A hypervapotron (HV) loop test facility was built to conduct some experiments of heat transfer. Phenomena of HV were observed using the techniques of planar laser-induced fluorescence, high-speed photography, and particle image velocimetry. According to the design of the ITER cooling water system, the fluid flow and condition parameters were utilized: 1) CuCrZr alloy material; 2) triangular and rectangular fin structures; 3) inlet subcooling temperature of 298 K; and 4) rhodamine B solution flow velocity of 0.3-0.5 m/s. It was found that the heat transfer coefficient of the rectangular fin was 1.3-1.5 times higher than that of the triangular fin under the same test conditions. Furthermore, the preliminary mechanism of the heat transfer was explained by the coupling effect of the vortex flow with vapor bubble in the fin pitch, and the heat transfer efficiency was extraordinarily dependent on maintaining the time of vortex formation between the fins.