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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: Dynamic behavior of PCM-27; Al2O3, SiO2 and TiO2 nano-inclusions; coacervation microencapsulation; more

Ben Welter - Tuesday, August 14, 2018

From International Journal of Thermal Sciences:

An experimental and a numerical analysis of the dynamic behavior of PCM-27 included inside a vertical enclosure: Application in space heating purposes

From Journal of Molecular Liquids:

Thermal conductivity enhancement in organic phase change material (phenol-water system) upon addition of Al2O3, SiO2 and TiO2 nano-inclusions

From Applied Thermal Engineering:

Experimental and numerical investigations of nano-additives enhanced paraffin in a shell-and-tube heat exchanger: A comparative study
Three-dimensional numerical and experimental investigation of the behavior of solar salts within thermal storage devices during phase change

From Energy Conversion and Management:

Formulation of a model predictive control algorithm to enhance the performance of a latent heat solar thermal system
Performance assessment of a new hydrogen cooled prismatic battery pack arrangement for hydrogen hybrid electric vehicles

From Carbohydrate Polymers:

Chitosan composite microencapsulated comb-like polymeric phase change material via coacervation microencapsulation

From Renewable Energy:

Analytical Considerations on Optimization of Cascaded Heat Transfer Process for Thermal Storage System with Principles of Thermodynamics

From Proceedings of Microscopy & Microanalysis 2018:

In-Situ TEM Observation of Crystallization in Phase-Change Material

From International Journal of Energy Research:

Research roundup: Humidity control material; solar water heaters; nanomaterials; flow-through wall elements; more

Ben Welter - Monday, July 09, 2018

From Energy and Buildings:

A Review on Enhancement of Phase Change Materials - A Nanomaterials Perspective
Phase change humidity control material and its impact on building energy consumption

From Solar Energy:

Optimization of melting and solidification processes of PCM: Application to integrated collector storage solar water heaters

From Applied Thermal Engineering:

Experimental Investigation on the Heat Transfer Enhancement in a Novel Latent Heat Thermal Storage Equipment
Recent advancements on thermal management and evaluation for data centers
Heat Transfer Characteristics of an Expanded Graphite/Paraffin PCM-Heat Exchanger used in an Instantaneous Heat Pump Water Heater

From Thermal Science and Engineering Progress:

Numerical simulation of the melting of a NePCM due to a heated thin plate with different positions in a square enclosure

From Journal of Building Engineering:

Numerical study of flow-through wall elements with phase–change materials

From Journal of Energy Storage:

Exploratory investigation of a new thermal energy storage system with different phase change materials having distinct melting temperatures

From Renewable Energy:

Optimization assessment of the energy performance of a BIPV/T-PCM system using Genetic Algorithms

From Sustainable Cities and Society:

Coupled cooling method and application of latent heat thermal energy storage combined with pre-cooling of envelope: Temperature control using phase-change chair

Solar-powered concept camper uses PCM to keep passengers comfortable

Ben Welter - Monday, July 02, 2018

Dethleffs' e.home concept camperDethleffs GmbH & Co.'s solar-powered concept camper, introduced last year, is one of four winners in the transportation category of the German Innovation Award 2018. The "e.home" features 334 square feet of thin solar panels and a heating system that uses phase change materials to absorb heat when the outside temperature rises above 79° F. Fully equipped, its driving range on a full charge is just over 100 miles.

Christoph Gawalleck, technical director at Dethleffs, oversaw the two-year development of the e-home. He answered a few question via email:

Q: Describe the phase change material used in the vehicle.

A: “The PCM is Micronal from BASF. But BASF sold this business unit to Microtek Laboratories in May 2017. It is a paraffin. The melting point is 26°C, the solidification takes place at 23° C.”

Cross section of PCM panel used in Dethleffs e.homeQ: How is the PCM contained?

A: “The PCM is in aluminum plates that are shaped like corrugated cardboard [right]. So the heat can be passed very quickly to the PCM. The plate contains 4 kilograms of Micronal per square meter.”

Q: How much PCM is used in the camper?

A: “Approximately 35 kilograms.”

Q: Have you collected data on how well the PCM manages temperatures in the camper? Has it met expectations?

