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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.




Research roundup: Polyvinyl alcohol foams; radially finned thermal storage unit; close-contact melting modeling; more

Ben Welter - Thursday, September 24, 2015

Heat Storage and Dimensional Stability of Poly(vinyl alcohol) Based Foams Containing Microencapsulated Phase Change Materials [Industrial & Engineering Chemistry Research]

Experimental Investigation of Encapsulated Phase Change Materials for Thermal Energy Storage [University of South Florida, Ph.D. dissertation]

Modeling of Constrained Melting in a Radially Finned Latent Thermal Energy Storage Unit [Advances in Computational Heat Transfer]

Modelling and optimization of CHP based district heating system with renewable energy production and energy storage [Applied Energy]

Molecular dynamics simulation of the domain size effect on the values of thermal conductivity of long chain n-alkanes [Advances in Computational Heat Transfer]

Investigation of Various Options for Numerical Modeling of Fluidized Beds for a Solar Thermal Application [Advances in Computational Heat Transfer]

Close-Contact Melting Modeling Combined with the Enthalpy Method [Advances in Computational Heat Transfer]

Research roundup: Window-based cooling unit; PCM-ceramic tiles; corrosion and molten salts; smectite; more

Ben Welter - Thursday, September 17, 2015

Thermal performance of a window-based cooling unit using phase change materials combined with night ventilation [Energy and Buildings]

Lightweight dense/porous PCM-ceramic tiles for indoor temperature control [Energy and Buildings]

Corrosion behavior of stainless and low-chromium steels and IN625 in molten nitrate salts at 600° C [Solar Energy Materials and Solar Cells]

District cooling systems: Technology integration, system optimization, challenges and opportunities for applications [Renewable and Sustainable Energy Reviews]

Observed-Predicted Shifts in Thermodynamic Functions of Water Adsorption by Smectite at Nanoscale [Soil Science Society of America Journal]

Preparation of microencapsulated medium temperature phase change material of Tris(hydroxymethyl)methyl aminomethane@SiO2 with excellent cycling performance [Applied Energy]

An inside look at U.S. Patent 8955763

Ben Welter - Wednesday, August 26, 2015

In an interview with Real Estate Weekly, Goldman Copeland CEO Charlie Copeland talks about the simple idea behind U.S. Patent 8955763, "Building heating system and method of operation," first filed on Oct. 4, 2007, and granted on Feb. 17, 2015: 

Charles Copeland, PE, LEED AP"To limit steam demand, Con Edison implemented a peak winter steam demand charge, much as it does for electricity. However, the utility was required to offer customers strategies to mitigate these high demand charges.

"Con Edison approached [Goldman Copeland], which had years of experience pioneering energy solutions and was known for its innovative thinking, to devise a way to reduce peak steam demand.

"Copeland recalled that the “aha! momentĖ® came after several different approaches had been considered.

"One day, while he was reviewing options and drawing on his experience with older buildings, he said, 'The idea came to me. There is a reservoir of water already in the perimeter systems (induction and fan coil unit) that could be used to store thermal energy in advance of the 8 to 11 am peak usage time, thereby requiring less steam during those peak hours.' ”

District cooling industry faces 'danger of stagnation'

Ben Welter - Monday, August 17, 2015

George Berbari, CEO at DC Pro Engineering in the United Arab Emirates, warns that district cooling technology is advancing at a much slower rate than competing HVAC applications and faces the "danger of stagnation." 

George BerbariBerbari, co-chair of the 2015 Middle East District Cooling Summit, said "newer and ultra-efficient HVAC systems pose a threat to district cooling in terms of better efficiency." He endorsed tri-generation district cooling – the simultaneous generation of electricity, heating and cooling from renewable resources – as a way forward for the industry.  

The summit will be held Nov. 10-11 in Doha, Qatar. The theme is "The Future of Renewable in the District Cooling Sector - Feasibility and Cost Implications." Topics include thermal energy storage and energy efficiency; sustainability and the environment; treated sewage water vs. seawater for cooling; delta T optimization; and, of course, tri-generation systems. ....

District energy seen as essential way for cities to cut greenhouse gases, improve energy efficiency

Ben Welter - Thursday, August 13, 2015

A survey of low-carbon cities worldwide identifies district energy systems as an essential tool for local governments seeking to reduce greenhouse gases and improve energy efficiency.

