PURPOSE: To improve heat transmission performance by a method wherein a jacket is formed on the outer periphery of a vessel body in a state that a specified gap is left therebetween, and cooling fluid is forced to flow through the gap at a high speed.

CONSTITUTION: A jacket 2 of an aluminum casting or weld structure securely closes the outer periphery of vessel body 1 through a packing ring 7 made of rubber. Fluid enters through a cooling fluid inlet (one spot or several spots) 3 in the jacket 2. After a cooling fluid chamber 5 is filled therewith, an uniform high speed is provided throughout the whole of a heat exchange part 6 having a gap of 0.5-1mm to cool a heat exchange part, and the fluid is discharged through the upper cooling fluid chamber 5 and a cooling fluid outlet 4. Fluid chamber parts are situated to the inlet end and the outlet end of the heat exchange part of the jacket, and has a sectional area being 5-7 times as large as that of the heat exchange part 6.