University of Illinois Grainger College of Engineering researchers are demonstrating next-generation energy technology using topology optimization and metal 3D printing to design ultra-compact, high-power heat exchangers (Most are commonly called radiators).

Used in most major industries – including energy, water, manufacturing, transportation, construction, electronic, chemical, petrochemical, agriculture and aerospace – heat exchangers transfer thermal energy from one medium to another. The team reported their technical advancement in the journal Joule.

For decades, heat exchanger designs have remained relatively unchanged. Recent advancements in 3D printing allow the production of three-dimensional exchanger designs previously thought impossible. These new and innovative designs operate significantly more effectively and efficiently but require specific software tools and design methods to manufacture the high-performance devices.

Using shape optimization to design an ultra-compact heat exchanger and manufacturing the devices using metal additive manufacturing makes a device with 20× higher specific power than a comparable commercial device. Image Credit: University of Illinois Grainger College of Engineering. Click image for the largest view.

Recognizing the need to unlock new, high-performing heat exchangers, Grainger College of Engineering researchers have developed software tools that enable new 3D heat exchanger designs.

William King, professor of Mechanical Science and Engineering at The Grainger College of Engineering and co-study leader said, “We developed shape optimization software to design a high-performance heat exchanger. The software allows us to identity 3D designs that are significantly different and better than conventional designs.”

The team started by studying a type of exchanger known as a tube-in-tube heat exchanger – where one tube is nested inside another tube. Tube-in-tube heat exchangers are commonly used in drinking water and building energy systems. Using a combination of the shape optimization software and additive manufacturing, the researchers designed fins (only made possible using metal 3D printing) internal to the tubes.

Nenad Miljkovic, associate professor of Mechanical Science and Engineering and co-study leader said, “We designed, fabricated and tested an optimized tube-in-tube heat exchanger. Our optimized heat exchanger has about 20 times higher volumetric power density than a current state-of-the-art commercial tube-in-tube device.”

With billions of heat exchangers in use worldwide today and even more attention placed on our need to reduce fossil fuel consumption, compact and efficient heat exchangers are increasing in demand, particularly in industries where heat exchanger size and mass significantly impacts performance, range and costs.

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Your humble writer finds this development quite interesting and very likely to find market legs. Whether one considers a tube in tube application of one controlled media to another or the common radiator moving heat into or out of a controlled media to an uncontrolled one, the team’s work is just getting started.

We’re seeing innovation intuition and inventiveness in a premium example here. This tech is sure to save a bunch of energy, expense, operating space, and other attributes across a very wide array of other technologies. One can well imagine the common radiator and other heat exchangers are just about to experience a revolution.

Researchers at the University of Central Florida have designed for the first time a nanoscale material that can efficiently split seawater into oxygen and hydrogen. Hydrogen fuel derived from the sea could be an abundant and sustainable alternative to fossil fuels, but the potential fuel source has been limited by technical challenges, including how to practically the produce the hydrogen.

The UCF researchers developed a stable, and long-lasting nanoscale material to catalyze the electrolysis reaction, shown here. Image Credit: University of Central Florida. Click image for the largest view.

The process of splitting water into hydrogen and oxygen is known as electrolysis and effectively doing it has been a challenge until now. The new UCF team developed, stable, and long-lasting nanoscale material to catalyze the reaction is explained in a paper published the journal Advanced Materials.

Yang Yang, an associate professor in UCF’s NanoScience Technology Center and study co-author said, “This development will open a new window for efficiently producing clean hydrogen fuel from seawater.” Yang noted the hydrogen used in fuel cell technology would be converted into electricity that generates water as product and makes an overall sustainable energy cycle.

The researchers developed a thin-film material with nanostructures on the surface made of nickel selenide with added, or “doped,” iron and phosphor. This combination offers the high performance and stability that are needed for industrial-scale electrolysis but that has been difficult to achieve because of issues, such as competing reactions, within the system that threaten efficiency.

Yang said the new material balances the competing reactions in a way that is low-cost and high-performance.

Using their design, the researchers achieved high efficiency and long-term stability for more than 200 hours.

Yang noted, “The seawater electrolysis performance achieved by the dual-doped film far surpasses those of the most recently reported, state-of-the-art electrolysis catalysts and meets the demanding requirements needed for practical application in the industries.”

The press release said the team will work to continue to improve the electrical efficiency of the materials they’ve developed. They are also looking for opportunities and funding to accelerate and help commercialize the work.

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That’s a material, with something of a life cycle, that might see some use after development. With wind power coming placed offshore there very well could be a future for this technology. One could simply dump the O2 right back into the water for marine life. Other than gathering the hydrogen, not a lot of difficulties that are obvious, other than marine life moving in and clogging up the works.

A Tohoku University research group has produced fresh insights about the release of oxygen in lithium-ion batteries, paving the way for more robust and safer high energy density batteries. As rechargeable batteries get more powerful, the chance of batteries overheating – thermal runaway – increases.

