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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: va-Q-tec opens North American headquarters; Viking Cold Solutions begins Phoenix-area installation

Ben Welter - Friday, January 19, 2018

• PCM maker va-Q-tec AG officially opened its new North American headquarters in Langhorne, Penn., this week. Va-Q-tec will use the 20,000-square-foot facility to showcase new products and to manufacture its small temperature-control shipping containers. The location will also serve as a hub for the company's rental and repair operation. “The investment in this new facility is a testament to our commitment to grow the business and expand our footprint in North America," said CEO Dr. Joachim Kuhn.

Drones that deliver sterile mosquitoes in the fight against the Zika virus will be field tested in Latin America early this year. The system, developed by the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture's Insect Pest Control Laboratory, uses phase change material to keep the mosquitoes inactive during transportation. 

• New from Greentech Media: "The Next Five Years in Energy Storage According to 500 Energy Professionals"

• New from Global Info Research: "North America Advanced Phase Change Materials (PCM) Market by Manufacturers, Countries, Type and Application, Forecast to 2022"

• New from Technavio: "Global Advanced Phase Change Materials Market 2017-2021

Viking Cold Solutions has begun installing its PCM-based thermal energy storage system in a 10,000-square-foot freezer at the Bashas food distribution center in the Phoenix area. The system, which consists of salt-hydrate-filled panels suspended from warehouse ceilings, is designed to significantly reduce energy costs by shifting peak demand to nighttime hours.

• The cost of renewable energy is falling so fast that it should be a consistently cheaper source of electricity than fossil fuels by 2020, according to a new report from the International Renewable Energy Agency

Utility Dive takes a close look at Nantucket Island's "hybrid" plan to add energy storage, including thermal storage, to stave off expensive grid enhancements.

PCM heat-recycling system keeps tugboats ready for action

Ben Welter - Friday, January 19, 2018

ZP Bison

Tugboats are the tireless workhorses of the world’s rivers and harbors. These powerful watercraft must remain on standby for long periods, ready to assist other vessels at a moment’s notice. The energy required to keep the engines warm and the cabin comfortable in cold climates is usually derived from electrical shore power. That’s expensive and inefficient.

Kotug International BV has developed an on-board system that captures heat produced by the engines and stores it in a tank that contains phase change material. The Dutch company installed the heat recycling system on one of its tugboats, the ZP Bison, in 2016. The result: Shore power consumption has been cut in half on the Hamburg-based tugboat.

Koos Smoor, manager for fleet performance and innovation at Kotug, oversaw development of the system, which won the Maritime Innovation Award 2017 in November.

“The use of PCM technology is new in the maritime industry and has great potential not only for tugboats, but for every type of vessel, as it can be tailored to different spaces and user profiles,” Smoor said. “Kotug is looking into more applications for temperature control purposes.”

Smoor answered a few PCM-related questions by e-mail:

Q: When did Kotug begin developing the heat recycling system?

A: “Two years ago we tested heat storage on our hybrid tugs to reduce the ‘hotel load’ during standby. The hotel load is the generator load in kilowatts when the tug is not working. It is mainly heating or cooling and pre-heating of the main engines.”

Q: What type of PCM is used in the system (salt hydrate, paraffin, biobased)?

A: “We are still testing multiple PCM materials.”

Q: What is the PCM's peak melting point?

A: “85 degrees is the 'coolwater' temperature of the engines. The coolwater of the main propulsion engines is used to heat up the PCM buffer. We also did test to use heat from the exhaust gasses to heat up the PCM buffer. However that is more complicated, and we stopped with that.”

Q: What is the PCM's heat capacity?

A: “The heat capacity is 73 Kwhr/m3.”

PCM tank in ZP Bison engine roomQ: How is the PCM tank configured, what are its dimensions, how much PCM is used? 

A: “The PCM tank [shown at right] is approximately 2 cubic meters. The PCM is warmed up by the coolwater of the engines. We like to keep the heat exchanger in the buffer for ourselves as we are working on a patent.”

Q: Who is the PCM manufacturer?

A: “The PCM material is manufactured in China.”

Q: How many tugboats are in Kotug's fleet?

A: “Worldwide Kotug and its joint ventures consist of approximately 120 tugboats.”

Q: Are there plans to install the heat recycling system in other Kotug vessels?

A: “Yes, we are looking into more installations on more tugboats. The installation can be done during the five-year maintenance period cycle of the tugboat. Note: Many tugs operate in the tropics where there is no need to preheat the engines. On these tugs there is no application for PCM materials.”

