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THERMAL ENERGY STORAGE
Axiom Exergy to install ‘Refrigeration Battery’ at Walmart in San Diego
With the support of California’s largest utilities, Axiom Exergy is installing its “Refrigeration Battery” energy storage system at a San Diego Walmart store.
Axiom’s system is designed to reduce a supermarket’s peak power use by up to 40 percent and provide backup cooling during power outages. It uses the excess capacity of a customer’s existing refrigeration system to “store cooling” at night by freezing a tank of salt water. The frozen tanks supply refrigeration to the building during peak afternoon hours, eliminating the need to run energy-intensive compressors and condensers.
“Walmart is actively evaluating different energy storage technologies that have the potential to reduce our operating costs and improve stores’ resilience during power outages and extreme weather events across our portfolio,” said Mark Vanderhelm, VP Energy of Walmart. “This demonstration is consistent with these efforts as well as Walmart’s commitment to fostering innovation — we are excited to review the potential of Axiom’s solution to these issues.”
The field demonstration with Walmart is funded by utility members of California’s Emerging Technologies Coordinating Council. The council is focused on identifying, assessing and supporting commercialization of energy-reducing technologies.
Energy density, thermal conductivity, price seen as areas to focus on
In a report prepared for the United Kingdom’s new Department for Business, Energy & Industrial Strategy, researchers have identified several areas with high potential for development of PCM applications, including water heaters and building materials, and predict that further materials research and increased demand will drive down costs.
The report, titled “Evidence Gathering: Thermal Energy Storage (TES) Technologies,” says these areas of technological and commercial development are worth focusing on:
• Integration of PCM into small and larger hot water tanks for improved performance.
• Development of PCMs that can provide storage for applications where water cannot be used as a storage medium.
• Increasing the energy density and thermal conductivity of PCMs to make charging and discharging more efficient.
• Better integration of heat exchangers into thermal stores.
• Improved performance of PCM-enhanced building materials.
• Expanded use of PCMs for air-conditioning, passive cooling and “coolth” storage.
• Ice store technology, such as the one developed by Viessmann.
Among the factors seen as key barriers to wider adoption of thermal energy storage technologies: Uncertainty around carbon savings. The report notes:
“Interest in TES is high because of the role it could play in transitions to a low- and
zero-carbon energy system. TES may have an important role as an enabler of low-carbon technologies, particularly renewable heat, electricity and CHP. However, at present, the existence of thermal storage capacity can increase carbon emissions. This is because all storage systems have losses, and these losses are effectively wasted fuel or wasted electricity (both still predominantly fossil-derived).
“Understanding the carbon impacts of TES is therefore not at all simple. At a whole-system level it would require complex system-modelling to justify any statements about a unit of TES (a kWh or kW) equating to a quantity of saved carbon. The carbon content of the TES itself is in all cases relatively low, as the storage material (whether water, rock or advanced PCMs or thermochemical materials) does not require excessive energy to produce and the containers do not use rare materials or energy intensive production methods.”
PATENTS
Integrated thermal energy module with air-cooled evaporator design
U.S. patent application 20160334154 (applicant Thermo King Corp., Bloomington, Minn.):
“A transport refrigeration unit comprising: a compressor configured to compress a heat transfer fluid; a condenser disposed downstream of the compressor, the condenser configured to condense the heat transfer fluid from a gaseous state to a liquid state; an expansion de ice disposed downstream of the condenser, the expansion device configured to release pressure of the heat transfer fluid; a first flow control device disposed downstream of the condenser, the first flow-control device configured to direct the heat transfer fluid downstream of the expansion device; a first evaporator disposed downstream of the expansion device and the first flow control device; a second evaporator disposed downstream of the expansion device and the first flow control device, wherein the second evaporator includes a thermal accumulator … defined as one or more apparatuses that include phase change material (PCM). Further, the “thermal accumulator” allows the PCM to exchange heat with the environment near the thermal accumulator. In one embodiment, the PCM can be eutectic fluid, e.g., propylene glycol (C3H8O2).”
Thermal receptacle with phase change material
U.S. patent application 20160332799 (applicants Raymond Booska, Melbourne, Fla., and J. Bruce Kolowich, Saline, Mich.):
“A liquid receptacle for rapidly lowering the temperature of a liquid contained therein to a warm range suitable for human contact and maintaining the liquid in the warm range for an extended period of time, the receptacle having a drinking lip at the uppermost end, the receptacle comprising: an inner vessel having an open upper end and closed lower end and a wall connecting the upper end and the lower end; the inner vessel having an inner surface with plurality of indentations or protrusions defined thereon and an outer surface with a plurality of corresponding protrusions or indentations defined thereon such that the effective surface area of the inner and outer surfaces is increased and heat transfer through the wall of the inner vessel is increased; an insulated outer shell spaced from the inner vessel defining an interstitial chamber therebetween, the insulated outer shell having an open upper end and a closed lower end; and a phase change material disposed within said chamber for regeneratively absorbing thermal energy from the liquid and then releasing the thermal energy to the liquid to maintain the temperature of the liquid.”