Seeking a way to make batteries safer, researchers have investigated one of thermal runaway’s main triggers: oxygen release. The team’s study paper has been published in Advanced Energy Materials.

Next-generation batteries that store more energy are critical if society is to achieve the UN’s Sustainable Development Goals and realize carbon neutrality. However, the higher the energy density, the higher the likelihood of thermal runaway – the overheating of batteries that can sometimes result in a battery exploding.

Oxygen release from battery materials which can cause thermal runaway. Image Credit: ⒸTakashi Nakamura at Tohoku University. Click image for the largest view.

Oxygen released from cathode active material is a trigger for thermal runaway, yet our knowledge of this process is insufficient.

The researchers from Tohoku University and the Japan Synchrotron Radiation Research Institute (JASRI) investigated the oxygen release behavior and relating structural changes of cathode material for lithium-ion batteries LiNi1/3Co1/3Mn1/3O2 (NCM111). NCM111 acted as a model oxide-based battery material through coulometric titration and X-ray diffractions.

The researchers discovered NCM111 accepts 5 mol% of oxygen release without decomposing and that oxygen release induced structural disordering, the exchange of Li and Ni.

When oxygen is released, it reduces the transition metals (Ni, Co and Mn in NCM111), lessening their ability to keep a balanced charge in the materials.

To evaluate this, the research group utilized soft-Xray absorption spectroscopy at BL27SU SPring-8 – a JASRI operated large-scale synchrotron radiation facility in Japan.

They observed selective Ni3+ reduction in NCM111 at the beginning stage of oxygen release. After the Ni reduction finished, Co3+ decreased, while Mn4+ remained invariant during 5 mol% of oxygen release.

Takashi Nakamura, coauthor of the paper said, “The reduction behaviors strongly suggest that high valent NI (Ni3+) enhances oxygen release significantly.”

To test this hypothesis, Nakamura and his colleagues prepared modified NCM111 containing more Ni3+ than the original NCM111. To their surprise, they discovered the NCM111 exhibited much severe oxygen release than expected.

Based on this, the research group proposed that the high valent transition metals destabilize lattice oxygen in oxide-based battery materials.

Nakamura concluded the press release noting, “Our findings will contribute to the further development of high energy density and robust next-generation batteries composed of transition metal oxides.”

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This is very, very welcome news. For those watching, there is quite list of battery fires and explosions littering technical news, providing considerable worthy concern. It looks like this team’s efforts will assist in development of not just stronger batteries, but those batteries just might be much safer. The need to park an EV a distance from things flammable might not last so long.

University of Michigan researchers have used machine learning to predict how the compositions of metal alloys and metal oxides affect their electronic structures. The finding could help pave the way toward cleaner fuels and a more sustainable chemical industry.

The electronic structure is key to understanding how the material will perform as a mediator, or catalyst, of chemical reactions.

The group’s paper has been published in Chem Catalysis.

A graphical illustration of Principal Component Analysis used to learn from Electronic Structure the Catalytic Properties. Image Credit: University of Michigan, Click image for the largest view.

Bryan Goldsmith, the Dow Corning Assistant Professor of Chemical Engineering said, “We’re learning to identify the fingerprints of materials and connect them with the material’s performance.”

A better ability to predict which metal and metal oxide compositions are best for guiding which reactions could improve large-scale chemical processes such as hydrogen production, production of other fuels and fertilizers, and manufacturing of household chemicals such as dish soap.\

Suljo Linic, the Martin Lewis Perl Collegiate Professor of Chemical Engineering said, “The objective of our research is to develop predictive models that will connect the geometry of a catalyst to its performance. Such models are central for the design of new catalysts for critical chemical transformations.”

One of the main approaches to predicting how a material will behave as a potential mediator of a chemical reaction is to analyze its electronic structure, specifically the density of states. This describes how many quantum states are available to the electrons in the reacting molecules and the energies of those states.

Usually, the electronic density of states is described with summary statistics – an average energy or a skew that reveals whether more electronic states are above or below the average, and so on.

“That’s OK, but those are just simple statistics. You might miss something. With principal component analysis, you just take in everything and find what’s important. You’re not just throwing away information,” Goldsmith noted.

Principal component analysis is a classic machine learning method, taught in introductory data science courses. They used the electronic density of states as input for the model, as the density of states is a good predictor for how a catalyst’s surface will adsorb, or bond with, atoms and molecules that serve as reactants. The model links the density of states with the composition of the material.

Unlike conventional machine learning, which is essentially a black box that inputs data and offers predictions in return, the team made an algorithm that they could understand.

Jacques Esterhuizen, a doctoral student in chemical engineering and first author on the paper said, “We can see systematically what is changing in the density of states and correlate that with geometric properties of the material.”

This information helps chemical engineers design metal alloys to get the density of states that they want for mediating a chemical reaction. The model accurately reflected correlations already observed between a material’s composition and its density of states, as well as turning up new potential trends to be explored.

