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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: Hollow aluminum bricks; animal-fat-based PCM for building applications; floor heating system design; more

Ben Welter - Wednesday, March 27, 2019

From Applied Thermal Engineering:

Thermal characteristics of aluminium hollowed bricks filled with phase change materials: Experimental and numerical analyses

From Energies:

Assessing the Potentiality of Animal Fat Based-Bio Phase Change Materials (PCM) for Building Applications: An Innovative Multipurpose Thermal Investigation

From Sustainable Energy and Fuels:

Innovative design of microencapsulated phase change materials for thermal energy storage and versatile applications: A review

From Environmental Research:

Design and analysis of phase change material based floor heating system for thermal energy storage

From Solar Energy Materials and Solar Cells:

Direct impregnation and characterization of Colemanite/Ulexite-Mg (OH) 2 paraffin based form-stable phase change composites
Experimental analysis of solar air collector with PCM-honeycomb combination under the natural convection

From Journal of Molecular Liquids:

Fabrication and characterization of phase change nanofluid with high thermophysical properties for thermal energy storage

From Renewable Energy:

Investigation of thermal properties and enhanced energy storage/release performance of silica fume/myristic acid composite doped with carbon nanotubes

From International Journal of Thermal Physics:

Thermal Property Characterization of a Low Supercooling Degree Binary Mixed Molten Salt for Thermal Energy Storage System

From Journal of Energy Storage:

From Energy Procedia:

Development of Corn-Oil Ester and Water Mixture Phase Change Materials for Food Refrigeration Applications
Experimental study on the performance of a new encapsulation panel for PCM's to be used in the PCM-Air heat exchanger

From Case Studies in Thermal Engineering:

Thermal characteristics on melting/solidification of low temperature PCM balls packed bed with air charging/discharging

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."

PCM briefing: Sonoco ThermoSafe partners with Cargolux; Axiom Exergy partners with Leap

Ben Welter - Friday, March 22, 2019

Amrit RobbinsAxiom Exergy has announced a partnership with Leap, a technology company that serves as an aggregator of flexible power loads in California. Axiom says the arrangement will unlock grid services revenue for its customers, including three Whole Foods Market facilities in Northern California.

Axiom's "Refrigeration Battery" system is designed to reduce a supermarket's peak power use by up to 40 percent and provide backup cooling during power outages. It uses the excess capacity of existing refrigeration systems to "store cooling" at night by freezing tanks of salt water.  

"Axiom Exergy is excited to announce that Whole Foods has connected three of their buildings to our platform, which will serve as our first Virtual Power Plant," Axiom CEO Amrit Robbins wrote in a LinkedIn post Friday. "Axiom’s platform will intelligently manage 340 kW of dispatchable load across these facilities in order to generate more value for Whole Foods and to help stabilize California’s electricity grid."

Sonoco ThermoSafe has announced a global partnership agreement with Cargolux for the leasing of the PharmaPort 360 temperature-controlled bulk shipping container. The agreement enables pharmaceutical shippers to lease PharmaPort 360 containers directly from the all-cargo airline based in Luxembourg.

• On LinkedIn this week, Ice Energy posted an update on its 5 MW contract with Riverside Public Utilities in California: "We are working to install 9 Ice Bear thermal #energystorage batteries and 13 rooftop units with Inland Mechanical Services Inc. at a car dealership in Riverside."

• A high-temperature thermal energy storage system inaugurated in Denmark this week stores heat in stones. The test system uses surplus wind power to generate hot air, which heats up small stones in an insulated container to 600 degrees. The stored heat is used to generate electricity when the wind doesn't blow. The system was developed by the energy company Seas-NVE, in collaboration with DTU Energy, Aarhus University Geoscience, Danish Energy, Energinet.dk and Rockwool.

Alexium International CEO Bob Brookins was among the presenters at the International Conference on Textile Coating and Laminating in Berlin earlier this month. His topic: "Advanced applications of phase change materials."

• The German Aerospace Center (DLR) is investigating whether Germany’s coal plants can be refitted to serve as thermal energy storage sites. "The research body, which has a track record in concentrated solar power (CSP) development, is planning a pilot that will involve ripping out the boiler from an old coal plant and replacing it with a molten salt thermal storage tank that will be heated using excess renewable energy," Greentech Media reports. "If the concept works, then advocates say it could help safeguard coal generation jobs while giving Germany tens of gigawatts of storage capacity for renewable energy load-shifting on the German grid." DLR says it is preparing a commercial-scale pilot in association with an unnamed German utility.

