Numerical investigation of severe slugging under conditions of a parabolic trough power plant with direct steam generation

The present study reveals a numerical investigation of severe slugging with the system code ATHLET. It is aimed to close knowledge gaps about the two-phase flow within the connection pipes of two adjacent collectors in a solar thermal power plant with direct steam generation. The underlying ATHLET model provides a one-dimensional 6 equation model with a mass, momentum and energy equation for each phase, respectively. This comprehensive model provides all features for the examination of water steam flows in this type of power plants. A validation of ATHLET for severe slugging conditions is performed and the results are in good agreement with experimental data. The probability of severe slugging is studied for numerous flow conditions and geometric conditions which are close to operation conditions and piping system at the DISS test facility at the Plataforma Solar de Almería, Spain. The results confirm that certain conditions prevent severe slugging in the DISS test facility. Especially, high pressure conditions are the reason for a stable operation. No severe slugging is observed at pressures P ≥ 30 bar in the simulations of a typical geometry of the DISS test facility.