N. Gasparini, X. Jiao, T. Heumueller, D. Baran, G. J. Matt, S. Fladischer, E. Spiecker, H. Ade, C. J. Brabec, and T. Ameri,“ Designing ternary blend bulk heterojunction solar cells with reduced carrier recombination and fill factor of 77%”, Nature Energy, 1, 16118, 2016.
6. L. Ke, J. Min, M. Adam, N. Gasparini, Y. Hou, J. Darío Pereaa, W. Chen, H. Zhang, S. Fladischer, A.-C. Sale, E. Spieckerd, R. R. Tykwinski, C. J. Brabec, T. Ameri, “A series of novel pyrene-substituted silicon phthalocyanines as near-IR sensitizers in organic ternary solar cells: Synthesis and Device fabrication”, Adv. Energy Mater., 6, 1502355, 2016.
7. N. Gasparini, M. Salvador, S. Fladischer, A. Katsouras, A. Avgeropoulos, E. Spiecker, C. L. Chochos, C. J. Brabec, and T. Ameri, “An Alternative Strategy to Adjust the Recombination Mechanism of Organic Photovoltaics by Implementing Ternary Compounds”, Adv. Energy Mater., 5, 1501527, 2015.
8. T. Ameri, P. Khoram, T. Heumüller, D. Baran, F. Machui, A. Troeger, V. Sgobba, D. M Guldi, M. Halik, S. Rathgeber, U. Scherf, C. J. Brabec, “Morphology analysis of near IR sensitized polymer/fullerene organic solar cells by implementing low bandgap heteroanalogue C-/Si-PCPDTBT”, J. Mater. Chem. A, 2, 19461, 2014.
9. T. Ameri, T. Heumuller, J. Min, N. Li, G. Matt, U. Scherf and C. J. Brabec, “IR sensitization of an indene-C60 bisadduct (ICBA) in ternary organic solar cells”, Energy Environ. Sci., 6, 1796, 2013.
10.T. Ameri, P. Khoram, J. Min, and C. J. Brabec, “Organic ternary solar cells: A review”, Adv. Mater., 25, 4245, 2013.
Electronics Research Institute, Egypt
Faeka Khater (IEEE Life SM) received BS, MS and PhD degrees in Electrical Engineering from Cairo University, Cairo, Egypt, in 1967, 1976 and 1982, respectively. From 1984 to 1987, she was an Honorary Fellow in the ECE Department at the University of Wisconsin, Madison, USA. Since Graduation, she has been working for the Electronics Research Institute (ERI) as, RA (1967-1982), Assistant Professor (1982-1987), and Associate Professor (1987-1992). Since 1992, she has been a Professor in the Department of Power Electronics & Energy Conversion, ERI, in which she was Department Chair from 2001 to 2006. She was a visiting Professor at the Institute of Power Electronics & Electric Drives, Aachen, Germany (May/June 2001). Her interests include electric machines, electric drives system control, power electronics converters, digital electronic control, renewable energy, and energy efficient techniques.
Recently, there are great needs to reduce the electricity consumption via using renewable energy systems and less energy consumption loads. Widespread application of photovoltaic (PV) systems provides achieving this goal. In addition, the need for “green” concepts in buildings is an important demand in particular for official buildings to depend on PV systems as sources of electric energy. Enormous energy savings are possible when using energy efficient lighting equipment and devices with effective controls and careful design. Electric lighting design also strongly affects visual performance and visual comfort. The proposed work investigates the techno economic visibility due to change of lighting from FLs to LEDs fed from PV system. The proposed change will cover the 1st stage (40 Labs & 90 Offices) of new buildings which consist of the Electronics Research Institute. The change includes using the PV arrays on the roof of the building to feed the LEDs while the excess energy gained will provide office or lab equipment with electricity or supplied to the grid. Using PV and energy efficient lighting reduces emissions that alter our climate dramatically for the associated CO2. Recent needs to use energy efficient systems become more urgent due to continuous increase in electricity price and reduction in subsidization. The full paper will present and discuss details of lighting design of labs & offices, PV system design & selection and economical expressions & computations. The investigation results in finance (Figure 1) and environment measure; and discussion that will be provided in the paper. The study illustrates: 1. Improve energy efficiency and reduce the energy consumption; 2. Provide more comfort working condition for the employees; 3. Make an active contribution to environmental and climate protection; 4. Reduce energy costs, and thus provide better budget use of buildings.
