Experimental study of heat transfer in an open thermosyphon

Abstract

Experimental study was performed on heat transfer of an open thermosyphon with constant wall heat flux. Water and aqueous glycerin were used as working fluids. Experimental range of modified Rayligh Number was 1×10 3 <3×l04, no turbulence was observed in the flow and thermal boundary layer was localized in the vicinity of the wall. Wall temperature rose towards upward. For 3×104 < 3×105, flow is considerably disturbed by the mixing of upward and downward flow in the upper part of the tube. However, flow is almost laminar in the lower part of the tube. Reduction of flow rate induced by the flow mixing at high Ra3 would be one of the major causes of the deterioration of heat transfer from the Lighthill's theory.