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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.




Sunamp signs its first major UK contract

Ben Welter - Friday, June 07, 2019

Sunamp Ltd. has signed a memo of understanding to supply its PCM-based heat batteries to Fischer Future Heat under an original equipment manufacturer contract. Sunamp, based in Edinburgh, Scotland, says the deal involves "many thousands" of units and will be worth seven figures as sales ramp up. Leicester-based Fischer began selling the product, dubbed the Aquafficient, in February.

Andrew BissellIn an email interview, Sunamp CEO Andrew Bissell filled in a few details on the deal.

Q: Can you tell me about the PCM aspects of this product?

A: "Sunamp’s success in making a super-stable (40,000+ cycles tested) salt hydrate PCM (very energy dense) at 58C and combining it (in a highly insulated, cuboid enclosure) with a very high power heat exchanger (high power, high flow rate hot water) made a whole class of heat battery devices possible. Not least electric water heaters, with about 4x the energy density of a classic electric hot water tank and 5+ gallon per minute performance. A key innovation (patent pending around the details) was to use electric elements immersed inside the PCM to melt the PCM and charge the heat battery."

Q: What can you tell me about the manufacturing process?

A: "Because Aquafficient by Fischer Future Heat is based on Sunamp UniQ, it’s effectively been in production at Sunamp Factory for nearly a year. 

"By going down this OEM white label route, Fischer Future Heat could hit the ground running with Aquafficient - which they did! Sunamp’s manufacturing has had to scale already this year from 75 units a month to 75 units a week, with 75 a day on the near horizon. This to keep up with exponentially rising combined demand from Fischer, other OEMs, and large housing and regeneration projects.

“We keep scaling production and the demand keeps outpacing us! We're working really hard on scaling up production and appreciate our partners’ and their customers patience when they sometimes have to wait quite a number of weeks for the product they want.”

PCM in stadium seating: For fans on the hot seat, it's a pretty cool idea

Ben Welter - Saturday, May 25, 2019

Dustin Schafer of Henderson EngineersDustin Schafer, senior vice president and director of engineering at Henderson Engineers of Lenexa, Kansas, first became familiar with phase change material when he read an ASHRAE article about conference room air conditioning.

The method struck him as a small-scale version of a stadium or arena. "From there," he says, "I began I began devising a plan for us to implement this into our large-scale venues we design." 

Schafer developed the idea of using PCM inside the hollow portions of seats and seating structures to keep open-air stadiums cooler on hot days. The concept underwent testing at Kansas State University and was awarded a U.S. patent, "Stadium Ambient Temperature Control System," in 2017. He is giving a presentation on the concept June 12 at an event sponsored by AIA Kansas City at the Center for Architecture & Design in Kansas City, Mo. In an email interview, he discussed the development process. 

Q: How long have you worked at your company?

A: "I joined Henderson in 2008 and have nearly 20 years of industry experience."

Q: Can you briefly describe the process of testing the concept?

A: "In looking to develop an innovative, cost effective, and energy efficient option, we began conducting research on the potential implementation of PCM on venue seats to increase the thermal mass in the space and extend the length of time occupants are comfortable. Essentially, the material could be frozen (the material we used has a freezing point of 70° F) prior to the event, then as the PCM reaches its melting point, it would absorb some of the heat brought on by the human and/or solar load, prolonging the time the space is comfortable for attendees.

Henderson patent application drawing"I led a team in conducting a variety of tests to determine the efficacy of this idea. We worked with Kansas State University and utilized their Institute for Environmental Research to complete our testing. We set up a lab that included actual stadium seats arranged in a layout consistent with typical venues. Each seat in the testing area had 10 pounds of PCM attached to the back and a dummy in the seat equipped with electric resistance heaters that produced an amount of heat equivalent to that of a human being. The layout also included suspended wires with thermocouples to create the temperature sensor array around the dummy occupant.

"We conducted two tests to evaluate the impact this technology could have, each with two test value temperatures, 90° F and 100° F. In both tests we took measurements in an environmental chamber that simulated different ambient conditions during an event and compared both a control chamber and a chamber with PCM attached to the chairs. The tests ran until the effect of PCM was no longer noticeable."