- Young Researchers Forum
Location: Munich, Germany
Dokuz Eylul University, Turkey
Gokce Guney has graduated from Engineering Faculty of Dokuz Eylul University, Turkey as an Environmental Engineer. Then she started working at Environmental Engineering Department of Dokuz Eylul University, Turkey as a Research Assistant. Later on, she obtained her Post-graduation (MSc) from The Graduate School of Natural and Applied Sciences of Dokuz Eylul University, Turkey from Environmental Engineering Department. Now, she has continued her PhD in Environmental Engineering Department and MSc in Occupational Health and Safety Department both at The Graduate School of Natural and Applied Sciences of Dokuz Eylul University, Izmir, Turkey.
Fossil fuels, including oil, coal and natural gas, are providing about 85% of our energy need worldwide. The main drawback of fossil fuels is that it is a finite resource and will be depleted in the near future. Unlike fossil and nuclear fuels, alternative energy comes from natural resources (wind, sunlight, geothermal power and biomass) which are constantly replaced. Conversion of CO2 for the synthesis of chemicals by photosynthetic organisms is an attractive target for establishing independence from fossil reserves. Tremendous academic and industrial efforts have been made to produce 1-butanol, which is one major type of biofuel. Oxidised forms of carbon, CO2, can be used to synthesise energy-rich organic molecules. The terpenoids can be classified into monoterpenes (C10), sesquiterpenes (C15), diterpenes (C20), triterpenes (C30) and tetraterpenes (C40) according to the number of isoprene structures. The thermochemical and thermophysical properties of some monoterpenes, sesquiterpenes and their derivatives make them ideal candidates as ‘drop-in’ JP-8, gasoline and diesel fuels. In this study, it was studied the direct conversion of CO2 into reduced fuel compounds with a merit such as 1-butanol and terpenoids (limonene and bisabolene) using a Cyanobacteria namely S. elongatus isolated from Guzelyali-Izmir in Agean Sea (Turkey). The productions of 1-butanol and terpenoids (limonene and bisabolene) by S. elongatus from CO2 were investigated. Under optimized conditions (0.5 mg L-1 dissolved oxygen, 0.8 mg L-1 NO3-N, 0.5 mg L-1 CaCl2) the growth kinetic depending on 1-butanol, bisabolene and limonene concentrations were detected under Monod kinetics. The effects of some environmental conditions on the 1-butanol and terpenoid (limonene and bisabolene) productions were investigated. The substrate accumulation and the low biomass/CO2 to 1-butanol, limonene and bisabolene yields were investigated with Lineawaever-Burck inhibition kinetics such as, non-competitive and un-competitive (Figure 1).
Foshan Power Supply Bureau, China
Wenjuan Chen graduated from Wuhan University in June 2016 with a Master's degree in Electrical Engineering. She is now working in Foshan Power Supply Bureau. Her main research direction is the power system harmonic monitoring, especially to improve the accuracy of harmonic measurement and to enhance the speed of harmonic parameter calculation in large area power grid.
Statement of the Problem: The proposal and development of smart grid corresponding brought a large number of inputs of power quality monitoring terminals in the regional power grid. Meanwhile, the increase of sampling frequency and the monitoring time has accelerated the explosion growth of sampling data in the power quality monitoring platform. In the traditional power quality monitoring platform, the monitoring terminal data uploaded and processed by adopting centralized mode. With the advancement of the smart grid construction, higher requirements of computing speed and precision of the power quality monitoring indexes are put forward. The storage capacity and computing ability of the server in traditional power quality monitoring platform can hardly meet the growing demands of operation requirements. Though purchasing a higher configuration server can temporarily meet the demand of computing, it will lead to large waste of resources when there are no running tasks. The purpose of this study is to realize a high efficiency calculation of sampling data of electric power system under low hardware cost and minor resource waste is a problem of research value.
Methodology & Theoretical Orientation: It is possible to make full use of the powerful data storage capacity and computing ability under Hadoop distributed file system and parallel programming model to calculate the basic sampling data in power quality monitoring platform; Based on the study of windowed interpolation theory of Fourier analysis method, a novel kind of improved sidelobe characteristics window function - time domain multiplication window can enhance the accuracy of calculation.
