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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.




Agenda set for 5th Swiss Symposium Thermal Energy Storage

Ben Welter - Monday, November 20, 2017

The 5th Swiss Symposium Thermal Energy Storage will be held at the Lucerne University of Applied Sciences and Arts on Jan. 26, 2018.

This year's symposium will focus on the importance of energy storage in energy systems and industrial processes; the economic aspects of thermal storage; and recent findings about new storage materials. Eleven presentations, all in English, are scheduled:

• "Macro-encapsulated Phase Change Materials for Thermal Energy Storage," Dieter Brüggemann, University of Bayreuth, Germany

• "Fast Loadable Phase Change Heat Storages for Multiple Applications," Sven Kunkel, Matthias Rädle, University of Applied Science Mannheim, Germany

• "Future Directions in Thermal Energy Storage Systems and Applications," Ibrahim Dinçer, University of Ontario Institute of Technology, Ontario, Canada 

• "Applying PCM Beyond the Building Sector," Esther Kieseritzky, Rubitherm Technologies GmbH, Germany

• "Thermal Recuperation with CrodaTherm PCM Using Axiotherm Heat Storage Technology," Yvonne Reimann, Croda GmbH, Germany; Dirk Büttner, Axiotherm GmbH, Germany

• "Integration of Variable Renewable Energy in Switzerland – Implications for Storage Technologies and System Flexibility," Tom Kober, Paul Scherrer Institute, Switzerland

• "Thermal Heat and Renewable Energy Integration in the Industry," François Maréchal, École polytechnique fédérale de Lausanne, Switzerland

• "Experimental and Numerical Investigation of Horizontal Packed Bed Thermal Energy Storages," Marco Prenzel, Vladimir Danov, Siemens AG, Germany

• "Seasonal Heat Storage, the Underestimated Pillar of our Future Energy System, Examples of Realized Projects," Stefan Brändle, Simon Büttgenbach, Amstein + Walthert AG, Switzerland 

• "Large Thermal Energy Storage for Large Cities – A New Dimension," Hannes Poier, TU Graz / S.O.L.I.D. Gesellschaft für Solarinstallation und Design GmbH, Austria

• "Ecological Comparison of Thermal and Electrical Storages for Load Shifting in PV and Heat Pump Systems," Michel Haller, Hochschule für Technik Rapperswil, Switzerland

The registration fee is 300 Swiss francs. Lunch is included. To register, visit

PCM briefing: Active vs. passive shipping solutions; registration open for Energy Innovation Summit

Ben Welter - Monday, November 20, 2017

• Registration is open for "Active vs. Passive Solutions: Which one is for me?" the next webinar in Sonoco ThermoSafe's temperature assurance packaging series. Ben Vanderplas, global product manager at Sonoco ThermoSafe, and David Bang, CEO of DHL LifeConEx, will lead the one-hour class, to be held Dec. 12.

Brooklyn Bedding's new Aurora mattress collection features TitanCool technology, "a phase change surface infusion" with "high conductivity properties."

• New from Transparency Market Research: "Thermal Management Technologies Market - Global Industry Analysis, Size, Share, Growth, Trends, and Forecast 2017 - 2027"

The UV-activated thermal energy storage material shows the rapid crystallization and heat discharge upon visible light (blue LED) illumination. (Grossman Group at MIT)MIT researchers have combined conventional phase change material with an organic compound that responds to a pulse of light. "The new system," MIT News reports, "uses molecular switches that change shape in response to light; when integrated into the PCM, the phase-change temperature of the hybrid material can be adjusted with light, allowing the thermal energy of the phase change to be maintained even well below the melting point of the original material." The system could be used in a thermal battery to store heat from the sun or any other source and release the heat when needed.

• Registration for the 2018 ARPA-E Energy Innovation Summit is open. The event, to be held March 13-15 at the Gaylord Convention Center, outside Washington, D.C., showcases emerging energy technologies. No agenda yet.

• Researchers at the University of Maryland College Park have developed a method of fabricating fibers with boron nitride and polyvinyl alcohol using 3D print technologies which allows heat to be transferred away from the body.  Clothes made with the nanocomposite thread could help keep wearers cool in hot conditions.

Stanford University researchers have developed a reversible fabric that keeps skin a comfortable temperature whatever the weather. "On one side," Stanford News reports, "a copper coating traps heat between a polyethylene layer and the skin; on the other, a carbon coating releases heat under another layer of polyethylene." The fabric can either warm or cool the wearer, depending which side faces out.

