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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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PCM briefing: Cold chain veteran joins Phase Change Energy Solutions; Outlast showcases new nylon filament yarn

Ben Welter - Friday, May 10, 2019

Bruce TruesdaleBruce Truesdale has joined Phase Change Energy Solutions of Asheboro, N.C., as director of business development - cold chain. He was formerly senior supply chain consultant at Verta Life Sciences and director of health care at Protek Pharma Worldwide. He declined an interview request, but his new job title suggests that PCES, whose product line now focuses on HVAC, building and thermal energy storage, has an interest in the temperature-controlled packaging market. Earlier this year, PCES announced an investment by Pegasus Capital Advisors, Emerald Technology Ventures and Third Prime, an early-stage venture fund and prior investor. The company said it would use the proceeds to fund the continued development of its thermal storage products and expand its operations globally.

Chalmers University of Technology of Sweden has an opening for a postdoctoral researcher in thermal energy storage for building applications. The research group Building Physics is working "to find out how novel TES with phase change materials (PCM) could complement the existing district heating and cooling networks and co-operate with other peak shaving techniques (water accumulator tanks, ground heat storage pumps, etc.) through smart thermal grids." The application deadline is June 9.

Outlast will showcase its new nylon filament yarn at the Techtextil trade show in Frankfurt, Germany, next week. "The PCMs optimized for this specific application," Outlast says, "are included directly inside the polyamide fibers." Potential applications include next-to-skin products such as undergarments, shapewear, sportswear and hosiery. The company says it now sources the majority of PCMs used in its products from renewable instead of synthetic raw materials.

PCM coolerA PCM coating designed to absorb heat from rockets is among the dozens of NASA spinoffs listed in the latest issue of Spinoff, an annual publication that has been documenting space agency spinoffs since 1976. In the early 2000s, Raj Kaul, a materials scientist at Marshall Space Flight Center, began researching a way to use PCM to keep the outside of spacecraft at a safe temperature. An entrepreneur eventually snapped up the patent for the coating Kaul developed and is working on a number of products based on the technology, including aircraft paint, pipe heat traps and an iceless cooler, shown at right. 

• The U.S. Department of Energy this week announced $89 million in funding for "innovative, advanced manufacturing research and development projects." "Innovations for the Manufacture of Advanced Materials," one of three areas to receive funding, includes phase change storage materials for heating and cooling applications. The department anticipates making up to 55 awards for up to three years. Concept papers are due on June 20.

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: Surface functionalization of composite PCM; EnergyPlus optimization; direct expansion solar heat pump; more

Ben Welter - Friday, April 26, 2019

From Applied Surface Science:

Effects of surface functionalization on thermal and mechanical properties of graphene/polyethylene glycol composite phase change materials

From Applied Energy:

Facile flexible reversible thermochromic membranes based on micro/nanoencapsulated phase change materials for wearable temperature sensor
Shape-remodeled macrocapsule of phase change materials for thermal energy storage and thermal management
Investigation on the thermal performance of a high temperature packed bed thermal energy storage system containing carbonate salt based composite phase change materials
Toward a new method for the design of combined sensible/latent thermal-energy storage using non-dimensional analysis
Strategic control and cost optimization of thermal energy storage in buildings using EnergyPlus
Adaptive measures for mitigating urban heat islands: The potential of thermochromic materials to control roofing energy balance

From Solar Energy Materials and Solar Cells:

Poly(styrene-co-divinylbenzene-co-acrylamide)/n-octadecane microencapsulated phase change materials for thermal energy storage

From Renewable and Sustainable Energy Reviews:

Recent advances in direct expansion solar assisted heat pump systems: A review
Review on nanoporous composite phase change materials: Fabrication, characterization, enhancement and molecular simulation

From Energy and Buildings:

Experimental Testing of Phase Change Materials in a Warm-Summer Humid Continental Climate

From International Journal of Energy Research:

Development of pentadecane/diatomite and pentadecane/sepiolite nanocomposites fabricated by different compounding methods for thermal energy storage

From Applied Thermal Engineering:

Heat transfer performance of graphene nano-platelets laden micro-encapsulated PCM with polymer shell for thermal energy storage based heat sink

From Journal of Applied Polymer Science:

Investigations on thermal properties of microencapsulated phase‐change materials with different acrylate‐based copolymer shells as thermal insulation materials

From Solar Energy:

Experimental investigation on the impact of thermal energy storage on the solar still performance coupled with PV module via new integration

From Thermochimica Acta:

Nanoencapsulated phase change material with polydopamine-SiO2 hybrid shell for tough thermo-regulating rigid polyurethane foam

From International Journal of Heat and Mass Transfer:

Optimization of the detailed factors in a phase-change-material module for battery thermal management

From Journal of Traffic and Transportation Engineering :

A review on the best practices in concrete pavement design and materials in wet-freeze climates similar to Michigan

From Case Studies in Thermal Engineering:

Study of a passive solar air heater using palm oil and paraffin as storage media

From Acta Microscopica:

Preparation of Graphene Hybrid Material and Thermal Properties of Polymer Composites

PCM briefing: 'Awareness' of PCM technology seen as key challenge; researchers develop novel anti-icing material

Ben Welter - Friday, April 26, 2019

University of Illinois at Chicago researchers say they've developed a material that can inhibit the formation of ice much longer than existing technologies, New Atlas reports. The anti-icing material is made of phase-changing liquids that have heat-trapping properties. Researchers say the material works effectively in temperatures as low as -15° C.

