JPS6446536A - Direct combustion furnace - Google Patents

Abstract

PURPOSE:To efficiently supply high-temperature heating medium air by dividing the heating medium air duct to a direct combustion furnace into three or more parallel passages whose surface opposing the surface of the direct combustion furnace is made of a material which is almost a black spot and making the duct area twice as large compared with that of the outlet area of a pressure fan. CONSTITUTION:The greater the number N of parallel division, the narrower the passage width 8 becomes. However, since the width becomes small, the heating medium air delivered from a pressure fan all flows between the heat exchanger surface and a separator wall 7 as a boundary layer as most of the air contacts the surface of the hot surface of the heat exchanger 1. (The effect becomes greater as the force of the pressure fan becomes higher.) The efficiency is improved as the heating medium air expands after exchanging heat. (i.e. the flow sped becomes high.) The surface of the separator wall 7 promotes the heat exchange because it receives the radiation heat from the surface of the heat exchanger 1, and its influence is great because of the short distance. The heating medium air having expanded after said heat exchange presents a greater draft resistance, resulting in the uniform passage.