Research roundup: Poly (methyl methacrylate) shell; calcium carbonate shell; macroscopic composite cement mortars; more

Ben Welter - Tuesday, March 19, 2019

From Energy Procedia:

Development of microencapsulated phase change material with poly (methyl methacrylate) shell for thermal energy storage
Supercooling study of erythritol/EG composite phase change materials
Thermal performance of pouch Lithium-ion battery module cooled by phase change materials
Active cooling based battery thermal management using composite phase change materials
Investigation on Thermal Performance of an Integrated Phase Change Material Blind System for Double Skin Facade Buildings
Experimental study on preparation of a novel foamed cement with paraffin/ expanded graphite composite phase change thermal energy storage material

From Colloids and Surfaces A: Physicochemical and Engineering Aspects:

Synthesis and performance evaluation of paraffin microcapsules with calcium carbonate shell modulated by different anionic surfactants for thermal energy storage

From Journal of Materials Chemistry A:

A novel shape-stabilization strategy for phase change thermal energy storage

From Journal of Molecular Liquids:

Melting of phase change materials in a trapezoidal cavity: Orientation and nanoparticles effects

From Energy and Buildings:

Development of new nano-enhanced phase change materials (NEPCM) to improve energy efficiency in buildings: lab-scale characterization

From Applied Sciences:

Efficient Characterization of Macroscopic Composite Cement Mortars with Various Contents of Phase Change Material

From Solar Energy:

Modelling and performance analysis of a new concept of integral collector storage (ICS) with phase change material

Sunamp signs agreement with Chinese heat pump maker

Ben Welter - Monday, March 18, 2019

Sunamp Ltd. of Scotland has signed a memo of understanding with a Chinese manufacturer to develop a heat pump water heater for the residential market.

Sunamp UniQ 12 heat batteryThe new technology will combine heat pumps made by Jiangsu Gomon Renewable Energy Development Co. and Sunamp's UniQ heat batteries, which use a salt-based phase change material to store excess energy generated by solar PV systems. The stored energy is released on demand to provide heat and hot water.

The two companies signed the agreement last week at the ISH trade fair in Frankfurt. The agreement sets the terms for manufacturing and marketing the product in China and worldwide. Sunamp says product testing is already underway.

“Sunamp aims to displace as many water tanks as possible with UniQ heat batteries," said Maurizio Zaglio, Sunamp's international business development manager. "The fact that one of the largest manufacturers of water tanks in the world has decided to develop a new product with us is an important milestone for Sunamp."

In a presentation at ISH, Zaglio put it more plainly: "We are not here to complement hot water tanks - we are here to replace them!"

The deal is Sunamp's second with a major Chinese manufacturer in the past four months. In November, the company signed an agreement with Trina Solar to develop an integrated solution combining Sunamp heat batteries now made in Scotland with heat pumps manufactured at Trina's new factory in Changzhou, China.

https://www.insider.co.uk/news/heat-storage-battery-pioneer-sunamp-14121831

Research roundup: Personal cooling system; optimization of active wall system; cement mortar; asphalt pavement; more

Ben Welter - Friday, March 15, 2019

From International Journal of Refrigeration:

Experimental study of enhanced PCM exchangers applied in a thermal energy storage system for personal cooling

JMR illustration of microencapsulated n-octadecane with silk From Journal of Materials Research:

Fabrication and characterization of microencapsulated n-octadecane with silk fibroin–silver nanoparticles shell for thermal regulation

From IOP Conference Series: Earth and Environmental Sciences:

Simple Thermal Energy Storage Tank for Improving the Energy Efficiency of an Existing Air-conditioning System
An optimization study into thermally activated wall system with latent heat thermal energy storage
Simulation of operation performance of a solar assisted ground heat pump system with phase change thermal storage for heating in a rural building in Xi'an
Experimental Study on the Demand Shifting Effects of PCM Integrated Air-Conditioning Duct

From International Journal of Energy Research:

Efficiency optimisation of the thermal energy storage unit in the form of the ceiling panel for summer conditions

From Materials Research Express:

Experimental study on thermal conductivity of composite phase change material of fatty acid and paraffin

From Energies:

Design Optimization of a Hybrid Steam-PCM Thermal Energy Storage for Industrial Applications

From Construction and Building Materials:

Analysis of thermoregulation indices on microencapsulated phase change materials for asphalt pavement