Mattress with a visco elastic polyurethane foam layer
U.S. patent application 20160331150 (applicant HSM, Hickory, N.C.):
“A foam mattress is provided having a body facing surface comprising a viscoelastic foam layer. The body facing surface further comprises a recess or cavity into which a layer including a core of springs may be provided. The foam mattress further having a layer of open cell foam beneath the viscoelastic foam layer. The open cell, or reticulated, foam layer provides increased breathability. Support for the mattress may further be provided by a bottom layer of conventional foam. … The viscoelastic foam may be gel infused and/or contain other elements including phase change materials, antimicrobials, or the like.”
IN BRIEF
• Sunamp Ltd. has completed installation of its SunampPV heat batteries in more than a thousand homes at Castle Rock Edinvar, one of Scotland’s largest housing associations. The company says the hybrid system will save households up to $370 a year each on their hot water and heating bills.
• In tests conducted by San Diego Gas and Electric and ASWB Engineering, Viking Cold Solutions’ PCM-based thermal energy storage system showed reductions in electricity consumption of 30 percent and 39 percent in two cold storage facilities in the San Diego area. Based on the results, SDG&E and ASWB recommended that California utilities include the technology in their energy efficiency and demand response incentive programs.
• Boca International Ltd. has signed a $3.4 million contract with Differ Commercial Management Ltd. to supply and install BocaPCM-TES systems in Differ properties in Xiamen City, China. Boca says its salt-based aqueous system is similar to ice- and water-based TES systems but covers a wider range of temperatures, allowing for “even and controllable energy usage, drawing energy from the storage directly during peak hour, which ultimately reduces the operating costs.”
• PCM maker va-Q-tec AG is increasing its equity stake in SUMTEQ GmbH, a technology company that develops lightweight, durable polymer nanofoams for use as insulating material.
• The International Fabrics Association International has issued a call for presenters for its next trade show and expo. Possible topics include flame retardancy, moisture management, polymer innovations and thermal control. Submissions are due Feb. 9. The expo will be held Sept. 26-29, 2017, in New Orleans.
• Greentech Media’s Jason Deign takes a look at what energy insiders around the world are making of Donald Trump‘s victory.
• New from QYResearch: “Global Phase Change Materials Market Research Report 2016.”
• SpecialChem is offering a 90-minute webinar on the impact of a new U.S. law on intellectual property. “U.S. Trade Secrets and How they are Protected: Easy to Understand Guide” will be held at 10 a.m. EST on Dec. 14. The cost is $268 for three participants on a single connection.
RESEARCH ROUNDUP
For our full list of recent academic research, see puretemp.com/academic. Here are highlights from the past week:
From Applied Thermal Engineering:• Experiments on Thermal Performance of Erythritol/Expanded Graphite in a Direct Contact Thermal Energy Storage Container
• Enhance heat transfer for phase-change materials in triplex tube heat exchanger with selected arrangements of fins
• Experimental study of the thermal characteristics of microencapsulated phase change composite cylinders
From Energy:
• Experimental study on heat storage system using phase-change material in a diesel engine
From Energy and Buildings:
• Dynamic thermal characteristics analysis of microencapsulated phase change suspensions flowing through rectangular mini-channels for thermal energy storage
From Journal of Thermal Biology:
• Hybrid cooling vest for cooling between exercise bouts in the heat: effects and practical considerations
From Powder Technology:
• Simulation Study of Anomalous Thermal Properties of Molten Nitrate Salt
From Renewable and Sustainable Energy Reviews:
• Influence of internal thermal mass on the indoor thermal dynamics and integration of phase change materials in furniture for building energy storage: A review
From Journal of Molecular Catalysis B: Enzymatic:
• Recycling Rhizopus oryzae resting cells as biocatalyst to prepare near eutectic palmitic-stearic acid mixtures from non-edible fat
From Research Gate:
• Experimental study of discharging PCM ceiling panels through nocturnal radiative cooling [pdf]
NETWORKING
Connect with PCM experts and industry leaders on LinkedIn
More than 950 of your peers have joined a LinkedIn group devoted to the discussion of phase change material and thermal energy storage. The Phase Change Matters group is an interactive complement to the award-winning blog and newsletter of the same name.
You are invited to join the group and connect with PCM and TES experts from around the world. New members include Emy Apodoulianaki, mechanical engineer, Netherlands; Eleftherios Bourdakis, Ph.D. student at Technical University of Denmark‘s International Center for Indoor Environment and Energy; Nichole Wolf, marketing specialist at Mesa Laboratories Inc., Denver, Colo.; and Jorge Payá Herrero, assistant professor at the Universitat Politècnica de València‘s Instituto de Ingeniería Energética.