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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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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."

http://www.freepatentsonline.com/20170321912.pdf

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 www.ait.ac.at/en/research-fields/sustainable-thermal-energy-systems/projects/storeitup-if.]

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]

Research roundup: Carbon-based nanoenhanced PCM; copper-powder-sintered frame/paraffin form stable PCM; thermoelectric harvester; more

Ben Welter - Monday, October 23, 2017

From Renewable and Sustainable Energy Reviews:

Experimental set-up for testing active and passive systems for energy savings in buildings – Lessons learnt
Review on thermal conductivity enhancement, thermal properties and applications of phase change materials in thermal energy storage

From Journal of Energy Storage:

Preparation and thermal performance of methyl palmitate and lauric acid eutectic mixture as phase change material (PCM)

From Applied Thermal Engineering:

A novel heat transfer model of a phase change material using in solar power plant

From Energy Procedia:

Experimental investigation of flow rate impact on thermal accumulation system with PCM

From Energy Conversion and Management:

Experimental and numerical investigation on the performance of carbon-based nanoenhanced phase change materials for thermal management applications

From International Journal of Thermal Sciences:

Thermal management of lithium ion batteries using graphene coated nickel foam saturated with phase change materials 

From Applied Energy:

Preparation of novel copper-powder-sintered frame/paraffin form-stable phase change materials with extremely high thermal conductivity
Experimental investigations of charging/melting cycles of paraffin in a novel shell and tube with longitudinal fins based heat storage design solution for domestic and industrial applications
A novel thermoelectric harvester based on high-performance phase change material for space application

From Sustainable Cities and Society:

Experimental Investigation of Phase Change Materials for Insulation of Residential Buildings
A comparison of battery and phase change coolth storage in a PV cooling system under different climates

PCM briefing: SaltX Technology wins Swedish prize; Axiom has opening for field engineer

Ben Welter - Monday, October 23, 2017

• SaltX Technology has been awarded Sweden's E-Prize, presented by European energy company E.ON and Swedish business magazine Veckans Affärer. SaltX won the category “Renewable Energy” as well as the “People’s Award.” SaltX's nano-coated salt energy storage technology is used in EnerStore, the company's large-scale energy storage system for heat and power generation.

Brooks Danahy, a senior majoring in chemical engineering, is one of 13 University of Kansas students to receive a $1,000 Undergraduate Research Award. His project: "Characterization of Melting Point Depression and Phase Change Behavior in Ionic Liquid + Compressed Gas Systems.”

• California startup Axiom Exergy, maker of a "Refrigeration Battery" designed to reduce supermarket energy costs, has posted an opening for a field engineer

• Registration is open for a SpecialChem online course, "Essential Concepts for Optimal Compounding," to be held on Nov. 2. The cost for three attendees on one connection is 300 euros.

The Atlantic's Derek Thompson got a virtual peek inside X, the secretive lab where Google's parent company is researching advanced technology. Current projects include salt-based thermal storage, which X believes could become the cheapest grid-scale storage technology in the world. 

• A ceramic-based mechanical pump developed at Georgia Tech is able to operate at record temperatures of more than 1,400º Celsius, expanding the range of materials that can be used in high-temperature thermal storage systems. “The hotter we can operate, the more efficiently we can store and utilize thermal energy," said Asegun Henry, an assistant professor in Georgia Tech’s Woodruff School of Mechanical Engineering. "This work will provide a step change in the infrastructure because now we can use some of the highest-temperature materials to transfer heat. These materials are also the hardest materials on Earth.” 

Schneider Electric of Andover, Mass., says augmented reality and mixed reality training regimens will become increasingly important at chemical plants as advances occur in both hardware and software. 

PCM briefing: Energy storage tax incentive advances in U.S. Senate; how to make your startup pitch shine

Ben Welter - Monday, October 09, 2017

• A bill that would create a tax credit for the purchase of energy storage systems, including thermal systems, is advancing in the U.S. Senate. The bill, known as the Energy Storage Tax Incentive and Deployment Act of 2017, is sponsored by Sen. Martin Heinrich (D-N.M.).  The bill was first floated last year and gained support from both Democrat and Republican senators, Energy Storage News reports.

Bloomberg BNA News reports that states could soon respond quicker to chemical accidents armed with information on file at the Environmental Protection Agency has. But first, they’ll have to prove they can protect chemical manufacturers' trade secrets.

• Looking to pitch your next big idea? David Beckett, an Amsterdam-based Brit who has coach more than 500 startups, has a few tips for you. No. 1: Memorize the first 60 seconds of your pitch. That'll keep you on track until that mind-numbing adrenaline wears off.  

Simba Hybrid pillow• The Simba Hybrid, the latest high-tech pillow to feature Outlast phase change material, hit stores last week. The price tag: $125. 

• Bedding foam producers are stepping up their research-and-development efforts and rolling out PU foams with improved performance, BedTimes Magazine reports. Temperature regulation remains among the most sought-after features among consumers, according to research conducted by FXI, a PU foam specialist based in Media, Penn.

Peli BioThermal has announced the expansion of its European manufacturing capabilities in France to produce CoolPall Vertos, the cold chain company's single-use bulk thermal shipper. 

• U.K.-based Softbox Systems has launched AEON, a line of reusable temperature-control parcel shippers that feature vacuum insulation panels and phase-change modules. Initially, AEON will be sold in three payload sizes for 2º C to 8º C temperature control. Other temperature ranges (15⁰ C to 25⁰ C and -20⁰ C) will be launched in December.