Experimental Investigations of Two‐phase Boiling Flow in a Complicated Channel

Experiments were carried out to investigate the characteristics of two‐phase boiling flow and heat transfer characteristics in a vertical complicated channel. The results showed that boiling heat transfer characteristics for R113 flow in the complicated channel were different from those in tubes with normal size, and flow boiling in a complicated channel can enhance the efficiency of convective heat transfer. The influences of flow rate, heat flux and temperature difference were analyzed. It was found the flow rate had small influence on the convective heat transfer coefficient in low heat flux area and in small temperature difference region. In addition, the flow visualization experiments were conducted to observe flow regimes and their transitions. It was found that flow regimes and transitions in the complicated channel were different from other normal tubes. In the present experiments, there were only four main flow patterns, which were bubble flow, slug flow, churn flow, and annular flow. In slug flo...