Phase Change Matters RSS


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.




Research roundup: Direct steam generation solar plants; d-mannitol-copper oxide nanocomposites; modified carbon nanotubes; more

Ben Welter - Wednesday, December 06, 2017

Thermal energy storage evaluation in direct steam generation solar plants [Solar Energy]

Potential of cascaded phase change materials in enhancing the performance of solar domestic hot water systems [Solar Energy]

Study of thermo-physical properties and cycling stability of d-Mannitol-copper oxide nanocomposites as phase change materials [Journal of Energy Storage]

Properties Enhancement of Phase-change Materials via Silica and Al Honeycomb Panels for the Thermal Management of LiFeO4 Batteries [Applied Thermal Engineering]

Experimental Investigation and Mathematical Modelling of Thermal Performance Characteristics of Textiles Incorporating Phase Change Materials [Environmental Engineering, 10th International Conference]

Thermal storage of solar energy [Physical Rendering]

Studies on the inward spherical solidification of a phase change material dispersed with macro particles [Journal of Energy Storage]

Review of latent heat thermal energy storage for improved material stability and effective load management [Journal of Energy Storage]

The effects of modified carbon nanotubes on the thermal properties of erythritol as phase change materials [Energy Conversion and Management]

Experimental study on the cooling charge and discharge characteristics of a PCM based fin-tube thermal energy storage exchanger [Procedia Engineering]

Energy Saving Potential of PCMs in Buildings under Future Climate Conditions [pdf] [Applied Sciences]

Experimental study of carbon fiber reinforced alkali-activated slag composites with micro-encapsulated PCM for energy storage [Construction and Building Materials]

Research roundup: Axisymmetric lattice Boltzmann model; slurry flow in heated helical coils; sebacic acid/CNT sponge PCM; more

Ben Welter - Monday, November 27, 2017

Optimized demand side management (DSM) of peak electricity demand by coupling low temperature thermal energy storage (TES) and solar PV [Applied Energy]

Investigation of solid-liquid phase change in the spherical capsule using axisymmetric lattice Boltzmann model [International Journal of Heat and Mass Transfer]

Thermodynamic assessment of binary erythritol-xylitol phase diagram for phase change materials design [Calphad]

Thermal Properties Optimization of Microencapsulated a Renewable and Non-toxic Phase Change Material with a Polystyrene Shell for Thermal Energy Storage Systems [Applied Thermal Engineering]

Heat transfer analysis of microencapsulated phase change material slurry flow in heated helical coils: A numerical and analytical study [International Journal of Heat and Mass Transfer]

Experimental test bed design and development for PCM-water exchangers characterization [Sustainable Cities and Societies]

Synthesis of novel phase change material microcapsule and its application [Polymer]

Sebacic acid/CNT sponge phase change material with excellent thermal conductivity and photo-thermal performance [Solar Energy Materials and Solar Cells]

Research roundup: Direct evaporative cooling unit; diatomite-stabilized paraffin; hyperbranched polyurethane; more

Ben Welter - Tuesday, November 21, 2017

Enhancement in free cooling potential through PCM based storage system integrated with Direct Evaporative Cooling (DEC) unit [Energy]

A Numerical Study on Phase Change Inside a Spherical Capsule [Exergetic, Energetic and Environmental Dimensions]

Performance of a thermal energy storage composite by incorporating diatomite stabilized paraffin as phase change material [Energy and Buildings]

Phase Change Materials for Application in Energy-Efficient Buildings [Cost-Effective Energy Efficient Building Retrofitting]

Thermal energy storage using poly(ethylene glycol) (PEG) incorporated hyperbranched polyurethane as solid-solid phase change material (PCM) [Industrial & Engineering Chemistry Research]

Comparative Research on Solar Phase Change Material Storage Wall Systems under Different Summer Working Conditions [Energies]

The Application of Carbon Materials in Latent Heat Thermal Energy Storage (LHTES) [Thermal Transport in Carbon-Based Nanomaterials]

H2O2-microwave treated graphite stabilized stearic acid as a composite phase change material for thermal energy storage [Royal Society of Chemistry]

Sodium acetate–urea composite phase change material used in building envelopes for thermal insulation [Building Services Engineering Research & Technology]

Integration of Pore Confinement and Hydrogen-Bond Influence on the Crystallization Behavior of C18 PCMs in Mesoporous Silica for Form-Stable Phase Change Materials [Sustainable Chemistry & Engineering]

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.

Patent application: Forced air thermal energy storage system

Ben Welter - Thursday, November 09, 2017

U.S. patent application 20170321912 (applicant Viking Cold Solutions Inc., Houston, Texas):

Viking Cold Solutions patent drawing"A system including a chilled air generation system, a forced air convection system, one or more phase change material (PCM) modules, and a controller. The controller is configured to regulate the temperature of a facility by selectively utilizing the chilled air generation system and the forced air convection system based on multiple factors, which may include energy source type(s), relative costs of the energy from the source(s), availability of energy from the source(s), facility temperature, PCM module temperature, and/or temperature of goods stored within the facility, among other considerations. The controller may thus advantageously and cost-effectively control the periods of time during which the chilled air generation system is used and those during which the thermal energy stored in the PCM modules is used."

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]