Abstract
An aggregate of nonwettable refractory particles can act as an off-on valve to control the flow of liquid metals. The performance of such a particle valve is evaluated experimentally and theoretically. The breakthrough pressure, PBR, which is the pressure differential required to initiate flow through the particle valve has been theoretically derived: PBR = -10.928 [γLV/d] cos θ′A where γLV is the liquid-vapor surface tension, d is the uniform particle diameter, and θ′A is the apparent advancing contact angle between the liquid and solid. Experimentally determined breakthrough pressures for the Sn/Al2O3 and Hg/Al2O3 systems agree with and confirm the derived expression. Mechanisms which may lead to premature breakthrough. of the liquid through the valve are: i) failure due to direct impingement of liquid droplets on the particle valve, ii) failure by augmented hydrostatic pressure caused by an impinging liquid droplet, and iii) failure due to buoyancy forces acting on individual particles. Critical operating limits for each mechanism are given.
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