NRF POC Awardees - 8th Grant Call (Nov 2012)

 

1. Stabilized Two-Phase Cooling for Effective Thermal Management of Power Electronics

The proposed project is to develop a novel and highly effective two-phase heat sink for effective thermal management of power electronics. Conventional thermal management solutions utilize either liquid or gas in a single phase cooling configuration. Two-phase cooling is a next generation cooling solution which involves a change from liquid to gaseous phase for the coolant at the heat sink. This can improve the cooling performance (heat transfer coefficient) by more than ten fold. However, two-phase flows are associated with flow instabilities. Flow instabilties can induce mechanical vibrations in the system, which may cause many problems such as reduce life-spans of heatsinks, o induce large pressure drops, increases pumping power requirement and thus pump size. The proposed project utilizes a stepped fin microchannel heat sink, which is able to dissipate a large amount of heat in a two-phase condition, and stabilize the flow in the system. This results in more reliable heat transfer performance unlike conventional straight microchannels which have very high pressure and temperature fluctuations. Experimental investigations have shown improved flow stability and significantly lower pressure drop without compromise on heat transfer performance. Hence this technology has a very good potential for effective thermal management of power electronics.

Lee Poh Seng
Assistant Professor
Department of Mechanical Engineering
National University of Singapore

 

 

 

Dr PS Lee obtained his BEng (1st Class Honours) and MEng from the Department of Mechanical Engineering at the National University of Singapore and was a Senior Tutor with the same department from 1999 to 2001. He then proceeded to obtain his PhD degree from the School of Mechanical Engineering, Purdue University, West Lafayette, USA in 2007. His current research interests include microfluidics and microscale heat transfer, high performance thermal management techniques (in particular microchannel single- and two-phase cooling) and hybrid solar energy harvesting systems. His work were published in top international journals and widely cited. One of his papers won the International Journal of Heat and Mass Transfer Most Cited Papers Award for 2005-2008. In addition, he developed various novel and effective passive techniques for enhancing the heat transfer performance of microchannel heat sinks and mitigating the critical issues of hotspots and large temperature gradients in electronics devices and holds 2 US patents related to these efforts. He has also received various awards such as the 2009 Tan Kah Kee Young Inventors Award, 2011 Asia Pacific Clean Energy Summit Top 10 Defense Energy Technology Solutions Award and the 2011 Institution of Engineers Singapore (IES) Prestigious Engineering Achievement Award.

 

2. Ceramic Pore-Channels with Inducted Carbon-nanotube Fence for Removing Oil from Water

The aim of this project is to create a mobile, effective and simple membrane module capable of thoroughly removing fine oil particles from polluted effluents, whilst offering hassle-free process integration, continuous operation and easy regenerability. Such technology is urgently needed in drilling rigs and isolated plants for oil/water purification as the cost and lead-time for treating oil-polluted water by the existing methods substantially reduce the profit for these companies. This tailored membrane separation method is more effective than the current secondary process using either biological treatment or activated carbon adsorption due to its shorten treatment time and smaller footprint, thereby translating to cost reduction. The principle of our design lies in the dual working mechanisms of separation: (1) size exclusion executed by the pore opening of the ceramic membrane, which rejects bigger oil particles; (2) adsorption by multiple soft oily layers developed on carbon nanotube fences, which effectively entraps smaller and/or dissolved oil particles. Choosing porous ceramic membrane as the separation medium also allows adequate chemical and thermal durability and hence regenerability. Our preliminary results have shown that the oil content in water could be reduced to below 5ppm from the initial feed of 300ppm after filtration through the membrane. Targeting a market of annual revenue of US$900 billion, our team has validated the need for this membrane with potential customers and aims to resolve the technical and business aspects commercialization requires, with the future objective of a start-up company. The project’s focus will be primarily on the product development from its infancy to a testing prototype, particularly improving the membrane’s flux by re-designing the pore-density and connectivity at micron scale and implementing anti-fouling capability in the membrane. Industrial wastewater will be tested and validated on the prototype to simulate the actual working conditions and the operational cost required.