Collin CokerIn an interview with Engineered Systems, Viking Cold Solutions' vice president of sales and marketing talks about the state of the thermal energy storage market and the company's PCM-based thermal storage systems. What's been the Houston company's biggest challenge over the past 18 months? "Awareness," said Collin Coker, right. "We constantly hear, 'This is really interesting; I've never seen it before; do you have fluid moving through the refrigeration system?' So, breaking it down and explaining that it’s non-mechanical and very simple is part of the challenge. Getting people to believe that this technology can provide savings in the range of 10-50% in some applications is also a challenge. A lot of folks are fairly guarded, because that level of savings has never been achieved in this industry before. It just seems too good to be true. "

• The World Bank announced a new program this week to accelerate the adoption of sustainable cooling technologies, including air conditioning, refrigeration and cold chain in developing countries. The program will provide technical assistance to ensure that efficient cooling is included in new World Bank Group investment projects.

Sonoco ThermoSafe has posted the agenda for the company's next Leading Minds Seminar, to be held May 29 in Princeton, N.J. Co-hosted by ELPRO, the seminars offer a chance for pharmaceutical manufacturers, supply chain partners and government representatives to discuss temperature-assurance packaging and data monitoring in a collaborative environment. Panelists for a discussion on reusable shipping systems include Mark Everitt, qualification engineer at AstraZeneca, and Michael English, director of engineering at Merck.

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: Ice Energy signs distribution deal; Bloom joins Sunamp as board chairman

Ben Welter - Monday, April 22, 2019

Ice Energy of Santa Barbara, Calif., has reached distribution agreements with four California companies to sell, install and maintain its ice-based thermal storage system, the Ice Bear 20. The companies are Correy Baker Heating and Air of Murrieta; Emery Mechanical Engineering of San Diego; H3 of Santa Barbara; and SunRize Mechanical of Temecula. “This distribution network will enable us to further expand our footprint in the residential market in Southern California,” said Marcel Christians, co-COO of Ice Energy.

Sonoco ThermoSafe and AirBridgeCargo Airlines have announced a global partnership agreement for the leasing of the PharmaPort 360 temperature-controlled shipping container. The agreement will enable pharmaceutical shippers to lease PharmaPort 360 containers directly from AirBridgeCargo.

Martin Bloom• Thermal battery maker Sunamp Ltd. of Scotland has appointed Martin Bloom as chairman of the board. Bloom, right, has extensive experience in high-growth technology and renewable energy companies, including Chinese solar company Renesola and Loughborough-based fuel cell specialist Intelligent Energy. Bloom succeeds Sunamp’s founding chairman, Bob Pettigrew, who oversaw its early growth.

Nominations are being accepted for the 2019 Poncelet Prize for Innovation in Microencapsulation, co-sponsored by Procter & Gamble and the Bioencapsulation Research Group. The award recognizes innovation in process design and modernization; development of new core and shell materials; innovation in characterization methods; or innovation in emerging fields of applications. The deadline for submitting nominations is May 31, 2019.

Peli BioThermal is rebranding its Chronos temperature-controlled shippers. CoolGuard PCM will replace Chronos Express, and CoolGuard Advance will replace Chronos Advance. The CoolGuard shippers will offer configurations with fewer components and additional temperature set points, such as 16º C.

• Registration is open for "Phase Change Material & Passive Cooling in Large Venues," a lunch-hour presentation by Henderson Engineers. The free event, sponsored by AIA Kansas City, will be held June 12 at the Center for Architecture & Design in Kansas City, Mo.

Axiotherm GmbH's kraftBoxx thermal energy storage system is a finalist for a Smarter E Award in the renewable energy category. KraftBoxx is a joint development with Klara Energy and Tuxhorn within the scope of the PCM-based HeatSel product line marketed by Axiotherm. Winners will be announced May 15 in Munich.

• PCM expert Harald Mehling's new book is available on Amazon: "Understanding the Basics of Energy: An Introduction from Simple to Complex Situations."

Tempur-Pedic of Lexington, Ky., says its new TEMPUR-breeze mattress will help sleepers "stay up to 8 degrees F cooler through the night." According to Tempur-Pedic: "At about 80°F, the molecules within TEMPUR-breeze’s most efficient Phase Change Material (PCM) to-date, PURECOOL+, activate, shifting from a solid to a liquid to absorb massive amounts of heat. For the first time, Tempur-Pedic’s scientists successfully altered these proprietary molecules to deliver more phase change material, increasing its capacity to absorb heat by 2x compared to other PCM."

• Two new ASHRAE publications will be available in June: "Owner’s Guide for Buildings Served by District Cooling" and an updated edition of the "District Cooling Guide" for designers and building owners around the world.

• Researchers at Sweden's KTH Royal Institute of Technology have developed a polyethylene glycol-infused wood material that could be used to make windows that absorb heat during the day and release it into the home at night. The researchers are working to increase the heat storage capacity of the transparent wood, Smithsonian.com reports.

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."