Experimental investigation of the vertical upward single and two-phase flow pressure drops through gate and ball valves

This paper presents an experimental investigation of the pressure drop through valves in vertical upward flows. Experiments were carried out using a 1¼" (DN 32) ball and a gate valve. Five opening areas have been investigated from fully open to the nearly fully closed valve, using air with a superficial velocity of (0-3.5 m/s) and water (0.05-0.91 m/s). These ranges cover single-phase and the bubbly, slug and churn two-phase flow regimes. It was found that for the single-phase flow experiments, the valve coefficient increases with the valve opening and is the same, in both valves, for the openings smaller than 40%. The single-phase pressure drop increases with the liquid flowrate and decreases with the opening area. The two-phase flow pressure drop was found considerably increased by reducing the opening area for both valves. It reaches its maximum values at 20% opening for the ball valve and 19% opening for the gate valve. It was also inferred that at fully opening condition, the two-phase flow multiplier, for both valves, has been found close to unity for most of the tested flow conditions. For the 40 and 20 % valve openings the two-phase multiplier decreases in the power-law with liquid holdup for the studied flow conditions. Models proposed originally for evaluating the pressure drop through an orifice in single-phase and two-phase flows were also applied and assessed in the present experimental data