In this paper, the heat transfer of air/water two-phase flow in a helicoidal pipe is experimentally investigated. It was observed that fully developed flow and heat transfer is achieved after two turn of the pipe. The temperature on the outer wall of the helicoidal pipe was always lower than that of the inner wall, and correspondingly, a higher heat transfer coefficient was obtained on the outer wall. On the other hand, the heat transfer coefficient was significantly affected by flow rates of the air and water. It seems that an increase of the water flow rate will increase the heat transfer coefficient when the air flow rate is kept constant.
