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Thermal-hydraulics is recognized as a key scientific subject in the development of different innovative nuclear reactor systems. In Europe, thermal-hydraulic issues for innovative reactors are the subject of the Thermal-Hydraulics of Innovative Nuclear Systems project (THINS) which is sponsored by the European Commission and runs from 2010 until 2014. This paper will describe the status of the on-going activities in this project. The project addresses the main identified thermal hydraulics issues for innovative nuclear systems taking into account existing experimental data and producing new experimental data where needed. The overall objectives of the THINS project are the development and validation of new physical models, improvement and qualification of numerical engineering tools and their application to innovative nuclear systems. A specific part of the project is devoted to education and training in order to disseminate the state-of-the-art scientific knowledge gained within the project which will be attractive to students and (young) researchers in the field of thermal-hydraulics internationally.

The heating of packed beds by a hot gas flow depends on the heat transfer between the gas and the particles beside the heat conduction and the radiation between the particles. In order to consider chemical reactions within the particles, it is necessary to take the local convective heat transfer into account. Therefore it is useful to have informations about the variations of the heat transfer coefficient as a result of non-uniform pore velocities in randomly packed beds. Transient heat transfer data is obtained for a nitrogen gas flow through packed beds of porous slate particles and of wooden cubes by local measurements of the particle and the gas temperature. The special arrangement of the test particles insures that heat conduction is excluded. The convective heat transfer coefficient between the flowing fluid and the solid particles is calculated from the temperature measurements. Variations of the gas temperature and the flow rate are taken into account. Increasing gas flow leads to larger values of the heat transport coefficient. The experimental results are compared with the functional relationships of the Nusselt number Nu d P = f ( Re 0 , d P ) given by multiple authors. Due to inhomogeneities of the pore velocities the experimental data shows a large variance in particular at low Reynolds numbers, i.e., Re 0 , d P 200 . This is treated by a statistical method resulting in logarithmic probability distribution functions for the different materials which are useful for the mathematical treatment of the heating of randomly packed beds. The influence of radiation on the heat transport is considered numerically by solving the equations of a one-dimensional particle model. It is shown, that below 500 °C, the influence of radiation is negligible.

An experimental setup for the generation and investigation of periodic equivalence ratio oscillations in laminar premixed flames is presented. A special low-pressure burner was developed which generates stable flames in a wide pressure range down to 20 mbar and provides the possibility of rapid mixture fraction variations. The technical realization of the mixture fraction variations and the characteristics of the burner are described. 1D laser Raman scattering was applied to determine the temperature and concentration profiles of the major species through the flame front in correlation to the phase-angle of the periodic oscillation. OH* chemiluminescence was detected to qualitatively analyze the response of the flame to mixture fraction variations by changing shape and position. Exemplary results from a flame at p=69 mbar, forced at a frequency of 10 Hz, are shown and discussed. The experiments are part of a cooperative research project including the development of kinetic models and numerical simulation tools with the aim of a better understanding and prediction of periodic combustion instabilities in gas turbines. The focus of the current paper lies on the presentation of the experimental realization and the measuring techniques.