Renewable Energy Global Innovations features: Sobol’s sensitivity analysis for a fuel cell stack assembly model with the aid of structure-selection techniques

Significance Statement

    This work presents a novel method for identifying the main parameters affecting the stress distribution of the components used in assembly modeling of proton exchange membrane fuel cell (PEMFC) stack. This method is a combination of an approximation model and Sobol’s method, which allows a fast global sensitivity analysis for a set of uncertain parameters using only a limited number of calculations.

Seven major parameters, i.e., Young’s modulus of the end plate and the membrane electrode assembly (MEA), the contact stiffness between the MEA and bipolar plate (BPP), the X and Y positions of the bolts, the pressure of each bolt, and the thickness of the end plate, are investigated regarding their effect on four metrics, i.e., the maximum stresses of the MEA, BPP, and end plate, and the stress distribution percentage of the MEA.

The proposed method was demonstrated to be feasible and effective at determining the most influential model parameters. Moreover, it enhances our understanding of the assembly of a PEMFC stack, and provides a valuable tool for a sensitivity analysis of a PEMFC stack assembly model.

The analysis reveals the individual effects of each parameter and its interactions with other parameters on the model performance regarding four metrics. The main findings from the results obtained are summarized as follows:

(1) The position of each bolt has a significant influence on the maximum stresses of the BPP and end plate, whereas the thickness of the end plate has the most crucial role in the maximum stress and stress distribution percentage of the MEA.

(2) The contact stiffness between the MEA and BPP has little effect on the maximum stresses of the BPP and end plate, and on the stress distribution percentage of the MEA. Moreover, it is not the most important factor affecting the maximum stress of the MEA when measured using a total-order sensitivity index. However, the contact stiffness interacting with the thickness of the end plate has a highly sensitive interaction effect on the maximum stress of the MEA.

(3) The parameter interactions contribute to a significant portion of the variation in the metric considering the maximum stress of the BPP. The interaction effects include the following: the thickness of the end plate interacts with its material property as well as the Y position of each bolt, the X position of each bolt interacts with its Y position, and the Y position of each bolt interacts with the pressure. 

About The Author

Dr. Wei Zhang received his B.Eng. in Engineering Mechanics from Hunan University, China in 2005, his M.Eng. and Ph.D. in Mechanical Engineering also from Hunan University, China in 2010 and 2013, respectively. He was an assistant engineer at Special Aircraft Research Institute of China from Aug. 2005 to Jun. 2007, and was a Post-Doctoral fellow at Department of Mechanical Engineering, Inha University, Korea from Nov. 2013 to Nov. 2015.

His research interests are in computational inverse techniques, uncertainty management and bioinspired design in composites. He is currently a research fellow at School of Mechanical & Aerospace Engineering, Queen’s University Belfast, UK. 

About The Author

Prof. Chongdu Cho received his B.Eng. in Mechanical Engineering from Seoul National University, Korea in 1983, his M.Eng. in Mechanical Engineering from KAIST, Korea in 1985 and his Ph.D. in Mechanical Engineering from University of Michigan, USA in 1991. He has been a visiting scholar in UCLA, USA from Jul. 2000 to Jul. 2001, and in Cornell University, USA from Aug. 2009 to Aug. 2010, respectively.

He has been developing FEA applications for various engineering products. He has published more than 150 referenced journal papers. Now, he is a fellow professor at Department of Mechanical Engineering, Inha University, Korea. 

Journal Reference

Journal of Power Sources, Volume 301, 2016, Pages 1–10.

