Low Cost Radiator for Fission Power Thermal Control

The low cost VCHP radiator developed under this Phase I and Phase II program would provide the waste heat rejection system necessary for the non-nuclear TDU to be tested at NASA GRC. Additional, longer term NASA candidate missions that the low cost VCHP radiator would support are initial power sources for human outposts on the Moon or Mars and nuclear electric propulsion systems (NEP) for Mars cargo transport. A benefit for Lunar and Martian radiators is that the VCHP can passively accommodate the large swings in environmental conditions between lunar (or Martian) day and night, including long periods at very low temperatures. In addition, the VCHP can passively accommodate large changes in thermal load, and avoid damage during periods of low thermal load. The non-condensable gas in the VCHP will also help with start-up during sudden increases in thermal load.

There is a commercial application for high temperature VCHP heat exchangers in fuel cell reformers. In a fuel cell reformer, steam, air and diesel fuel react in a High Temperature Shift (HTS) and a Low Temperature Shift (LTS) reactor to produce as much hydrogen as possible. Feed streams to and from the reactors must be maintained under tight temperature control, typically within 30�C despite a turndown ratio of 5:1 in reactant flow rate. ACT believes that VCHP heat exchangers can replace the current heat exchanger and control system with a passive system. The VCHP heat pipes passively adjust the heat removed, to maintain the output stream at a constant temperature. The direct bonding of the single facesheet GFRC to the titanium condenser would allow low cost and mass radiators for atmospheric high altitude applications like waste heat rejection from balloon payloads or from UAV electronics. More »