ACT Develops Loop Thermosyphon for Solar ThermoElectricity

Lancaster, PA October 24, 2016 – Advanced Cooling Technologies (ACT) announces the successful design, manufacturing, and testing of a loop thermosyphon based thermal valve in conjunction with the National Renewable Energy Laboratory (NREL).  The loop thermosyphon developed by ACT uses liquid sodium as the working fluid, and is capable of transferring over 3 kW of energy from source to sink when operated at 600°C.  It was developed to test and show the feasibility of modular, dispatchable, and scalable energy sources.

The Solar ThermoElectricity via Advanced Latent Heat Storage (STEALS) program integrates several state-of-the-art technologies to provide electricity on demand. In the envisioned STEALS system, concentrated sunlight is converted to heat at a solar absorber. The heat is then delivered to either a thermoelectric (TE) module for direct electricity generation, or to charge a phase change material for thermal energy storage. The key to making STEALS a dispatchable technology lies in the development of a “thermal valve,” which controls when heat is allowed to flow through the TE module, thus controlling when electricity is generated.

ACT’s contributions to this project started with a design study, iterated on various design items including transport length, evaporator and condenser designs, and valve design.  The project evolved into building a prototype unit for successful testing.  NREL is moving forward with Phase 2 of this program which involves additional testing and may move to Phase 3, where ACT may build a larger version.

“Sodium loop thermosyphons with integral valves offer the high performance, high reliability and control features that are required to meet next generation thermal and electrical storage requirements,” explains Rebecca Weigand, R&D Engineer at ACT.

ACT is looking forward to the opportunity to build a higher capacity iteration of the loop thermosyphon to better fit within scaled up final configurations of the ultimate system. ACT has developed and built loop thermosyphons for use in various power electronics, medical, and aerospace applications in the past.


ACT specializes in advanced thermal technology development and custom thermal product manufacturing. ACT designs and manufactures cold plates, HiK™ plates, heat pipes, pumped liquid and two-phase loops and thermal storage devices for customers in diverse markets including Aerospace, Electronics, Temperature Calibration, Medical Device, and Energy Recovery Systems.

ACT’s team consists of personnel with established track records in technology development, commercialization and production. Many of them were involved in the pioneering work on heat pipes, loop heat pipes and other single and two-phase heat transfer devices. They are the inventors/co-inventors on numerous U.S. and international patents and the authors/co-authors of hundreds of scientific publications.

The R&D team at ACT has engineers with backgrounds in mechanical, electrical, chemical, aerospace, nuclear, materials, manufacturing and physics. Their expertise assures we can serve wide variety of material, thermal and modeling challenges in diverse applications.

ACT’s Facility measures more than 50,000 square feet, including office, laboratory and manufacturing spaces. With ISO9001 and AS9100 certified quality system in place, the facility has designed and manufactured high quality, cost effective, thermal management solutions for dozens of mission critical satellite, and military programs as well as for numerous commercial applications. Simultaneously ACT’s broad and diverse R&D efforts are developing thermal solutions for tomorrow’s emerging technologies.

For more information about ACT, please visit


Amanda Hershey
Marketing Specialist
Phone: +1 (717) 205-0625

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