Wei Zhang¹, Chongdu Cho¹, Changhao Piao¹, Hojoon Choi²

Show Affiliations

1. Department of Mechanical Engineering, Inha University, Incheon 402-751, South Korea
2. Korea Institute of Industrial Technology, Incheon 406-840, South Korea

Abstract

This paper presents a novel method for identifying the main parameters affecting the stress distribution of the components used in assembly modeling of proton exchange membrane fuel cell (PEMFC) stack. This method is a combination of an approximation model and Sobol’s method, which allows a fast global sensitivity analysis for a set of uncertain parameters using only a limited number of calculations. Seven major parameters, i.e., Young’s modulus of the end plate and the membrane electrode assembly (MEA), the contact stiffness between the MEA and bipolar plate (BPP), the X and Y positions of the bolts, the pressure of each bolt, and the thickness of the end plate, are investigated regarding their effect on four metrics, i.e., the maximum stresses of the MEA, BPP, and end plate, and the stress distribution percentage of the MEA. The analysis reveals the individual effects of each parameter and its interactions with the other parameters. The results show that the X position of a bolt has a major influence on the maximum stresses of the BPP and end plate, whereas the thickness of the end plate has the strongest effect on both the maximum stress and the stress distribution percentage of the MEA.

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Renewable Energy Global Innovations features: Catalytic fuel cell used as an analytical tool for methanol and ethanol determination. Application to ethanol determination in alcoholic beverages

Significance Statement

DMFC device used as an analytical tool for ethanol and methanol determination: applications to the analysis of real matrices.

Recently our research group has performed an experimental research [1,2], devoted to the utilization of Direct Methanol Fuel Cell (DMFC) as an analytical device, for methanol, or ethanol determination in real samples. After optimizing the best, among possible measurement formats, i.e. the open circuit, kinetic and potentiostatic format (the latter has been demonstrated the better) and discussing the effects of cross-over and temperature, it has been showed as a small commercial DMFC fuel cell can be useful to determine ethanol in alcoholic beverages, i.e. several wine and beer commercial samples. The obtained results have been compared both with ethanol content declared by the producer firm and with data obtained analyzing the same samples using a commercial amperometric catalase enzyme sensor [3]. The obtained correlation was found satisfactory and the precision, or lifetime of two methods comparable, only the measurement time was longer using the fuel cell. Nevertheless the possibility of improving the features, from the analytical point of view, of the catalytic fuel cell for methanol and ethanol, by introducing an enzyme (alcohol dehydrogenase), immobilized into a dialysis membrane small bag, in the anodic area of the fuel cell, has been recently demonstrated [4]. Using the enzymatic DMFC device, we have reached the goal concerning the drastic reduction of the measurement time by the fuel cell used for analytical purposes, enhancing at the same time its sensitivity [4]. Lastly the determination of other organic molecules, which contain an alcoholic function (although with a much lower sensitivity than methanol or ethanol) in real matrices, which do not contain high concentrations of possible alcoholic interfering compounds, was also demonstrated [4].

References

[1] M.Tomassetti, R.Angeloni, G. Merola, M. Castrucci, L.Campanella. Catalytic fuel cell used as an analytical tool for methanol and ethanol determination. Application to ethanol determination in alcoholic beverages. Electrochimica Acta, 191 (2016) 1001–1009.

[2] M. Tomassetti, R. Angeloni, G. Merola, M. Castrucci, L. Campanella. Catalytic Fuel Cell as an Analytical Tool for Methanol and Ethanol Determination. Proceedding of  2015 XVIII AISEM Annual Conference. 978-1-4799-8591-3/15/$31.00 ©2015 IEEE.

[3] R. Angeloni, M. Tomassetti, M. Castrucci, L. Campanella. Ethanol Determination in Alcoholic Beverages Using Two Different Amperometric Enzyme Sensors. Current Analytical Chemistry, 11 (2015) 56-67.

[4] M. Tomassetti, G. Merola, R. Angeloni, S. Marchiandi, L. Campanella. Further development on DMFC device used for analytical purpose. “manuscript in preparation”.

      

 

Figure Legend: DMFC H-TEC Model F111 Fuel Cell, obtained from Fuel Cell Store (College Station, TX, USA).

 

About The Author

Prof. Mauro Tomassetti, bachelor  in Chemistry (1969) and in Pharmacy (1977).  Full Professor of Analytical Chemistry at the University of Rome ‘La Sapienza’ since 2003; already Associate Professor since 1985 to the same University.

