To obtain a high heat transfer rate through slight superheating and a simple structure by a method wherein a heat-of-vaporization transfer device is constituted of the introduction of steam bubbles into an evaporating chamber, the elevation of the steam bubbles in the evaporating chamber, the deformation of the steam bubbles between the walls of a heat exchanger, and the discharge of the steam bubbles grown by discharging steam for using the same for another use.

High-temperature steam is blown into a condensing chamber 16 from a hole 24 through a pipe 22. The diameter of the hole 24 is designed so as to be slightly larger than the width of the condensing chamber 16 at a place where discharging high-temperature steam bubbles 39 are blown therethrough. Accordingly, the steam bubbles are deformed upon elevation and are adhered to the wall 14 of a heat exchanger whereby a thin liquid film having an excellent heat transmitting characteristic is formed. Remaining high-temperature steam is discharged sideward at the upper end of the condensing chamber 16 together with condensed matter, dropping upon the discharge. Remaining heating steam is blown into an evaporating chamber 28 through a sending tube 30 and the hole 32 while blown steam bubbles 40 are elevated between the walls 14 of the heat exchanger to promote the transfer of heat and the remaining steam bubbles, grown by receiving the discharging steam, are delivered to a discharging steam chamber 38 and are discharged through an outlet tube 10.