Findings: The harmonic analysis algorithm based on time domain multiplication window is applied to the MapReduce framework of the power quality monitoring platform. The feasibility and superiority of the proposed parallel processing model of the power quality platform are verified through the experiment based on a small Hadoop cluster.
Irina Stamo holds a Bachelor’s degree in Economics with a major focus on the European Economy. She expanded her knowledge by receiving her Master’s degree in Political Economy of European Integration from the Berlin School of Economics and Law. She is currently a Research Associate at the Institute for Climate Protection, Energy and Mobility (IKEM), working on projects dealing with energy efficiency, sector coupling, and urban renewal. Before joining IKEM, she has gained experience amongst others at the German Energy Agency (dena), German Solar Association and Arepo Consult. She has been involved in different projects and scientific activities, dealing with energy efficiency, European Energy Policy drafts, LNG, energy storage as well as the National Solar Market. She has done extensive scientific research dealing with the Norwegian energy market, which she intensifies in her ongoing PhD thesis at the University of Flensburg as well as Environmental Research Center in Berlin.
The installed capacity of hydropower contributed 16% of a worldwide electricity supply. This makes a renewable and highly flexible source hydropower with its capabilities and unique role in the nature very important for modern electricity systems, not only due to production issues, but also because of coordinating the operation of hydropower plants with other types of generating units. Doing so, hydropower is able to stabilise fluctuations between demand and supply, to alleviate challenges dealing with the volatile character of renewable energy sources. This is where Norway comes into play as the sixth largest hydropower producer in the world and the largest in Europe, having large pumped storage capacity. The need for compensation of the difference between production and consumption of increased levels by wind and solar power generation in Europe shows the feasibility of the bigger design power output of the Norwegian hydroelectric power plants. Their capacity is directly dependent on how much power can be provided in scarce periods and how much power can be absorbed in case of overproduction. Here comes an idea of energy exchange. Interconnectors will be built today not only as a back-up option for failures and shortages, but increasingly with a purpose of connection of different energy markets. Interconnectors bring a sustainability aspect along: By trading decarbonised hydro and wind power, cables integrate renewable energy into European electricity grid. Idea of such transnational cables is based upon a possibility and a wish of exchanging the electricity with national systems being in “power surplus”, additionally adding value to the security of energy supply. Driven by a concept of internal electricity market in Europe, cross-border interconnections aim to foster competition, promote trade and provide incentives for development of new market models which may improve overall welfare.
Jiangsu University, China
Daniel Adu is a PhD Student at the National Research Centre of Pumps, Jiangsu University, China working on Fluid Machinery Engineering in the research area of Small Hydropower Development in Africa. He has his expertise in evaluation and passion in improving electricity situation in Africa. He has done a lot of research into how this electricity crisis in Africa especially sub-Saharan Africa can be solved, and found small hydropower as one of the best ways to solve these challenges due to its enormous potential in the continent.
A number of resources and efforts have been devoted into many studies in relation to the small hydro potential (SHP) sites in Ghana, but still most of these potential sites are still not yet developed. The rural communities within the region have been deprived of electricity for so many years now with even those in the urban centers experiencing a lot of power cut off resorting in the development of thermal power as supplement to the inadequate hydropower source in the countries. The importance of small hydropower in the generation for sustainable power based on its capacity to provide electricity to the rural communities as well as contributing to the national grid towards alleviate the serious shortage of electricity within the sub-Saharan African Region and ensure sustainability of hydropower. This paper focuses on the situation and potentials of small-hydropower in Sub-Saharan Africa particularly the rural areas as well as areas that are still outside the main grid. An equitable complete small hydropower technology report has been presented with the situation of electricity supply to the rural areas within the region also presented. This paper has shown that there are many important hydropower resources in Saharan Africa region with low installation level. Generally, the level of electricity access in the region is very low combined with various challenges. Challenges preventing development of SHP technology in the region have been identified and discussed; for instance those relating to technology, climate change, finance, and policy. Small hydropower technology has been discussed as one of the promising spread out power generation system for rural electricity supply in the country. Therefore, the need to develop an extensive small hydropower turbine that can help alleviate the current energy situation and support economic progress of the Sub-Saharan Africa Countries. The paper will draw conclusions on the significance of designing small hydro turbines for Sub-Saharan Africa, and better carrying out small hydropower in Sub-Saharan Africa.