His research interests are in the development of electrochemical sensors, biosensors and immunosensors working both in aqueous and organic solvents and in their application to environmental, biopharmaceutical and food analysis.

He has also interest in thermal analytical studies (TG, DTA, DSC) for the purity control, or the characterisation of several materials (drugs, foodstuffs, polymers, etc.) and in the study and characterisation of archaeological finds and cultural heritages, investigated by means of several instrumental techniques of chemical analysis.

Member of teaching staff of  PhD in Engineering and Process.

Member of “Centro di ricerche applicate alla Protezione dell’Ambiente e dei Beni Culturali (CIABC)“, Sapienza University.

Member of “Istituto per lo Studio dei Materiali Nanostrutturati (ISMN)” of CNR .

Associate Editor of Current Analytical Chemistry.

Member of Editorial Board of Current Pharmaceutical Analysis.

Author of about 506 papers, 243 of which original research paper published on international Journals, and of about 460 communications to congress, overall in the above recorded fields of  research. 

Journal Reference

Electrochimica Acta, Volume 191, 10 February 2016, Pages 1001–1009.

Mauro Tomassetti*, Riccardo Angeloni, Giovanni Merola, Sergio Marchiandi, Mauro Castrucci, Luigi Campanella.

Department of Chemistry, University of Rome “La Sapienza”, p.le Aldo Moro, 5, 00185, Rome, Italy.

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Renewable Energy Global Innovations features: Comparison and verification of the deviation between guaranteed and measured wind turbine power performance in complex terrain

 

Journal Reference

Energy, Volume 85, 2015, Pages 23-29.

Hyunseok Oh¹, Bumsuk Kim²

Show Affiliations

1. Korean Register of Shipping, 6F, Haewoon-Bldg, Gukhoe-daero68-gil 17, Yeongdeungpo-gu, Seoul, 151-742, Republic of Korea
2. Faculty of Wind Energy Engineering, Jeju National University, Jejudaehak-ro 102, Jeju-si, Jeju Special Self-Governing Province, 690-756, Republic of Korea

Abstract

After a wind farm construction is completed, the power performance guaranteed by the wind turbine manufacturer is usually verified based on the international standard IEC61400-12-1. Because of an insufficient project budget and the constraint on the minimum separation distance of the meteorological mast from the installed wind turbines, it is a common practice to verify the power performance of one representative wind turbine and apply the result as the reference power performance guarantee for all the wind turbines. In this study, the power performances of five wind turbines operating at a commercial wind farm located on complex terrain were measured and analyzed. The results showed large power performance differences between the turbines. Because the power performance of one representative wind turbine cannot guarantee the power performances of all the wind turbines in a wind farm located on complex terrain, we submit that it is necessary to carry out power performance verifications on many or all of the wind turbines.

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About The Author

Bumsuk Kim received his B.S. in Mechanical Engineering from Korea Maritime and Ocean University in 2001 and M.S. and Ph.D. from the same university in 2003 and 2005. After receiving his Ph.D., he worked as a Principal Research Engineer at New & Renewable Energy Research Center of Korean Register of Shipping from 2006 to 2013. He was a Head of Wind Energy Business Group at Innovation KR from 2013 to 2014. He is currently working at Faculty of Wind Energy Engineering of JEJU National University as an Assistant Professor from 2014. His research interests include wind energy, ocean energy converters and CAE application for engineering simulation. 

 

About The Author

Hyunseok Oh received his B.S. in Mechanical Engineering from JEJU National University in 2009 and M.S. from the same university in 2011. After receiving his M.S, he worked as a Principal Research Engineer at Korean Register of Shipping from 2011. He is currently a Ph.D. candidate at JEJU National University, where his research interests include power performance uncertainty analysis and load measurement of large wind turbines.

 

 

 

 

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Renewable Energy Global Innovations features: Assessment of grouted samples from monopile wind turbine foundations using combined non-destructive techniques

About The Author

Mr Iliopoulos is a graduate mechanical engineer of the National Technical University of Athens, Greece. Currently, he is a PhD student of the Vrije Universiteit Brussel (VUB)focusing on the development of modal based techniques for response estimation and fatigue assessment of offshore wind turbines.  