Q: Are there plans to license the technology for use by other towage operators?

A: “We are still looking into this.”

Patent application: Thermal energy storage apparatus with PCM

Ben Welter - Friday, January 19, 2018

Neothermal patent drawingU.S. patent application 20180017337 (applicant NeoThermal Energy Storage Inc., Timberlea, Canada):

"A thermal energy storage apparatus is disclosed. The apparatus includes a base and fluid flow plates which cooperate with the base to define a cavity; a phase change material contained within the cavity; an extendable extension spring [40] at least partially contained within the phase change material [14]; and end plates which cooperate with the fluid flow plates to define fluid flow channels. Inlet and outlet ports allow for the ingress and egress of a heat exchange fluid into the fluid flow channels. In operation, the extension of the extendable extension spring induces solidification of at least a portion of the phase change material from a supercooled liquid state to a solid state, releasing thermal energy, allowing for the transfer of thermal energy across the fluid flow plates from the phase change material to the heat exchange fluid."

http://www.freepatentsonline.com/20180017337.pdf

Research roundup: Review of latent heat storage systems; triple-glazed window with PCM; myristic acid; more

Ben Welter - Wednesday, January 17, 2018

Design of a Latent Thermal Energy Storage System From Constructal Approach [ASME 2017 International Mechanical Engineering Congress and Exposition]

Latent Heat Thermal Energy Storage Systems with Solid–Liquid Phase Change Materials: A Review [Advanced Engineering Materials]

Simulation Research on the Dynamic Thermal Performance of a Novel Triple-glazed Window Filled with PCM [Sustainable Cities and Society]

Charging and Discharging Period Analysis of Myristic Acid as Phase Change Material [pdf] [International Journal of Current Engineering and Technology]

Solid-liquid phase equilibria of stearic acid and dicarboxylic acids binary mixtures as low temperature thermal energy storage materials [Journal of Chemical Thermodynamics]

Comparative study on the solar still performance utilizing different PCM [Desalination]

Temperature stabilization using salt hydrate storage system to achieve thermal comfort in prefabricated wooden houses [Energy and Buildings]

Multiobjective optimization of a building envelope with the use of phase change materials (PCMs) in Mediterranean climates [International Journal of Energy Research]

Experimental research in the phase change materials based on paraffin and expanded perlite [Phase Transitions]

Enhanced Thermal Conductivity and Thermal Performance of Polyethylene Glycol (PEG)/Modified SiO2 Composite Phase Change Material [Science of Advanced Materials]

PCM briefing: Cleanergy to develop solar TES in Morocco; SpaceX has opening for a thermal engineer

Ben Welter - Friday, January 12, 2018

Cleanergy AB of Sweden and the Moroccan Agency for Sustainable Energy have agreed on a framework to jointly develop a thermal energy storage system using Cleanergy's Stirling-based solar electricity technology.

• Applications are being accepted for the World Materials Forum Startup Challenge. Companies with fewer than 50 employees are eligible for the competition, which recognizes technical or organizational breakthroughs in one of five categories, including materials composition, product design and 3D manufacturing. The winning company will receive a 50,000 euro award at the World Materials Forum in June in Nancy, France.

Grace Hsia, co-founder and CEO of Warmilu LLC, is among 14 entrepreneurs in the running for the $1 million top prize in the WeWork Creator Awards Global competition. The winner will be announced in New York City on Jan. 17.

• Prize money totaling 52,500 euros, financed by Germany's National Climate Initiative, is up for grabs in the German Refrigeration Prize 2018 competition, honoring innovations in air conditioning and refrigeration. The entry deadline is Jan. 31. Winners will be announced at the Berlin Energy Days conference in May.

SpaceX is seeking candidates for the position of thermal engineer.  

Pacific Gas & Electric will introduce a new electric time-of-use rate in April. The California utility says the optional rate will make energy use more efficient and minimize peak demand challenges. The peak pricing will be from 4 p.m. to 9 p.m.

Bain & Co. has analyzed how chemical companies can "demystify" the R&D process. Among the three common "failure modes" Bain identified: "strong team running in too many directions."

Buro Happold associate Mark Dawson will speak on the topic of "phase change materials for ultimate thermal efficiency" at the 2018 Materials for Architecture conference in London in April.

