The University of Tokyo

Waki Factory Inc.

Futaba Industrial Co., Ltd.

M-k Sale Co., Ltd.

Kandori Industry Ltd.

Naoki Shikazono

Shiro Ikuta

Tsunehito Wake

Yuji Suzuki

Kenichi Morimoto

Kentaro Fukuda

Nobuhide Kasagi

Isamu Kandori

Yoshinori Suzue

Koji Matsuoka

Isao Hayase

Each finis designed to have continuous lines of wave crestsand continuous lines of wave troughsarranged at a preset angle in a specific angle range of 10 degrees to 60 degrees relative to the main stream of the air flow and symmetrically folded back about folding lines of a preset folding interval W along the main stream of the air flow. A ratio (a/p) of an amplitude 'a' of a waveform including one wave crestand one adjacent wave troughto a fin pitch 'p' satisfies a relation of 1.3&#xd7;Re&#x3c;a/p&#x3c;0.2. A ratio (W/z) of the folding interval W to a wavelength &#x2018;z&#x2019; of the waveform satisfies a relation of 0.25&#x3c;W/z&#x3c;2.0. A ratio (r/z) of a radius of curvature &#x2018;r&#x2019; at a top of the wave crestor at a bottom of the wave troughto the wavelength &#x2018;z&#x2019; of the waveform satisfies a relation of 0.25&#x3c;r/z. The continuous lines of the wave crestsand the continuous lines of the wave troughsare arranged to have an angle of inclination a of not less than 25 degrees at a cross section of the waveform. This arrangement effectively improves the heat transfer coefficient of a heat exchanger and thereby allows effective size reduction of the heat exchanger.

Heat exchanger

A heat exchanger assembled from multiple heat exchanging tubes. Each of the multiple heat exchanging tubes is formed as a flattened tube of 0.5 mm in thickness by press work or bending work of a stainless steel plate member having a thickness of 0.1 mm. Each of the multiple heat exchanging tubes is structured to have multiple lines of sequential wave crests and multiple lines of sequential wave troughs formed on each of flattened faces of the heat exchanging tube. The multiple lines of the sequential wave crests and the multiple lines of the sequential wave troughs are arranged to have a preset angle &#x3b3; relative to a main stream of an air flow. The lines of the sequential wave crests and the lines of the sequential wave troughs are symmetrically folded back about folding lines arranged at a preset interval W along the main stream of the air flow.

A heat exchanger has multiple laminated fins. Each finhas multiple topsand multiple bottomsarranged to have a preset acute angle &#x3b3; (for example, 30 degrees) to an air flow line at an air inlet and to make an air flow in a cavity region behind each of multiple heat transfer tubestoin an air flow direction at an air outlet. This design of the finsproduces effective secondary flows of the air to improve the heat transfer efficiency and makes an additional contribution to heat exchange, due to the air flow in the cavity region behind each of the heat transfer tubestoin the air flow direction. This arrangement effectively prevents separation of the air flow and a local speed increase of the air flow, while improving the overall heat exchange efficiency by production of the effective secondary flows of the air.

Fin structure for fin tube heat exchanger

A plurality of flat tubes formed as a tube having notches by linearly cutting upper and lower parts from a hollow flat circular doughnut shape are stacked to structure a tube laminate. It is attached to a case so that a notch aligns with the notch and faces upward by an exhaust inflow end plate and that a notch aligns with the notch and faces downward by an exhaust outflow end plate. A cutoff valve is provided at an exhaust outflow end of an exhaust communication tube passing through the center of the tube laminate by heat insulation. While an internal combustion engine is warming up, the cutoff valve is closed to cause the exhaust to flow in gaps of the respective flat tubes from upward to downward as a whole and also a heat exchange medium is caused to flow in the respective flat tubes from downward to upward as a whole to have heat exchanged between the exhaust and the heat exchange medium to recover the exhaust heat.

Heat recovery system

Growing community of inventors

Tokyo, Japan

Naoki Shikazono