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Exhaust gas heat exchanger

a heat exchanger and exhaust gas technology, applied in the direction of machines/engines, lighting and heating apparatus, laminated elements, etc., can solve the problems of pressure loss of exhaust gas flowing in the tube and the restriction of the hydraulic resistance of cooling fluid (such as cooling water), and achieve the effect of improving performan

Inactive Publication Date: 2008-01-17
DENSO CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0014]In view of the above-described disadvantages, it is an object of the present invention to provide an exhaust gas heat exchanger having an improved performance in the case where an offset fin is used as an inner fin.
[0016]Thus, the pressure loss of the exhaust gas flowing in the tube and the hydraulic resistance of the cooling fluid (such as cooling water) can be restricted. Therefore, the tube can be restricted from being clogged, and can be provided with a higher heat-radiating capacity.
[0019]Thus, the gas density which is a factor considering both the cooling capacity and the pressure loss will be larger than or equal to 93%, so that the exhaust gas heat exchanger has an improved performance can be provided.
[0023]Therefore, the gas density can be larger than or equal to 97%. Thus, the exhaust gas heat exchanger has the further improved performance can be provided.
[0026]Thus, the gas density can be larger than or equal to 93%, so that the exhaust gas heat exchanger has an improved performance can be provided.

Problems solved by technology

Thus, the pressure loss of the exhaust gas flowing in the tube and the hydraulic resistance of the cooling fluid (such as cooling water) can be restricted.

Method used

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Examples

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embodiments

First Embodiment

[0042]An exhaust gas heat exchanger according to a first embodiment of the present invention will be described with reference to FIGS. 1-8. The exhaust gas heat exchanger can be suitably used as an exhaust gas recirculation cooler 10 (EGR cooler), for example.

[0043]As shown in FIG. 1, the EGR cooler 10 can be provided for an exhaust gas recirculation device. The exhaust gas recirculation device has, for example, an air cleaner 3, a variable tube actuator 4, an inter cooler 5 and an intake manifold 6 which are arranged at a halfway portion of an air suction passage 2 of an engine 1.

[0044]The tube actuator 4 and a DPF 8 (diesel particulate filter) are arranged at a half portion of an exhaust passage 7 of the engine 1. A first exhaust gas recirculation pipe 9 is connected with a downstream side of exhaust gas of the DPF 8 and an upstream side of suction air of the tube actuator 4. The EGR cooler 10 and an exhaust gas recirculation valve 11 (EGR valve) are arranged at a ...

second embodiment

[0076]According to a second embodiment of the present invention, the optimum specifications of the inner fin 22 are determined according to different criterions and parameters from those of the above-described first embodiment.

[0077]In the second embodiment, the optimum specifications of the inner fin 22 are determined based on the relation between an equivalent circle diameter de and an EGR gas density ratio ρ.

[0078]In this case, as shown in FIG. 6, the equivalent circle diameter de means a diameter of an equivalent circle into which the field C in the cross section (substantially perpendicular to exhaust gas flowing direction) of the inner fin 22 is converted. The field C is positioned between the convex portions 31 which are arranged at the crest positions (or trough positions) and adjacent to each other, and surrounded by the inner fin 22 and the tube 21. The equivalent circle diameter de can be calculated by the following formula (2).

de=4×S / W  (2)

[0079]S represents an area (whi...

third embodiment

[0093]According to a third embodiment of the present invention, the optimum specifications of the inner fin 22 are determined according to different criterions and parameters from those of the above-described embodiments.

[0094]In the third embodiment, the optimum specifications of the inner fin 22 are determined based on the relation between the segment length L and the EGR gas density ratio (ρ ratio).

[0095]FIG. 11 shows the relation between the segment length L and the EGR gas density ratio (ρ ratio), which is a ratio when the maximum value of the EGR gas density ρ is set as 100%. The relation shown in FIG. 11 is obtained with the same condition as that of FIG. 10, excepting the fin height fh and the segment length L.

[0096]The curve F in FIG. 11 is calculated when fh<7 and fp≦5, for example, when fh is equal to 4.6 and fp is equal to 4.5. Thus, when the segment length L is in the range of 0.5

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Abstract

An exhaust gas heat exchanger has a tube which is made of a stainless steel and in which exhaust gas flows, and an inner fin which is made of a stainless steel and arranged in the tube to improve a heat exchange between the exhaust gas and cooling water. The cooling water flows at an outer side of the tube. The fin pitch fp of the inner fin is substantially in the range of 2 mm<fp≦12 mm, and the fin height fh of the inner fin is substantially in the range of 3.5 mm<fh≦12 mm.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application is based on a Japanese Patent Application No. 2006-190428 filed on Jul. 11, 2006, the disclosure of which is incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to an exhaust gas heat exchanger. For example, the exhaust gas heat exchanger can be suitably used for an exhaust gas recirculation cooler (EGR cooler), which is provided in an exhaust gas recirculation device (EGR) to cool exhaust gas.BACKGROUND OF THE INVENTION[0003]Generally, an exhaust gas recirculation cooler (EGR cooler) is used in a diesel type engine or the like as an exhaust gas heat exchanger. For example, with reference to JP-2004-77024A, the general EGR cooler is arranged at a halfway position of an exhaust gas recirculation pipe for partially refluxing exhaust gas of the engine directly to the suction side of the engine.[0004]In this case, the EGR cooler is provided with multiple tubes which are stacked and in eac...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): F28F1/36
CPCF02B29/0406F02M25/0737F02M25/0744Y02T10/121F28D9/0031F28D21/0003F28F3/027F28D7/1684F02M26/32F02M26/38Y02T10/12
Inventor OOFUNE, YUUHAYASHI, TAKAYUKI
Owner DENSO CORP
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