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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.

Two Entropy advisors, Dr. Mohammed Farid and Lucas B. Hyman, are pleased to take your questions about PCMs and thermal energy storage. Send your questions to bwelter@puretemp.com. We'll select the best and post the answers here each week.

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Research roundup: Waste heat extraction; thermal sintering Pickering emulsion-based colloidosomes; more

Ben Welter - Tuesday, April 18, 2017

Micro-encapsulated phase change material (MPCM) slurries: Characterization and building applications [Renewable and Sustainable Energy Reviews]

Coupling waste heat extraction by phase change materials with superheated steam generation in the steel industry [Energy]

Large-scale high-temperature solar energy storage using natural minerals [Solar Energy Materials and Solar Cells]

Hierarchical nano-activated silica nanosheets for thermal energy storage [Solar Energy Materials and Solar Cells]

Microencapsulation through thermal sintering Pickering emulsion-based colloidosomes [Soft Matter]

Preparation of polyurea microcapsules containing phase change materials in a rotating packed bed [RSC Advances]

Dynamic measurement of the thermal conductivity of phase change materials in the liquid phase near the melting point [International Journal of Heat and Mass Transfer]

Investigation of Energy Performance in Conventional and Lightweight Building Components with the use of Phase Change Materials (PCMS): Energy Savings in Summer Season [Procedia Environmental Sciences]

Novel synthesis of cobalt/poly vinyl alcohol/gamma alumina nanocomposite for catalytic application [Applied Physics A]

Research roundup: Solar PCM storage wall system; novel caprylic acid/nonanoic acid mix; double glazing units; more

Ben Welter - Monday, April 17, 2017

Experimental study of a modified solar phase change material storage wall system [Energy]

A novel binary mixture of caprylic acid/nonanoic acid as latent heat storage for air conditioning and cooling [Energy and Buildings]

A General Method for Retrieving Thermal Deformation Properties of Microencapsulated Phase Change Materials or Other Particulate Inclusions in Cementitious Composites [Materials and Design]

Effect of PCM thickness and melting temperature on thermal performance of double glazing units [Journal of Building Engineering]

Research roundup: Cenospheres in concrete; form-stable composites with polyacrylic; rice bran distilled fatty acid; more

Ben Welter - Thursday, April 13, 2017

Numerical studies on thermal and electrical performance of a fully wetted absorber PVT collector with PCM as a storage medium [Renewable Energy]

Integrating phase change materials into concrete through microencapsulation using cenospheres [Cement and Concrete Composites]

Testing and performance analysis of micro encapsulated rice bran distilled fatty acid [International Journal of Computer Aided Engineering and Technology]

Enhanced thermal management with microencapsulated phase change material particles infiltrated in cellular metal foam [Energy]

Thermal performance study of form-stable composite phase change material with polyacrylic [AIP Conference Proceedings]

Design and Preparation of Carbon Based Composite Phase Change Material for Energy Piles [Materials]

Single-walled carbon nanotube for shape stabilization and enhanced phase change heat transfer of polyethylene glycol phase change material [Energy Conversion and Management]

Applications of Nanocomposite-Enhanced Phase-Change Materials for Heat Storage [Materials Science Forum]

Fatty acids and related phase change materials for reliable thermal energy storage at moderate temperatures [Solar Energy Materials and Solar Cells]

A study of a eutectic salt of lithium nitrate and sodium chloride (87–13%) for latent heat storage [Solar Energy Materials and Solar Cells]

Thermal stabilization and permanent deformation resistance of LWA/PCM-modified asphalt road surfaces [Construction and Building Materials]

Research roundup: SiO2 nanoparticles; multilayer wall thermal performance; spherical shells

Ben Welter - Wednesday, April 05, 2017

Effects of SiO2 nanoparticles on structure and property of form-stable phase change materials made of cellulose acetate phase inversion membrane absorbed with capric-myristic-stearic acid ternary eutectic mixture [Thermochimica Acta]

Influence of the PCM Layer Location on the Multilayer Wall Thermal Performance [Open Journal of Energy Efficiency]

Numerical Model for Solidification and Melting of PCM Encapsulated in Spherical Shells [Energy Procedia]

Inspired by nature: PCM capsules shaped like red blood cells show promise in study

Ben Welter - Monday, April 03, 2017

Capsules fabricated for use in Chinese study

Phase change material used in latent thermal energy storage systems must, of course, be encapsulated. The stiff containers, often made of high-density polyethylene, come in a variety of familiar shapes. The two most common are cylinders and spheres. Fins and dimples can be added to improve melting and solidification rates.

Researchers at Shanghai Jiao Tong University in China say they have identified a better shape. They found it in the circulatory systems of mammals.

Red blood cells, or RBCs, are filled with hemoglobin, not PCMs, and their purpose is to deliver oxygen, not thermal energy. Still, the researchers wondered, is the distinctive biconcave shape conducive to more effective heat transfer?

In a paper recently accepted for publication in Applied Thermal Engineering, “Thermal performance analysis of a novel PCM capsule in red blood cell shape,” Xiwen Cheng and Xiaoqiang Zhai described their investigation, in which they compared the RBCs with four other shapes by experimental and simulation methods. 

All five tested shapes – RBCs, spheres, cylinders, drums and ring-shaped capsules – were sized to contain 25.5 grams of PCM (capric acid, lauric acid, palmitic acid). The sphere’s interior diameter was 40 mm. The shell material was nylon 12 with a thickness of 1.5 mm.

The researchers found that the RBC-shaped capsule performed significantly better than the other shapes. The average charging rate of the RBC capsule, for example, was twice as fast as that of the sphere. 

