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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: 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."

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

Patent application: One-piece insulating container

Ben Welter - Friday, March 15, 2019

U.S. patent application 20190077576 (inventors Drayton G. Miller, Dauphin Island, Ala., and William J. Gunn, Springfield, Ill.):

"A one-piece cushioning and insulating container and insulation template for forming the container are provided. The insulation template includes a case blank and an insulating member secured thereto. The template may be formed into a three-dimensional container that provides cushioning and insulating items contained inside the container by simultaneously folding the case blank and insulating member. The template is designed to provide a completely enclosed space that is cushioned and insulated on all sides. The dimensions of the template may be adjusted to create containers of varying dimensions. The container may be constructed of various materials with a layer of soft, flexible material secured therein. The template may have heating or cooling elements, including phase change materials, incorporated into insulating member."

http://www.freepatentsonline.com/20190077576.pdf

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.