EP0108377A1

EP0108377A1 - Heat exchanger

Info

Publication number: EP0108377A1
Application number: EP83110906A
Authority: EP
Inventors: Isao Takeshita; Yoshiaki Yamamoto; Seikan Ishigai
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1982-11-04
Filing date: 1983-11-02
Publication date: 1984-05-16

Abstract

57 A heat exchanger (k1, K2, K3, K4, K5) including a plurality of plates (A, B, C, D) of a substantially identical shape stacked one on another so as to effect heat exchange between at least first and second fluids. The plates (A, B, C, D) are, respectively, formed with a plurality of flow plates (1A, 1B, 1C, 1D) and at least first and second communicating passages (3A', 3B, 2C', 2D; 4A, 5B', 5C, 4D') such that the first and second fluids flow in first and second directions, respectively.

Description

BACKGROUND OF THE INVENTION

The present invention generally relates to heat exchangers for effecting heat exchange between two fluids and more particularly, to an improved construction of a heat exchanger for effecting heat exchange between two of gas, liquid, gas-liquid two-phase flow, etc.
For such a purpose, there have been conventionally proposed a shell and tube type heat exchanger, a double pipe type heat exchanger, a plate type heat exchanger, etc. which have features, respectively.
At present, effective utilization of energy is urged from the standpoint of energy saving and there is a strong demand for compact heat exchangers having excellent temperature efficiency.
Although several types of heat exchangers are, respectively, employed according to applications, the double pipe type heat exchangers have been most frequently used for effecting heat exchange between two liquids or between liquid and gas-liquid two-phase flow. In the known double pipe type heat exchanger provided with a double pipe including an outer pipe and an inner pipe inserted into the outer pipe, it has been generally so arranged that first and second fluids are caused to flow in the inner pipe and between the inner pipe and the outer pipe, respectively, and the double pipe is spirally wound so as to make the heat exchanger compact in size as shown in Fig. 1. However, the know double pipe type heat exchanger has such inconveniences that, since portions associated with heat transfer are restricted to surfaces of the inner pipe but surfaces of the outer pipe are not associated with heat transfer, the heat exchanger becomes large in size and thus, requires a large amount of materials therefor.
On the other hand, as shown in Fig. 2, in a heat exchanger (referred to as a "spiral two-stack-pipe type heat exchanger", hereinbelow) having two pipes of a rectangular cross section stacked one on the other and wound spirally for effecting heat exchange between two fluids, it may be estimated that, if adjacent ones of the stacked pipes are thermally connected to each other completely, most of metallic wall surfaces of the stacked pipes are associated with heat transfer, so that heat is transferred form - upstream and downstream flow paths and thus, the spiral two-stack-pipe type heat exchanger can be made more compact and efficient than the double pipe type heat exchanger.
It is to be noted here that, in the same manner as the spiral two-stack-pipe type heat exchanger, there has been also proposed a heat exchanger (referred to as a "spiral three-stack-pipe type heat exchanger", hereinbelow) having three pipes of a rectangular cross section stacked one on another and wound spirally for effecting heat exchange among three fluids as shown in Fig. 3.
In order to make the spiral two-stack-pipe type heat exchanger more efficient, the pipes are required to be flattened as far as possible. However, when the pipes are flattened to some degree, it becomes impossible to wind the pipes spirally. Furthermore, partly due to a fact that it has been actually impossible to obtain rectangular pipes which are flattened sufficiently, an ideal spiral two-stack-pipe type heat exchanger has not been put to practical use so far.
Meanwhile, in the above described double pipe type heat exchanger, the double pipe is spirally wound only for ease of operation thereof. However, in the spiral two-stack-pipe type heat exchanger, it is essential that the two pipes are required to be not only wound spirally but connected to each other thermally.
Although the two rectangular pipes stacked one on the other and wound spirally may provide improved heat transfer characteristics as described above, it is estimated that excellent heat transfer characteristics cannot be obtained as far as pipes are employed.