Journal Reference

Construction and Building Materials,  8 December 2015.

A.N. Iliopoulos1 D. Van Hemelrijck1, J. Vlassenbroeck2, D.G. Aggelis1

Show Affiliations

1. Vrije Universiteit Brussel, Department of Mechanics of Materials and Constructions, Pleinlaan 2, B-1050 Brussels, Belgium
2. Inside Matters NV, Sylvain Van der Guchtlaan 24, 9300 Aalst, Belgium

Abstract

The vast majority of offshore wind farms uses wind turbines on monopile foundations for cost effective designs. These foundations are complex structures consisting of steel and a high strength cementitious grout that fills the annulus between the two concentric steel pipes known as monopile and transition piece. The grouted connection is potentially prone to structural failures when subjected to harsh offshore conditions due to combinations of extreme wind and wave excitations. Already grouting failures related to slippage of the transition piece relative to the monopile due to weakening of the adhesion between the grout and the steel have been observed at several windfarms during the construction phase. Therefore, a thorough investigation of the grouted connection is of utmost importance. In this study, a large population of cementitious cores were sampled from as many as four offshore wind turbines. The samples were subjected to Ultrasonic Pulse velocity (UPV) non-destructive testing (NDT) and compression testing while a smaller set of samples was subjected to X-ray analysis as well. This paper presents the results of the combined use of the UPV and X-ray techniques as well as correlations with compressive strength results and critically discusses the possibility of using the techniques for in situ application. To the authors’ knowledge it is the first time that these techniques are applied for assessment of the grouted connection of offshore wind turbines on monopile foundations.

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Renewable Energy Global Innovations features: Optimization of Enzyme Hydrolysis of Seafood Waste for Microwave Hydrothermal Carbonization

Significance Statement

Seafood processing operations generate enormous quantities of waste in the form of solid residues and liquid effluents. Currently there is an increasing demand for attractive seafood waste utilization strategies that could minimize environmental pollution while recovering products that are of commercial interest. Hydrothermal carbonization (HTC) is a technique that utilizes wet biomass to produce a solid product called hydrochar that has potential for wide applications in the field of energy, agriculture, and material science. Hydrothermal carbonization has been in use mainly to treat lignocellulosic biomass such as wood or agricultural waste. Recently, the Hydrothermal carbonization process has been gaining attention as an efficient waste management tool that can utilize high-moisture-containing complex waste streams, a mixture of lignocellulosic and nonlignocellulosic biomass, such as sewage and municipal waste. However, there is limited knowledge on the effectiveness of Hydrothermal carbonization on purely nonlignocellulosic industrial wastes such as seafood waste.

Here, we prove for the first time that purely nonligocellulosic wastes such as fish and shrimp waste could be utilized by Hydrothermal carbonization to produce a solid coal-like biofuel called hydrochar. By using an enzyme cocktail of Viscozyme, Lipase, and Protease, it was found that an enzyme ratio of 1:1:1 (w/w/w), and an enzyme concentration between 10 and 20% with a treatment time of 6 h, resulted in maximal hydrolysis of fish and shrimp waste. Subsequently, hydrochar and biocrude liquor were generated from hydrolyzed fish and shrimp waste by microwave hydrothermal carbonization (MHTC) using a high-pressure MiniWAVE Digestion Module (SCP Science, Canada) with quartz vessels at conditions of 150 °C for a 1 h reaction time.

The unique aspect of this method is the use of microwaves as the source of thermal energy required to drive the process.  Microwaves provide volumetric heating which minimizes heat transfer limitations and is also more rapid, energy efficient, and easier to control. Thus this study would potentially expand the use of Hydrothermal carbonization to other nonlignocellulosic wastes such as meat waste, and  leather industry waste.