Q: Can you provide a summary of the test results?

A: "In our research, we determined that PCM could be an impactful option for open stadiums situated in mild climates where the night temperatures drop low enough to freeze the material. To have an even greater impact, application of PCM should be seriously considered in enclosed arenas. Because the HVAC system could be used to pre-charge the bowl and freeze the material, this application could be even more significant. Additionally, the cooling result could materially affect the peak load needs for the HVAC systems in these spaces, saving the owner on energy costs.

"We also identified areas where PCM would not make sense a part of the temperature control solution, such as in climates with high winds that would simply blow away the cooled air, areas where the temperature does not drop below 70° F and thus doesn’t allow the PCM to freeze, or areas where the temperature rises too far above the melting point prior to the event meaning the cooling effect is lost before it is needed. Finally, we’ve found it necessary to note that this process only impacts spaces that need to be cooled – it cannot be used in heating conditions.

"We determined that phase change material does have a significant and sustained impact on occupant comfort. While it is not the whole solution, it can be a meaningful portion of the overall answer."

Q: Can you provide information on the PCM used in testing?

A: "We used InsolCorp’s Infinite-R phase change material." 

Q: Is Henderson now working on any projects that include the use of PCMs in this manner?

A: "We are not working on any projects that include the use of PCM."

Q: What interests you most about the use of PCM in building and construction?

A: "It’s a sustainable solution that is relatively low cost. It’s not the end all, be all, but it’s a small step that can have a nice impact. Professional sports teams focus heavily on the fan experience and this is a difference maker when it comes to their in-venue comfort."

Research roundup: Night ventilation study; residential ice storage; fly ash and slag cement slurry; more

Ben Welter - Friday, May 24, 2019

From Building and Environment:

A parametric study of phase change material behaviour when used with night ventilation in different climatic zones

From Energy and Buildings:

Development and Evaluation of a Generalized Rule-Based Control Strategy for Residential Ice Storage Systems
Characterization of potassium carbonate salt hydrate for thermochemical energy storage in buildings

From International Journal of Energy Research:

Fly ash and slag cement slurry containing microencapsulated phase change materials

From Applied Energy:

Thermal response of annuli filled with metal foam for thermal energy storage: An experimental study
A scalable environmental thermal energy harvester based on solid/liquid phase-change materials

From International Journal of Hydrogen Energy:

Thermal management of metal hydride hydrogen storage reservoir using phase change materials

From Macromolecular Research:

Multiple Energy Harvesting Based on Reversed Temperature Difference Between Graphene Aerogel Filled Phase Change Materials

From Solar Energy:

Experimental studies on the effect of using phase change material in a salinity-gradient solar pond under a solar simulator

From Chemical Engineering Journal:

Thermal enhancement and shape stabilization of a phase-change energy-storage material via copper nanowire aerogel

From U.S. Office of Scientific and Technical Information:

Prototype Testing of Encapsulated Phase Change Material Thermal Energy Storage (EPCM-TES) for Concentrated Solar Power

From E3S Web of Conferences:

A PCM based cooling system for office buildings: a state of the art review

From Solar Energy Materials and Solar Cells:

Design of MtNS/SA microencapsulated phase change materials for enhancement of thermal energy storage performances: Effect of shell thickness

From Journal of Molecular Liquids:

Investigating the effects of hybrid nanoparticles on solid-liquid phase change process in a Y-shaped fin-assisted LHTESS by means of FEM

From Renewable and Sustainable Energy Reviews:

A review of microencapsulated and composite phase change materials: Alteration of strength and thermal properties of cement-based materials

PCM briefing: Axiotherm wins smarter E Award; update on Malta thermal battery project

Ben Welter - Friday, May 17, 2019

Axiotherm GmbH of Germany was among the winners at this year's smarter E Awards in Munich. Axiotherm was honored in the renewable energy category for kraftBoxx, a thermal energy storage system that uses phase change technology for heating and hot water. The company says kraftBoxx has a higher energy storage capacity than conventional heat and cold storage systems. KraftBoxx is a joint development with Klara Energy and Tuxhorn within the scope of the PCM-based HeatSel product line marketed by Axiotherm. 

