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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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ACT is awarded a U.S. patent for PCM with tunable melt point

Ben Welter - Friday, January 10, 2020

Advanced Cooling Technologies of Lancaster, Pa., has been awarded a U.S. patent for a phase change material with a tunable melting point.

The hydration level of the PCM, a salt hydrate consisting primarily of salt and water, is altered to change the melting point to a desired set point using changes in humidity of the system.

“In an ARPA-E ARID funded program, we showed that you could change the melting point of salt hydrate phase change materials by changing the hydration levels of the salt hydrate in-situ,” Richard Bonner, ACT’s vice president for R&D, wrote in a LinkedIn post. “We also applied this technology to power plant cooling, where the seasonal variations in ambient temperature necessitate different melting points. Congratulations to the inventors: Dr. Ying Zheng, Dr. Chien-hua Chen, Dr. Howard Pearlman, and Dr. Fangyu Cao."

ACT worked with Lehigh University and the University of Missouri to develop the PCM. The idea was prompted by ACT’s interest in utilizing seasonal shifts in weather for the company’s day/night thermal storage application. A tunable melt point allows the PCM to be more easily solidified in cold and hot seasons.

The targeted melt temperatures in the project were from 25° C to 45° C for low-grade thermal energy storage, but could be extended to higher temperatures with other salt hydrates, the company said.

The project was funded, in part, with a $3.2 million ARPA-E ARID grant, awarded in 2015. ARID stands for "Advanced Research in dry Cooling." The project teams were challenged to "develop innovative, high-performance air-cooled heat exchangers and supplemental cooling systems and/or cool-storage systems" for use in thermoelectric power plants, to replace existing technologies that use a substantial amount of water to cool plant condensers.

The ARID project was completed in 2018. ACT's invention is now at the lab-scale testing phase. The most difficult hurdle, the company said, will be to scale up to commercialization level.  “From a manufacturing standpoint, shifting of the hydration level would require a large infrastructure for altering the humidity,” the company said.

“The concept could also be applied to the HVAC industry (building comfort) to provide day/night load shifting,” the company said, “as well as PCM synthesis and preparation for a consistent product. “
 

Sunamp's UniQ heat storage product earns RAL certification

Ben Welter - Monday, December 16, 2019

The RAL Quality Association PCM has awarded the RAL Quality Mark to Sunamp Ltd. for its UniQ line of thermal batteries.

RAL quality markThe product, which has been installed in thousands of homes across Europe, uses a specially formulated phase change material to store large amounts of energy from renewable and other sources and release it as heat to deliver hot water and space heating as needed. The PCM is sodium acetate trihydrate-based with a patented formulation giving a melt point of 58 degrees Celsius. 

In independent testing conducted by ZAE Bayern, the PCM was successfully melted and solidified in a UniQ heat battery for 10,000 cycles. At the end of the test, no significant differences in stored thermal energy capacity were found between the cycled samples and an uncycled sample of the PCM. The product, which also passed leak testing, earned the association's highest level of certification, Grade A. 

Over 3,000 UniQ units are now in service, with Sunamp projecting a tenfold growth in sales next year. The quality mark will be featured on Sunamp’s website and in other marketing materials, UniQ manuals and product labels.

“We are delighted that our thermally charged UniQ product range of heat batteries has been awarded a globally recognized mark of quality,” said Kate Fisher, Ph.D., a materials integration scientist at Sunamp, which is based in Edinburgh, Scotland. “RAL certification is a huge accolade and cements Sunamp’s position as world leaders at the forefront of the technology.”

Sunamp UniQ heat batteriesThe RAL Quality Association PCM was established in 2004 to develop standards for the PCM industry. Members include Axiotherm, Microtek Laboratories, Rubitherm, Croda Europe, va-Q-tec, PCM Technology, Global-Systems Europe, Sasol, Sunamp, Pluss Advanced Technologies and PureTemp LLC.

Members and non-members alike can submit their products to the association for independent testing and earn the RAL Quality Mark. To qualify for the mark, products and materials must meet standards for energy storage capacity and phase transition temperature and stability, as defined in RAL-GZ 896.