PCM briefing: Registration open for PCM 2018 in Quebec; MIT finds new way to mix oil, water

Ben Welter - Friday, November 10, 2017

• Registration is open for PCM 2018, the 12th IIR Conference on Phase Change Materials and Slurries for Refrigeration and Air Conditioning. The conference will be held May 21-23, 2018, in Orford, Québec. Topics will include thermal energy storage; thermophysical and rheological properties of PCMs and slurries; and transport phenomena and time-dependent behavior of PCMs and slurries.

MIT researchers have developed a new way to mix oil and water and create an emulsion that remains stable for long periods — no shaking required.

• Registration is open for "Towards a Sustainable Solution to Melt Snow and Ice on Concrete Pavement: Use of Phase Change Materials, a presentation by Dr. Yaghoob Farnam, an assistant professor in the Department of Civil, Architectural and Environmental Engineering at Drexel University. Farnam will discuss his research on the use of PCM-enhanced concrete to inhibit the buildup of snow and ice on pavement. The program will be held Nov. 30 in King of Prussia, Penn.

• "Innovative Thoughts" blogger Harvey Wade visited the 3M Customer Innovation Centre in Bracknell, U.K., last month to find out how the big company sustains its innovative edge. Lesson No. 1: 3M listens to its customers. "They don’t guess what the customer needs," Wade writes, "they invest their time to know their needs, discovering the big problems that they can try to solve." 

BMW PCM Ride jacketBMW's 2018 Motorrad collection includes the latest version of the PCM Ride jacket, featuring microencapsulated phase change material that "adapts permanently and smartly to the current temperature."

Peli BioThermal has opened a service center in Brussels, Belgium, to handle its Credo line of reusable temperature-controlled packaging. 

Ember Technologies' newest temperature-control product, a $79 ceramic mug with an active heating system, contains no phase change material. The company's first product, a PCM-lined travel tumbler, sells for $150.

Grace Hsia, founder and CEO of Warmilu, a Michigan startup that makes an infant warming blanket, talks about the stresses and rewards of building a company from scratch. "I find my body will sometimes crash," Hsia told Crain's Detroit Business, explaining how 90-hour workweeks have led to bouts of pneumonia and bronchitis. "I've been trying to get more sleep, which is tough."

The preliminary program has been released for the fifth Building Enclosure Science & Technology conference, known as BEST5. It will take place April 15-18 in Philadelphia. 

• The American Chemical Society has won its lawsuit against Sci-Hub, a widely used pirate site for scientific papers that was established in 2011 by former neuroscientist Alexandra Elbakyan.

• New from Intellectual Research Partners: "Global Thermal Energy Storage (TES) systems Market By Technology (Molten salt, Phase change materials, Water based, Electric thermal and Solar) End User Application (Air Conditioning, Cold Storage, Power Storage, Process Cooling) Region (North America, Europe, APAC) Forecast To 2023"

PCM mats will be put to the test in 'tiny house' at Colorado School of Mines

Ben Welter - Friday, November 10, 2017

The effectiveness of bio-based phase change material is being tested in a 200-square-foot “tiny house” under construction at the Colorado School of Mines in Golden, Colo.

Katie Schneider, Colorado School of MinesKatie Schneider, a junior majoring in engineering physics, is chairing the two-year student project, which is scheduled for completion in May 2018.

Though its interior is incomplete, the Mines Tiny House was exhibited at last month’s Solar Decathlon in Denver. Schneider said the project attracted interest from representatives of the energy and sustainability industry, as well as from other schools that might want to partner with the School of Mines for the next Solar Decathlon in 2020.

“It was a great experience for us to interact with others interested in what we're doing,” Schneider said, “and we got plenty of good ideas from the competitors as well.” 

Entries in the Solar Decathlon, sponsored by the U.S. Department of Energy, are judged on energy efficiency, design, affordability and consumer appeal.

The University of Nevada-Las Vegas, one of 11 teams in this year’s decathlon, used a PCM product in the ceiling of its entry, a 990-square-foot home that won first place in the innovation category. Ecole Polytechnique of Lausanne, Switzerland, was the overall winner.

The School of Mines team is installing ENRG Blankets donated by Phase Change Energy Solutions of Asheboro, N.C. The multi-layer polymer mats, shown above, contain plant-based PCM with a melt-freeze transition temperature of 23º C (73º F). The mats are designed to absorb, store and release energy to help keep living spaces at comfortable temperatures and reduce energy costs.