China says it will raise tariffs on $60 billion of U.S. goods June 1, including palmitic acid, stearic acid and their salts and esters. The move is response to the U.S. tariff hike on $200 billion worth of Chinese goods that took effect on May 10.  

• In an interview with SolarPACES, Malta Inc. engineer Sebastian Freund provides an update on the Massachusetts company's plans to develop a standalone thermal storage battery using molten salts. “We plan to build a pilot plant with 10MW power and at least six hours of storage duration, depending on customer specifications,” Freund said. Malta hopes to attract enough investors over the next three years to complete an 80MWh thermal energy storage pilot.

Research roundup: High-conductivity nanomaterials; paper board packaging; battery thermal management; more

Ben Welter - Thursday, May 16, 2019

From Heat and Mass Transfer:

Experimental and numerical analysis of composite latent heat storage in cooling systems for power electronics

From Journal of Sol-Gel Science and Technology:

A robust, flexible superhydrophobic sheet fabricated by in situ growth of micro-nano-SiO2 particles from cured silicone rubber

From Journal of Thermal Analysis and Calorimetry:

High-conductivity nanomaterials for enhancing thermal performance of latent heat thermal energy storage systems

From Building Simulation:

Optimization and sensitivity analysis of design parameters for a ventilation system using phase change materials

From Journal of Packaging Technology and Research:

Thermal Analysis of Paper Board Packaging with Phase Change Material: A Numerical Study

From Energy Storage:

Thermal performance of battery thermal management system using composite matrix coupled with mini‐channel

From Phase Transitions:

A study on preparation and properties of carbon materials/myristic acid composite phase change thermal energy storage materials

From ACS Applied Materials & Interfaces:

Melamine Foam Supported Form-stable Phase Change Materials with Simultaneous Thermal Energy Storage and Shape Memory Property for Thermal Management of Electronic Devices

From International Conference on Thermal Engineering:

Performance Enhancement of Unitary and Packaged Air Conditioners With Phase Change Material
Performance Comparison of Different Phase Change Materials For Solar Cooking During off Sun Sunshine Hours
A Review on Enhancement of Thermophysical Properties of Paraffin Wax PCM With Nanomaterials
Nano-Enhanced PCMs for Low Temperature Thermal Energy Storage Systems and Passive Conditioning Applications

From Chemistry Select:

Designing Coconut Oil Encapsulated Poly(stearyl methacrylate‐co‐hydroxylethyl metacrylate) Based Microcapsule for Phase Change Materials

From Evolution in Polymer Technology Journal:

Enhancement of Thermo-Regulating Textile Materials Using Phase Change Material

From Materials Research Express:

Improved thermal characteristics of Ag nanoparticles dispersed myristic acid as composite for low temperature thermal energy storage

From Applied Energy:

On the performance of ground coupled seasonal thermal energy storage for heating and cooling: A Canadian context

From Solar Energy Materials and Solar Cells:

Thermal stability enhancement of d-mannitol for latent heat storage applications

Research roundup: Zinc oxide coating; TEG-PCM power enhancement; graphen-oxide aerogel beads; more

Ben Welter - Friday, May 10, 2019

From Advanced Materials Interfaces:

Doubly Coated, Organic–Inorganic Paraffin Phase Change Materials: Zinc Oxide Coating of Hermetically Encapsulated Paraffins

From Applied Energy:

Efficiency analysis and experimental validation of the ocean thermal energy conversion with phase change material for underwater vehicle
A numerical and experimental analysis of an integrated TEG-PCM power enhancement system for photovoltaic cells
Molten salt selection methodology for medium temperature liquid air energy storage application

From Applied Energy Materials:

Graphene-Oxide Aerogel Beads Filled with Phase Change Material for Latent Heat Storage and Release

From Journal of Wuhan University of Technology:

Effect of Modified Vermiculite on the Interface of a Capric Acid-expanded Vermiculite Composite Phase Change Material with Phase Transition Kinetics

From Journal of Molecular Liquids:

Numerical simulation of the melting process of nanostructured based colloidal suspensions phase change materials including the effect of the transport of the particles