“I am delighted that more and more products with PCM technology can be awarded the RAL Quality Mark as meaningful and transparent proof of quality and longevity,” said Stefan Thomann, the association’s managing director. “The great thing about Sunamp´s UniQ heat batteries is that they can be installed and used in homes very easily and save a lot of energy costs and carbon emissions immediately. The fact that they passed more than 10,000 cycles make sure that users will be able to profit from these benefits for decades.”

PCM briefing: Acumen invests in Promethean Power Systems; Viking Cold wins Cleanie award

Ben Welter - Monday, October 14, 2019

• Social venture capital investor Acumen has invested an undisclosed amount in Promethean Power Systems Inc., which makes PCM-based refrigeration systems for cold-storage and milk chilling applications in off-grid and partially electrified areas of developing countries. Jiten Ghelani, chief executive of Promethean, which is based in Boston, Mass., and Pune, India, said the investment would help the company accelerate the adoption of its products across India and other markets, and also expand its cooling-as-a-service offerings. 

Air New Zealand pillow• Two new consumer products featuring temperature-control fabrics from Outlast Technologies hit the market recently: A pillow designed to improve the quality of sleep for passengers on Air New Zealand's long-haul flights and a Calloway pullover designed to keep golfers cool in warm weather and warm in cold weather

Viking Cold Solutions of Houston, Texas, won a Platinum Cleanie Award last month for a PCM-based storage and demand management project in Massachusetts. The Cleanie Awards, presented at this year's North America Smart Energy Week in Salt Lake City, Utah, recognize companies and individuals shaping the clean-tech and renewable energy industries. The Viking Cold project involved the installation and commissioning of TES systems to store refrigeration energy and facilitate 1.3 MW of energy demand reduction across eight customer facilities, including the Greater Boston Food Bank.

Sonoco ThermoSafe of Arlington Heights, Ill., has introduced a new temperature-controlled box rental service. "The new Orion r product line is based on the existing ChillTech product," said Ben VanderPlas, manager of engineering and product management at Sonoco. "We’ve made changes to make the product more reusable (added EPP) and have increased the VIP insulation. The PCMs remain the same, using paraffin-based materials. ChillTech was developed by Laminar Medica in the UK prior to their acquisition and integration into the ThermoSafe business. Solutions will exist for 2-8, 15-25 and frozen temperatures."

Sonoco ThermoSafe has posted an opening for a Senior Account Manager Europe, to be based in Netherlands.

Microtek Laboratories Inc. of Dayton, Ohio, has introduced a new line of PCM-equipped pouches and panels for use in temperature-controlled shipping.

PCM briefing: Viking Cold is finalist for innovation award; Sonoco launches sustainable packaging initiative

Ben Welter - Friday, September 20, 2019

Viking Cold Solutions is a finalist for an Energy Storage of North America Innovation Award. The behind-the-meter thermal energy storage systems up for the award are part of an Eversource demand management program in Massachusetts. 

A thermal storage project in Northamptonshire, England, is expected to provide 47 new homes with hot water and heat via renewable energy sources such as solar power. The borehole technology, developed by Caplin Solar of Leicester, stores heat in the ground in warmer months for later use in colder periods.

• Packaging giant Sonoco of Hartsville, S.C., has announced the creation of its EnviroSense sustainable packaging initiative. EnviroSense products are designed to incorporate a number of elements associated with more sustainable packaging, including optimized package-to-product ratio; increased use of recycled and recyclable content; fiber sourcing; compostability; and the use of bio-based materials.

• Registration is open for Sonoco ThermoSafe's next Leading Minds Seminar, "Collaborative Learning that FUELS Your Temperature Sensitive Healthcare Products," to be held Nov. 14 in Amsterdam. The seminar is designed for European supply chain, logistics, quality and packaging professionals responsible for the protection and management of temperature sensitive healthcare clinical supplies and finished products. 

Hydrostor, a Canadian developer of advanced compressed air energy storage projects, has announced the closing of $37 million (USD) in growth financing. Hydrostor has three projects in operation or under construction in Canada and Australia 

• A projected tripling of heat-related deaths in the United Kingdom over the next 30 years will require a drastic rethinking of ways to cool buildings, a parliamentary select committee warns. “The risk of overheating in terms of minimising risks to health and safety of occupants should be enshrined into regulations for new build homes and retrofits," the Environmental Audit Committee said. "This should be considered alongside an integrated review of energy efficiency and ventilation, and be included in the government’s planned Future Homes Standard, to include improvement in the measurement of current and future overheating risk and prioritise passive cooling measures.”

