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Title:

Experimental Investigation of Phenomena in Heat Transfer to Water at Near Critical Pressures

Document type:
Konferenzbeitrag
Author(s):
Oettig, J.; Licht, L.; Ferrand, T.; Westermeier, M.; Schifflechner, C.; Pioro, I.; Spliethoff, H.
Abstract:
The knowledge of heat transfer at near-critical pressures is crucial for the safety design of thermal hydraulic systems like supercritical water reactors. Starting from a supercritical state during normal operation, loss of pressure accidents can lead to thermodynamic subcritical conditions, so that boiling crises can occur if the critical heat flux is exceeded. This phenomenon may leads to a significant increase in the wall temperature of heated surfaces. The following failure of the fuel rod material can cause safety-relevant damages. The safety design of novel reactor concepts, working at thermodynamic supercritical conditions, requires therefore meaningful correlations to predict those phenomena and their impact. Current correlations are however often meaningful at reduced pressures pr < 0.7 but uncertain above. The “High Pressure Evaporation Rig – HIPER” at the Chair of Energy Systems at the Technical University of Munich provides experimental heat transfer data on water at near critical pressures. This facility consists of a closed loop with a vertical smooth test section. 300 kW electrical power can be applied to the current 15.8 mm evaporation tube to achieve CHF. This pipe is used to investigate the pressure and mass flux dependence of CHF. A future optimized test section with an internal diameter of 10.0 mm, will be used to study the influence of the hydraulic diameter. In addition, the new test section will provide accurate data to test current fluid-fluid scaling theories, as comparable experiments are currently being conducted internationally using CO2 and R134a instead of water. In summary, this contribution provides insights into currently conducted experimental data and future experimental investigations on heat transfer at high sub- and supercritical pressures.
Book / Congress title:
14th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-14)
Year:
2024
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