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The award-winning Phase Change Matters blog tracks the latest news and research on phase change materials and thermal energy storage. E-mail tips and comments to Ben Welter, communications director at Entropy Solutions. Follow the blog on Twitter at @PureTemp. Subscribe to the weekly PCM newsletter. Or join the discussion on LinkedIn.

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Research roundup: Solar storage tank; concentric PCM module; supercooling degree improvement; more

Ben Welter - Monday, January 21, 2019

From Journal of Thermal Science:

Energy Storage Performance of a PCM in the Solar Storage Tank

From International Journal of Applied Engineering Research:

Numerical assessment of suitability of phase-change materials in a concentric PCM-module for thermal storage applications [pdf]

From International Journal of Energy Research:

Experimental measurements and numerical computation of nanofluid and microencapsulated phase change material in porous material

From IOP Conference Series: Materials Science and Engineering:

Nano-enhanced phase change material effects on the supercooling degree improvement: A review

From Renewable Energy:

Potential of ventilation systems with thermal energy storage using PCMs applied to air conditioned buildings

From Journal of Mechanical Engineering and Technology:

Thermal performance analysis of nano enhanced paraffin wax and myristic acid

From Solar Energy:

Synthesis and characterization of microencapsulated phase change materials with comb-like acrylic co-polymer shell as thermal energy storage materials
Sensible and latent heat energy storage systems for concentrated solar power plants, exergy efficiency comparison

From Solar Energy Materials and Solar Cells:

Thermal energy storage characteristics of myristic acid-palmitic eutectic mixtures encapsulated in PMMA shell

From Thermal Science and Engineering Progress:

Parametric analysis and optimization of an underfloor solar assisted heating system with phase change materials

From International Journal of Heat and Mass Transfer:

The improved enthalpy-transforming based lattice Boltzmann model for solid-liquid phase change

From Applied Energy:

Innovative design of superhydrophobic thermal energy-storage materials by microencapsulation of n-docosane with nanostructured ZnO/SiO2 shell

From AIP Conference Proceedings:

Preparation and characterization of nanoparticle blended polymers for thermal energy storage applications

PCM briefing: CEO Hopkins leaves Ice Energy; 1414 Degrees says TESS-IND commissioning verified

Ben Welter - Monday, January 21, 2019

Mike HopkinsMike Hopkins, right, CEO of Ice Energy since 2014, has left the Riverside, Calif., company to pursue a "soon to be revealed" opportunity. Ice Energy makes ice-based thermal energy storage systems. According to an Ice Energy representative: "Dr. Marcel Christians (previously CIO) and Alex Collins (VP at Pacific Advantage Capital, majority shareholder in Ice Energy) have joined together to lead the company as co-COOs. Other than that, it’s business as usual as the company pushes most of its resources towards finding viable candidates for its 20+ MW thermal energy storage contract with major California utility, Southern California Edison."

AIMPLAS, a plastics technology center in Spain, is among 10 participants in a European project led by the Polytechnic University of Valencia. The consortium is developing new components for geothermal systems offering high thermal-conductivity properties.  

1414 Degrees Ltd. has announced that the commissioning of the Australian company's TESS-IND has been verified by Bureau Veritas. In three- and eight-hour test runs, the molten silicon heat store powered the system's turbine to generate average electricity outputs of 104kW and 148kW. "The maximum verified temperature of the phase change material heat store was 1418 degrees Celsius," the company said.

PCM with enhanced thermal properties developed for rail/truck container

Ben Welter - Saturday, January 12, 2019

Professor Yulong DingYulong Ding, the University of Birmingham professor who directed the development of a rail/truck shipping container designed to keep perishables cold without a power supply, says his team developed an organic phase change material with enhanced thermal properties for the project. The PCM is designed to keep the temperature inside the container between 5 and 12˚ C for up to 120 hours. Ding, director of the university's Center for Energy Storage, provided additional detail on the project in an interview this week.

Q: Describe your organization's role in the project.

A: It was funded by CRRC Shijiazhuang, a Chinese railway equipment manufacturer, and the project was collaborative. Our work at Birmingham included PCM materials development and fabrication, cold storage device design and testing, cold charging method and design. Work began in October 2017.

Q: What role did CRRC Shijiazhuang play?

A: CRRC was the project sponsor. Their work included manufacture and test of the device and cold charge device, installation of cold storage devices into large container, data-logging and IT, real application demonstration and testing (35,000 km combined road and railway testing across a wide climate zones).

Q: Can you briefly describe the testing methods and results?