• The most entertaining obituary of a self-taught chemist you will read this month. Rest in peace, Joe Heller.

PCM briefing: Glacier Tek sponsors wheelchair cyclists in Kenya fundraiser; CCT closer to commercializing silicon battery

Ben Welter - Monday, September 09, 2019

Dom Coleman, Regain trustee and grants officerGlacier Tek LLC of Minneapolis is sponsoring seven quadriplegic cyclists taking part in a fundraising ride in Kenya's Rift Valley next month. The Kenya Cycle Challenge 2019, organized by Regain, a U.K.-registered charity, is on track to raise 80,000 pounds to support quadriplegic athletes in Great Britain. More than 50 riders are expected to participate. The seven sponsored riders will be wearing PureTemp-powered Glacier Tek cooling vests to help them handle the 32º C heat they will likely encounter on the five-day ride. People with spinal cord injuries are vulnerable to heat stress because their bodies cannot send the signals needed to initiate sweating in response to hot conditions. 

• Heat battery manufacturer Sunamp Ltd. is among the exhibitors at the InstallerSCOTLAND trade show in Glasgow, Scotland, on Thursday.

CCT Energy Storage is on track to install its first commercial thermal energy device at a mobile phone base station in Adelaide, South Australia, before the end of the year following an agreement in principle with an Australian infrastructure provider. CCT unveiled its first 24kW device in March, describing it as the world’s first working thermal battery using silicon as a phase change material.  

• Hundreds of Australia’s most environmentally advanced homes will open their doors to visitors on Sunday, Sustainable House Day 2019. At least two of the homes – Farrell’s House in Narara, New South Wales, and the 10 Star Home in Cape Paterson, Victoria – feature phase change technology. More than 33,000 people visited 226 homes across Australia last year.  

Research roundup: Corrosion effect of Micronal PCMs; photovoltaic-thermal system optimization; diatomite-based composite; more

Ben Welter - Monday, September 09, 2019

From Renewable Energy and Sustainable Buildings:

Study of Corrosion Effect of Micronal® Phase Change Materials (PCM) with Different Metal Samples
Use of Phase Change Materials for Solar Systems Applications
Performance Optimization of Concentrated Photovoltaic-Thermal (CPV-T) System Employing Phase Change Material (PCM) in Hot Climate

From Asia International Symposium on Mechatronics:

Investigation for a Phase Change Immersion Cooling System

From Energy Conversion and Management:

Experimental study of active phase change cooling technique based on porous media for photovoltaic thermal management and efficiency enhancement

From Renewable Energy:

Enhanced properties of diatomite-based composite phase change materials for thermal energy storage
Hybrid thermal energy storage with phase change materials for solar domestic hot water applications: Direct versus indirect heat exchange systems

From Journal of Applied Polymer Science:

Surface modification of MWCNT and its influence on properties of paraffin/MWCNT nanocomposites as phase change material

From Energy and Buildings:

Energy and emissions analysis of ice thermal energy storage in the western US
Thermal energy storage characterization of cementitious composites made with Recycled Brick Aggregates containing PCM

From Solar Energy:

Innovative passive heat-storage walls improve thermal performance and energy efficiency in Chinese solar greenhouses for non-arable lands

From Construction and Building Materials:

Development of structural thermal energy storage concrete using paraffin intruded lightweight aggregate with nano-refined modified encapsulation paste layer

From Applied Energy:

A comprehensive review on positive cold energy storage technologies and applications in air conditioning with phase change materials

From International Journal of Energy Research:

Preparation and characterization of nano‐enhanced myristic acid using metal oxide nanoparticles for thermal energy storage
Performance comparison of different combined heat and compressed air energy storage systems integrated with organic Rankine cycle

From xPRESS Polymer Letters:

Editorial corner – a personal view / Thermal management with polymer composites

From International Symposium on Asphalt Pavement & Environment:

Impregnation of Lightweight Aggregate Particles with Phase Change Material for Its Use in Asphalt Mixtures

From Journal of Sol-Gel Science and Technology:

Development of new inorganic shape stabilized phase change materials with LiNO3 and LiCl salts by sol-gel method

From Advanced Functional Materials:

Functional Soft Composites As Thermal Protecting Substrates for Wearable Electronics

PureTemp shows energy-saving potential in EnergyPlus simulations

Ben Welter - Wednesday, August 28, 2019

In EnergyPlus simulations using hysteresis data, the integration of PureTemp phase change materials in a building's suspended ceiling tiles showed potential savings in cooling energy ranging from 5.5 percent to 37.4 percent.

Ceiling tile drawingThe PCM modeling research, conducted at University of Manitoba, also found a reduction in "discomfort hours" from 10 percent to 29 percent, depending on the zone and PCM type.

The researchers set out to investigate the feasibility of integrating PCMs within a suspended ceiling using the hysteresis method in EnergyPlus 8.9. The hysteresis effect, wherein a PCM has different melting/freezing temperature curves, complicates the simulation of PCM use in buildings. The EnergyPlus modeling software was updated in 2017 to include the effect of hysteresis.

Minneapolis-based PureTemp LLC provided the researchers with the thermo-physical properties of PCMs required for modeling in EnergyPlus. Five types of PCMs, namely PCM20 (PureTemp 20), PCM21, PCM22, PCM23 (PureTemp 23), and PCM24, were tested and analyzed. The melting and freezing temperatures of the five PCMs fall within the thermal comfort range and operation of the HVAC system of the building the researchers chose as a case study: the University of Manitoba's new Stanley Pauley Engineering Building.

Miroslava KavgicThe number of each PCM represents the material's peak melting temperature in degrees Celsius. The theoretical properties of PCM21, PCM22 and PCM24 were derived from the actual properties of PureTemp 20, PureTemp 23 and PureTemp 25.

One of the study's authors, Dr. Miroslava Kavgic, right, is an assistant professor of civil engineering at the university. She answered questions about the research by email.

Q: What do you think is the most important finding, as far as impact on manufacturers of PCMs and PCM products?

A: "The findings of our research study suggest a promising future for the applications of PCMs in buildings located in cold climates. Furthermore, our study showed that in addition to already proven cooling energy-saving potential, PCMs can be very efficient in reducing heating energy demand. As a result, the findings from our study can increase application of PCMs in buildings located in the dominant heating climates, and therefore increase the demand for these unique building materials. We also hope that higher demand for PCMs will bring down their price which currently hinders the more extensive application of PCMs in areas with the lower energy prices such as Manitoba."

Q: Why did you choose to use PureTemp data? Was there a preference to use a biobased PCM? Or was data on other products hard to obtain?

EnergyPlus model: enthalpy-temperature method
EnergyPlus PCM model, enthalpy-temperature method
A: "PureTemp shares valuable thermo-physical properties of its PCM products on its website. Furthermore, upon our request PureTemp provided additional information required for the modeling of PCMs in EnergyPlus using hysteresis method. PureTemp also provides other useful information related to various applications and experimental testing of PCMs. Finally, PureTemp’s PCM products are produced from agricultural sources, and they are readily biodegradable and non-toxic. These positive characteristics of the PureTemp’s PCM products can enable the development of environmentally friendly solutions that can significantly reduce buildings’ energy consumption while improving their indoor thermal comfort."

Q: Given the impact of a PCMs hysteresis the final simulation results, is there a standard you’d like the industry to establish for consistent data from the PCM manufacturers?

EnergyPlus model: hysteresis method
EnergyPlus PCM model, hysteresis method

A: "Consistent data from the PCM manufacturers would increase confidence in the modeling results, and this applies to both hysteresis and temperature-enthalpy methods. Moreover, the consistent PCM properties could also be beneficial for the manufacturers as they will allow the end-user to test multiple PCMs and purchase several different materials for real-world implementation. This is particularly important considering the need for numerical analysis before the real-world implementation due to both complex behavior of PCMs and their relatively high price. The sensitivity analysis of the hysteresis input parameters suggests that manufacturers should pay partial attention to the parameters that have high impact on the simulation results."