Dr. William R. Sutterlin, Entropy Solutions’ chief science officer, who was not involved in this research, said he was intrigued by the results. "Until good alternatives are established to increase the thermal conductivity of the PCMs themselves,” he said, “novel designs such as these, which increase surface area, are welcome developments."

Research roundup: Capsule in shape of red blood cell; helical fin; graphene-enhanced enhanced myo-inositol; more

Ben Welter - Wednesday, March 29, 2017

Thermal performance analysis of a novel PCM capsule in red blood cell shape [Applied Thermal Engineering]

Experimental demonstration, modeling and analysis of a novel latent-heat thermal energy storage unit with a helical fin [International Journal of Heat and Mass Transfer]

Preparation, characterization and thermal properties of fatty acid eutectics/bentonite/expanded graphite composites as novel form–stable thermal energy storage materials [Solar Energy Materials and Solar Cells]

Parametric study and approximation of the exact analytical solution of the Stefan problem in a finite PCM layer in a steady periodic regime [International Communications in Heat and Mass Transfer]

Synthesis, characterization and applications of microencapsulated phase change materials in thermal energy storage [Energy and Buildings]

Graphene nanoplatelets enhanced myo-inositol for solar thermal energy storage [Thermal Science and Engineering Progress]

Research roundup: Fast charging with expanded graphite; rebar corrosion in PCM-enhanced concrete; hybrid cooling vest; more

Ben Welter - Tuesday, March 28, 2017

Fast charging of thermal energy storage systems enabled by phase change materials mixed with expanded graphite [International Journal of Heat and Mass Transfer]

Synthesis and characterization of a narrow size distribution nano phase change material emulsion for thermal energy storage [Solar Energy]

Analysis of the effects of use of thermal energy storage device (TESD) in solar air heater [Alexandria Engineering Journal]

Experiment and simulation of thermal management for a tube-shell Li-ion battery pack with composite phase change material [Applied Thermal Engineering]

Novel model for the prediction of SSLE temperatures and crystallization paths of any mixture containing palmitic, stearic, oleic, linoleic and linolenic acid [Thermochimica Acta]

A review on recent advancements in photovoltaic thermal techniques [Renewable and Sustainable Energy Reviews]

A comparative study on corrosion behavior of rebar in concrete with fatty acid additive as phase change material [Construction and Building Materials]

Novel phase change materials based on fatty acid eutectics and triallyl isocyanurate composites for thermal energy storage [Journal of Applied Polymer Science]

Optimal cooling intervention for construction workers in a hot and humid environment [Building and Environment]

Patent application: Composite foam and methods of preparation and use

Ben Welter - Thursday, March 23, 2017

U.S. patent application 20170072604 (applicant Empire Technology Development LLC, Wilmington, Del.):

"Composite foams having cells containing shape-stabilized phase change material (ss-PCM) particles are described. Composite foams may be made by contacting a plurality of ss-PCM particles and one or more pre-polymer reactants, wherein each ss-PCM particle can form a nucleation site for foam cell generation. The composite foams may be used in regulating the temperature of an article wherein the foam undergoes a phase transition as the surrounding temperature of the article approaches the foam's phase transition temperature. The thermostatic material may exchange heat with the article during the phase transition, resulting in regulation of the temperature of the article. The composite foams may be used as a thermostatic packaging material having a cavity for storing goods."

http://www.freepatentsonline.com/20170072604.pdf

Research roundup: PCM compatibility with metals, plastic; desiccant packet for cooling vest; paraffin viscosity; more

Ben Welter - Thursday, March 23, 2017

Investigation of the corrosive properties of phase change materials in contact with metals and plastic [Renewable Energy]

Preparation and thermal properties of SAT-CMC-DSP/EG composite as phase change material [Applied Thermal Engineering]

A numerical study on the usage of phase change material (PCM) to prolong compressor off period in a beverage cooler [Energy Conversion and Management]

Abilities and limitations of thermal mass activation for thermal comfort, peak shifting and shaving: A review [Building and Environment]

Corrosion effect of phase change materials in solar thermal energy storage application [Renewable and Sustainable Energy Reviews]

A review for phase change materials (PCMs) in solar absorption refrigeration systems [Renewable and Sustainable Energy Reviews]

Sodium nitrate – Diatomite composite materials for thermal energy storage [Solar Energy]

Innovative PCM-desiccant packet to provide dry microclimate and improve performance of cooling vest in hot environment [Energy Conversion and Management]

Heat transfer study of phase change materials with graphene nano particle for thermal energy storage [Solar Energy]

Energy performance evaluation of heat-storage gypsum board with hybrid SSPCM composite [Journal of Industrial and Engineering Chemistry]

Empirical equation to estimate viscosity of paraffin [Journal of Energy Storage]

Yearly energy performance of a photovoltaic-phase change material (PV-PCM) system in hot climate [Solar Energy]

Patent application: Methods for making low remnant free formaldehyde microcapsules

Ben Welter - Friday, March 10, 2017

U.S. patent application 20170065956 (applicant Microtek Laboratories Inc., Dayton, Ohio):

"Methods for producing microcapsules begin by preparing an emulsion of a surfactant, core material, and water, followed by the addition of a crosslinking agent and a melamine formaldehyde prepolymer, which is subsequently polymerized. The crosslinking agent is added before the melamine formaldehyde prepolymer, with a first addition or a second addition of a melamine formaldehyde prepolymer, or is divided for addition with both a first addition and a second addition of melamine formaldehyde prepolymer."

http://www.freepatentsonline.com/20170065956.pdf