About The Author

Shrikalaa Kannan is a PhD candidate at the Department of Bioresource Engineering, McGill. Her research combines two global challenges – increasing sustainability in the current energy technologies and reducing environmental pollution from bio-waste. Her work focuses on the generation of biofuels from bio-waste. 

About The Author

Yvan Gariepy is a professional associate in the Department of Engineering, McGill. He is a senior engineer with expertise in a wide range of fields ranging from food security and food safety to microwave assisted thermal processes.

About The Author

Dr. Vijaya Raghavan is a James McGill Professor at the Department of Bioresource Engineering, McGill University. He is presently the President-Elect of the Royal Society of the Canada Academy of Science, the Director of the Applied Science and Engineering division of Science of the Royal Society of Canada, and the President of the Canadian Society for Bioengineering.

Dr. Raghavan is involved in a wide range of research areas which includes post-harvest or post-production processes and technologies, food safety and security, electrotechnologies for food drying and storage, microbial fuel cells and biofuel production. 

Journal Reference

Energy Fuels, 2015, 29 (12), pp 8006–8016.

Shrikalaa Kannan, Yvan Gariepy, Vijaya Raghavan

Department of Bioresource Engineering, Macdonald Campus, McGill University, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada

Abstract

Hydrothermal carbonization (HTC) is a promising technique that converts wet biomass into a coal-like material and has a wide application to the fields of energy, material science, and nanotechnology. Hydrothermal carbonization has been primarily used to treat a limited number of feedstocks, mainly lignocellulosic biomass such as wood. Recently, the Hydrothermal carbonization process has been utilized to treat high-moisture-containing complex waste streams, a mixture of lignocellulosic and nonlignocellulosic biomass, such as sewage and municipal waste. However, there is limited knowledge on the effectiveness of Hydrothermal carbonization on purely nonlignocellulosic industrial waste like seafood waste. Processing of seafood generates enormous amounts of waste in the form of solid residues and liquid effluents. Currently there is a demand for attractive seafood waste utilization strategies that minimize environmental pollution while recovering products that are of commercial interest to the industry. In this study, we have devised one such strategy where seafood waste is pretreated by enzymatic hydrolysis for subsequent Hydrothermal carbonization to produce hydrochar and biocrude liquor. Enzyme hydrolysis conditions including enzyme concentration, incubation time, and enzyme ratios were carefully optimized for maximal hydrolysis of seafood waste. By using an enzyme cocktail of Viscozyme, Lipase, and Protease, it was found that an enzyme ratio of 1:1:1 (w/w/w), and an enzyme concentration of 10–20% with a treatment time of 16 h, resulted in maximal hydrolysis of fish and shrimp waste. Subsequently, hydrochar and biocrude liquor were generated from hydrolyzed fish and shrimp waste by microwave hydrothermal carbonization (MHTC) using a high-pressure Mini WAVE Digestion Module (SCP Science, Canada) with quartz vessels at conditions of 150 °C for a 1 h reaction time. The results of this study show for the first time that MHTC can be successfully employed to produce valuable products from pure nonlignocellulosic waste like seafood waste. This would pave the way for effective utilization of other moisture-rich nonlignocellulosic industrial wastes.

Copyright © 2015 American Chemical Society

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Renewable Energy Global Innovations features: Operation of an inexpensive bipolar alkaline electrolyser producing a mix of H2/O2 fuel

Significance Statement

The objective of this work was to develop a low cost and portable device to produce an alternative form of fuel or a fuel that can be used to improve combustion efficiency on internal combustion engines and reduce emissions of PM, CO, CO2 and NOx with an incentive to users of improved fuel efficiency. A technology suitable for the users of today.

Much research work is available on Hydrogen IC engines, water injection, and emulsified fuel but few have been shown to address suitability for use on heavy goods vehicles and public transport. Water injection has been shown to reduce combustion temperature and thereby reduce harmful NOx emissions but a practical device has not yet materialised. Emulsified fuel (water in diesel) is currently in use for public transport in some European cities and is generally used in conjunction with hydrogen. This emulsified fuel has limited applications as it is unstable and will separate and is therefore only suitable for high fuel users. Its use has been shown to substantially reduce particulates and NOx emissions.