Q: For future work, is there interest in comparing the same PCM measured with different methods, such as T-history and DSC?

A: "The t-history method is relatively inexpensive and straightforward to measure the phase-change enthalpy of PCM products using considerably larger sample sizes compared to DSC, and therefore for non-uniform PCMs it is a good testing alternative to DSC."

Table 3. Thermo-physical properties of the tested PCM:

Hysteresis properties PCM20 PCM21 PCM22 PCM23 PCM24
Latent heat during the entire phase change process (J/kg) 171,000 189,000 208,000 227,000 207,000
Peak melting temperature (°C) 20 21 22 23 24
Peak freezing temperature (°C) 18 19 20 21 22
Liquid-state thermal conductivity (W/(m∙K)) 0.14 0.143 0.146 0.15 0.15
Solid-state thermal conductivity (W/(m∙K)) 0.23 0.236 0.243 0.25 0.25
Liquid-state density (kg/m3) 680 730 780 830 840
Solid-state density (kg/m3) 950 936 923 910 930
Liquid-state specific heat (J/(kg∙K)) 2150 2096 2043 1990 2140
Solid-state specific heat (J/(kg∙K)) 2070 1993 1916 1840 1915

 

The full version of the paper is available here through the end of September 2019:

https://authors.elsevier.com/a/1ZZ3u4r6KuzlE4

Research roundup: Analysis of hysteresis method in EnergyPlus; pinecone biochar; passive cooling; thermal responses of concrete slabs; more

Ben Welter - Thursday, August 15, 2019

From Applied Thermal Engineering:

Application and sensitivity analysis of the phase change material hysteresis method in EnergyPlus: A case study

From Scientific Reports:

A promising form-stable phase change material prepared using cost effective pinecone biochar as the matrix of palmitic acid for thermal energy storage

From Applied Energy:

Geometry-induced thermal storage enhancement of shape-stabilized phase change materials based on oriented carbon nanotubes
Passive cooling through phase change materials in buildings. A critical study of implementation alternatives

From Cement and Concrete Composites:

Thermal responses of concrete slabs containing microencapsulated low-transition temperature phase change materials exposed to realistic climate conditions

From Solar Energy Materials and Solar Cells:

Preparation and thermal properties of low melting point alloy/expanded graphite composite phase change materials used in solar water storage system
Frost and high-temperature resistance performance of a novel dual-phase change material flat plate solar collector

From Energy:

Novel micro-encapsulated phase change materials with low melting point slurry: Characterization and cementing application

From IOP Conference Series: Materials Science and Engineering:

Thermal performances and characterization of microencapsulated phase change materials for thermal energy storage

From Journal of Physics: Conference Series:

Effect of thermal performance on melting and solidification of lauric acid PCM in cylindrical thermal energy storage

From Construction and Building Materials:A sodium acetate trihydrate-formamide/expanded perlite composite with high latent heat and suitable phase change temperatures for use in building roof

From Materials Research Express:

Investigation of magnesium nitrate hexahydrate based phase change materials containing nanoparticles for thermal energy storage

From Journal of the Brazilian Society of Mechanical Sciences and Engineering:

Selection of phase change material for solar thermal storage application: a comparative study

From Renewable Energy:

Experimental study on the thermal performance of a grey water heat harnessing exchanger using phase change materials

From International Journal of Energy Research:

Climate applicability study of building envelopes containing phase change materials

New dorm at Massachusetts college features 18,000+ square feet of PCM mats

Ben Welter - Thursday, August 15, 2019

Garfield passive house elements

A new dormitory at Williams College in Massachusetts is equipped with 18,200 square feet of mats filled with phase change material.

Garfield House, completed in time for the first students to move in this month, is designed to achieve Passive House PHIUS+ certification and LEED Gold certification. It features R-38 walls, R-60 roofs, triple-pane windows, high-efficiency energy recovery ventilation units, drainwater heat recovery and a 50 kw photovoltaic array.

The Infinite R PCM mats, made by Insolcorp LLC of New London, N.C., will help keep the passively cooled building comfortable when the weather is warm. The PCM is a salt hydrate with a peak melting point of 73 degrees F and a thermal storage capacity of about 170 joules per gram. The mats are deployed within Garfield's interior walls and above ceilings.

