EXPERIMENTAL INVESTIGATION OF AIR-WATER TWO PHASE UPFLOW ACROSS HORIZONTAL TUBE BUNDLES - 1. FLOW PATTERN AND VOID FRACTION.

Abstract

Experiments of air-water mixtures flow pattern and their mean void fraction in horizontal tube bundles are dealt with. The tube bundles are staggered with equilateral triangular arrangement of three different pitch/tube diameter ratios (1. 4, 1. 28, 1. 08) and they consist of six different tube rows (7, 9, 11, 13, 15, 20) for each ratio. Experimental ranges are as follows; superficial air velocity (cm/s) 1. 5-50, superficial water velocity (cm/s) 0. 032-0. 32, flow direction upward flow. The observed mixture flows can be classified into 1. bubbly flow 2. slug flow 3. froth flow 4. spray flow with liquid forming a film around the tubes and spraying from tube to tube downstream. Besides, a simple empirical equation for void fraction is proposed.