EFFECT OF VALVE LIFT AND DISK SURFACE ON 2-PHASE CRITICAL FLOW AT HOT-WATER RELIEF VALVE

Critical flows through disk-type relief valves with different disk sur faces and lifts were investigated experimentally. The disk surfaces us ed were fouling brass with calcium scale, mirror-finished brass and cl ean Teflon. The critical flow rare obtained from the experiment was su fficiently higher than that calculated by the empirical correlation wh ich is often used for calculation of valve capacity. From the comparis on with data and a nonequilibrium homogeneous model, nonequilibrium ef fect was smallest in a valve using a disk of fouling brass and highest in a valve using a disk of mirror-finished brass. The nonequilibrium state was affected with flashing characteristics of valve disks and ef fects of lift were relatively small.