Jacob Higginbottom Jacob Higginbottom, director of higher education design at SGA in Boston, was project manager. He first learned about the potential use of phase change material in building envelopes and interiors in March 2018.

"A member of our team had run across the Infinite R product at a trade show and our client was looking for ways to introduce passive cooling techniques since it’s their campus standard to build residence halls without active cooling," said Higginbottom, right. "Upon research we convinced the client that this could help and they decided to give it a try."

Garfield House has no active cooling system. Did that present any special challenges?

"The fact that Garfield did not have cooling wasn’t necessarily a challenge for the PCM, but perhaps was more of an opportunity for the project itself," said Mick Dunn, Insolcorp president. "The project wasn’t without a cooling source altogether. The design team implemented well-designed ERV/ventilation to leverage cool overnight temperatures. As part of the Passive House design process, some issues were identified with cooling and being able to maintain comfort without the introduction of A/C. So we worked with them to analyze a suitable amount of PCM to help address that cooling issue and help negate the need for investment in mechanical cooling other than ventilation.

"We’ve had numerous applications where the PCM has been used with no active cooling. Most of these have been very large industrial applications where the PCM has been used to control peak plant temperatures in buildings with very high internal heat loads. The results have been very good, and we’ve seen reductions as much as 10 to 15F compared with baseline temps. Sometimes we’ll be using a higher temp PCM to promote natural re-freezing. In more conventional occupied office/housing applications we’d typically still be looking for some kind of mechanical cooling mechanism such as ventilation if air conditioning is not present. And we’d probably be more likely to consider this as a viable strategy in climates such as California or New England than say Florida where humidity and overnight temperatures are very high."

The engineering firm Thornton Tomasetti of New York conducted whole building energy modeling in WUFI Passive, the program required by the Passive House Institute US (PHIUS). The models project cooling demand of 0.74 kBtu per square foot per year and a cooling load of 1.64 Btu per hour per square foot. A PCM thermal simulation model projects a peak cooling reduction of 10 degrees F.

Will the building's actual performance be measured against these metrics in the first year of occupancy?

Elsa Mullin, senior sustainability consultant at Thornton Tomasetti, says PHIUS "does not require post-occupancy measurement and verification after initial occupancy."

Higginbottom said LEED certification for the design portion is completed. All construction requirements have been submitted and he expects a LEED Gold certificate from the U.S. Green Building Council by the end of the month.

He said the use of PCM won't be a factor in the certification process.

"A building like this can easily achieve LEED Gold without the use of this material," he said. "PCM was introduced to address thermal comfort. Active cooling does not dramatically affect the building energy consumption in a use type like this (most loads come from domestic HW and plug loads and ventilation fans which are still required irrespective of cooling design)."

It's the first time Higginbottom has used PCM in a project. He hopes to use it in future projects.

"The interesting part about this product is the ability to fine-tune a building towards net zero or net positive and also to flatten out the demand for cooling and possibly downsize equipment in the future and save money on operating and up front costs," he said. "We would like to have more research to back that up, but it’s a speculation on our part that this would be a benefit to building owners’ first costs and life-cycle costs."

Patent application: PCM-based enhancement for reversed-cycle defrosting

Ben Welter - Thursday, July 25, 2019

U.S. patent application 20190226735 (applicant Sunamp Ltd., Lothian, Great Britain):

"A thermal energy storage system in the form of a reverse-cycle defrosting vapour compression system suitable for use with systems adapted to transfer heat from at least one heat source to at least one heat sink (heat transfer system), wherein said thermal energy storage system comprises: at least two thermal energy storage units; said thermal energy storage units comprise a thermal store comprising a heat exchanger with the storage units comprising a primary coil and a secondary coil; the primary coil is dedicated for use with refrigerant fluids and is adapted for inter-connection to both a condenser and a pressure-lowering device for use with a heat transfer system; the secondary coil is dedicated for use with heat transfer fluids and wherein said secondary coils are adapted to exchange heat with the phase change material in each thermal storage unit; said primary and secondary coils are surrounded by a suitable phase change material."

http://www.freepatentsonline.com/20190226735.pdf