A: I believe two standard containers were used, goods include all sorts of vegetables, flowers and fruits. Energy saving data have not been processed for the real tests but we do have testing data from labs, which is around 20 percent.

Q: Describe the PCM used in the application.

A: We used organic based PCM reformulated for enhanced thermal properties. Melting temperatures can be turned between -4 and 4 degree C, and the thermal storage capacity is >~200 kJ/kg.

Q: How big are the rail containers, typically, and how much PCM is used in each container?

A: We used the standard container for road transportation, which can be used for rail use. I prefer not to say the amount of PCM used, which may need approval from our sponsor.

Q: How is the PCM charged, and how long does it take to charge the PCM in a typical container?

A: We have a mobile charge device. The charging time is relatively short. The details will need our sponsor to approve before I can tell.

Q: In what material is the PCM contained (HDPE, film, metal)?

A: We used composite PCM contained in PCM storage device.

Q: How is the PCM deployed in the rail containers?

A: The PCM devices are installed inside the container.

Q: Does CRRC plan to manufacture the rail containers?

A: I doubt they would make the container.

https://www.birmingham.ac.uk/news/latest/2018/12/scientists-develop-world-first-cold-storage-roadrail-container.aspx

Microtek sponsors Spanish entry in Solar Decathlon Europe 2019

Ben Welter - Saturday, January 12, 2019

A team representing the Polytechnic University of Valencia, Spain, plans to use phase change material in the energy-efficient home it is building for Solar Decathlon Europe 2019. Azalea, one of 16 teams selected for the competition, is made up of 30 students and professionals representing fields such as architecture and engineering. 

Microtek Laboratories of Dayton, Ohio, is providing Azalea with technical and financial support.

Tim Riazzi"We are proud to be a sponsor of the Polytechnic team and the Azalea Project," said Tim Riazzi, Microtek president. "As a company who practices and is concerned with environmental stewardship, we are excited about their efforts to create a sustainable ecological dwelling that will reduce our impact on the environment and reduce our energy consumption." 

Riazzi said Microtek provided Azalea with Micronal 28D (formerly Micronal 5528X).

"Instead of providing them with a final product," Riazzi said, "we have worked with the team and decided that it would be better to provide them our dried Micronal product so that they could use it in the specific areas that they needed. We can say that they are incorporating it into a variety of elements/components of their wall and floor design, but they have asked us not to divulge the exact use of it because the competition is active. ... We can say that we have provide them over 200 kg of material."

https://www.microteklabs.com/blog/azalea-project-solar-decathlon-europe

PCM briefing: New Outlast materials on display at Heimtextil; agenda set for Jan. 24 workshop at Nottingham

Ben Welter - Saturday, January 12, 2019

Outlast recycled polysterNew Outlast products based on recycled materials were on display at the Heimtextil show in Frankfurt, Germany, this week. "In the new Outlast products," the company said, "temperature-regulating technology is applied to base material (knitted fabric or nonwoven) which is produced from 100% recycled polyester textiles or PET bottles and therefore meets the Global Recycle Standard (GRS). Further products that use renewable materials for other components of the technology are planned to expand the portfolio in the near future."

Tempur-Pedic says the latest version of its Breeze mattress line features a new "PureCool+ breathable phase change technology [that] absorbs excess heat and recharges faster to help the sleeper feel cooler when falling asleep."

Eindhoven University of Technology is seeking candidates for a Ph.D. position in nanoporous materials for thermal energy storage

Chemical & Engineering News is seeking candidates for a six-month science-writing editorial fellowship for 2019.

• A proposal to use microencapsulated phase change material to help motor vehicles run smoothly in extreme cold has been honored by Azerbaijan's Ministry of Economy as the best youth startup project of the year. A team of chemical engineering students from Baku Higher Oil School developed the concept.

The agenda has been posted for the Workshop on Energy Efficient Buildings & Thermal Energy Storage Systems to be held Jan. 24 at the University of Nottingham in the United Kingdom. Topics include "Enhanced geothermal borehole heat exchangers with PCMs," "Innovative composite smart materials for heating, cooling and humidity control in buildings" and "Demonstration of the TESSe2b system in three demo sites." The free, all-day workshop is part of the European Union-supported project TESSe2b.

•  From LinkedIn: "Pluss Advanced Technologies Pvt. Ltd. is expanding its vendor development team for its PCM and polymers business. Candidates with prior experience in purchase or vendor management will be preferred, others will be considered too. Want to understand more about the opportunity? Please write to Ruchika Garg at jobs@pluss.co.in."  

