Heat exchange – Flow passages for two confined fluids – Interdigitated plural first and plural second fluid passages
Reexamination Certificate
1999-04-02
2001-04-03
Flanigan, Allen (Department: 3743)
Heat exchange
Flow passages for two confined fluids
Interdigitated plural first and plural second fluid passages
C165S146000, C165SDIG003
Reexamination Certificate
active
06209630
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a heat exchanger including high-temperature fluid passages and low-temperature fluid passages defined alternately by folding a plurality of first heat-transfer plates and a plurality of second heat-transfer plates in a zigzag fashion.
BACKGROUND ART
A heat exchanger is already known from Japanese Patent Application Laid-open Nos. 59-183296 and 59-63491, which is formed by cutting, into an angle shape having two end edges, opposite ends in a flowing direction of each of first and second heat-transfer plates disposed adjacently and alternately with each other to define high-temperature fluid passages and low-temperature fluid passages. A heat exchanger is also already known from Japanese Patent Application Laid-open No. 58-40116, which includes high-temperature fluid passages and low-temperature fluid passages alternately defined by folding a band-shaped heat-transfer plate in a zigzag fashion.
The volume flow rate of a high-temperature fluid flowing through high-temperature fluid passages in a heat exchanger is not necessarily equal to the volume flow rate of a low-temperature fluid flowing through low-temperature fluid passages in the heat exchanger. For example, in the case of a heat exchanger used in a gas turbine engine, the volume flow rate of a high-temperature fluid comprising a combustion gas is larger than the volume flow rate of a low-temperature fluid comprising air. However, the above known heat exchanger suffers from a problem that the pressure loss of the fluid having the larger volume flow rate is increased and the pressure loss in the entire heat exchanger is also increased, because the lengths of the two end edges of the angle shape are set equal to each other.
When the heat-transfer plates formed in the zigzag folded fashion are disposed radiately to define high-temperature fluid passages and low-temperature fluid passages alternately with each other in a circumferential direction, if an attempt is made to form a heat exchanger having a center angle of 360° from a single folding plate blank, the folding plate blank is required to have a large length, thereby making it difficult to produce the heat exchanger. Moreover, there is a problem that the yield of the blank is degraded. Therefore, it is conceived that a module having a predetermined center angle is formed from a folding plate blank having a suitable length and a plurality of the modules are connected together in the circumferential direction to form a heat exchanger having a center angle of 360°. If the structure of bond zones between adjacent modules are not taken into consideration sufficiently, the following problem is encountered: the heat-transfer plates may be fallen down in the circumferential direction in the vicinity of the bond zones, whereby they may not be arranged correctly in a radial direction, moreover, the heat mass in the bond zones may be increased. Another problem is that if the accuracy of the end edges of the folding plate blank is not controlled precisely, a misalignment is liable to occur between the end edges of the folding plate blank in the bond zones.
DISCLOSURE OF THE INVENTION
Accordingly, it is a first object of the present invention to ensure that an increase in pressure loss based on a difference between the volume flow rates of the high-temperature and low-temperature fluids is avoided, thereby decreasing the pressure loss in the entire heat exchanger. It is a second object of the present invention to ensure that when an annular-shaped heat exchanger is formed by bonding a plurality of modules together, the generation of an increase in heat mass and an increase in flow path resistance to the fluid in the bond zones is avoided. Further, it is a third object of the present invention to ensure that when an annular-shaped heat exchanger is formed by bonding a plurality of modules together, the misalignment of the bond zones and the increase in heat mass are suppressed to the minimum, while preventing the falling of the heat-transfer plate in the circumferential direction.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a heat exchanger, which is formed from a folding plate blank comprising a plurality of first heat-transfer plates and a plurality of second heat-transfer plates which are alternately connected together through folding lines, and in which high-temperature fluid passages and low-temperature fluid passages are alternately defined between adjacent ones of the first and second heat-transfer plates by folding the folding plate blank in a zigzag fashion along the folding lines, and opposite ends of each of the first and second heat-transfer plates in a flowing direction are cut into angle shapes each having two end edges; whereby a high-temperature fluid passage inlet is defined by closing one of the two end edges and opening the other end edge of one of the angle shapes at one end of the high-temperature fluid passage in the flowing direction, and a high-temperature fluid passage outlet is defined by closing one of the two end edges and opening the other end edge of the other angle shape at the other end of the high-temperature fluid passage in the flowing direction; and a low-temperature fluid passage inlet is defined by opening one of the two end edges and closing the other of the two end edges of the other angle shape at one end of the low-temperature fluid passage in the flowing direction, and a low-temperature fluid passage outlet is defined by opening one of the two end edges and closing the other of the two end edges of the one of the angle shapes at the other end of the low-temperature fluid passage in the flowing direction, characterized in that the lengths of the two end edges of each of the angle shapes are unequal to each other, and a flow rate of a fluid in the high-temperature fluid passage inlet and outlet is reduced, in order to suppress to the minimum a sum of pressure losses produced in the high-temperature fluid passage inlet and outlet and the low-temperature fluid passage inlet and outlet.
With the above arrangement, when the one ends of the first and second heat-transfer plates in the flowing direction are cut into the angle shape to define the high-temperature fluid passage inlet and the low-temperature fluid passage outlet, and the other ends of the first and second heat-transfer plates in the flowing direction are cut into the angle shape to define the high-temperature fluid passage outlet and the low-temperature fluid passage inlet, the lengths of the two end edges of each of the angle shapes are unequal to each other. Thus, the flow rate of the high-temperature fluid flowing in the high-temperature fluid passages can be relatively reduced, thereby suppressing the generation of a pressure loss in the entire heat exchanger to the minimum.
To achieve the second object, according to a second aspect and feature of the present invention, there is provided a heat exchanger, having axially extending high-temperature fluid passages and low-temperature fluid passages defined alternately in a circumferential direction in an annular space that is defined between a radially outer peripheral wall and a radially inner peripheral wall, the heat exchanger comprising a plurality of modules formed by folding a plurality of folding plate blanks each comprised of a plurality of first heat-transfer plates and a plurality of second heat-transfer plates which are alternately connected together through folding lines, in a zigzag fashion along the folding lines, the high-temperature fluid passages and the low-temperature fluid passages being defined alternately in the circumferential direction by the first and second heat-transfer plates disposed radiately between the radially outer peripheral wall and the radially inner peripheral wall, by connecting the plurality of modules together in the circumferential direction; and a high-temperature fluid passage inlet and a low-temperature fluid passage outlet which are defined so as to open at axially
Tsunoda Tadashi
Yanai Hideyuki
Arent Fox Kintner & Plotkin & Kahn, PLLC
Flanigan Allen
Honda Giken Kogyo Kabushiki Kaisha
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