"We plan to put the PCMs in the ceiling first, between the insulation and our ceiling paneling," Schneider said. "We want to take temperature measurements with and without the PCMs to really test their effectiveness. Then we will possibly put them in the walls, especially near the wheel wells of the trailer because that is a vulnerable point of heat loss for the tiny house."

Research roundup: Cascaded cold storage unit with multiple PCMs; evolution of global heat transfer coefficient; more

Ben Welter - Tuesday, November 07, 2017

Evolution of global heat transfer coefficient on PCM energy storage cycles [Energy Procedia]

Thermal performance analysis of a cascaded cold storage unit using multiple PCMs [Energy]

An experimental investigation of discharge/solidification cycle of paraffin in novel shell and tube with longitudinal fins based latent heat storage system [Energy Conversion and Management]

An alternative approach for assessing the benefit of phase change materials in solar domestic hot water systems [Solar Energy]

Organic-inorganic hybrid shell microencapsulated phase change materials prepared from SiO2/TiC-stabilized pickering emulsion polymerization [Solar Energy Materials and Solar Cells]

Preparation of phase change material emulsions with good stability and little supercooling by using a mixed polymeric emulsifier for thermal energy storage [Solar Energy Materials and Solar Cells]

Optimal design of PCM thermal storage tank and its application for winter available open-air swimming pool [Applied Energy]

Research roundup: Biocatalysts combined to make new PCMs; tankless solar heating system; dual PCM gypsum board; more

Ben Welter - Thursday, November 02, 2017

Combining biocatalysts to achieve new phase change materials. Application to non-edible animal fat [Molecular Catalysis]

Performance evaluation of dual phase change material gypsum board for the reduction of temperature swings in a building prototype in composite climate [Energy and Buildings]

Study on a tankless solar heating system using phase-change material plaster [Building and Environment]

Performance Enhancement of a Building-Integrated Photovoltaic Module Using Phase Change Material [Energy]

Low cracking ratio of paraffin microcapsules shelled by hydroxyl terminated polydimethylsiloxane modified melamine-formaldehyde resin [Colloids and Surfaces A: Physicochemical and Engineering Aspects]

Numerical and experimental research of cold storage for a novel expanded perlite-based shape-stabilized phase change material wallboard used in building [Energy Conversion and Management]

Comparative study in the identification of liquid to solid transition phase with DSC, Raman spectra analysis and chemiometrics methods applied to phase change materials used for icing-delay in civil engineering infrastructures [Applied Thermal Engineering]

Thickness Determination of a Three-layer Wall with Phase Change Materials in a Chinese Solar Greenhouse [Procedia Engineering]

Experimental Study on Thermal Performance Improvement of Building Envelopes Integrated with Phase Change Materials in an Air-conditioned Room [Procedia Engineering]

Phase Change Humidity Control Material and its Application in Buildings [Procedia Engineering]

Hybrid sensible-latent heat storage concept achieves high energy densities

Ben Welter - Tuesday, October 31, 2017

Christoph Zauner of AITChistoph Zauner, a research scientist at the Austrian Institute of Technology, has been investigating the use of phase change material for a variety of applications since 2010. His most recent papers include “Experimental characterization and simulation of a hybrid sensible-latent heat storage,” published earlier this year in Applied Energy. He discussed his work in an email interview. 

Q: How did you first become interested in phase change material?

A: I worked for quite some time in the field of solar thermal energy and was especially focusing on industrial application with non-standard solar collector, so-called medium temperature collectors. This more efficient class of collectors (concentrating and non-concentrating) can produce temperature up to 250° C heating pressurized water, oil and generate steam. In order to achieve high solar fractions (i.e. cover much more than 10% of the total required process energy by solar energy), one needs to store energy. Standard storages (steam, oil, water) have limitations and latent storage certain advantages. Thus, we started developing such storages. In the meantime, we want to use it for a much broader range of applications (not only solar thermal).

Q: Describe the hybrid sensible-latent heat storage concept you have been working on.

Inverted shell and tube heat exchanger

A: In our new concept, we place the PCM inside the tubes of a modified shell-and-tube heat exchanger [shown above]. This is in contrast to the well-known approach of placing it outside. On the shell side we use a heat transfer fluid (in our first prototype we used oil) which at the same time serves as a sensible storage medium. Thus, we achieve a hybrid sensible-latent heat storage, which offers several opportunities:

• Heat transfer fluid (in our case oil) and PCM fractions can be varied over a wide range, i.e. a hybrid sensible-latent heat storage is realized. Advantages of both domains can be exploited, such as high energy density of the PCM and high power density of sensible storages

• Fewer weld seams as for the standard concept (PCM outside many small tubes) leads to storage cost reduction

• Larger heat transfer area between tubes and PCM enables higher storage power

• Our tubes serve as a macroencapsulation of the PCM, which serves as protection and increases storage lifetime.

