Cascaded Cryogenic Flexible Loop Heat Pipe

Period of Performance: 08/05/1999 - 08/04/2000


Phase 2 SBIR

Recipient Firm

Thermacore, Inc.
780 Eden Rd Ofc
Lancaster, PA 17601
Principal Investigator


The principal Phase II objective is to develop, build and deliver a cryogenic (oxygen) loop heat pipe (LHP), operating in the temperature range from 60 K to 150 K, cascaded with an LHP operating at a higher temperature (for example, ethane) in order to facilitate startup of the cryogenic LHP, without using active means to achieve supercritical startup. In the Phase I, an oxygen LHP cascaded with an ethane LHP was built and tested at Thermacore in this effort. The oxygen LHP, contained in a vacuum tube, successfully cooled down and started in several nearly horizontal orientations (including the evaporator end elevated 1" versus the condenser end) without any active cooling of the evaporator and transport lines. The oxygen LHP maximum heat transfer capability was 12 W- The lowest temperature of the LHP reached in the test with liquid nitrogen cooling was 100 K. Phase II will pursue advanced development of cryogenic LHPs, including the oxygen deliverable LHP and long low-temperature LHPs that will find applications by military and commercial entities, such as cooling of x- spectrometers. Lower temperature working fluids such as neon and hydrogen will also be evaluated for loop heat pipes operating between 20 K and 40 K.