From Fibers and Polymers:

Encapsulated Phase Change Material Embedded by Graphene Powders for Smart and Flexible Thermal Response

From Applied Thermal Engineering:

Influence of orientation on thermal performance of shell and tube latent heat storage unit

From Journal of Energy Storage:

Development and validation of the numerical model of an innovative PCM based thermal storage system

From 2nd International Conference on Power, Energy and Environment:

Feasibility Study of the Application of a Latent Heat Storage in a Solar Dryer for Drying Green Chili

From Solar Energy:

Tetradecyl oxalate and octadecyl oxalate as novel phase change materials for thermal energy storage
An analytical and comparative study of the charging and discharging processes in a latent heat thermal storage tank for solar water heater system
Effect of alkaline pH on formation of lauric acid/SiO2 nanocapsules via sol-gel process for solar energy storage

From Journal of Applied Polymer Science:

Preparation and characterization of paraffin microcapsules for energy‐saving applications

From Energy:

Flexible heatsink based on a phase-change material for a wearable thermoelectric generator

From Journal of Nanoscience and Nanotechnology:

Superior Form-Stable Phase Change Material Made with Graphene-Connected Carbon Nanofibers and Fatty Acid Eutectics

From Construction and Building Materials:

Thermal and rheological characterization of bitumen modified with microencapsulated phase change materials

From Thermochimica Acta:

Development of spherical α-Al2O3-based composite phase change materials (PCMs) and its utilization in thermal storage building materials

From Journal of Power Sources:

Thermophysical properties of trimethylolethane (TME) hydrate as phase change material for cooling lithium-ion battery in electric vehicle

From Solar Energy Materials and Solar Cells:

Applications of cascaded phase change materials in solar water collector storage tanks: A review
Thermal conductivity enhancement of hydrated salt phase change materials employing copper foam as the supporting material

Research roundup: Spherical encapsulation; thermal therapy respirator; nanoporous composite; PCM effect on cement; more

Ben Welter - Friday, May 03, 2019

From Journal of Energy Storage:

Performance comparison of four spherically encapsulated phase change materials for medium temperature domestic applications

From International Journal of Thermal Sciences:

Exploration of a thermal therapy respirator by introducing a composite phase change block into a commercial mask

From Renewable and Sustainable Energy Reviews:

Review on nanoporous composite phase change materials: Fabrication, characterization, enhancement and molecular simulation

From Sci:

The Effect of Phase Change Materials on the Physical, Thermal and Mechanical Properties of Cement 

From Applied Energy:

High energy-density and power-density thermal storage prototype with hydrated salt for hot water and space heating

From Journal of Thermal Science and Engineering Applications:

Thermal Cycling of Calcium Chloride Hexahydrate With Strontium Chloride as a Phase Change Material for Latent Heat Thermal Energy Storage Applications in a Nondifferential Scanning Calorimeter Set-Up
Numerical Investigation of Scheffler Concentrator Receiver for Steam Generation Using Phase Change Material

From IntechOpen:

Solar Thermal Energy Storage Using Paraffins as Phase Change Materials for Air Conditioning in the Built Environment

From Reactive and Functional Polymers:

Design and fabrication of pH-responsive microencapsulated phase change materials for multipurpose applications

From Advances in Fluid and Thermal Engineering:

Experimental Investigation on a Solar Thermal Energy Packed Bed Sensible Heat Storage Combined with Latent Heat Storage

From Bulletin of Materials Science:

Development of an acetanilide/benzoic acid eutectic phase change material based thermal energy storage unit for a passive water heating system

From International Journal of Heat and Mass Transfer:

Solidification performance of a latent heat storage unit with innovative longitudinal triangular fins

Research roundup: PCM use in mortars; compatibility with selected plastics; myo-inositol sugar alcohol; more

Ben Welter - Tuesday, April 23, 2019

From Materials:

Phase Change Materials for Energy Efficiency in Buildings and Their Use in Mortars

From Polymer Testing:
From Renewable Energy:

From Molecules:

From Applied Energy:

Natural convection during melting in vertical finned tube latent thermal energy storage systems
Year-round performance analysis of a photovoltaic panel coupled with phase change material