U.N. Environment Program logoThe U.N. Environment Program report, "District Energy in Cities – Unlocking the Potential of Energy Efficiency and Renewable Energy," calls for the accelerated deployment of district energy systems around the world. From the report's executive summary:

"The development of modern (i.e., energy-efficient and climate-resilient) and affordable district energy systems in cities is one of the least-cost and most-efficient solutions for reducing greenhouse gas emissions and primary energy demand. A transition to such systems, combined with energy efficiency measures, could contribute as much as 58 per cent of the carbon dioxide (CO2) emission reductions required in the energy sector by 2050 to keep global temperature rise to within 2-3 degrees Celsius."

Paris, one of the 45 "champion" cities surveyed, developed Europe's first cooling network, part of which uses the Seine River. The Paris Urban Heating Co., which now serves the equivalent of 500,000 households, aims to use 60 percent renewable or recovered energy by 2020. Other cities in the report include TokyoMunichHong KongGuelph (Canada), Warsaw (Poland) and Christchurch (New Zealand).

Off-peak pricing still drives TES, but energy savings can be 'significant benefit'

Ben Welter - Wednesday, August 05, 2015

Want to pitch your thermal energy storage system to a customer? Dan Mizesko, managing partner at U.S. Chiller Services International in Dubai, says the project's success is unlikely unless three or more of these conditions are true:

• Electricity energy charges vary significantly during the course of a day.
• Electricity demand charges are high or ratcheted.
• The average cooling load is significantly less than the peak cooling load.
• The electric utility offers other incentives (besides the rate structure) for installing TES.
• An existing cooling system is expanded.
• There is new construction.
• Older cooling equipment needs replacing.

"Historically, the driving force for developing TES has been reduction of on-peak electric demand and the corresponding reduction of electricity costs," Mizesko writes in Climate Control Middle East magazine. "While this is still important, and may be the most significant factor affecting application, cost-effectiveness and energy savings are possible, and can be a significant benefit when the entire cooling system, and not just the storage media and vessel are considered."

Research roundup: Graphene oxide-grafted PCM; properties of granular materials; flat micro-heat pipe; more

Ben Welter - Tuesday, July 07, 2015

Novel slurry containing graphene oxide-grafted microencapsulated phase change material with enhanced thermo-physical properties and photo-thermal performance [Solar Energy Materials and Solar Cells]

Properties of granular materials as heat transfer and storage medium in CSP application [Solar Energy Materials and Solar Cells]

PCM thermal storage system for ’free’ heating and cooling of buildings [Energy and Buildings]

Experimental study of the heat transfer characteristics of a new-type flat micro-heat pipe thermal storage unit [Applied Thermal Engineering]

Structural performance of water tank under static and dynamic pressure loading [International Journal of Impact Engineering]

German city refitting coal bunker with TES tanks

Ben Welter - Wednesday, July 01, 2015

A remnant of the coal age is making way for a thermal energy storage project in Münster, Germany.

Renewables International reports that the city is investing $1.9 million to install four hot water tanks in an old coal bunker. The system will use off-peak electricity from the grid to generate and store heat for use during hours of peak demand. Electric heaters reacting to energy price fluctuations will charge the 2-million-liter tanks, which will be linked to the city's district heating system

Research roundup: Polyurethane/docosane microcapsules; district heating; nanoparticles; water tank shapes; more

Ben Welter - Monday, June 29, 2015

New Polyurethane/Docosane Microcapsules as Phase-Change Materials for Thermal Energy Storage [Chemistry - A European Journal]

On-sun demonstration of a 750° C heat transfer fluid for concentrating solar systems: Dense particle suspension in tube [Solar Energy]

Thermodynamic analysis and performance assessment of an integrated heat pump system for district heating applications [Applied Thermal Engineering]

Preparation and properties of lauric acid/diatomite composites as novel form-stable phase change materials for thermal energy storage [Energy and Buildings]

A New Phase Change Material Based on Potassium Nitrate with Silica and Alumina Nanoparticles for Thermal Energy Storage [pdf] [Nanoscale Research Letters]

Comparative study of the influences of different water tank shapes on thermal energy storage capacity and thermal stratification [Renewable Energy]

Energy Storage Applications | An Introduction to Phase Change Materials [Thermal Energy Storage Using Phase Change Materials]

Assessing the feasibility of incorporating phase change material in hot mix asphalt [Sustainable Cities and Society]

Research roundup: Bischofite as PCM for thermal energy storage; phase change composite; solar fresh air system

Ben Welter - Monday, June 08, 2015

Use of polyethylene glycol for the improvement of the cycling stability of bischofite as thermal energy storage material [Applied Energy]

High thermal conductivity phase change composite with percolating carbon fiber network [Applied Energy]

Thermal storage exchanger based on phase change material applying to solar fresh air system [Materials Research Innovations]

Industrial Surplus Heat Utilization through Mobile Thermal Energy Storage with Enhanced Operating Strategy [Greenstock 2015 conference paper]