The model simplifies the density of states into two pieces, or principal components. One piece essentially covers how the atoms of the metal fit together. In a layered metal alloy, this includes whether the subsurface metal is pulling the surface atoms apart or squeezing them together, and the number of electrons that the subsurface metal contributes to bonding. The other piece is just the number of electrons that the surface metal atoms can contribute to bonding. From these two principal components, they can reconstruct the density of states in the material.

This concept also works for the reactivity of metal oxides. In this case, the concern is the ability of oxygen to interact with atoms and molecules, which is related to how stable the surface oxygen is. Stable surface oxygens are less likely to react, whereas unstable surface oxygens are more reactive. The model accurately captured the oxygen stability in metal oxides and perovskites, a class of metal oxides.

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This development could very well increase the results of catalyst and mediator development. Admittedly, little thought is given by the average consumer about the importance of molecular recombination to modern life. Perhaps molecular reformation began with fire hardening wooden spear points, or perhaps it was the fire itself. Today, most everything has a basis in molecular reformation, with no end in sight.

Researchers have found carbon nanotubes woven into thread-like fibers and sewn into fabrics become a thermoelectric generator. The invisibly small carbon nanotubes aligned fibers can turn heat from the sun or other sources into other forms of energy.

The Rice University lab of physicist Junichiro Kono led an effort with scientists at Tokyo Metropolitan University and the Rice-based Carbon Hub to make custom nanotube fibers and test their potential for large-scale applications.

The team’s small-scale experiments led to a fiber-enhanced, flexible cotton fabric that turned heat energy into enough electrical energy to power an LED. With further development, they say such materials could become building blocks for fiber and textile electronics and energy harvesting.

The same nanotube fibers could also be used as heat sinks to actively cool sensitive electronics with high efficiency.

The team’s paper about the project appeared in Nature Communications.

The effect seems simple: If one side of a thermoelectric material is hotter than the other, it produces usable energy. The heat can come from the sun or other devices like the hotplates used in the fabric experiment. Conversely, adding energy can prompt the material to cool the hotter side.

Until now, no macroscopic assemblies of nanomaterials have displayed the necessary “giant power factor,” about 14 milliwatts per meter kelvin squared, that the Rice researchers measured in carbon nanotube fibers.

Rice graduate student Natsumi Komatsu, lead author of the paper said, “The power factor tells you how much power density you can get out of a material upon certain temperature difference and temperature gradient.” She noted a material’s power factor is a combined effect from its electrical conductivity and what’s known as the Seebeck coefficient, a measure of its ability to translate thermal differences into electricity. “The ultrahigh electrical conductivity of this fiber was one of the key attributes,” she said.

The source of this superpower also relates to tuning the nanotubes’ inherent Fermi energy, a property that determines electrochemical potential. The researchers were able to control the Fermi energy by chemically doping the nanotubes made into fibers by the Rice lab of co-author and chemical and biomolecular engineer Matteo Pasquali, allowing them to tune the fibers’ electronic properties.

While the fibers they tested were cut into centimeter lengths, Komatsu said there’s no reason devices can’t make use of the excellent nanotube fibers from the Pasquali lab that are spooled in continuous lengths. “No matter where you measure them, they have the same very high electrical conductivity,” she said. “The piece I measured was small only because my setup isn’t capable of measuring 50 meters of fiber.”

Pasquali is director of the Carbon Hub, which promotes expanding the development of carbon materials and hydrogen in a way that also fundamentally changes how the world uses fossil hydrocarbons. “Carbon nanotube fibers have been on a steady growth path and are proving advantageous in more and more applications,” he said. “Rather than wasting carbon by burning it into carbon dioxide, we can fix it as useful materials that have further environmental benefits in electricity generation and transportation.”

Whether the new research leads to a solar panel you can throw in the washing machine remains to be seen, but Kono agreed the technology has great and varied potential. “Nanotubes have been around for 30 years, and scientifically, a lot is known,” he said. “But in order to make real-world devices, we need macroscopically ordered or crystalline assemblies. Those are the types of nanotube samples that Matteo’s group and my group can make, and there are many, many possibilities for applications.”

Co-authors of the paper are Rice graduate students Oliver Dewey, Lauren Taylor and Mitchell Trafford and Geoff Wehmeyer, an assistant professor of mechanical engineering; and Yota Ichinose, Professor Yohei Yomogida, and Professor Kazuhiro Yanagi of Tokyo Metropolitan University.

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This technology is double interesting in that one can harvest heat power and use some power for cooling. As its still summer the idea of a cooled band inside your humble writer’s hat is immensely interesting. Perhaps one’s shirt can power the hat band?

Your humble writer isn’t joking. Personal power is a very desirable property. It could very well be life saving and prolonging. Cell phones and fitbits and earbuds aside, there many very useful ideas that could come to market with a little power everywhere for everyone.


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