Effect of Heat Transfer Features on Maximal Surface Temperature of Spherical Fuel Element

The heat exchange in conditions of pebble bed with spherical fuel were studied in wide range of main operational parameter variation. The inlet velocity of the flow was varied in range 0.5-5 m/s, the pressure - in range 3-9 MPa, inlet gas temperature - 573-1073 K, heat generation rate - 1-20 MW/m(3). The helium was used as the coolant. The surface temperatures were determined by thermodynamic calculations and simulation via Ansys, The correction factor to the heat transfer coefficient value was introduced to match the maximal fuel surface temperature obtained by simulation and engineering calculations. The main factors affecting the maximal surface temperature of spherical fuel in conditions of pebble bed reactor were determined.