Helically coiled tubes are utilized for heat exchanger in many cryogenic industries. The helically coiled tube shows the different flow mechanism with vertical tubes, i.e. secondary flow and phase separation. In order to understand the boiling heat transfer characteristics in a helically coiled tube, experiment was conducted by using a forced convective boiling system with liquid nitrogen. Test section had 4 mm in inner tube diameter, 100 mm in coil diameter and 3150 mm in heated length. The experimental conditions were as follows; mass flux was 200-710 kg/m2s and system pressure was 0.3 MPa. As experimental results, the pressure drop, boiling heat transfer coefficient and critical heat flux had been evaluated including the post-dryout region.