Q: Is HDPE in use as a PCM in any commercialized application?

A: HDPE is a so-called commodity plastics. It is the kind of polymer used most out of all polymers. As such it is produced in a multi-million-ton scale each year. Also a versatile recycling industry is in place, which allows for further cost reduction potential (we know which types are suitable and which ones are not). Usually HDPE is used to contain PCMs only. There are no commercial applications yet, where HDPE is used as PCM. Currently we are investigating various possible applications.

Q: How do you anticipate the viscosity of the PCM affecting the thermal modeling? At what point does this significantly contribute to the internal convection in the tube?

A: Convection plays a minor role for our HDPE grade. This may be somewhat different for other grades and was analyzed in our lab. Our models can be adapted to incorporate convection, too. If necessary, we also have 3d-CFD models available.

AIT test tank
A 40 kWh, 100 kW peak power hybrid latent-sensible storage system was successfully tested at AIT labs at temperatures up to 200 °C.
Q: Beyond manufacturing costs, what are the benefits of the inverted shell-and-tube in comparison to other geometries such as a packed bed?

A: Apart from the advantages mentioned above, there is one particular key advantage over packed beds: packing density. Our storage can achieve up to 90% PCM volume density, whereas the theoretical limit for ideally packed spheres is 74%. In a packed bed, however, one does not have “ideal packing,” but the situation of “random packing,” where PCM volume fractions of 64% are achieved.

We found a certain way, which we do not disclose, how to actually fill up the whole tubes even for the crystallized (shrinked) PCM. Usually, PCM macroencapsulations are filled up to 100% only in the molten state, which further reduces the final volume PCM fraction of the whole storage (i.e. kWh/m3).

So summing up: We achieve much higher energy densities. 

Q: How was the DSC data implemented into the thermal modeling?

A: Actual measurement data can be easily implemented in our Dymola model. We use different approaches for the two models described in the paper (Stefan-model, cp(T)-model).

However, it is important to emphasize that one has to perform the DSC measurement “in the correct way.” This means one has to use the correct DSC parameter sets. By comparing the data obtained from different DSC settings to experimental storage data, we found out that very often DSC measurements are done in the wrong way. Wrong DSC settings lead to incorrect material values (especially melting temperature, sub-cooling and phase change enthalpy). However, we know now how to do it correctly and implemented the corresponding curves in the models.
Q: Would a sharper phase change peak be advantageous to the proposed application? How would this also affect the Stefan model?
A: We already designed storages for different applications (various combinations of low/high power, low/high capacity, different temperature levels). Sometimes it is very important to actually have a PCM with a sharp peak and sometimes even large subcooling doesn’t matter. It depends on the application.

Of course, one has to be careful by applying the various models (not only the Stefan model) and not to spoil the underlying assumptions. We learned a lot in that direction by comparing experimental storage data to simulations and know now very well where the limits are.
Q: What are the next steps in your investigation of this storage concept for district heating networks and industrial processes? How close is it to possible commercialization?

A: It is important to emphasize that AIT is not a university, but more like a real company which has to do “real business” and earn “real money.” We do business in various ways and offer different business models.

This ranges from material characterization or simulations directly done (and paid) by customers. We also offer storage engineering using our models and experimental know-how to storage manufacturers. We also demonstrate storages at real demo sites (currently we have projects in polymer extrusion and aluminum die casting) and evaluate their potential in various companies (e.g. we are currently investing a specific process in steel industry using a PCM-steam-storage concept).

We can provide various services or even serve as a “one-stop-shop” for energy optimization of industrial processes using storages. This starts from analyzing the process in detail (incl. monitoring), designing the storage (including integration), organization of storage manufacturing, integration at the plant and commissioning. Also this includes financing aspects (contracting, subsidies, R&D projects etc.).

The storages are permanently optimized but can be bought right away as we are only using industrially available PCMs (we also tested [PureTemp PCMs] and might use them, of course) and heat exchanger/storage manufacturing techniques.

Q: What other projects are you working on that might be of interest to the PCM community?

A: We also work on “overheating solutions” using PCM. Some articles have been published in that direction already, including “High temperature phase change materials for the overheating protection of facade integrated solar thermal collectors.” Also, we employ PCMs in car batteries and developed concepts there. We simulated and tested various prototypes of real batteries.