A: “The vehicle was at many shows last year, so the tests are still running at the moment.”

Q: What was the development team's great challenge?

A: “The biggest challenge was to get access to the battery capacity of the vehicle in addition to the solar cells.”

Q: Are there plans to commercialize the e.home camper?

A: “The vehicle was meant to present our ideas to customers and match them with their wishes. Of course, various individual elements, such as connectivity, will be incorporated into production vehicles.”

Q: Are there plans to use PCM technology in other Dethleffs campers?

A: “This is not known until the tests have been completed.”

PCM-equipped personal air conditioner set for commercial release in 2019

Ben Welter - Tuesday, June 26, 2018

Developers of a personal air conditioner designed to reduce energy use in office buildings say they’re on track for commercial release next year. The “μX” micro climate system features a phase change material that solidifies at about 18 degrees C to store cooling generated at night for use during the day.

mX early version
The evolution of the μX: an early design ...
Dr. H. Ezzat Khalifa of Syracuse University led the development team, which includes Air Innovations, Cornell University, United Technologies Research Center and Bush Technical LLC. The team has been working on the system since 2015, funded in large part by a $3.2 million grant from the U.S. Energy Department’s Advanced Research Projects Agency-Energy. The New York State Energy Research and Development Authority provided $400,000 in follow-on funding in 2016.

Sam Brown, OEM custom director at Air Innovations, is in charge of bringing the product to market. He and Michael Wetzel, president and CEO at Air Innovations, talked about their company’s role in the project.

Q: Describe the μX system size, components and functionality.

Brown: “The current unit is about twice size of a standard PC computer tower. The unit utilizes a phase change material that melts over time. We then run a fan over the material to create an active cooling effect. A compressor then re-solidifies the PCM in the off-peak hours for future on-demand needs.”

Q: Describe the phase change material used in the system: type, melt point, thermal storage capacity, amount used in each unit.

Brown:Rubitherm, 68F, 8-10 hours, 40 pounds.”

mX early version
... a version displayed at a recent conference ...
Q: Were different PCMs tested, or did the team focus on one from the start?

Wetzel: “Many PCMs were considered and analyzed before settling on Rubitherm, but no others were tested in operating systems.”

Q: Preliminary tests indicate the prototype can remove more than 32W of heat, surpassing the ARPA-E grant target of 23W. Is the final production model likely to hit that higher number?

Wetzel: “23 watts is the target heat removal directly from a person. Our manikin results showed us exceeding that number in all tests. We tested three different diffuser methods. Some achieved as high as 32 watts removed from the manikin. In all cases we are actually generating more than 500 watt-hours of cooling, enough to cool the airstream 8 degrees F for 10 hours.”

Q: The system is now known as "μX." Will that name be used for the commercial product?

Brown: “No, the commercialized name will more closely reflect the manner in which it's utilized.”

Q: What was the greatest technical hurdle the team faced in developing this product?

Wetzel: “There were many challenges on this project. Part of the program required the development of the world’s smallest scroll compressor. This also means that there was no performance data or design simulation data with which to develop the rest of the system. Our partners on the project had to develop simulation tools based on testing each new component. At Air Innovations our main challenges are designing for manufacturability and the integration and testing of off-the-shelf components as alternatives, as some of the elements of the ARPA-E units are not yet commercially available.”

mX early version
... and, finally, says Brown, "where we think the unit will potentially go in final production."
Q: What is happening with the project right now? Is it at the pilot stage?

Brown: “Currently, we are working through ARPA-E and New York State Energy grants to fully develop the technology. We are developing the unit for two scenarios. The primary is for 8-10 hours of cooling in any office environment. The other is for four hours to off-load the grid in metropolitan areas with peak power capacity concerns. Several units have been built and tested in controlled environments. We are currently seeking grant opportunities to support larger field trials.”

Q: Can you offer any details on the timeline, projected price, target market and sales projections?

Brown: “Further human testing will be necessary in order to right-size the final product. The unit will likely be ready for market sometime in 2019. The initial price point of the unit will be higher, and then come down based on quantity and market demand, settling around $2,500. It is our goal to bring to market 250-500 units in the first year.

