Validation of Modified Wine-Rack Thermal Design for Nickel-Hydrogen Batteries in Landsat-7 Spacecraft Thermal Vacuum Test and in Flight

A heritage wine-rack thermal/mechanical design for the nickel-hydrogen batteries was the baseline at the Land-sat-7 Preliminary Design Review. An integrated thermal and power analysis of the batteries performed by the author in 1994 revealed that the maximum cell-to-cell gradient was 6.6°C. The author proposed modifying the heritage wine-rack design by enhancing heat conduction from cells to cells, and from cells to battery frame. At the 1995 Intersociety Energy Conversion Engineering Conference (IECEC), the author presented a paper on methods of modifying the wine-rack design [1]. It showed that the modified wine-rack option, which uses a metallic filler, could reduce the maximum cell-to-cell temperature gradient to 1.3°C, and could also reduce the maximum cell temperature by as much as 8°C. That design concept was adopted by the Landsat-7 Project Office, and a design change was made at the Critical Design Review. Results of the spacecraft and instrument integrated thermal balance (T/B) and thermal vacuum (T/V) test, and temperature data in flight show that the temperatures of the battery cells are very uniform. The maximum cell-to-cell gradient is 1.4°C. They validate the modified wine-rack thermal design.