Hong Liang (PI)
Associate Professor
Department of Chemical and Biomolecular Engineering
National University of Singapore

 

 

A/P Hong obtained his PhD in chemical engineering from SUNY Buffalo (New York, US) in 1996. His research interests include synthesis and chemical modifications of polymers, ceramic mixed-conductive membranes, inorganic membrane and materials for gas and water application and colloidal dispersions for development of functional coating. He strongly believes that arts and fundamental science are essential for doing well as a researcher.

Dr Chen Xinwei (co-PI)
Department of Chemical and Biomolecular Engineering
National University of Singapore

 

 

 

 

3. Development of Novel Polymer Electrolytes for Applications in Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cells (PEMFCs) are widely accepted to be one of the key technologies that will fundamentally transform the current fossil fuel based energy system into an environmentally-friendly and efficient energy system. The PEMFC technologies, to be deployed in commercial scales starting from 2015, will revolutionize the automotive and energy storage industries with substantially higher energy efficiency and essentially zero emission compared to the traditional combustion based technologies.

Proton conducting polymer electrolyte membranes are one of the key-components of PEMFCs. Conventional PEMFCs typically operate at a temperature below 90 °C using Nafion® as PEM membranes. However, to reduce the complexity and increase the efficiency and CO-tolerance of PEMFC systems, there is an increasing demand for PEMs capable of sustaining operations above 100 °C. Unfortunately, the proton conductivity of Nafion® suffers greatly from the elevated temperatures due to loss of water. In addition, the barrier properties of Nafion® are insufficient when methanol is used as a fuel. These factors, in addition to the high cost of Nafion®, have triggered an extensive research for alternative PEM materials.

The main objectives of this proposal are: (1) to develop a class of hydrated polymeric membranes with high proton conductivity (> 0.01 S cm-1), low fuel and O2 permeability, and high electrochemical, thermal and mechanical stability and (2) to scale up the membrane fabrication to a dimension of 10”×10” with a thickness of approximately 100µm and an operating temperature above 100oC. By incorporating carefully tailored hydrophilic groups into PEM membranes and utilizing sulphuric acid as the proton conducting media, high proton conductivity and good water retention capacity can be achieved. Fabrication of the PEM membranes can be performed in a solution process with good scalability.

Cheng Hansong
Associate Professor
Department of Chemistry
National University of Singapore

 

 

A/P Cheng obtained his BSc from Wuhan University in 1982 and Ph.D. from Princeton University in 1991. He uses the state-of-the-art computational chemistry methods and experimentations to understand mechanistic aspects of physical and chemical processes and thus to enable design and discovery of novel materials for a variety of applications. Specific areas of his current research interests include:

1. Fabrication of transparent conducting oxide thin films for displays and solar cells;
2. Highly polarized materials for applications in Li-ion batteries and proton exchange fuel cells
3. Surface chemistry including processes of semiconductor thin film growth and heterogeneous catalysis;
4. Reactive force field development for metallic nanoparticles.

 

4. Development of advanced nanofiltration membranes for high removing rate of dyes in textile wastewater

Textile industry generates 12 billion tons of wastewater every year. Currently the available technologies such as chemical method, biological method or ultrafiltration membrane process have difficulty to effectively remove the residue dyes from the wastewater. Not only being poisonous, these dyes even in very low content make the wastewater highly colourful. With intensified environmental consciousness, textile industry is faced with a big challenge to discharge safer and cleaner wastewater. Recently, we have successfully developed advanced hollow fiber nanofiltration (NF) membranes that can offer > 99% dye removal efficiency and superior water production rate. Very encouraging results have been observed with applying our newly-developed NF membranes to real industry wastewater samples. Encouraged by our preliminary findings, we would continue our work on the NF membranes in terms of different water sources, scale up the membrane modules, investigate fouling and cleaning in a real environment, as well as build and evaluate pilot-scale NF system for long-term test. We believe that our technology would be the ultimate solution to process textile wastewater with higher efficiency but lower cost.

Dr Sun Shipeng
Department of Chemical and Biomolecular Engineering
National University of Singapore

 

 

 

 

Dr Sun Shipeng is a research fellow at the National University of Singapore. He received his bachelor degree of Chemical Engineering at Tianjin University of China in 2007. After that, he joined the PhD programme of Singapore-MIT Alliance under the supervision of Prof. Neal Chung Tai-Chung at NUS and Prof. T. Alan Hatton at MIT. His PhD work mainly focused on the sustainable manufacture in pharmaceutical industry by developing high-performance nanofiltration hollow fiber membranes for recycling high-value added product and minimizing waste generation. After completing his PhD study in 2011, Dr. Sun joined Prof. Neal Chung’s membrane research group and expanded his research into developing new membranes for water reclamation and solvent recovery in textile, pharmaceutical, and other industries. So far, he has authored and co-authored 6 papers in top international journals. His invention on double-repulsive membrane has found great market potential for textile waste water reclamation. 2 patents have been filed on this technology.

