Renewable Energy Global Innovations features: Molecular insights into water vapor absorption by aqueous lithium bromide and lithium bromide/sodium formate solutions

Significance Statement

A commonly used liquid desiccant, lithium bromide faces some shortcomings such as corrosion, crystallization at high concentrations and their need for high energy inputs to regenerate the absorbent.

Molecular dynamic simulations have recently been applied in understanding of molecular driving forces such as vapor pressure and absorption rate that influence performance of liquid desiccants. Despite knowledge provided by molecular dynamic simulations on solution behavior, little efforts have been made on microscale kinetics of liquid desiccants including current ternary working fluids.

Researchers led by Professor Gloria D. Elliott from University of North Carolina at Charlotte, published an article in Applied Thermal Engineering conducted a series of molecular dynamic simulations of the absorption of water vapor into aqueous lithium bromide and lithium bromide /sodium formate mixtures at various temperatures.

The molecular dynamic simulation was able to provide a quasi-static absorption process as lithium bromide solution absorbs water vapor at a nearly constant rate. Large number of water molecules was absorbed by 60wt% lithium bromide solution at a temperature of 443K after a simulation time of 20ns which yielded an approximate absorption rate of 38Kg·m²/s but decreased as temperature decreases. It was also seen that absorption of water molecules increases as concentration of lithium bromide increases at a minimum temperature of 373K.

Analysis on mass density profiles of lithium and bromide ions with water molecules showed a decrease in interfacial thickness layer of lithium bromide solution as its concentration increases when observed at 383K and 408K, but no effect was found with respect to temperature. It was also observed that the interfacial dipoles were most likely to lie in a plane parallel to the interface.

Effects of addition of sodium formate into the LiBr + H₂O system when simulated at a temperature of 373K showed good correlation of density profile of lithium ions Li⁺ to that of formate anion COOH^– in all the mass ratios which maintains local proximity throughout the solution.

“What we found the most interesting was that the strong interaction between Li⁺ and COOH^– created cavities of various sizes that can accommodate water molecules,” said Dr. Lindong Weng, a former postdoctoral researcher in Elliott’s lab and the first author of the study. “Such fascinating morphology of ion placement provides a geometrical explanation for the increase in absorption capacity with added formate.”

The study also found that when the molar ratios of LiBr to NaCOOH are about 1.5:1 and 0.8:1, respectively, Li+-COOH^– clusters size mainly 5< (cluster size: defined as number of lithium ions that can be linked together with each other via COOH^–). This result showed that more addition of sodium formate led to more extended and interwoven lithium and formate ion clusters. The effect of addition of sodium formate also led to a decrease in water vapor absorption rate despite increase in absorption capacity.

The authors successfully optimized the advantages of lithium bromide and lowered crystallization temperature (minimal thermal energy needed via including formate salt). The molecular design and simulation methods presented in this study can aid in improved defined compositions to undergo more detailed experimental studies.  

About The Author

Dr. Gloria D. Elliott

Professor and Associate Chair, Research.
Department of Mechanical Engineering & Engineering Science- University of North Carolina at Charlotte

Dr. Gloria Elliott is the founding Director of the Charlotte Banks Research Initiative, an academic think tank integrating economics, technology, and policy to address logistical challenges in organ and tissue transport, with the aim of accelerating growth in regenerative medicine, transplantation, and the tissue engineering sector.

Dr. Elliott completed post-doctoral training at Harvard Medical School and Massachusetts General Hospital.  She received her BS degree in Applied Chemistry at the University of Waterloo in Canada, and her MS and PhD in Mechanical Engineering from Michigan State University.

Dr. Elliott currently directs the Biostability Lab at the University of North Carolina at Charlotte (UNCC). Her research area is experimental thermodynamics with applications to living systems.  Dr. Elliott’s group has been developing technology and investigating the underlying science of biopreservation, and she holds several patents in this area.  Her research program has included the development of stabilization technologies for biomolecules, viruses, cells, gametes, and tissues, for diagnostic and therapeutic use.

Dr. Elliott has over a decade of experience as a pioneer in engineering education at UNCC, with a focus on training in thermodynamics and energy transport phenomena. She has created numerous new courses with biomedical engineering and energy production themes, and has also been an architect of several new programs, including a Research Experience for Undergraduates program and two separate degree concentrations in Energy Engineering and Biomedical Engineering.  She currently provides academic integrity oversight as a member of the Chancellor’s Advisory Council on Inter-collegiate Athletics, and she has also previously served on the UNCC Academic Integrity Board.