• The world's first grid-scale pumped heat energy storage is now in operation at Newcastle University. "The system consists of two containers – a cold store and a hot store – filled with gravel and an inert gas," Utility Week reports. "They are connected via a reversible heat pump/engine. When surplus energy needs to be stored, gas is withdrawn from the cold store and compressed using an electrically-powered pump, thereby raising its temperature. The gas is injected into the hot store where the heat is transferred to the gravel. It is then withdrawn from the hot store, expanded to further lower its temperature and returned to the cold store. To recover the stored energy, the process is reversed."

Dominic Hyde, vice president of Credo on Demand at Pelican BioThermal, said the rental program increased its temperature-controlled container fleet size by 90 and increased revenue by 90 percent in 2018.

Patent application: Air-permeable sponge composition with PCM

Ben Welter - Friday, January 11, 2019

U.S. patent application 20190010300 (applicant Xilinmen Furniture Co. Ltd., Zhejiang, China):

Xilinmen Furniture Co. patent drawing"An air-permeable sponge composition and a method for preparing an air-permeable sponge by using the same belong to the field of articles for daily use. An air-permeable sponge composition includes a sponge body and an air-permeable coating, and an outer surface layer of the sponge body being coated with the air-permeable coating. A method for making the air-permeable sponge utilizes the composition of the air-permeable sponge, wherein the air-permeable sponge is made from the air-permeable sponge composition under specific process parameters. The sponge body and air-permeable coating have the same or similar contents of isocyanate, polyether polyol and polymeric polyol and a similar porous structure. ... a phase change material is evenly distributed in the framework during the reactions to achieve a homogeneity."

http://www.freepatentsonline.com/20190010300.pdf

Patent application: Enclosure cooling for thermal management of unmanned aerial vehicles

Ben Welter - Friday, January 11, 2019

Qualcomm drone patent drawing

U.S. patent application 20190009878 (applicant Qualcomm Inc., San Diego, Calif.):

"Arrangements described herein relate to apparatuses, systems, and methods for a housing of an unmanned aerial vehicle (UAV), the housing includes but is not limited to a metallic porous material having a shape of an enclosure of the UAV, and a phase change material (PCM) provided in at least a portion of the metallic porous material. The metallic porous material and the PCM are configured to passively cool the UAV."

http://www.freepatentsonline.com/20190009878.pdf

Research roundup: Hydrophobic lauric acid; paraffin in heat exchanger; EnergyPlus vs. IES; more

Ben Welter - Thursday, January 10, 2019

From Journal of Energy Storage:

Preparation of hydrophobic lauric acid/SiO2 shape-stabilized phase change materials for thermal energy storage

From Applied Thermal Engineering:

Development of paraffin wax as phase change material based latent heat storage in heat exchanger

From Renewable Energy:

Characterization and stability study of a form-stable erythritol/expanded graphite composite phase change material for thermal energy storage

From Journal of Building Engineering:

Comparison of EnergyPlus and IES to model a complex university building using three scenarios: Free-floating, ideal air load system, and detailed

From 4th International Conference on Renewable Energies for Developing Countries :

Phase Change Materials in a Domestic Solar Hot Water Storage Tank of the Lebanese Market
Numerical and experimental investigations of a PCM integrated solar chimney
Integrating a High Solar Combi-Plus System using PCM Storage in a Smart Network: KSA Case Study

From International Journal of Advanced Research In Applied Sciences, Engineering and Technology:

Solar Cooker with Heat Storage System: A Review [pdf]

From Energy and Buildings:


From Solar Energy Materials and Solar Cells:

Bio-based poly (lactic acid)/high-density polyethylene blends as shape-stabilized phase change material for thermal energy storage applications

From Construction and Building Materials:

Microstructure-guided numerical simulation to evaluate the influence of phase change materials (PCMs) on the freeze-thaw response of concrete pavements

From Energy Conversion and Management:

Thermal management of Li-ion battery pack with the application of flexible form-stable composite phase change materials
Experimental investigation on cylindrically macro-encapsulated latent heat storage for space heating applications

From International Communications in Heat and Mass Transfer:

Experimental investigation on using a novel phase change material (PCM) in micro structure photovoltaic cooling system
Experimental investigation on a novel composite heat pipe with phase change materials coated on the adiabatic section

From Journal of Cleaner Production:

PCM briefing: Sunamp among 'Scottish tech companies to watch' in 2019; C-Therm webinar on new thermal conductivity instrument

Ben Welter - Monday, January 07, 2019

Rail shipping container with PCM

• The University of Birmingham's Center for Energy Storage has teamed up with a Chinese railway equipment manufacturer to develop a shipping container that uses phase change materials to maintain a low temperature over several days without a power supply. "Once ‘charged’, PCM inside the container - which can be transferred from train to truck and vice versa - can keep the inside temperature between 5-12 ˚C for up to 120 hours," the university reports.