“The exciting opportunity with the μX technology is that it further expands upon our existing Micro Environments product line. The commercialized unit will be able to control the users’ complete environment while not only offering active cooling and heating, but to control their entire surroundings as seen in our other models. Furthermore, our customers will see an ROI with the μX technology by allowing set points in the summer to run higher and temps to run cooler in the winter, reducing building HVAC power needs with a more personal temperature control directly at the desk. We believe this technology can improve worker productivity by allowing individual control, at all times, of their specific environment.”

Research roundup: N-octadecane/polystyrene/expanded graphite composites; decorative wood-based panels for thermal energy storage; more

Ben Welter - Monday, June 11, 2018

From Energy:

Experimental investigation on n–octadecane/polystyrene/expanded graphite composites as form–stable thermal energy storage materials

From Green Energy and Environment:

Thermal characterization of bio-based phase changing materials in decorative wood-based panels for thermal energy storage

From Chemical Engineering Science:

Melt-Front Propagation and Velocity Profiles in Packed Beds of Phase-Change Materials Measured by Magnetic Resonance Imaging

From Thermal Science and Engineering Progress:

Employment of Finned PCM Container in a Household Refrigerator as a Cold Thermal Energy Storage System

From Energy Conversion and Management:

Melting and solidification of PCM embedded in porous metal foam in horizontal multi-tube heat storage system
Evaluation of paraffin infiltrated in various porous silica matrices as shape-stabilized phase change materials for thermal energy storage

From Construction and Building Materials:

Potential applications of phase change materials to mitigate freeze-thaw deteriorations in concrete pavement
A practical ranking system for evaluation of industry viable phase change materials for use in concrete
Experimental and numerical study of thermal performance of the PCM wall with solar radiation
Utilizing blast furnace slags (BFS) to prepare high-temperature composite phase change materials (C-PCMs) 

From International Journal of Thermophysics:

Behavior of a PCM at Varying Heating Rates: Experimental and Theoretical Study with an Aim at Temperature Moderation in Radionuclide Concrete Encasements

PCM briefing: DowDuPont shifts to small-scale R&D projects; Viking Cold Solutions has opening for business development manager

Ben Welter - Monday, June 04, 2018

Arktek vaccine carrierWired takes a close look at Arktek, "the Ebola vaccine's high-tech thermos." The World Health Organization is using the PCM-equipped container to transport the temperature-sensitive vaccine to wherever it's needed, whatever the conditions. The container is designed keep payloads colder than -65 C for five days.

• With an eye toward increased profits, CEO Edward Breen says DowDuPont is moving away from large-scale R&D projects in favor of less risky initiatives of $30 million or less.

Viking Cold Solutions has posted an opening for a business development manager for the Northeastern United States.

ASHRAE has published a new standard describing a methodology to apply building energy modeling throughout the design process. ASHRAE Standard 209-2018 defines minimum requirements for providing energy design assistance using building energy simulation and analysis.

Pelican BioThermal is opening its first Canadian drop point for the Credo on Demand rental program. The new drop point, at ATS Healthcare headquarters in Toronto, offers customers an additional location to return temperature-control pallet and bulk shippers. 

Phase change composite shows potential to double AC compressor efficiency

Ben Welter - Friday, June 01, 2018

Using a phase change composite material, researchers at the University of Illinois at Chicago have developed a novel thermal energy storage system that has the potential to downsize conventional air-conditioner compressors by 50 percent and double compressor efficiency during off- and mid-peak hours.

The research is described in a paper titled “Design and optimization of a hybrid air conditioning system with thermal energy storage using phase change composite,” recently accepted for publication in Energy Conversion and Management. One of the authors, Said Al-Hallaj, a research professor of chemical engineering at UI-Chicago and CEO of AllCell Technologies LLC, answered a few questions by e-mail.

Q: Who led the research team, and how long did the project take?

A: “It is an ongoing project since 2015 at the University of Illinois at Chicago, where I work as a Research Professor of Chemical Engineering, and part of the PhD thesis for my graduate student Ahmed Aljehani.”

Q: Who funded the project? 

A: “Ahmed has a scholarship from his government in Saudi Arabia and we get technical support from our industry partners NETenergy and AllCell Technologies LLC.”