Dr. Elliott currently serves as a scientific advisor to the Organ Preservation Alliance and is a co-organizer of the upcoming Organ Banking Summit.  She is a member of the Bioengineering Technology Advisory Panel for the American Society of Mechanical Engineers. Dr. Elliott’s strategic planning experience also includes service on the executive committee of the Society of Cryobiology.

She currently serves on several research advisory committees at the university, most notably the Standing Committee on Conflicts of Interest and Commitment, the university’s highest research integrity oversight and advisory committee.  

Journal Reference

Lindong Weng ¹, Wei Song^2, ,  Donald J. Jacobs², Gloria D. Elliott¹. Molecular insights into water vapor absorption by aqueous lithium bromide and lithium bromide/sodium formate solutions, Applied Thermal Engineering 102 (2016) 125-133.

Show Affiliations

1. Department of Mechanical Engineering and Engineering Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, United States.
2. Department of Physics and Optical Science, University of North Carolina at Charlotte, Charlotte, NC 28223, United States.

 

 

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Renewable Energy Global Innovations features: Structural dynamics of innovation networks funded by the European Union in the context of systemic innovation of the renewable energy sector

Significance Statement

In a recent article of Kang and Hwang (2016) which was published in Energy Policy, examined whether related innovation activities transforms into a systemic direction when considering the European Union funded international networks while also checking whether the European Union has contributed to establishing an effective ecosystem for systemic renewable energy innovation.

Several structural properties as indicators were used to evaluate the systemic innovation conditions of a network due to its dual dimensions as appropriate measurement were suggested. Two network properties; the structural closure and structural holes diagnosed the overall network structure with respect to market exploitation and technology exploration, measuring the overall degree of connectivity.

The other indication applied two properties namely; the hierarchy and disassortativity in order to evaluate interoperability between technology exploration and market exploitation. The use of the hierarchy with a core-periphery structure reveals the heterogeneity in relations of capable organization across the network. The disassortativity property showed the tendency of the nodes in the network to connect one another with those who exhibit dissimilar degrees.

For effective combination of openness strategies for network positioning, the authors regarded the country boundary as a condition for judging organization openness to external partnerships provided that renewable energy innovation depends on geographical factors, market readiness and institutional schemes. A two-step approach was also implemented to determine whether an organization has more relationship with foreign or domestic firms and later measured by use of an external-internal index and secondly, correlation between external-internal index while checking whether the actors are in line with systematic innovation in the network based on their openness strategies.

The authors also employed framework programs and Intelligent Energy Europe sub-program for studying correlation between technology exploration and market exploitation.

When observing the overall network structures, both actual and random networks in period I (2003-2007) and period II (2008-2013) were similar in average path lengths indicating small-world tendencies but a larger overall clustering coefficient in actual networks was found. Higher constraint were also found in actual networks in both periods compared to random networks depicting a major relational redundancies of the renewable energy innovation networks while structural holes were missing.

The renewable energy innovation network under the European Union which follows the small-world model direction had a diminished structural hole assembly as overall connectivity increases which is characterized by a high centralization and segmentation.

The hierarchy in both actual and random network was significant with cohesiveness of core organizations but the degree distribution in actual network was stronger compared to random network. A greater degree of correlations between that of focal length and its direct neighbors was more positive for actual networks compared to random networks which confirms presence of an assortative structure.

The core-periphery model when compared to the random models can be likened to a systemic renewable energy innovation under the European Union’s program. The core and periphery structures are dense and assortative but less segmented. This means that the core and peripheries are not effectively combined which can be related to the dissociation between the explorative and exploitation phase for systemic renewable energy innovation.

This study shows an increasing number of organizations have appropriate openness strategies based on their network positions which proposes its capability for systemic renewable energy innovation after a period of time.

  

About The Author

Dr. Jongwoon Hwang
Head of Smart Convergence Group, KIST Europe 

Dr. Jongwoon Hwang is Head of Smart convergence group of KIST Europe. He joined KIST Europe in 2000 and is in charge of international cooperation especially between the EU and Korea.

He has involved in many national and international projects such as FP7 KESTCAP, FP7 KORRIDOR, FP7 KONNECT, Development of smart energy monitoring system etc. He also leaded studies such as Sustainable Waste Management Strategy for Green Printing Industry Business of FP7 ECO-INNOVERA and strategic global regulation compliance for Samsung.

He got his doctoral degree in information and communication management system at Technical University of Berlin in Germany with the topic ‘Architecture model for the SOA-based IT-services in the power supply industry’ and has relevant and interdisciplinary experiences in Science and Technology Cooperation.  