CNET's Scott Stein takes a close look at PowerStation, "a battery of sorts that can keep a low-power sensor running off the temperature differences in everyday weather conditions." The device, made by Matrix Industries of Menlo Park, Calif., stores heat in a substance the company calls "Luna Phase Change Material" and later releases the heat in the form of electricity.

Scottish Business Insider has named Sunamp Ltd. one of five Scottish tech companies to watch in 2019. "The £2.2m raised in its latest fundraising sets the company up for a Series A round in 2019 as it looks to expand its international footprint and further scale its operations," Insider writes. "Sunamp heat batteries have so far been installed in over a thousand homes across the UK." 

C-Therm managing director Adam Harris is hosting a webinar this week to introduce the company's new thermal conductivity instrument, the C-Therm Trident. Advance registration is required for the webinar, which will be held at 1 p.m. EST Thursday, Jan. 10.

• At a business summit in Wisconsin last month, Encapsys President Mary Goggans said the Appleton-based company offers internships to students at regional colleges, including the children of employees. “The interns see the jobs and technologies they are interested in right here in the area,” Goggans said. “They realize they don’t need to get a job outside of the region to have the career they are looking for.”

PCM-equipped infant warming mat set for large-scale trial in Rwanda

Ben Welter - Monday, January 07, 2019

Dr. Anne HansenAn infant warming mat developed at Lawrence Berkeley National Laboratory in California is undergoing approval for a six-month trial at 10 hospitals in Rwanda beginning next fall. The DREAM infant warmer uses biobased phase change material to keep newborns warm in places where electricity is unavailable or unreliable. Dr. Anne Hansen, medical director of the neonatal intensive care unit at Boston Children's Hospital, helped develop the mat and is directing the trial. In an interview, she provided background on the device and explained how it works.

Q: Tell me about the need for this device. What problem does it solve?

A: In low- and middle-income countries, hypothermia is a contributing cause in about one million infant deaths per year. Newborn babies, especially babies who are low birth weight or preterm or both, tend to cool to the temperature of their environment. Therefore even in warm climates like that of sub-Saharan Africa, newborns can become dangerously cold. It's rare for hypothermia to be the primary cause of death, but hypothermia in newborns can contribute to respiratory problems, glucose regulation, immune system function, and most importantly growth, including brain growth, and therefore neuro-developmental outcome. This can perpetuate the cycle of poverty.

Q: Why is this a particular problem for babies born in lower-income countries?

A: Babies born in a rich country receive a heat chain that protects them all the way from the delivery room until they go home from the hospital. This includes electric warming tables and incubators. In poor countries, this heat chain is more difficult to ensure. The supply of electricity can be inconsistent at best, the expensive warmers and incubators may be unaffordable. If they can be acquired, the nurses may not have the training to work these complex medical devices, causing hypo- and hyperthermia, as well as raising infection control concerns given how hard they can be to clean between uses. Finally, unless the facility has advanced biomedical engineers to provide the maintenance and repairs, the warmers do not last long. Because of all these problems, ensuring that newborns in resource-limited settings have access to a consistent heat chain requires a lot of workarounds. 

The World Health Organization recommends skin-to-skin care, where you put a newborn directly on the mother's chest and she provides the external heat source. Skin-to-skin is great; we are total fans of skin-to-skin. The problem is that there are times where it's not very feasible, when the mother is sick or the mother dies in childbirth or if she has twins or triplets. If the baby is sick and requires medical assessment and treatments, the skin-to-skin positioning may not be feasible. Also, importantly, it's hard to be a human incubator for weeks to even months while a preterm baby gets old enough and mature enough to not need this external heat source. So providing heat by continuous skin-to-skin all day, all night for a long time, mothers just can't do that. They need to bathe, they may need to cook over a fire, or take care of their other children. So they have to stop; they put the baby down on a regular bed and then the baby gets cold. Finally, for the smallest babies, skin-to-skin may not provide enough heat; they're only getting heat from the part of their skin that is in direct contact with the mother's chest, but they aren't getting any heat from their backs.

We set out to design a warmer both to complement to skin-to-skin care when a mother wants to put her baby down, that could also be additive to skin-to-skin care when it is not providing enough heat. It needed to be electricity-free, inexpensive, intuitive to use, requiring minimal training, easily washed and reused with a goal of a thousand cycles.

Q: What was your role in the development of the device?