Q: Who supplied the PCM?

A: “I believe it is n-tetradecane (C14H30) PCM that we bought from a distributor and not sure about actual source.”

28 slabs of phase change composite materialQ: What is its peak melting point? 

A: “4-6 degrees Celsius.”

Q: What is its thermal storage capacity?

A: “180 kJ/kg (78% PCM, 22% graphite).”

Q: Describe the benchtop PCC/TES system size, components and functionality.

A: “The actual 4 kWh PCC-TES structure is made of 28 slabs of PCC [right]. The whole PCC-TES structure is thermally insulated with building insulation materials. Each slab represents a graphite structure that has been soaked into n-tetradecane for at least 24 h until impregnated with n-tetradecane. The slabs are numbered from top to bottom; top being number 1. The second component is the copper tubes or the copper coils, which pass back and forth in between the 28 slabs. The copper tubes enter the PCC-TES structure from the top and exits from the bottom of the structure.”

Q: Is the concept intended mainly for commercial AC systems, or could it be adapted for residential use?

A: “It should work for both, but commercial AC applications are more economically beneficial due to rate structure and peak demand requirements.”

Q: What are the next steps in developing this concept?

A: “NETenergy, our technology commercialization partner, is partnering with National Renewable Energy Laboratory and a major OEM to build and test a full-scale prototype at NREL facilities in the next year or so.”


https://www.sciencedirect.com/science/article/pii/S019689041830517X

Research roundup: Thermoelectric generator system; solar chimney; novel thermal management system for lithium-ion battery pack; more

Ben Welter - Friday, May 18, 2018

From Energy:

Protection and Thermal Management of Thermoelectric Generator System Using Phase Change Materials: An Experimental Investigation
Performance analysis of a novel thermal management system with composite phase change material for a lithium-ion battery pack

From Solar Energy:

Efficient energy storage technologies for photovoltaic systems
The experimental appraisement of the effect of energy storage on the performance of solar chimney using phase change material

From Applied Thermal Engineering:

Improving thermal management of electronic apparatus with paraffin (PA)/expanded graphite (EG)/graphene (GN) composite material
Experimental exploration of incorporating form-stable hydrate salt phase change materials into cement mortar for thermal energy storage

From Thermal Science and Engineering Progress:

Role of Metallic Foam in Heat Storage in the Presence of Nanofluid and MicroEncapsulated Phase Change Material

From International Journal of Heat and Mass Transfer:

Numerical investigation of thermal and optical performance of window units filled with nanoparticle enhanced PCM

From Applied Energy:

Cost estimation and sensitivity analysis of a latent thermal energy storage system for supplementary cooling of air cooled condensers
Influence of design on performance of a latent heat storage system at high temperatures

From Energy Conversion and Management:

Preparation and investigation of distinct and shape stable paraffin/SiO2 composite PCM nanospheres

From Energy and Buildings:

Parametric Analysis of Using PCM Walls for Heating Loads Reduction

Phase change material ensures a hot shower from the start

Ben Welter - Friday, April 20, 2018

The morning alarm sounds. You wake up, hop in the shower, turn on the tap and … wait. The water might be ice cold for 10 seconds or more, as hot water makes its way from the heater. A Portuguese startup has developed a line of PCM-based products designed to eliminate the wait – and the waste.

Hoterway shower fixtureHeaboo’s Hoterway shower fixture incorporates a thermal battery that heats the water instantaneously until hot water arrives from the heater. The PCM then recharges as heated water passes through the battery. A thermal mixing faucet automatically keeps the incoming water at a constant temperature.

Heaboo, which delivered its first units to Kickstarter backers last year, also offers standalone thermal batteries designed to supply hot water to sinks, tubs and other fixtures.

Rui Teixeira, Heaboo founder and general director, talked about the products in an e-mail interview:

Q: What kind of PCM is used in the products?

A: “We are currently using a paraffin with additives in our products. We are also trying to use more conventional paraffin to reduce the cost of the PCM. The one that we are using has a heat storage capacity of 230 Joules per gram.”

Q: What is the PCM's peak melting point?