 

About The Author

Ms Moon Jung Kung
PhD candidate, TU Berlin, Innovation Economics

Moon Jung Kang holds a Diplom degree in Environmental Science from Leuphana University Lueneburg, Germany. Since 2011, she has been doing the Ph.D. study on “International Networks for Promoting the Eco-innovation in the Era of Climate Change” at Technical University of Berlin, Chair of Innovation Economics in Germany. She has published several SCI papers as well as many academic articles based on data from OECD, Eurostat, Clean Development Mechanisms, EU’s R&I programs (FP, IEE, and Horizon2020), and EU’s Community Innovation Survey on eco-innovation.

Moon Jung Kang was a research scientist at Smart Convergence Group, Korea Institute of Science and Technology (KIST) Europe located in Saarbruecken, Germany where she worked from 2007 to 2016. At KIST Europe, she participated in a number of European and Korean projects on strategy & policy developments in the fields of eco-innovation as well as international S&T cooperation between the EU and Korea.  

Journal Reference

Moon Jung Kang^1, 2, Jongwoon Hwang². Structural dynamics of innovation networks funded by the European Union in the context of systemic innovation of the renewable energy sector, Energy Policy 96 (2016) 471-490.

Show Affiliations

1. Chair of Innovation Economics, Technical University of Berlin, Müller-Breslau-Straße 15, 10623 Berlin, Germany.
2. Industry and Technology Strategy Department, Korea Institute of Science and Technology Europe, Campue E 71 Uni des Saarlandes, 66123 Saarbruecken, Germany.

 

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Renewable Energy Global Innovations features: Enhanced Oil Recovery (EOR) Using Nanoparticle Dispersions: Underlying Mechanism and Imbibition Experiments

Significance Statement

Nanofluids have become attractive agents for EOR recently. Higher ultimate oil recovery has been reported previously by using nanofluids. The two major mechanisms reported in literature in achieving this feature include: The reduction of interfacial tension between the aqueous phase and oil phase, and the rock wettability alteration. Despite recently widely conducted research using a nanofluid for EOR, the underlying operating mechanism of recovery by a nanofluid is still not well understood.

A new approach which makes use of nanofluids for displacement of oil from solid substrate by nanoparticle structuring leads to structural disjoining pressure which separates oil from the solid substrate. Other factors such as combination of nanoparticle formulation, contact angle and capillary pressure are also known to influence the separation of oil from substrate.

Researchers from Illinois Institute of Technology at Chicago presented results of imbibition experiments using a silica nanofluid and an Illinois Institute of Technology (IIT) nanofluid that displaces crude oil from Berea sandstone and single-glass capillaries. The researchers developed a nanoparticle formulation in view of surviving at a high-salinity environment containing calcium and magnesium ions accompanied with study of structural disjoining pressure mechanism for crude oil displacement. The work was published in peer-reviewed journal, Energy & Fuels.

Through imbibition test, 55% of the crude oil was recovered using the silica nanofluid, compared to only 2% recovered with the pH 9.7 DI water after 15 days. At an increased temperature of 55 ^oC, the IIT nanofluid displaced crude oil approximately 50% from Berea sandstone compared with 17% by the brine solution.

For the mechanistic study, the researchers observed rapid shrinkage of contact region after introduction of brine and the position of contact region didn’t change with time after wedge region was formed, hence oil drop was not detached. However, for the nanofluid case, a new contact line (inner contact line) appears and spreads due to nanoparticles ordering in the oil/solid/aqueous three phase contact region after the wedge film formed. This confirms the structural disjoining pressure mechanism. It is the first time that this mechanism of crude oil displacement from a solid substrate is demonstrated experimentally.

The authors finally conducted model studies of crude oil displacement using single glass capillaries to directly visualize the crude oil displacement process from inside the pore. Around 60% crude oil was displaced by IIT nanofluid compared to 3% in the brine. Moreover, the authors were able to show from their results that the IIT nanofluid thrives in harsh saline environment where silica nanoparticles cannot.

 

About The Author

Hua Zhang is a Ph.D. Student in the Chemical and Biological Department at Illinois Institute since 2011. He received his B.S. and M.S. degrees in Chemical Engineering from Beijing University of Chemical Technology, China in 2008 and 2011 respectively.

His research area lies in wetting and spreading of nanofluids on solid substrate; dynamics of liquids in the capillary; surface cleaning and enhanced oil recovery using nanofluids.  

Journal Reference

Hua Zhang, Alex Nikolov, Darsh Wasan.  Enhanced Oil Recovery (EOR) Using Nanoparticle Dispersions: Underlying Mechanism and Imbibition Experiments, Energy Fuels 28 (2014) 3002-3009.

Department of Chemical and Biological Engineering, Illinois Institute of Technology, Chicago, Illinois 60616, United States.

 

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