Advanced Cooling Technologies of Lancaster, Pa., has been awarded a U.S. patent for a phase change material with a tunable melting point.
The hydration level of the PCM, a salt hydrate consisting primarily of salt and water, is altered to change the melting point to a desired set point using changes in humidity of the system.
“In an ARPA-E ARID funded program, we showed that you could change the melting point of salt hydrate phase change materials by changing the hydration levels of the salt hydrate in-situ,” Richard Bonner, ACT’s vice president for R&D, wrote in a LinkedIn post. “We also applied this technology to power plant cooling, where the seasonal variations in ambient temperature necessitate different melting points. Congratulations to the inventors: Dr. Ying Zheng, Dr. Chien-hua Chen, Dr. Howard Pearlman, and Dr. Fangyu Cao."
ACT worked with Lehigh University and the University of Missouri to develop the PCM. The idea was prompted by ACT’s interest in utilizing seasonal shifts in weather for the company’s day/night thermal storage application. A tunable melt point allows the PCM to be more easily solidified in cold and hot seasons.
The targeted melt temperatures in the project were from 25° C to 45° C for low-grade thermal energy storage, but could be extended to higher temperatures with other salt hydrates, the company said.
The project was funded, in part, with a $3.2 million ARPA-E ARID grant, awarded in 2015. ARID stands for "Advanced Research in dry Cooling." The project teams were challenged to "develop innovative, high-performance air-cooled heat exchangers and supplemental cooling systems and/or cool-storage systems" for use in thermoelectric power plants, to replace existing technologies that use a substantial amount of water to cool plant condensers.
The ARID project was completed in 2018. ACT's invention is now at the lab-scale testing phase. The most difficult hurdle, the company said, will be to scale up to commercialization level. “From a manufacturing standpoint, shifting of the hydration level would require a large infrastructure for altering the humidity,” the company said.
“The concept could also be applied to the HVAC industry (building comfort) to provide day/night load shifting,” the company said, “as well as PCM synthesis and preparation for a consistent product. “