| 摘要 |
PURPOSE:To enable to suppress the temperature of heat medium to a heat resistant temperature or lower by partly notching a fin at the lower end of a heat transfer tube opposed to combustion gas. CONSTITUTION:A heat transfer tube 8 with a fin which is disposed at the upper end of a cylinder 6 is provided at a heat transfer tube 7 which is spirally wound on the outer surface of the cylinder 6 which forms a combustion chamber 5, and the fin of the lower end of the tube 8 is partly notched. In the above structure, the peripheral wall temperature distribution a and the elevational heated fluid temperature distribution b of the tube 8 become as designated by a solid line b and a dotted broken line d, the heat transfer from the fin 8 at the lower end of the tube 7 is eliminated, the local temperature rise is eliminated, and the temperature of the heated fluid does not exceed the heat resistant temperature in the vicinity of the wall surface at the lower end of the tube 7 as designated by the line d. |
