Experimental investigation on thermal behavior of non-boiling slug and bubbly two phase-flow in helical tube with spiral

Abstract

The present study provides experimental results of the flow pattern and thermal behavior of a none-boiling air-water two-phase flow in a helical tube with a turbulator. In order to evaluate the thermal behavior, a glass tube was put under constant heat flux. The inlet, outlet, and surface temperature of the helical tube were measured to calculate the heat transfer coefficient. The results showed that the addition of the turbulator in the helical tube leads to a rapid conversion from bubble flow to slug flow. Also, the formed bubbles are much smaller and spread radially throughout the pipe. Findings showed that the turbulator significantly improved the heat transfer of the two-phase flow, in which ratios of heat transfer enhancement with and without turbulator is 28% and 19%, respectively. Finally, cost-to-benefit ratio (C.B.R) analysis confirmed that when air-water two-phase flow transits through the helical tube are not affected by the presence or absence of turbulator.