Peculiarities of flow structure and heat transfer in coil steam-generating channels

The objective of the work is to study experimentally a structure of air-water and steam-water flows in a steam generator coil channel and to establish a relation between temperature conditions of heated surface and structure of two-phase flow. The coil was made of steel 16x2mmxmm tube. The helical winding diameter constituted 96 mm, pitch - 40 mm; total coil length-2.5m. Experimental data are obtained in the following rane of regime parameters: 0.1 MPa pressure; 300-1000 kg/(m2xs) flow rate; 0.13-13 m/s ir flow reduced rate; 0.3-1.0 m/s water flow reduced rate; 0.1-0.98 volumetric void fraction. Investigation of temperature conditions of the electric heated model is performed to evaluate magnitudes of pulsations, wall temperature, their range of existence, and also potential hazard of steam-generating channel. Experiments were performed under the following conditions: p=10-16 MPa; rhoω=87-2000 kg/(cm2 x s); specific thermal load approximately(40-520)x103 W/m2; relative enthalpy -(-0.05-0.6). The above investigation of flow structure and temperature conditions makes it possible to establish a range of coil steam generator operation parameters, in which intensive temperature pulsations occur due to flow structure rearrangement