Abstract: A method of manufacturing a heat-transfer wall for vapor condensation comprising the step of forming on the heat-transfer surface, a number of shallow grooves substantially in parallel at a fine pitch, and then forming, on the heat-transfer surface and in the direction across said shallow grooves, a number of grooves deeper than the shallow grooves at a fine pitch by cutting and turning up the heat-transfer surface in the plowing manner. Said method may further comprise a subsequent step of curling the edges of the ridges formed in the above-mentioned step into said deep grooves.

Abstract: A heat transfer wall for boiling liquids having a multiplicity of minute tunnels parallelly extending and spaced a distance of not more than 1 mm under the metal wall surface in contact with liquid. Each tunnel is communicated with the outside by a multiplicity of tiny holes formed at regular intervals of not more than 1 mm along the tunnel. The wall surface portion is in one piece with the wall body. The holes combinedly account for from 2 to 50% of the total surface area of the wall. The regularly formed holes are substantially triangular shaped. The wall is made of either copper or aluminum.