From Energy Procedia:

A Review of the Performance of Buildings Integrated with Phase Change Material: Opportunities for Application in Cold Climate

From Journal of Applied Polymer Science:

Encapsulation of polar phase change materials via multiemulsification and crosslinking method and its application in building

From Journal of Energy Storage:

Thermal performance of shell and tube latent heat storage unit: Comparative assessment of horizontal and vertical orientation
Experimental investigation of phase change in a multitube heat exchanger

From Chemistry Select:

Preparation and Thermal Properties of Stearic Acid/n‐Octadecane Binary Eutectic Mixture as Phase Change Materials for Energy Storage

From Journal of Materials Research:

Synthesis of novel shape-stabilized phase change materials with high latent heat and low supercooling degree for thermal energy storage

From Science of Advanced Materials:

Fabrication and Performance of Polyurethane/Polyurea Microencapsulated Phase Change Materials with Isophorone Diisocyanate via Interfacial Polymerization
Design and Analysis of Battery Box Based on Graphite-Phase Change Material and Air Cooling

From Experimental Techniques:

Design, Build, and Test a Hybrid Cooling System for Crash Helmet

From Journal of Thermal Analysis and Calorimetry:

Capric acid/intercalated diatomite as form-stable composite phase change material for thermal energy storage
Preparation and thermal performances of microencapsulated phase change materials with a nano-Al2O3-doped shell

PCM briefing: $33M in funding for CSP thermal storage research; Walero undergarment put to the test in race simulator

Ben Welter - Friday, March 29, 2019

• The U.S. Department of Energy has announced $33 million in research funding to advance technologies that work toward achieving the department's 2030 cost target of 5 cents per kilowatt-hour for CSP-generated electricity with at least 12 hours of thermal energy storage. "This research," DOE writes, "includes new materials and technologies that significantly reduce the cost of manufacturing, enable new energy storage technologies, and develop solutions that enable a solar field to operate autonomously without any human input."

Jack MitchellWalero racewear, which uses Outlast phase change technology to regulate temperature in race and rally drivers, has been put to the test on reigning British GT4 champion Jack Mitchell in a temperature-controlled race simulator. The tests were directed by racing performance coach Dean Fouache. On the first day, Mitchell, right, wore standard Nomex underwear; on the second day, he wore Walero underwear. Three measurements were recorded every five minutes during the hourlong tests: body temperature, heart rate and weight loss. In all three areas, Walero showed measurable advantages over the Nomex. "Jack sweated around 40 percent less in the Walero underwear and his average heart rate was eight beats less over the course of the hour," Fouache told Autosport magazine. "So, all in all, relatively conclusive results - even though it is a small comparison test."

• New this month from Central West Publishing in Australia: "Phase Change Materials," edited by Vikas Mittal, an associate professor of chemical engineering at the Petroleum Institute in Abu Dhabi.

• The International Conference on Innovative Applied Energy in the United Kingdom earlier this month featured a number of experiments with phase change materials, including Auburn University's development of micro-encapsulated phase change materials that can be combined with many different media. Other PCM research included a bio-composite made with hemp lime concrete and a novel utilization of fly ash to encapsulate phase change materials.

James Joule• The 200th anniversary of the birth of physicist James Prescott Joule will be commemorated with the unveiling of a plaque in Sale, United Kingdom, in April. The English physicist and mathematician, who gave his name to the unit of energy, was born on Dec. 24, 1818, in Salford. He died in Sale in 1889.

• The deadline for submitting manuscripts for "Phase Change Materials of Buildings," a special issue of the journal Buildings, is Sunday, March 31. Dr. Morshed Alam of Australia's Swinburne University of Technology is the guest editor.

PCM system inefficiencies blamed on design flaws, operator errors

Ben Welter - Monday, March 25, 2019

A PCM-based thermal energy storage system installed in an 11-story building at an Australian university used just 15 percent of its heat storage capacity to shift peak cooling load, according to researchers who monitored system performance for 25 months.

