SBIR Phase I: High Efficiency Multi-fluid Jet Refrigeration

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This Small Business Innovation Research Phase I project will demonstrate a highly efficientsupersonic ejector vapor compression technology that converts low-to-medium grade thermal energy(200-400F) into useful refrigeration (20F-50F) at high condenser temperatures (100-120F). The proposedmulti-fluid jet cooler maximizes heat transfer efficiency by using a propellant with relatively low latent tocontinuously entrain and compress an immiscible low temperature refrigerant of relatively high latentheat. Initial prototypes have 400% higher efficiencies than conventional single-fluid ejectors. Phase Iresearch will extend these gains while operating at elevated condenser temperatures. Specific researchfoci are: 1) Highly efficient jet nozzles to supersonically expand a high molar mass, low specific heatratio propellant without the expansion/compression losses observed when using conventional nozzledesigns; 2) Mixing of subsonic refrigerant into the supersonic propellant with minimal kinetic energy lossby avoiding sonic choking of the refrigerant; and 3) Maximum pressure recovery diffusers utilizing weak,oblique compression waves instead of strong, normal shock waves to transition the mixed supersonic flowto subsonic velocity. Potential applications for the two-fluid ejector compression technology includenatural gas powered air conditioning, concentrated solar thermal chiller plants, lower cost combinedheating power and cooling plants, and thermally-driven water desalination.The broader impact/commercial potential of this project is reduced economic and climate burdenassociated with the world?s growing demand for space cooling. Air conditioning is the leading usage forpeak-time electricity in the U.S. and largest energy expense for commercial buildings. Globally, the$65billion air conditioning equipment market is growing at 5% p.a.; and because it is dominated by theelectrically-driven mechanical vapor compression cycle the strain on electrical grids - and by extensionthe environment and economy - is rising likewise. A quiet, clean, reliable and cost effective heat-drivensolution would greatly reduce these risks. Unfortunately, status quo technologies suffer low efficiencies,large form factors, and require expensive water-cooled condensers. Initial R&D efforts have proven anejector vapor compressor using optimized fluid pairs built with low cost components can operate atefficiencies competitive with electric compressors when operating in moderate ambient conditions. Massmarketadoption, however, requires efficient operation at extreme outside temperatures. Phase I researchwill maximize cooling power and discharge pressure (thus operability at high condenser temperatures) byminimizing irreversible losses incurred during supersonic expansion and compression of the immisciblefluid pairs. Project findings will benefit adjacent fields of hypersonic avionics and low atmosphere jetpropulsion