A: “It depends on the specifications of the markets we are addressing. The first product uses a PCM with the melting point 45ºC, but for example in France they would prefer to have a PCM with a melting point above 50ºC; as they supply hot water at the temperature around 60ºC. There is not a big deal because we just need 4-5ºC of temperature differential to ensure that the material melts during the shower period.”

Q: How much PCM is used in each Hoterway?

A: “We are optimizing it, but right now we should be talking about 5 kilograms.”

Q: Who is your PCM supplier?

A: “We currently have two European suppliers, but the main one is still Rubitherm from Germany.”

Q: What material is used to contain the PCM?

A: “We use a PVC extruded pipe with some particular design." 

Q: In addition to Kickstarter, where you raised about 26,000 euros, what are your funding sources for this project?

A: “We had to seed investors in the R&D phases. We have four products already in the market and the sales are growing but not as we would like. :)

“We are also looking for industrial partnerships in order to adapt the technology to other applications to diversify our source of income in this early stage and beside that we are looking for an additional investment mainly to optimize production process and increase the go-to-market strategy.”


Q: Heaboo announced a partnership with the Portuguese manufacturer OLI last year. Is the Hoterway manufactured entirely in Portugal?

A: “The partnership with OLI was mainly commercial for the Portuguese market. Currently we have a partnership with an important French manufacturer but I can't reveal the name yet because we are still finishing details about the project. We will adapt the technology to other products related to domestic hot water; the production is still 100% Portuguese but we include accessories that are not made in Portugal, the PCM itself and also the thermal insulation. We use silica vacuum panels to ensure a great insulation with low thickness.”

Q: Will OLI also serve as a distributor of the Hoterway?

A: “OLI is our distributor for Portuguese market but not in exclusivity; in France and Italy we are also developing a distribution network to bring the product there, hopefully during this year." 

Q: How many units have you delivered so far, and how many do you expect to sell in 2018?

A: "Right now we have about 60 units delivered and most of them are installed already; we would like to finish 2018 with 500 units sold." 

Q: What kind of feedback are you getting from consumers?

A: “The feedback is great. The product does exactly as we announced and the users just get rid of the problem they had before. You simply install the product and the waiting time is gone.

“We announce the capacity of the device to be 10 liters after 24 hours from last use, but normally the customer has less quantity of water stagnated in the pipes. That means that they actually still got instant hot water even if they don't use the shower for 48 hours and sometimes 72 hours. This is something highly valued by the customers because it seems that the device works better than we actually said to them.”

Contributions sought for new database on thermal storage materials

Ben Welter - Monday, April 16, 2018

A new database for thermal energy storage materials is being developed within the framework of the International Energy Agency’s Energy Conservation through Energy Storage group, Annex 29 and SHC Task 42.

The database is designed to provide characteristic data for phase change, sorption and thermochemical materials. The website, www.thermalmaterials.org, also offers a wiki with definitions related to thermal energy storage. Both areas are open for contributions.

The phase transition data provided for PCMs must be measured according to a DSC-measurement standard. To ensure the quality of the submitted data, contributors must provide a reference measurement using a PCM provided by Fraunhofer ISE.

Stefan Gschwander, head of Group Heat and Cold Storage at Fraunhofer ISE in Freiburg, Germany, said all submitted data will undergo a review process. “If the data is in line with our requirements it can be published in the public area,” he said.

So far, 15 PCMs are listed in the public area. A restricted area of the database is limited to  independently measured materials.

“The data stored is high-quality data which can be used for research, for example
simulation or to design a system,” Gschwander said. “So for our database, the manufacturers normally do not provide data but sample material that is measured from the institutions that are able to measure according the definitions. So far we have measured PCM from Rubitherm, Sasol and BASF. …

“So far we have about 20 different materials in the restricted area and, as we have used it for the development of the measurement standard, many of the materials have been measured several times by different laboratories so that we have a lot more measurements stored in the database.”

Fraunhofer ISE offers independent characterization of PCM, with fees depending on the material and the DSC required to do the measurement.

The ECES is a technology collaboration group that supports the development of electrical energy storage, thermal energy storage, distributed energy storage and borehole thermal energy storage. For more information on the material database project and characterization services, contact Gschwander at stefan.gschwander@ise.fraunhofer.de.