To provide a double tube type heat exchanger of high heat exchanging efficiency by preventing deposition of scale components.
This double tube type heat exchanger comprises a small diameter tube 7 in which a first fluid flows, and a large diameter tube 8 disposed outside of the small diameter tube 7 to allow a second fluid to flow between the small diameter tube 7 and the large diameter tube 8. The small diameter tube 7 has the spiral shape, and pitch lengths of the spiral shape are various at an upstream side and a downstream side of the first fluid, so that the pitch length of the spiral shape is long at a place where the scale components are often deposited to reduce resistance of a flow channel, thus the scale components are hardly deposited, and heat transfer coefficient can be improved.
COPYRIGHT: (C)2007,JPO&INPIT
ONO KATSUTOSHI
NOMURA MASAKAZU
SHIRAI KENJI
HAMADA MASAYUKI
HAYASHI BUNJI
Hiroki Naito
Daisuke Nagano