Combustion heater

Abstract

The combustion heater includes an inner tube having a supply passage for combustion gas in an inner portion, and an outer tube disposed to provide a separated combustion space in an outer periphery of the inner tube. A hole part for ejecting the combustion gas being formed on a tube wall of the inner tube and a radiation promoting surface is disposed on an outer periphery of the inner tube. This structure suppresses excess temperature increase in the inner tube and improves heating efficiency in the combustion heater.

1 . A combustion heater comprising:
 a plurality of inner tubes each having a supply passage for combustion gas in an inner portion, an outer tube disposed around the inner tubes to provide a separated combustion space in an outer periphery of the inner tubes, a stagnation point formation member comprising a bluff body, the bluff body facing a hole part in at least one of said inner tubes located along an axial direction of the combustion space and configured to form a stagnation point of combustion gases ejected from the hole part, and a radiation promoting surface disposed on an outer periphery of the inner tubes,   wherein the bluff body is disposed coaxially to the outer tube,   wherein an axial line of the bluff body is aligned with the central axis of the outer tube, the bluff body is surrounded by the inner tubes, and the bluff body includes a concave surface facing the hole part, about the axis of the inner tube having the hole part, and extending in an axial direction of the inner tube having the hole part.   
     
     
         2 . The combustion heater according to  claim 1 , wherein the radiation promoting surface is a coated layer provided on an outer peripheral surface of the inner tube. 
     
     
         3 . The combustion heater according to  claim 1  further comprising a radiation promoting surface on an inner peripheral surface of the outer tube. 
     
     
         4 . The combustion heater according to  claim 3 , wherein the radiation promoting surface is a coated layer provided on the inner peripheral surface. 
     
     
         5 . The combustion heater according to  claim 1 , wherein the radiation promoting surface is formed using a ceramic binder. 
     
     
         6 . The combustion heater according to  claim 1 , wherein the supporting member is a heat transfer member that is provided to connect the inner tube and the outer tube in the combustion space and to transfer heat between the outer tube and the inner tube 
     
     
         7 . A combustion heater comprising:
 a plurality of inner tubes each having a supply passage for combustion gas in an inner portion;   an outer tube disposed to provide a separated combustion space in an outer periphery of the inner tubes;   a stagnation point formation member comprising a bluff body, the bluff body facing a hole part in at least one of said inner tubes, along an axial direction of the combustion space, the bluff body being configured to form a stagnation point of combustion gases ejected from the hole part, and a radiation promoting surface is disposed on an outer periphery of each inner tube,   wherein the bluff body is disposed coaxially to the outer tube,   wherein an axial line of the bluff body is aligned with the central axis of the outer tube and the circumference thereof is surrounded by the inner tubes, and the bluff body includes a concave surface that faces the hole part and is formed about and along the axis of the inner tube having the hole part.