Fluorination process enhances barrier properties of HDPE

Ben Welter - Friday, January 12, 2018

HDPE panelsHigh-density polyethylene (HDPE) is a popular choice for containment of paraffin- and plant-oil-based phase change material. But under some conditions, PCM-filled HDPE containers are vulnerable to leaching.

Inhance Technologies of Houston has developed a process called ColdShield™ to enhance HDPE's barrier properties. In an email interview, Prakash Iyer, senior vice president of business development and technology at Inhance, answered questions about the process.

Q: How does ColdShield work?

A: HDPE is not stable when exposed to organic solvents such as paraffins and plant oils. Many PCM formulations are organic in nature and will readily permeate through HDPE, causing contamination of the surroundings and irreversible damage to the contents being transported. Inhance, through the use of its proprietary barrier treatment process, developed ColdShield technology to specifically prevent permeation of paraffin and plant oil based phase change materials.

"ColdShield provides a double barrier layer by protecting the inside and outside wall of the PCM container. The technology converts the surface of ordinary HDPE into a high-performance barrier material which repels paraffins and plant oils. The surface of HDPE is converted into a ‘PTFE’ like material with excellent barrier properties. By keeping the PCM formulation in the bottle from permeating, Inhance’s ColdShield prevents temperature drifts of the packaging due to selective absorption of the PCM formulation into the bottle walls. In addition, due to its superior barrier protection, ColdShield allows reuse of the PCM containers for many years with minimal to no reconditioning."

Q: Inhance tested five PureTemp formulations in ColdShield-enhanced HDPE containers. Describe the results.

A: "Inhance tested PureTemp 4N, PureTemp 8N, PureTemp 18X, PureTemp 20X and PureTemp 23N to study how these PCM formulations permeated through HDPE containers. Testing for permeation was done at 50° over 28 days, which would roughly equate to a two-year shelf life. All PureTemp PCM formulations, except for PT20X, showed varying amounts of permeation (ranging from 0.25-3% weight loss) through HDPE. The same PCM formulations when tested in ColdShield-treated HDPE containers exhibited less than 0.1% permeation weight loss. In addition to PureTemp formulations, Inhance also tested hexadecane and tetradecane, which are commonly used in PCM formulations. The permeation rates of hexadecane and tetradecane without barrier protection is 3-5%, while ColdShield reduces this to 0.1%. The chart below reflects the data."

Q: How do you test ColdShield-treated containers for leaching?

A: "One of the simplest tests to evaluate for leaching is to do a weight-loss test on HDPE containers filled with these PCM formulations. Testing can be done at different temperatures for varying amounts of time. 49CFR.173 Appendix B, describes the commonly used test procedure to evaluate for permeation of liquids in plastic packaging, and is generally done at 18°C for 180 days, or 50°C for 28 days, or 60°C for 14 days. Per the U.S. Department of Transportation, the maximum permissible permeation rate for the above testing conditions should not be greater than 2% for nonpoisonous liquids."

Q: Describe the shape and dimensions of the containers tested with PureTemp, including wall thickness. 

A: "The testing was done with 16-ounce round containers with a nominal wall thickness of 1mm. To give one perspective, the 16-ounce round container will be the best-case scenario for permeation since the surface area to volume of liquid is minimized, resulting in lower permeation numbers. In the case of HDPE PCM containers, they are generally flat and rectangular, increasing the surface area to volume ratio, which would result in worse permeation numbers."

Q: Is the ColdShield process patented?

A: "ColdShield technology has been developed by Inhance using proprietary process technologies. The technology itself is based on post-mold fluorination of HDPE containers, but Inhance has worked to understand the market needs and worked closely with its customers to come up with the optimum barrier required to eliminate permeation of PCM formulations."

Q: Are ColdShield-enhanced HDPE containers now being produced commercially for any PCM manufacturers?

A: "ColdShield-enhanced HDPE containers are being commercially used by some of the largest manufacturers of PCM formulations as well as OEMs involved in the cold chain logistics chain."
 
Q: On a percentage basis, how much does the ColdShield process add to the cost of an HDPE container?

A: "The cost of ColdShield is minimal compared to the value that it brings to the OEMs. The permeation of PCM into the package can result in costly recalls and contamination issues. Cold chain is used to often transport vaccines, biologics and organs across the globe and the loss/contamination of these contents can run into the millions. ColdShield provides the best barrier solution for HDPE rigid gel packs, thereby maintaining the PCM composition, while providing safe storage during transportation."

Q: Has research on ColdShield performance been published?