A related topic is development of new insulations, especially aerogel-based. This is very much needed for storages and also for energy efficiency in industries (“stop wasting energy first, then re-use it!”). 

[For more examples, see]

We are very much looking for partners for new PCMs. We do not produce them on our own. However, we do some development with partners on organic PCMs.

Research roundup: Metal corrosion rate assessment; industrial heat storage; erythritol, glycerol and olive oil; more

Ben Welter - Monday, October 30, 2017

A Review of Phase Change Materials as an Alternative for Solar Thermal Energy Storage [Materials Today]

Step by Step Methodology for the Assessment of Metal Corrosion Rate with PCMs Suitable for Low Temperature Heat Storage Applications [Materials Today]

Investigation of the effect on the efficiency of phase change material placed in solar collector tank [Thermal Science and Engineering Progress]

Generalized diagrams of energy storage efficiency for latent heat thermal storage system in concentrated solar power plant [Applied Thermal Engineering]

Thermal energy storage with phase change materials to increase the efficiency of solar photovoltaic modules [Energy Procedia]

Development of industrial PCM heat storage lab prototype [Energy Procedia]

High Power Latent Heat Storages With 3D Wire Structures – Numerical Evaluation Of Phase Change Behavior [Energy Procedia]

Experimental comparison of two heat exchanger concepts for latent heat storage applications [Energy Procedia]

Erythritol, glycerol, their blends, and olive oil, as sustainable phase change materials [Energy Procedia]

PCM briefing: Thermal storage capacity on the rise; clinical trial for prosthetics liner

Ben Welter - Friday, October 27, 2017

• Thermal energy storage exceeds the capacity of battery storage now in operation, according to a new report from the International Renewable Energy Agency. Greentech Media reports that a recent resurgence in concentrated solar power development promises to increase that advantage.

• New from QYResearch Group: "Global Thermal Energy Storage Market Size, Status and Forecast 2022"

• New from Persistence Market Research: "Advanced Phase Change Material (PCM) Market - Global Industry Analysis and Forecast to 2020"

Alpha SmartTemp liner• The effectiveness of a PCM-infused prosthetics liner made by Ohio Willow Wood Co. will be put to the test in a two-year clinical trial. The liner is designed to absorb heat and reduce sweating where a prosthesis meets skin. The study, funded by a $140,000 Department of Defense grant, will be conducted by the University of Pittsburgh and Widener University.

• Registration is open for "2-8°C Solutions: Design variables and constraints," the next webinar in Sonoco ThermoSafe's temperature assurance packaging series. Frank Butch, director of engineering at Sonoco ThermoSafe, and Lisa Barbieri Moher, North American head of distribution packaging and graphics at Sanofi, will lead the one-hour class, to be held Nov. 14.

Sonoco ThermoSafe's development of the LD7 Quarter PMC pallet shipper won first place for Excellence in Collaboration at the Cold Chain GDP & Temperature Management Global Forum in Chicago last month. ThermoSafe's ChillTech reusable PCM system was runner-up in the Excellence in Technological Innovation category.

In a recent interview with Innovation in Textiles, CEO Dirk Van Hyning of PCM-maker Alexium International discussed U.S. efforts to curb the use of halogenated flame retardants.

Research roundup: TES in Toronto high-rises; rotary desiccant cooling systems; natural convection characterization; more

Ben Welter - Tuesday, October 24, 2017

Experimental investigation of latent thermal energy storage in high-rise residential buildings in Toronto [Energy Procedia]

Study on the Performance of Heat Storage and Heat Release of Water Storage Tank with PCMs [Energy and Buildings]

Design of effective fins for fast PCM melting and solidification in shell-and-tube latent heat thermal energy storage through topology optimization [Applied Energy]

Integrating photovoltaic thermal collectors and thermal energy storage systems using phase change materials with rotary desiccant cooling systems [Sustainable Cities and Society]

Development of thermal energy storage cementitious composites (TESC) containing a novel paraffin/hydrophobic expanded perlite composite phase change material [Solar Energy]

Experimental analysis of solar photovoltaic unit integrated with free cool thermal energy storage system [Solar Energy]

Natural convection characterization during melting of phase change materials: Development of a simplified front tracking method [Solar Energy]

Thermal behavior of latent thermal energy storage unit using two phase change materials: Effects of HTF inlet temperature [Case Studies in Thermal Engineering]

Experimental Investigation of a New Passive Thermal Management System for a Li-Ion Battery Pack Using Phase Change Composite Material [Electrochimica Acta]