PURPOSE: To increase temperature difference from the existing city water, promote natural convection and improve heat transfer rate around the flow path of heat medium by a method wherein multistages of heat medium flow paths, communicating with each other, are formed and the entrance of the heat medium is provided at the lowermost stage.
CONSTITUTION: Second annular heat transfer fin 9 is provided with communicating openings 10 to form flow paths between the annular fins and double tube 11, arranged so as to be located immediately below a double wall heat transfer tube is connected to the paths between annular fins through the end face 12 of the double wall heat transfer tube to constitute the heat exchanging fluid flow path. A fluid outflow tube 14, communicated with the double tube 11 and the flow paths between annular fins, is penetrated through and welded to the double wall heat transfer tube end face 13 of a flange provided at the other end. The temperature difference between ambient city water is large in case the high-temperature heating fluid flows thereinto through the double tube 11, therefore, the natural convection may be promoted and the heat transfer rate around the double wall heat transfer tube, located immediately above the double tube 11, may be improved.
IKOMA MITSUHIRO
ADACHI MASAAKI
TANAKA HIROYOSHI
TSUDA YOSHIYUKI