 

5. Up-scaling a Novel Method of Microneedle Fabrication

The administration of drugs into human body via skin is typically achieved by a transdermal patch or a hypodermic needle. As an alternative approach, microneedle arrays have recently been extensively explored to meet therapeutic needs while being non-invasive, convenient, and having the option of self-administration. Critical limitations in advancing the usage of microneedle arrays are their small sizes and their high costs. We propose to develop large microneedle arrays from biocompatible polymers, alleviating the need for multiple microneedle applications to treat large skin area as well as ensuring safety on skin applications. The biocompatible large-size microneedle arrays will potentially translate to lower cost for customers. Recently, we have developed a photolithographic approach for fabricating microneedle arrays using a biocompatible polymer. Our method is potentially up-scalable to fabricate microneedle arrays with larger areas. Technically, ensuring the uniformity and robustness of the microneedles throughout the patch is a challenge and may be addressed by optimizing the UV parameters and geometrical dimensions on the photomask for fabrication. The fabricated large-size microneedle arrays will subsequently be evaluated for skin their applications.

Dr Kang Lifeng
Department of Pharmacy
National University of Singapore

 

 

 

Dr Kang Lifeng is a lecturer at the Department of Pharmacy, National University of Singapore. His laboratory is focused on micro- and nano-scale technologies for tissue engineering and drug delivery. In drug discovery and delivery, miniaturized platforms are used to precisely control the fluid flow, enable high-throughput screening, and minimize sample or reagent volumes. In tissue engineering, micro-scale technologies are used to fabricate scaffolds with increased complexity and vascularization. He obtained his Ph.D from the National University of Singapore in 2006 in Department of Pharmacy. His thesis was on organic gels for drug delivery. Upon graduation, he was awarded an NUS-Overseas Postdoctoral Fellowship. Later, he went to the Massachusetts Institute of Technology to study tissue engineering. He focused on the development of embryonic stem cells and cardiac progenitor cells in microwell arrays fabricated with hydro-gels for tissue regeneration. He also studied hydro-gels as drug carriers for his M.S. degree in China Pharmaceutical University where he completed his undergraduate. Dr. Kang has published nearly 30 peer-reviewed papers, 32 abstracts and filed 3 US patent applications.

 

6. Biocompatible and Photostable Quantum-dot-sized Organic Nanoparticles for Noninvasive Long-term Cell Tracing

The ability to image single-cell migration in real time is important to several research areas such as embryogenesis, cancer metastasis, stem cell therapeutics, and lymphocyte immunology. This requires continual tracking of biological processes by cytocompatible fluorescent probes over long periods of time and on an inheritable basis following cell-division of initially tagged cells. The proposal focuses on high fluorescence organic NPs with tuneable absorption/emission wavelengths and surface functionalization to create a library of organic NPs and cell tracer probes to address the performance shortfalls of current quantum dot (QDs) based probes. The outcome of this project will produce high performance replacements for current QD and fluorescence imaging reagents. The organic NPs produced from this project will address a major unmet need for long term cell tracing and expand the rapidly growing in vitro diagnostics and research reagent market, especially in the areas of molecular diagnosis and live cell imaging.

Liu Bin
Department of Chemical and Biomolecular Engineering
National University of Singapore

 

 

Dr. Liu Bin is an Associate Professor of the Department of Chemical and Biomolecular Engineering, National University of Singapore (NUS). She obtained her BSc degree from Nanjing University and Ph.D degree from NUS in 2001 before she went for postdoctoral training in the University of California at Santa Barbara. Her research interest is to design and synthesize functional materials and explore their applications in optoelectronic devices and chemo/biosensors. Dr. Liu is the winner of the NUS Young Investigator Award 2006, the Singapore National Science and Technology Young Scientist Award 2008 and L’Oreal-Singapore women in Science National fellowship 2011.

 

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