Experimental Investigation of the Flow Resistance Characteristics of Air Vertically Flowing through a Horizontal Tube Bundle with Falling Film Water

The pressure drops and the friction factor of the air flowing up and down through a horizontal tube bundle with falling film water are investigated in this work, and the effects of air velocity, water spray density and air flow direction are studied. The experiment is conducted on a 13-row horizontal tube bundle with a tube diameter of 38 mm and a total of 33 tubes. The experimental data covers an air velocity range of 2.5~6.4 m/s, a water spray density range of 0.056~0.111 kg/(m·s), an air temperature of 20 °C, an air relative humidity of 60% and a spray water temperature of 30 °C. The pressure drop has a positive relationship with the spray density and air velocity, and the counter flow has a slightly larger pressure loss compared with the cocurrent flow. The proportions of the pressure drop caused by the friction between the air and spray water to the total pressure are observed to increase with the spray density and decrease with the air velocity for both counter and cocurrent flow. These proportions for the two flow patterns are approximately 10~30% for counter flow and 10~25% for cocurrent flow, respectively. Based on experimental data, prediction correlations of the friction factors through horizontal falling film tube bundles are proposed, and the prediction deviation for almost all experimental data is within ±5%.