Water AzeotropeWorking Fluids for Advanced Spacecraft Thermal Management

A promising new class of working fluids / refrigerants (i.e. water azeotropes) has been identified, which offer the potential to provide advanced capabilities for next-generation spacecraft thermal control systems.nbsp;Water-based azeotropes have been identified as a class of working fluids that offer the following:nbsp;high thermodynamic performance than ammonia above 25ordm;C,nbsp;low global warming potential, capability to be used in high heat lfux applications, capability to be used in applications requiring a high turn-down ratio,nbsp;significantly lower freezing points than water,nbsp;near-zero density change upon freezing,nbsp;low environmental impact, and low toxicity.nbsp;nbsp;Important auxiliary applications are possible for related applications, including refrigeration / AC systems and pumped loops.nbsp;A development program isnbsp;proposed to evaluate their potential, define their properties, identify leading candidate mixtures, and complete operational tests on a representative water azeotrope heat pipe.