COSMOS-H (plant under construction)

Critical heat flux On Smooth and MOdified Surfaces – High pressure loop

Contact: stephan.gabriel∂; giancarlo.albrecht∂

The thermohydraulics test facility COSMOS-H is set up for the investigation of boiling phenomena and complex flow phenomena that can occur in power plants. It will initially be used as part of reactor safety research by the 'multiphase flows' group at the Institute for Thermal Energy Technology and Safety (ITES). After commissioning, physical processes, such as the boiling cries that occur when the critical heat flux density is reached, can be investigated under prototypical thermodynamic conditions with pressures of up to 170 bar and temperatures of up to 360°C. A heating capacity of almost 2 MW is available for the heating and evaporation of the working medium water.

1. CAD model of the high-pressure plant View from north

In addition, COSMOS-H enables the investigation of questions concerning heat transfer and material and component testing, which are of interest in the field of power plant technology, as well as in chemical and process engineering. The special quality of the experimental results results from the unique combination of the high level of instrumentation of the plant and test section at simultaneously high pressures and temperatures.

Table 1 - Design parameters of the plant

For the joint project NUBEKS (Numerical Description of Critical Boiling Processes), measurements are carried out in cooperation with the Institute of Thermal Process Engineering (TVT) for the development and validation of new CFD codes for the calculation and prediction of the boiling crisis. In this context, the flow conditions occurring at the onset of boiling crisis under reactor-typical conditions are to be fully recorded. For this purpose, TVT is currently building a modular high-pressure test section with extensive instrumentation.

2. CAD model of the high-pressure plant View from the West

This modular test section, despite the demanding operating conditions, will also be equipped with several sight glasses. These will make it possible to produce high-speed images of the flow and use optical measurement methods in addition to conventional instrumentation. Within the scope of NUBEKS, investigations will be carried out on a single heated rod in the annular gap at this test section. In the further course of the project, measurements on a rod bundle are also planned.   

CAD model of the test section