The cost of going “Green” will remain a burden on taxpayers and users of public transport. London Transport are using some electric buses and for every route two buses are required as one must stop to recharge. Governments continue to impose carbon taxes instead of funding a solution.

On most commercial and industrial electrolysers, the catalyst used is 25%/35% wt/wt potassium hydroxide (KOH) and in this volume the gas cannot be used in engines due to corrosion.

The methodology in this work was to identify a balance between the multiple variables involved in water electrolysis which include a suitable low cost electrode, electrode surface area, variable voltage, current density, electrical resistance, temperature and the type and volume of electrolyte. Reliability of such device and with no electrode erosion could only be achieved with minimal electrolyte concentration and with a low current density.

The design result was achieved by using low cost stainless steel electrodes in a bi-polar configuration whereby electrodes are of solid state in the absence of any perforations and with exposed perimeter edges concealed from the electrolyte, to avoid current loss. This was achieved by the slotted gables in the polypropylene enclosure. When power is applied the top edge of electrodes become exposed in a gas void. An electronic controller was developed in-house and is used to control current/ gas volume to a prescribed setting. The initial voltage per electrode is 2.3 volts which ensures a fast warm up of the electrolyte and as it begins to heat, the voltage reduces by change in resistance, which improves energy efficiency as the electrolyte heats to approx. 60 deg C. We are now producing a combustible gas of H2/O2 which has almost three times more heat energy than gasoline but we also have a form of water injection with the vapour.

This result can be achieved with 0.12M KOH catalyst with laboratory analysis showing no trace in the evolved gas and therefore will not cause engine corrosion. This was also confirmed by analysis of the electrolyte after hours of operation when electrolyte had depleted and the catalyst concentration increased. This result is of particular interest to users as replenishment is carried out with de-ionised water only.

The polypropylene enclosure is designed to accommodate a PEM to separate the oxygen from the evolved gas to permit storage of the H2. Due to the high efficiency the gas can now be produced using solar PV. Testing has been carried out on most vehicles types and the result is significant.

The new administration in the Irish Government has shown considerable interest and we are ready to commence trials using the Reformer on Public Transport where efficiency and emissions testing will be carried out by an independent specialist. 

About The Author

Professor John Cassidy was awarded a diploma in Applied Science by Dublin Institute of Technology, his BSc (Applied Sciences) by University of Dublin, and completed his PhD at the University of Utah, USA. He has since lectured in Analytical Chemistry in DIT, Kevin Street. He was appointed Assistant Head of School in 2001 and awarded Professorship of DIT in 2009.

His research interests include Analytical Chemistry and Instrumentation. This involves the theory and operation associated with Modern Analytical Instruments in the area of spectroscopy, electrochemistry and chromatography. 

 

Journal Reference

International Journal of Hydrogen Energy, Volume 41, Issue 4, 2016, Pages 2197-2201.

Cian O’Reilly¹, Michael Farrell², David Harvey³, John Cassidy¹

Show Affiliations

1. School of Chemical and Pharmaceutical Sciences, Dublin Institute of Technology, Kevin St., Dublin D08 NF82, Ireland
2. School of Electrical and Electronic Engineering, Dublin Institute of Technology, Kevin Street, Dublin D08 NF82, Ireland
3. NuNrg Reformers Ltd, Fardrum, Athlone, Co., Westmeath, Ireland

Abstract

This paper describes the operation of a bipolar alkaline electrolyser which is at least 60% efficient at evolving a hydrogen/oxygen mix. The electrolyser consists of 12 stainless steel (SS316L) electrodes of area 5400 cm² in a sealed polypropylene unit. A pulsed potential waveform is applied to the electrodes in 0.12 M KOH electrolyte yielding on the order of 320 dm³/kWh of the hydrogen/oxygen mix. This compares favourably with commercial devices that are designed to yield hydrogen alone.

