A novel positive displacement, high pressure, vertical axis wind pump (HP-VAWP) was evaluated for the application of stand-alone high-pressure reverse-osmosis desalination and drip irrigation systems. The direct interface between a vertical axis wind turbine (VAWT) and a positive displacement pump, that delivers a constant volume of liquid per revolution, has never been studied before. Understanding the interaction between turbine and pump efficiencies, where delivery pressure is determined by backpressure alone, is critically important for efficient design. Wind tunnel experiments were conducted on a small-scale two-bladed turbine (0.4m2 cross-sectional area) that operated on a dynamic stall principle. At these small laboratory scales, the turbine and pump efficiencies were relatively low (15% and 28%, respectively); nevertheless, the system produced nearly constant pressures in excess of 1.5 bar for a large operational range. Moreover, the system exhibited a self-priming capability and the turbine could easily be braked by overloading the pump. A conservative field-scale analysis of an HP-VAWP system indicated that a medium-size turbine (12.5m2 cross-sectional area) can attain a peak efficiency of 12.4%, which easily exceeds the 4%-8% typical of widely-used American multi-bladed wind-pumps. Indeed, our research indicates that an HP-VAWP system is viable and requires further development. The benefits of zero carbon emissions during operation, high relative efficiency and easy manufacturing and maintenance make HP-VAWP ideal for stand-alone or off-grid environments.

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