Research on pressure drop characteristics in inverted half U-tube bundle under two-phase cross-flow condition

An experimental research has been carried out for vertically upward two-phase flow of air-water across inverted half U-tube bundle with or without anti-vibration bars. Pressure drop characteristics in inverted half U-tube bundle and anti-vibration bars were obtained and analyzed. New correlations for total pressure drop of two-phase flow in inverted half U-tube bundle and local pressure drop of two-phase flow in anti-vibration bars were developed. The measured two-phase pressure drops in inverted half U-tube bundle of three walls in the test sections were unequal. The pressure drop in the side wall dominated the total pressure drop of two-phase flow in inverted half U-tube bundle for 57 ≤ G < 114 kg·m⁻²·s⁻¹, while the pressure drop in the front wall dominated for 114 < G ≤ 143 kg·m⁻²·s⁻¹. An obvious mass velocity effect was observed for the total pressure drop of two-phase flow in inverted half U-tube bundle. For a given Martinelli parameter, the total pressure drop of two-phase flow in inverted half U-tube bundle decreased with an increasing mass velocity. The two-phase local pressure drop data of anti-vibration bars could be fitted well in terms of the Martinelli parameter and mass velocity.