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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.




Patent application: Reflective temperature modulating blanket

Ben Welter - Thursday, April 11, 2019

U.S. patent application 20190106878 (inventor Robert Joe Alderman, Poteet, Texas):

"A temperature modulating blanket utilizing a reflective surface to block radiation away from a phase change material [110] during daylight and in thermal conductivity with the material to allow heat conduction out of the material at night at a faster rate than it is absorbed during the daylight. The reflective surface is uniquely tailored to both serve a reflective function during daylight while also being sufficiently thermally conductive to facilitate the heat conduction as indicated during night. Additionally, the facilities may be uniquely configured to promote an attic circulation that further facilitates freezing and recharge of the phase change material of the blanket during night hours."

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.

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."

Patent application: Gel comprising a phase change material

Ben Welter - Sunday, March 24, 2019

U.S. patent application 20190085226 (applicant Cold Chain Technologies Inc., Franklin, Mass.):

CCT PCM gel product"Gel including a phase-change material and a gelling agent. In one embodiment, the phase-change material may be n-tetradecane, n-hexadecane or mixtures thereof. The gelling agent may be a high molecular weight styrene-ethylene-butylene-styrene (SEBS) triblock copolymer with a styrene:rubber ratio of about 30:70 to 33:67% by weight. To form the gel, the phase-change material and the gelling agent may be mixed at an elevated temperature relative to room temperature to partially, but not completely, dissolve the gelling agent. The mixture may then be cooled to room temperature. Alternatively, the phase-change material and the gelling agent may be mixed at room temperature, and the mixture may then be heated to form a viscoelastic liquid, which is then cooled to room temperature. The invention is also directed at a method of preparing the gel, a thermal exchange implement including the gel, and a method of preparing the thermal exchange implement."

Patent application: Multilayer thermal laminate

Ben Welter - Saturday, March 23, 2019

U.S. patent application 20190089027 (applicant Dell Products L.P., Round Rock, Texas):

"A multilayer thermal laminate with aerogel is used for a battery cell enclosure to improve thermal properties and to reduce thermal inhomogeneity in the form of localized hotspots that exceed a desired rated temperature, thereby enabling a more compact design within rated thermal design limits for a given electrical performance. ... [The third layer of the laminate] serves as a thermal storage medium and may accordingly be comprised of a phase change material, such as a wax. The phase change material may be selected to have a desired melting temperature range, such as between 30 C and 70 C, between 45 C and 65 C, or between 40 C and 60 C, in given implementations, among other possible melting temperature ranges."

Patent application: Removable sticker for cooling hot spots in cellular phones

Ben Welter - Saturday, March 23, 2019

U.S. patent application 20190086158 (inventor James Hirschfeld, Delray Beach, Fla.):

"A removable cooling sticker secured to the surface of a cellular telephone for extraction of heat from the cellular telephone. The cooling sticker is thin and sized to be conveniently carried. [Using phase change material as the active heat extraction material,] the cooling sticker is adhered to the cellular telephone at its hot spot for maximum efficiency. An optional feature employs thermal strips that indicate when the electronic device is exceeding a temperature threshold sticker."

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

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

Patent application: Mobile lab for rapid detection and analysis of biological targets

Ben Welter - Friday, March 15, 2019

U.S. patent application 20190076844 (applicant MRIGlobal, Kansas City, Missouri):

"A mobile field-deployable laboratory to more conveniently enable the detecting, sequencing and analyzing of biological agents at the point-of-need. This device enables field operators to go from sample to actionable information in the field without the need for an internet connection or grid-based power. ... [The] cooling system includes a phase-change cooling system capable of holding a predetermined selected temperature constant for a predetermined time period."