- Video Presentations
Location: Munich, Germany
Reliance Power Ltd, India
Avijit Mallick has nearly 10 years’ experience in operation of both sub-critical and super critical thermal power plant. He currently serves as a Senior Manager in operation of the Super Critical Thermal Power Plant of Reliance Power Ltd. He is also acting as Technical Team Leader with responsibilities to lead and guide the operation of Boiler, Turbine, ESP & BOP, etc., and is involved in calculating plant daily performance parameters and all energy savings activities. He has a BTech in Power Engineering (2003-2007) from National Power Training Institute (NPTI), India, a PG-Diploma in Quality Engineering and Management from Institution of Engineers India (IEI) securing highest mark and got the Merit Award; is a certified Energy Auditor after passing Energy Auditor exam from Bureau of Energy Efficiency, India; an IntPE after passing 'International Professional Engineers' exam in Mechanical Engineering conducted by Institution of Engineers India (IEI) and has completed the Familiarization Program in 'Integrated Management System'.
Developing countries like India require abundant reliable and continuous supply of energy to boost up its economic development. In the recent years, there is a huge rise in demand of electricity due to rapid growth in population and economy. Presently these demands in electricity are nearly 60% matched by coal based thermal power plant. India has the fifth largest power generation portfolio in the world and its current renewable energy contribution stands at 44.812 GW. Whereas total thermal power plant installed capacity is 212467 MW. Due to abundance of national coal reserve and political promises for free electricity to farmers and others backward section, the progress on renewable source of electricity has been reviewed and highlighted in this paper in details. On the other hand coal power generation is characterized by local and regional environmental degradation as well as green house gas emission leading to climate change. Recently India has an ambitious target of 175 GW of renewable power by 2022. So with this target a comparison study has been done between the growth in renewable energy and the coal based thermal power generation as well as the green house gas emission. India is also equally stand by the target to restrict the global temperature increases to 20C by the year 2020 as discussed by COP21. Thus the Indian government has taken several positive steps to tackle climate change. In this paper, progress in renewable energy growth and how it is influencing the market share of coal based thermal power plant electricity generation has been discussed in detail. The challenges and mitigations for enforcing the renewable source of electricity suppressing the coal based thermal power plant generation that has environmental impact are also highlighted.
National Sun Yat-Sen University, Taiwan
Peng-Sheng Wei received PhD in Mechanical Engineering Department at University of California, Davis, in 1984. He has been a Professor in the Department of Mechanical and Electro-Mechanical Engineering of National Sun Yat-Sen University, Kaohsiung, Taiwan, since 1989. He has contributed to advancing the understanding of and to the applications of electron and laser beam, plasma, and resistance welding through theoretical analyses coupled with verification experiments. Investigations also include studies of their thermal and fluid flow processes, and formations of the defects such as humping, rippling, spiking and porosity. He has published more than 80 journal papers, given keynote or invited speeches in international conferences more than 90 times. He is a Fellow of AWS (2007), and a Fellow of ASME (2000). He also received the Outstanding Research Achievement Awards from both the National Science Council (2004), and NSYSU (1991, 2001, and 2004), the Outstanding Scholar Research Project Winner Award from National Science Council (2008), the Adams Memorial Membership Award from AWS (2008), the Warren F Savage Memorial Award from AWS (2012), and the William Irrgang Memorial Award from AWS (2014). He has been the Xi- Wan Chair Professor of NSYSU since 2009, and Invited Distinguished Professor in the Beijing University of Technology, China, during 2015-2017.
This study theoretically identifies the factors affecting the keyhole collapse during drilling with a high power density laser or electron beam from fundamental principles of thermal physics. Laser drilling is widely used in various manufacturing technologies. This work studies quasi-steady one-dimensional compressible flow behavior of the two-phase vapor-liquid dispersion in a vertical keyhole of varying cross-section, paying particular attention to the transition between the annular and slug flows. The results show increases in absorbed energy, beam radius, entrained energy and specific heat ratio reduce capability of drilling. The drilling keyhole in which a subsonic gas mixture flows usually gives rise to keyhole collapse. The predicted results agree with physical intuition and exact closed-form solutions derived in the absence of friction and energy absorption. Controlling the factors to enhance efficiency and quality of drilling is therefore provided in this work and informed that would help this recognition.