A: I've been working with Partners In Health (called Inshuti Mi Buzima in Rwanda) for almost 10 years. They work in very close collaboration with the Rwanda Ministry of Health. When I first went there in 2010, we helped them to develop and implement their national standards for newborn medicine. One of the problems that really stood out for me was that the options for thermoregulation were not working. When I came home, I partnered with Lawrence Berkeley National Lab to think about some other alternatives. We looked at a lot of ideas and ultimately settled on this phase change approach because it's so simple and straightforward.

DREAM warming mat thermosThe engineers did the actual design work, but we worked closely with them over many years to fine-tune it, figuring out how long it needed to be, how heavy it could be, how much people were willing to pay for it. From the outset we worked hand in glove with both Rwandan clinicians and the Ministry of Health. For example, the warmer is heated in thermos that holds boiling water to melt the PCM. The Ministry of Health was insistent that the thermos be wide-based and stable so that it wouldn't tip over when it was being filled with the boiling water and present any risk of burns.

We have completed two clinical studies of the warmer in Rwanda and it has performed extremely well. We are just gearing up to do what I hope will be a definitive large study with 10 hospitals in Rwanda this year. The Rwanda Ministry of Health has been amazing through all of this, supporting and facilitating all of our studies. We' want to have the warmer approved by the Rwandan Standards Bureau, which is like their FDA. They have also expressed interest in sponsoring the warmer for an international approval process, but we are going to wait on this until after we have the results from our large trial that we will be conducting later this year.

Q: Describe how the device functions.

DREAM warming mat packsA: We use your phase change material, PureTemp 37, configured as a set of 12 candles, each in its own plastic sleeve. The mat measures about 45.7 cm, by 25.4 cm, by 1.91 cm thick and contains about 1.2 kilograms of PCM. This arrangement allows the mat to be rolled up for charging or storage. Boiling water is used to charge the mat. All human civilizations know how to heat water, whether it is using a tea kettle with electricity or coal without. You heat 1.7 liters of water to boiling temperature, which provides the exact amount of energy needed to melt all the wax. The mat has a little temperature indicator that shows when it is cool enough to be safe to use. Once it has cooled, you dry it off and slip it in a little insulating pad. Then you put the baby, ideally naked, on the pad. This tends to be a population that does not have diapers, so a critical piece of the design was to avoid any fabric, Velcro or anything else that couldn't easily be cleaned with standard hospital cleanser. Ideally you give the baby a hat, and socks if you've got them, and then you wrap the baby and the warmer up in a blanket. The warmer stays hot for up to six hours, exactly at skin temperature.

Q: What's the projected price for a single unit?

A: Our goal is to keep it well under $100.

Q: Tell me about the upcoming study.

A: We're going to start this study in September of 2019 and it will run for six months. It's a complex study design called a step wedge study, specifically chosen to avoid the ethical conflict of having control patients such that one cold baby gets the warmer and another in the next bed does not. Instead, we will collect pre-data prior to introducing the warmer and this will serve as our control data. Then we will introduce the warmer, and use our post-data as our treatment data. Our hope is that we will find a reduction in hypothermia, hospital length of stay, and mortality, with improvement in growth. If so, then we we'll move to full-scale production, first for distribution across the rest of Rwanda and then in other appropriate countries in the sub-Saharan Africa.

Q: Where does the mat stand as far as approval processes in Africa?

A: We are still really at the prototype phase. We met this summer with a representative of the Rwandan Standards Bureau in Kigali. He said that, based on the results of our two preliminary pilot studies with 204 uses, it would be appropriate to for us to submit the paperwork for approval. We have not done that yet because they want to approve the absolutely final design, and we are still doing a bit more work, finding a more robust plastic and temperature indicator. Once we have our final design, we will submit the paperwork to the Rwandan Standards Bureau, sponsored by the Ministry of Health. Based on our feedback from this summer's meeting I am optimistic that they will approve it.

Rwandan twins on warming mat

Q: What's been the most satisfying part of this project for you?

A: That is the easiest question. It is absolutely 100 percent the mothers. I will never forget the very first patients that we enrolled, a pair of twins. When we walked into the hospital that very first day, we had just explained to the nurses how to prepare the warmer, we were ready to enroll our first patients, and there was this mother with these twins. She looked so tired, not smiling or really interacting. Through a translator I asked her if she would like to have her babies enrolled in this study. She learned what it was, and signed the consent form.

One of the babies was so cold that we did the combination of the skin-to-skin and warmer across the back, and the other baby went straight on the warmer. She looked at the babies and she saw them getting warm. She just had this unbelievable look of relief - she was so happy. She said, "This is the first time that I've seen my babies look comfortable since they were born."