Thermo-hydraulic flow in a sudden expansion (LIMTECH)

With the increase of renewable energy of the total energy net production the improvement of power plants is intensified.

One option for a renewable energy source is the sun. Here concentrated solar power plants are of great interest as they have a high power output (up to 370MW). To reach this power, very high temperature and high thermal load is exerted on the solar collector. If the heat is transported poorly away from the collector, very high thermal stresses are created and reduce the lifetime of the collector. One possibility to reduce the stresses is provided by the application of liquid metals. They have a very high thermal conductivity which would cool the receiver very effectively.

In order to predict the thermal field sufficiently simulations of the heat transfer are required. As the heat diffusion of liquid metals is much higher than the viscous diffusion, new heat transport models have to be developed.

Figure: Geometry of a backward facing step.

The goal of this research is to develop new heat transport models suitable for low Prandtl number fluids as such as liquid metals. Therefore several turbulence models are tested on their performance to capture the flow physics in complex geometries e.g. a backward facing step.

Additionally heat transfer models from the literatrure are compared with DNS results for liquid metals simulations to assess their capabilities.

Based on these results, suitable heat transport models are derived.

Figure: Sample disribuion of axial velocity and fluctuating temperature variance.