This proposed research addresses NASA 2004-1 SBIR Topic B3.01, "Environmental Control of Spacecraft Cabin Atmosphere." The objective of this proposed effort is to demonstrate the freeze/thaw properties and fault tolerance of a water pump loop using an environmentally-friendly, non-toxic, drop-in replacement heat exchange fluid. These fluid formulations are comprised of novel, non-flammable, non-explosive, non-toxic, non-corrosive compounds which will not expand upon freezing and therefore diminish the chances that a heat exchanger will rupture. The fluid formulations also have a much lower freezing point than water which can broaden the temperature operating range of the heat exchanger. The objective of using a drop-in replacement is also very cost effective since little to no change in hardware would be required. This proposal specifically addresses the following need cited in the solicitation description under subheading Environmental Control and Thermal Systems: "Alternative heat transfer fluids that are non-toxic, non-flammable, and have a low freezing temperature."