Sub-Project A


The scientific goal is the investigation of the CHF and Post-CHF heat transfer at high pressure with R-134a. A extensive database will be set up through experimental investigations. The influence of various parameter on the CHF and Post-CHF will be analyzed. Existing models for predicting the CHF and Post-CHF heat transfer will be evaluated with the aid of the database. If necessary, new models will be developed. Furthermore, an optical access to a single-rod channel will be used to develop models to predict the droplet size and -velocity. The meaningfulness of the STH-program ATHLET will be increased with the implementation of the new developed models and validation.

IATF is responsible for the Workpackage WP4 and is also involved in WP1, WP2 as well as in WP3.

Sub-Project B

Universität Stuttgart - IKE

The research of heat transfer behaviour of CO2 as a coolant will be conducted in “SCARLETT” test facility at IKE. The experiments cover the heat transfer up to the boiling crisis, the determination of the critical heat flux density at both DNB and dryout conditions and also the post-CHF heat transfer.Experiments will be conducted with both homogenous and variable heating profiles. To predict the occurrence of the boiling crisis at high steam qualities, a mechanistic model focusing on high pressures shall be developed. The model is to be validated using the preassesed experimental database and implemented in ATHLET code.

IKE is responsible for the Workpackage WP2 and is also involved in WP1 and WP3.

Sub-Project C


The scientific goal of the sub-project C is the investigation of the boiling crisis (CHF) and the Post-CHF heat transfer during the evaporation of water at high pressure. In addition to the experimental part at the HIPER facility, the modelling of the Departure from Nucleate Boiling (DNB) is also an important task. With the database of all three sub-projects and the aid of fluid-to-fluid scaling, a fluid independent model will be developed.  The results will be implemented in to the thermohydraulic software ATHLET and will ensure its direct applicability.

LES is responsible for the Workpackage WP1 and is also involved in WP2 and WP3.

Sub-Project D


The goal of the sub-project D is the education of the Ph.D. students and employees of the project partners in the STH-Code ATHLET. There will be introduction courses and advanced courses, which will present the CHF and Post-CHF models as well as the models for supercritical water. Furthermore, there will be an education to learn the program language of ATHLET. In addition, there will be explanations of practical examples, the requirements for verification, validation and documentation as well as the software architecture and the source code. During the project, the GRS will support the modelling and the implementation of the specific models in ATHLET.

GRS gGmbH is responsible for the Workpackage WP3.