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Renewable Energy Global Innovations features: Multiscale modeling and performance analysis of evacuated tube collectors for solar water heaters using diffuse flat reflector

Significance Statement

The deployment rate of solar water heaters (SWHs) is rapidly increasing for various domestic, industrial and commercial applications. Among stationary solar collectors, evacuated tube collectors (ETCs) have captivated more attention because of their satisfactory performance, reliability and cost-effectiveness.

However, using ETCs for various solar water heaters may endure deficits in collecting the necessary thermal energy for water heating particularly in cold seasons. This is because of the cylindrical shape of evacuated tubes which makes the upper circumference of the cylinder is directly exposed to sunrays, while the lower circumference usually misses the beam and also most of the diffuse irradiance.

This study highlights the role of installing a diffuse flat reflector (DFR) layer at the back of ETC array to improve heat capture rate. A comprehensive and generic model in computing solar thermal gain, annual fuel/electricity savings, and small-scale technology certificates (STCs) is developed. While this model is optimized for a promising energy saving compared to the conventional ETC-SWHs in four Australian solar zones, it can be custom-designed for any thermal load at any location worldwide.

This model is able to optimize the azimuth/tilt angles and be sized for the highest annual/seasonal achievable performance. The outcome of this research demonstrates a tangible techno-economic feasibility for many solar water heaters applications. 

About The Author

Dr Dia Milani is currently the energy team leader in the Laboratory for Multiscale Systems (LMS) at the University of Sydney. He obtained a M.S. degree in Environmental Engineering Management from UTS in 2006, a Graduate Certificate in Innovation & Enterprise in 2011, and PhD in Chemical Engineering in 2012 from The University of Sydney.

His research focus is at the water-energy-carbon interfaces with primary emphasis on novel technologies in renewable energy, thermal energy storage, carbon capture, CO₂ utilization, waste management, and solar-assisted power cycles.

About The Author

Associate Professor Ali Abbas received both his Bachelors and PhD in Chemical Engineering from University of Sydney, Australia. He has held academic appointments at Nanyang Technological University (NTU), and UNSW Asia in Singapore before joining, in 2007, the School of Chemical and Biomolecular Engineering at the University of Sydney. His engineering research and expertise is in the area of Process Systems Engineering with emphasis on model-based optimal operation of energy, particulate and bio-systems.

In 2008, A/Prof. Abbas was awarded the PSE Model-based innovation prize (London, UK) recognizing his work in model-based optimal process operations. He was later awarded the Australia-Harvard Fellowship in 2011 as well as the Academy of Technological Sciences and Engineering (ATSE) Fellowship (Australia-China Future Leader in Clean Coal Technologies) in 2012.

He has strong interests in engineering science education with particular focus on curriculum design and integration as well as on experiential e-learning and virtual worlds.

Journal Reference

Renewable Energy, Volume 86, 2016, Pages 360-374.

Dia Milani, Ali Abbas

School of Chemical and Biomolecular Engineering, The University of Sydney, NSW 2006, Australia

Abstract

Using evacuated tube collectors (ETCs) in solar water heaters (SWHs) may endure deficiencies (i.e. in winter season) in collecting the necessary thermal energy for water heating. This is because of the cylindrical shape of evacuated tubes which makes the upper circumference of the cylinder is directly exposed to sunrays, while the lower circumference usually misses the beam and also most of the diffuse irradiance.

In this paper, the role of using a diffuse flat reflector (DFR) at the back of ETC array to improve heat capture rate is examined. A comprehensive model to estimate the annual energy savings and small-scale technology certificates (STCs) is developed. This model is applied on four major Australian cities representing four Australian solar zones. The tilt and azimuth angles for these four zones are optimized.

This optimal setting along with DFR presence could improve the STC entitlements by 14.6% for zone 1; 20.2% for zone 2; 25.9% for zone 3; and 27.9% for zone 4, respectively. This specific-tailored model may increase the annual energy saving up to 95.8% for zone 1; 91.3% for zone 2; 81% for zone 3; and 74% for zone 4 correspondingly.

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