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Aluminum wire is receiving increased attention for automotive applications due to the potential for cost and weight savings. Termination of aluminum wire is problematic due to the tenacious surface oxide on the strands. The oxide is an electrical insulator and is difficult to displace during termination. Consequently, many of the strands within a crimped wire bundle can be electrically isolated from the terminal, which can result in higher than expected crimp resistance, less stable crimp resistance, and the potential for excess heating of the termination. Prior solutions employed additives such as brass powder to puncture the oxide film and form a diffusion bond between strands, or features such as screens or serrations that increase wire deformation and displace the oxide mechanically to promote strand-strand bonding. Both solutions have drawbacks. Additives increase cost and process complexity and can serve as contaminants to adjacent processes.

Current environmental control thermal management systems use a two-loop, two-exchanger arrangement to isolate the crew from potentially hazardous ammonia or Freon in the final heat reject loop. Although that method does provide isolation, it is not fault-tolerant and does not provide advance warning of an exchanger leak. A heat pipe heat exchanger under development improves the existing system by providing two levels of isolation between the fluid streams. The new heat exchanger is fault-tolerant and can provide advance warning of a leak. Described are the heat exchanger design, test results from a sub-scale exchanger segment, and the results of a design optimization and trade study.