From Applied Thermal Engineering:

Experimental and numerical characterization of an impure phase change material using a thermal lattice Boltzmann method

From Energy Conversion and Management:

Experimental and numerical study of a vertical earth-to-air heat exchanger system integrated with annular phase change material

From Materials:

Thermal and Structural Characterization of Geopolymer-Coated Polyurethane Foam—Phase Change Material Capsules/Geopolymer Concrete Composites

From Applied Sciences:

Microstructure and Mechanical Properties of Cement Mortar Containing Phase Change Materials

PCM briefing: 2-day training school in Barcelona; Alexium to launch foam bedding, 'top of bed' products

Ben Welter - Friday, March 15, 2019

A training school on thermal energy storage material selection, optimization and characterization will be offered May 20-21 at the University of Barcelona. The university's Center for Design and Optimization of Processes and Materials is hosting the event. The fee is 230 euros. Lecturers include Camila Barreneche, Ana Inés Fernández, Mercè Segarra and Pablo Gamallo of the University of Barcelona; Luisa Cabeza and Alvaro de Gracia of the University of Lleida, Spain; and Yulong Ding of the University of Birmingham, United Kingdom.

Alexium International Group Ltd. was among the companies making presentations this week at the Gabelli & Company Specialty Chemicals Conference in New York City. Alexium, based in Greer, S.C., and Perth, Australia, makes flame-retardant and PCM-enhanced fabric treatments. Among its "cornerstone" initiatives is a plan to launch a new product line in early 2019, Alexicool FM, the application of the company's Alexicool technology to foam mattress and "top of bed" products.  

• Thermal materials specialist va-Q-tec reports that its annual revenue grew by 8 percent in 2018. The company, based in Würzburg, Germany, said sales from its products business, including vacuum insulation panels and phase change materials, increased by 12 percent to 20.1 million euros, up from 18 million euros in 2017. However, its earnings fell by 58 percent, to 3 million euros. It blamed earnings decrease on investment costs and a rise in sales from its lower-margin products business.

• Australian researchers are challenging the belief that 22° C (72° F) is the optimum temperature to maintain worker productivity. A team from Griffith University’s School of Engineering and Built Environment and Cities Research Institute performed an extensive review of research literature on the relation of moderate thermal environment to cognitive performance. "From the research point of view," the lead researcher, Fan Zhang, said in an interview with the Cooling Post, "there is no empirical evidence that this temperature [22ºC] should be maintained. In effect, it is inconsistent with the already-established comfort benchmarks such as ASHRAE 55-2017, which recommends a summer time thermal comfort zone of 23-26ºC. I would say 23-26 is a safe summer temperature set point range for western developed countries."

Research roundup: Radiant floor heating system; mitigation of supercooling; hot water stratification; more

Ben Welter - Friday, March 08, 2019

From Energies:

Analysis of Thermal Performance and Energy Saving Potential by PCM Radiant Floor Heating System based on Wet Construction Method and Hot Water

From Applied Energy:

Supercooling of phase-change materials and the techniques used to mitigate the phenomenon

From Polymer Chemistry:

Encapsulating an organic phase change material within emulsion-templated poly(urethane urea)s

From AIP Advances:

Thermal expansion effects on the one-dimensional liquid-solid phase transition in high temperature phase change materials

From Journal of Materials Chemistry A:

A thermal energy storage composite with sensing function and its thermal conductivity and thermal effusivity enhancement

From Materials Science and Engineering:

Experimental Measurements of Hot Water Stratification in a Heat Storage Tank

From Thermochimica Acta:

Modification of physical and thermal characteristics of stearic acid as a phase change materials using TiO2-nanoparticles

From Energy and Buildings:

Thermal and Structural Performance of Geopolymer Concrete Containing Phase Change Material Encapsulated in Expanded Clay
An experimental study on applying organic PCMs to gypsum-cement board for improving thermal performance of buildings in different climates

From International Journal of Biological Macromolecules:

Sodium alginate/feather keratin-g-allyloxy polyethylene glycol composite phase change fiber

From Construction and Building Materials:

Thermal properties of lightweight concrete incorporating high contents of phase change materials

From Progress in Organic Coatings:

Fabrication and characterization of microencapsulated n-heptadecane with graphene/starch composite shell for thermal energy storage

From Sustainable Energy and Fuels:

A thermal energy storage prototype using sodium magnesium hydride

From Thermal Science and Engineering Progress:

Experimental investigation of the thermal performance of a helical coil latent heat thermal energy storage for solar energy applications

From International Journal of Sports Physiology and Performance:

Exploring the Efficacy of a Safe Cryotherapy Alternative: Physiological Temperature Changes from Cold Water Immersion vs Prolonged Phase Change Material Cooling

From Applied Sciences:

A Form Stable Composite Phase Change Material for Thermal Energy Storage Applications over 700° C

PCM briefing: Boston food bank installs Viking Cold TES system; 2-day workshop on microencapsulation

Ben Welter - Friday, March 08, 2019

The Greater Boston Food Bank is reporting a 75 percent reduction in energy use during targeted peak hours since the beginning of the year after installing a Viking Cold Solutions thermal energy storage system for the refrigeration units at its 117,000 square-foot, high-efficiency Yawkey Distribution Center.

Maria Telkes• To mark Women's History Month, 24/7 Wall St. has compiled a list of "50 Things You Never Knew Were Invented by Women." MIT researcher Maria Telkes, a pioneer in the field of solar thermal storage, is on the list at No. 30. She created the first solar-heated system for her home in Dover, Mass., in 1947. The system used a phase change material, sodium sulfate decahydrate, to store solar heat.

• Researchers at the Chinese Academy of Sciences say they have developed an inexpensive, flexible film that renders the objects it covers virtually invisible in infrared light. The film's main components are DuPont's Kevlar, a synthetic fiber with high tensile strength, and polyethylene glycol, a phase change material that can store heat. 

• French utility ENGIE has begun production at one of South Africa’s largest renewable energy projects, the 100MW Kathu Solar Park. The concentrated solar plant's molten salt storage system provides up to 4.5 hours of thermal energy storage.

• The Southwest Research Institute is hosting a two-day workshop on microencapsulation March 25-26 in San Antonio, Texas. The introductory course will cover topics such as atomization (spray drying, spray chilling, spray congealing) and spray coating (fluid bed coating, granulation). The cost is $950.

• The University of California is winning praise for its decision to end its subscription deal with Elsevier, the world’s biggest publisher of scientific journals. UC is the first major university system to push for open-access publishing. UC, which had been paying $11 million a year to Elsevier in subscription fees, generates about 10 percent of the research produced in the United States. “It’s ridiculous that, in this age of the internet, researchers are paying huge fees for access to academic papers and for publication of their own work,” the San Jose Mercury News said in a March 6 editorial.   

PCM briefing: Energy Storage Europe includes sessions on thermal storage; C-Therm offers webinar on thermal performance of textiles

Ben Welter - Monday, March 04, 2019

• The Energy Storage Europe conference and trade fair, set for March 12-14 in Dusseldorf, Germany, includes a number of sessions on thermal energy storage: "Heat Storage - an essential contribution to energy transition," Oliver Baudson, TSK Flagsol Engineering GmbH; "Advanced Thermal Energy Storage Concepts," Dr. Robert Pitz-Paal, DLR Institute of Solar Research; "High Temperature Storage," Doron Brenmiller, Brenmiller Energy; "Material and Component Development for Thermal Energy Storage," Christoph Rathgeber, ZAE Bayern; and "Thermal Energy Storage for Cost-Effective Energy Management & CO2 Mitigation," Dr. Dan Bauer, German Aerospace Center - DLR e.V.

• The deadline for submitting paper proposals for next fall's Advanced Building Skins conference in Bern, Switzerland, is March 10. The list of topics includes thermal performance of phase change materials.

• Thermal battery maker Sunamp Ltd.'s collaboration with the University of Edinburgh’s School of Chemistry won the "Powerful Partnership" award at the Scottish Knowledge Exchange Awards 2019 last month. The organizations began work on the development of new phase change materials in 2010. 

• Croda International Plc has been recognized for its commitment to "a deforestation-free supply chain." Croda earned an A- in that category in CDP's climate change report for 2018, up from a B the previous year. The specialty chemical company says it has a special focus on palm oil and is committed to supplying RSPO-certified palm oil derivatives. 

• Thermal instrumentation maker C-Therm Technologies Ltd. is hosting a free webinar this week, "Quantifying Thermal Performance of Textiles (Warm Feel / Cool Touch)." The webinar, aimed at "anyone working in the product performance testing of textiles and fabrics where temperature regulation is an important function," will be held at 1 p.m. EST Wednesday.