A: "ColdShield brochures are available on www.inhanceproducts.com. For further information contact info@inhanceproducts.com. Inhance is glad to partner with companies to educate them on the advantages of ColdShield and works closely with its customers to provide the optimum solution. Inhance also has test capabilities to carry our permeation testing as well as other fitness testing of different PCM formulations."

Q: Has the effect on heat transfer or other PCM performance characteristics been tested? How about the effect of, say, thousands of freeze/melt cycles on barrier properties?

A: "Inhance’s ColdShield technology has been tested and approved by OEMs and molders through stringent testing, including, but not limited to, permeation, freeze/melt cycles as well as mechanical testing. Since ColdShield is not a coating – ColdShield chemically transforms the surfaces of containers into a material that is resistant to solvents – there is no cracking or peeling of the barrier layer. In addition, since ColdShield does not change the bulk properties of the rigid gel pack, there is no change in the heat transfer profile. In addition, ColdShield provides a double layer of protection since the inside and the outside of the container is protected equally."

Q: Who are your competitors in this field, and how are your processes different?

A: "There are three or four options when it comes to how PCMs are packaged today. These include non-barrier HDPE containers, metal or barrier plastics such as nylon. In many cases, Inhance's ColdShield is the most economical and the best performing barrier solution in the market. As the market moves more towards better temperature control ranges, more paraffins and plant-oil based PCM formulations, ColdShield is the preferred barrier solution in the industry."

Q: What is the potential market size for ColdShield?

A: "Inhance currently treats millions of rigid PCM containers using its ColdShield technology. The market for these containers that need barrier protection from PCM formulations is growing significantly, due to some of the above stated reasons. The addressable market for Inhance’s ColdShield continues to grow with greater adoption of PCM formulations."

Inhance Technologies video image

A company video illustrates some of Inhance Technologies' capabilities.  

Patent application: Capsules having surfactant tethered outer shells

Ben Welter - Thursday, January 11, 2018

U.S. patent application 20180009996 (applicant Microtek Laboratories Inc., Dayton, Ohio):

"Microcapsules are disclosed that have a core composition encapsulated within a polymer wall, and an inorganic shell connected to an exterior surface of the polymer wall by a surfactant. The inorganic shell has a cation attracted to the surfactant and an anion or anion equivalent chemically bonded to the cation to form the shell or has the metal portion of a metal-containing compound attracted to the surfactant to form the shell. The shell may comprise a Ca, Mg, or Ag metal compound. The shell may be a graphene oxide-metal compound."

http://www.freepatentsonline.com/20180009996.pdf

Patent application: Encapsulated PCM and thermal battery

Ben Welter - Thursday, January 11, 2018

U.S. patent application 20180010862 (Valeo Systemes Thermiques, Le Mesnil Saint-Denis, France):

Valeo patent drawing"The present invention relates to an encapsulated phase-change material comprising a phase-change material (3) contained within a tube (5), said tube being made of plastic and that it has a sealing weld (9) at least at one of its ends. ... The presence of sealing welds allows good sealing and also reduces the risk of leakage of phase-change material notably when the latter is in the liquid phase."

http://www.freepatentsonline.com/20180010862.pdf

Research roundup: Protective clothing for firefighters; PCM-integrated wall insulation; TES using diesel engine exhaust; more

Ben Welter - Thursday, January 11, 2018

Guidelines for the specification of a PCM layer in Firefighting Protective Clothing Ensembles [Applied Thermal Engineering]

Summer thermal performances of PCM-integrated insulation layers for light-weight building walls: effect of orientation and melting point temperature [Thermal Science and Engineering Progress]

Numerical investigation on cooling behaviour of buildings using phase change material [International Journal of Renewable Energy Technology]

An experimental investigation of PCM based thermal energy storage system using diesel engine exhaust-gas [International Journal of Renewable Energy Technology]

Thermal storage/management system with phase change materials for building [Advances in Mechanical Engineering]

Patent application: Heating water with refrigerant and PCM

Ben Welter - Thursday, January 11, 2018

U.S. patent application 20180010822 (applicant Rheem Manufacturing Co., Atlanta, Ga.):

"An apparatus for heating water has a tank for storing water and an air conditioning system that defines a refrigerant flow path through which refrigerant flows. The refrigerant flow path passes through a heat exchanger so that refrigerant heat is contributed to the tank. The heat exchanger houses a phase change material. A controller controls operation of the water heating apparatus."

http://www.freepatentsonline.com/20180010822.pdf