Analysis of Two Phase Counter Flow in Heat Pipe By Neutron Radiography

The heat pipe operates by the four processes composed of evaporation, vapor flow, condensation and reflux of the working fluid. Neutron radiography and neutron television were applied to investigate the thermal-hydraulic behavior of the working fluids (boiling, vapor flow, condensation and liquid flow) in steel heat pipes. Light and heavy waters, propanol, isooctane, sodium and 10%lithium-sodium were used as working fluids. All the bulk condensates were easily visualized. The films of light water, propernol, isooctane and 10%lithium-sodium contained in the wick were also detectable. Dimension of the liquid films and the spatial distribution of the working fluids were evaluated by image processing. The interface between vapor and non-condensable gas in the 10%Li-Na heat pipe was speculated from the condensing position of the vapor.