Dependence of the critical heat flux over a cylinder in a cross flow on the thermal resistances of tube wall and heating medium

1988 ◽  
Vol 22 (6) ◽  
pp. 309-313
Author(s):  
G. Meyer ◽  
E. S. Gaddis ◽  
A. Vogelpohl
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Tube Wall ◽  
Cross Flow ◽  
Heating Medium

Study on the Prediction of DNB-Type Critical Heat Flux in Rod Bundle Under Motion Conditions

2018 ◽  
Author(s):  
Siyang Huang ◽  
Xiaoyan Wang ◽  
Wenxi Tian ◽  
Ronghua Chen ◽  
Junmei Wu ◽  
...  
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Nuclear Reactor ◽  
Cross Flow ◽  
Nucleate Boiling ◽  
Heated Wall ◽  
Coupled Analysis ◽  
Flow Conditions ◽  
Local Flow ◽  
Rod Bundle

In the nuclear reactor design, the critical heat flux (CHF) is one of the most important parameters for the reactor safety analysis. The occurrence of CHF will cause a sharp increase in the fuel rod surface temperature, which will result in the failure of fuel claddings and damage of the core. The CHF depends on the local flow conditions and the geometry of the flow channels, which makes the prediction of CHF in a fuel assembly more difficult when considering the cross flow between neighboring channels, spacer grids and mixing vanes. In this paper, the departure from nucleate boiling (DNB) type CHF in rod bundles under motion conditions is investigated based on the coupled analysis of the subchannel method and a CHF mechanism model, namely the liquid sublayer dryout model. The liquid sublayer dryout model assumes that there is a thin liquid sublayer underneath a vapor blanket formed by the coalescence of small bubbles near the heated wall. The dryout of this sublayer is considered as the CHF occurrence. In the liquid sublayer dryout model, sublayer thickness, velocity and length of the vapor blanket are three crucial parameters. In present research, the subchannel code calculates the local flow conditions for the rod bundle and provides input parameters for the liquid sublayer dryout model to predict CHF. In order to verify the method above, the predicted results are compared with the CHF Look-Up Table 2006 (LUT-2006) and a reasonable agreement can be achieved. In addition, the effects of rod bundle inlet coolant mass flow rate, subcooling and motion conditions on the CHF are analyzed.

Sign in / Sign up

Export Citation Format

Share Document