Morshed AlamA team led by Morshed Alam of Swinburne University of Technology in Hawthorn found that the PCM reduced chiller cooling load by 12 to 37 percent in winter but remained inactive in summer, partly because the ambient temperature was not cold enough to charge the PCM tank. The tank was designed to reduce the daytime cooling load on the chiller by 33 percent.

The results of the study are reported in "Energy saving performance assessment and lessons learned from the operation of an active phase change materials system in a multi-storey building in Melbourne," published in Applied Energy earlier this year.

"The factors that contributed to the underperformance of active PCM system," the researchers concluded, "include mismatch between designed and actual operation of the PCM system, inefficient operation logic of the system, poor material quality, and limited knowledge of maintenance staffs during the operation stage."

FlatICE PCM panels in TES tankThe TES system, installed in the 11th floor of Swinburne's Advanced Manufacturing and Design Centre, completed in 2015, was designed to minimize the daytime cooling load on the chiller and increase the building energy efficiency. The system includes a 5x4x2-meter tank filled with 5,120 FlatIce PCM panels made by PCM Products Ltd. Each HDPE panel is 500x250x45 mm and is filled with a salt hydrate PCM with the melting temperature of 13–15 °C. Water is used as the heat transfer fluid.

The researchers reported two problems with the PCM: a "very high degree of supercooling" that slowed the solidification process and a measured latent heat capacity (53 joules per gram) that was much lower than the manufacturer's specification (160 J/g).

Alam, a senior research fellow at Swinburne's Centre for Sustainable Infrastructure, Department of Civil and Construction, answered a few questions about the research in an email interview.

Q: This the first comprehensive report I've seen that analyzes the actual performance of a PCM/TES system in a commercial building. Do you know of others? For example, has the TES system at Melbourne CH2 undergone this kind of analysis?

A: "I am aware of the PCM system installed in CH2 building in Melbourne. But no such study was carried out to understand the performance of the system. The system went out of order within 5-6 years."

Q: Any theory on why the PCM's thermal storage capacity of 53 J/g, as measured using differential scanning calorimetry, did not match the manufacturer's specified capacity of 160 J/g?

A: "The DSC test is widely used by the researchers around the world to test PCM capacity. But it may not be an appropriate approach to test PCM thermal energy storage capacity. That is why we are now in the process of conducting an experimental study where 6 degree Celsius chilled water will be supplied in a small PCM tank. We will measure the flow rate, melting and solidification temperature and time required to completely solidify and melt the PCM. Based on the result we will optimize the system."

Q: Have the researchers' recommendations been put into practice?

A: "We are now working with our facilities department to put the recommendations in practice. We need to finish the optimization and cost-benefit analysis study. Then we can define the ideal operating condition of PCM in this building. We will be able integrate those maybe before next summer in Australia."

I shared results of the paper with Zafer Ure of PCM Products Ltd. and asked him to comment on the authors' observations on supercooling and specified-vs-measured latent heat capacity.

Zafer Ure"We have been supplying the same PCM for the last 20 years and many of the installations are 10~15 MWh levels," Ure wrote. "You cannot use the DSC machine to work out the latent heat for sulphate-based hydrated salts, it only picks up one of the chemicals in the mixture and gives you the data for that chemical. This is a well-known handicap for the DSC application for sulphate-based PCM testing. Moreover, DSC sample is less than gram quantities and this is a mixture of multiple salts, nucleating agent, stabilizers and thickening agent so if you do not pick up the correct mixture, which is very difficult unless you pick it up from the reactor vessel while you are making the PCM (i.e. while the agitators and mixers working at the correct temperature (some salts crystallize at room temperatures), you may not be able to pick up true sample.

"They took the sample out of one of the containers and no idea where and how they took the sample. If you do not have the true sample, especially lack of nucleating agent in the very small gram quantity sample, you can get it very wrong data as this is the case for their DSC. We would not ship any PCM unless QA release the goods and our records show the product supplied was within the standard capacity level. The actual latent heat can only be established using air test and actual freeze and melt profiles.

"If they managed to charge and discharge the tank fully they would have measured the tank performance which would have shown the true TES capacity. Sounds like their chilled water design and control did not allow that and therefore there is no way of evaluating the TES tank performance."