SUMMARY OF THE INVENTION

Accordingly, an essential object of the present invention is to provide an improved heat exchanger (referred to as a "spiral stack-plate type heat exchanger", hereinbelow) provided with two spiral passages and including a plurality of plates stacked integrally one on another and each formed with a flow path of a sufficiently flattened cross section, which is excellent in heat transfer characteristics, with substantial elimination of the disadvantages inherent in conventional heat exchangers of this kind.
Another important object of the present invention is to provide an improved heat exchanger of the above described type which is simple in structure, highly reliable in actual use and suitable for mass production at low cost.
In accomplishing these and other objects according to one preferred embodiment of the present invention, there is provided an improved heat exchanger including a plurality of plates of a substantially identical shape stacked one on another so as to effect heat exchange between at least first and second fluids, the improvement comprising: a plurality of flow paths for effecting the heat exchange, which are each formed on one flat face of each of said plates such that some of said flow paths and the other ones of said flow paths allow said first and second fluids to flow through said some of said flow paths in a first direction at corresponding positions of said some of said flow paths and through said other ones of said flow paths in a second direction at corresponding positions of said other ones of said flow paths, respectively; and at least first and second communicating passages for connecting, wholly or partially in series, said some of said flow paths to one another and said other ones of said flow paths to one another, respectively, which are formed on each of said plates, whereby at least first and second passages of spiral configurations for passing said first and second fluids therethrough, respectively are formed independently of each other in said heat exchanger.
In the heat exchanger of the present invention, there are provided a first flat plate having a first flow path formed therein and a second flat plate formed with a second flow path having a shape identical to that of the first flow path such that a communicating passage for connecting, in series, a terminal end of the first flow path to a starting end of the second flow path is formed on either one of the first and second plates and a third flat plate formed with a third flow path, which is interposed between the first and second plates, whereby first and second spiral passages for passing first and second fluids therethrough, respectively are formed. Namely, it is so arranged that the first and second fluids are caused to flow in first and second directions in the plates, respectively as viewed from a direction perpendicular to the plates, which is a characteristic of the spiral passages.
Thus, in accordance with the present invention, since the plates are integrally stacked one on another as in the case of the known plate type heat exchanger such that the heat exchanger of the present invention has the above described structure, the passages can be flattened arbitrarily, it becomes possible to design the heat exchanger considerably unrestrictedly under given conditions such as its pressure loss, heat transfer characteristics, etc.
More specifically, in the heat exchanger of the present invention, two kinds of plates are required to be prepared for each of fluids subjected to heat exchange. Namely, in the case where first and second fluids are subjected to heat exchange, four kinds of first, second, third and fourth plates stacked one on another sequentially in this order and formed with first, second, third and fourth flow paths, respectively are employed such that the first and third flow paths allow the first fluid to flow therethrough, with the second and fourth flow paths allowing the second fluid to flow therethrough. In the third plate, relative positions of an inflow port and an outflow port of the third flow path are provided opposite to those of the first flow path of the first plate. Likewise, in the fourth plate, relative positions of an inflow port and an outflow port of the fourth flow path are-provided opposite to those of the second flow path of the second plate.
Furthermore, in accordance with the present invention, the number of kinds of plates to be prepared for each of fluids subjected to heat exchange is reduced to one. Namely, in the case where first and second fluids are subjected to heat exchange, first and second plates are stacked integrally one on the other alternately and formed with first and second flow paths, respectively are employed such that the first and second flow paths allow the first and second fluids to flow therethrough, respectively. Thus, an inlet and an outlet of the first flow paths are provided on the first plate, while an inlet and an outlet of the second flow paths are provided on the second plate. Since a first communicating passage for the first fluid and a second communicating passage for the second fluid are, respectively, formed on the second and first plates, spiral first and second passages for the first and second fluid, respectively are formed.
Moreover, in accordance with the present invention, only one kind of plates are required to be prepared for first and second fluids subjected to heat exchange. Each of the plates is of a regular polygon having n sides (n=positive integer). Each of the plates is formed with a flow path and two communicating passages. When the plates are integrally stacked one on another, adjacent ones of the plates are sequentially deviated by an angle of (360/n) degrees, whereby spiral first and second passages for the first and second fluids, respectively are formed.
In addition, in accordance with the present invention, there is provided an alternative arrangement in which only one kind of plates are required to be prepared for first and second fluids subjected to heat exchange. Each of the plates is formed with a flow path for the first fluid and a bypass for the second fluid. A shape of each of the plates, elongated portions of the flow path for effecting heat exchange between the first and second fluids, and inflow ports and outflow ports of the first and second fluids are so formed as to be diametrically symmetric with respect to an axis extending at right angles to a plane of each of the plates. When the plates are integrally stacked one on another, the plates are each rotated through 180° about the axis, whereby spiral first and second passages for the first and second fluids, respectively are formed.
Accordingly, in accordance with the present invention, at most several kinds of plates are integrally stacked one on another, whereby the spiral stack-plate type heat exchanger provided with the two spiral passages and having excellent heat transfer characteristics can be manufactured.

BRIEF DESCRIPTION OF THE INVENTION

These and other objects and features of the present invention will become apparent from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which:

Fig. 1 is a schematic perspective view of a prior art double pipe type heat exchanger (already referred to);
Fig. 2 is a schematic perspective view of a prior art spiral two-stack-pipe type heat exchanger (already referred to);
Fig. 3 is a schematic perspective view of a prior art spiral three-stack-pipe type heat exchanger (already referred to);
Figs. 4(a) to 4(d) are top plan views of four kinds of plates each formed with a flow path employed in a spiral stack-plate type heat exchanger according to a first embodiment of the present invention, respectively;
Fig. 4(e) is a cross-sectional view taken along the line IV(e)-IV(e) in Fig. 4(a);
Fig. 5 is a view explanatory of connections of the flow paths of the plates of Figs. 4(a) to 4(d);
Figs. 6(a) and 6(b) are top plan views of two kinds of plates employed in a spiral stack-plate type heat exchanger according to,a second embodiment of the present invention, respectively;
Fig. 6(c) is a cross-sectional view taken along the line VI(c)-VI(c) in Fig. 6(b);
Fig. 7 is an exploded view showing two passages defined by the plates of Figs. 6(a) and 6(b) stacked one on another;
Figs. 8(a) to 8(c) are top plan views of three kinds of plates employed in a spiral stack-plate type heat exchanger according to a third embodiment of the present invention, respectively;
Fig. 8(d) is a cross-sectional view taken along the line VIII (d) -VIII (d) in Fig. 8(c);
Fig. 9 is a view explanatory of three passages defined by the plates of Figs. 8(a) to 8(c) stacked one on another in one sequence;
Fig. 10 is a view similar to Fig. 9, particularly showing a modification thereof;
Fig. 11(a) is a top plan view of a plate employed in a spiral stack-plate type heat exchanger according to a fourth embodiment of the present invention;
Fig. 11(b) is a cross-sectional view taken along the line XI(b)-XI(b) in Fig. 11 (a);
Fig. 12 is a view explanatory of relative positions of the plates of Fig. 11(a) stacked one on another;
Fig. 13 is a view showing two passages defined by the plates of Fig. 11(a) stacked integrally one on another;
Fig. 14 is a top plan view of a plate employed in a spiral stack-plate type heat exchanger according to a fifth embodiment of the present invention;
Figs. 15(a), 15(b) and 15(c) are cross-sectional views taken along the lines XV(a)-XV(a), XV(b)-XV(b) and XV(c)-XV(c), respectively; and
Fig. 16 is an exploded view showing two passages defined by the plates of Fig. 14 stacked one on another.

Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout several views of the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, there are shown in Figs. 4(a) to 4(e), four kinds of first, second, third and fourth plates A, B, C and D of a circular shape employed in a spiral stack-plate type heat exchanger Kl for effecting heat exchange between first and second fluids, according to a first embodiment of the present invention. As shown in Figs. 4(a) and 4(e), the first plate A is formed with a groove or recess of a substantially circular shape acting as a first flow path 1A and with an elongated separating portion 6a for intercepting the first flow path lA, which radially extends from a central portion thereof to a peripheral circumferential wall 1A, thereof. The separating portion 6A is formed with slots 2A and 3A extending into opposite side thereof in opposite directions parallel to each other such that the slot 2A is disposed radially outwardly of the slot 3A. A through-hole 3A' is provided in the slot 3A, while a through-hole 4A is formed on the separating portion 6A so as to be disposed radially inwardly of the through-hole 3A' such that the through-hole 3A' is radially disposed between the slot 2A and the through-hole 4A.
Likewise, the second plate B is formed with a second flow path 1B, a peripheral circumferential wall 1B^I and a separating portion 6B. On the separating portion 6B, two slots 5B and 4B and a through-hole 3B are formed so as to be disposed radially outwardly in this order. A through-hole 5B' is provided in the slot 5B such that the slot 4B is radially disposed between the through- holes 3B and 5B'.
The third plate C is formed with a third flow path 1C, a peripheral circumferential wall 1C' and a separating portion 6C. On the separating portion 6C, a through-hole 5C and two slots 3C and 2C are formed so as to be disposed radially outwardly in this order. A through-hole 2C' is provided in the slot 2C such that the slot 3C is radially disposed between the through-holes 2C' and 5C.
The fourth plate D is formed with a fourth flow path 1D, a peripheral circumferential wall 1D' and a separating portion 6D. On the separating portion 6D, two slots 5D and 4D and a through-hole 2D are formed so as to be disposed radially outwardly in this order. A through-hole 4D' is provided in the slot 4D so as to be radially disposed between the through-hole 2D and the slot 5D.
It is to be noted that the first, second, third and fourth plates A, B, C and D are identical, in shape, to one another except for the separating portions 6A, 6B, 6C and 6D. It should be further noted that, when the first, second, third and fourth plates A, B, C and D are stacked one on another, the slot 2A and the through-holes 2C' and 2D are brought into alignment with one another, while the through-holes 3A' and 3B and the slot 3C are brought into alignment with one another. Likewise, when the first, second, third and fourth plates A, B, C and D are stacked one on another, the through-hole 4A, the slot 4B and the through-hole 4D' are brought into alignment with one another, while the through-holes 5B' and 5C and the slot 5D are brought into alignment with one another.
When a plurality of sets, for example, two sets of the first, second, third and fourth plates A, B, C and D, i.e., a first set of first, second, third and fourth plates A₁, B₁, C₁ and D₁ and a second set of first, second, third and fourth plates A₂, B₂₁ C₂ and D₂ are integrally stacked one on another sequentially in this order as shown in Fig. 5, the first plate A₁, third plate C₁, first plate A₂ and third plate C₂ are connected in series to one another so as to define a first passage Tl for the first fluid as shown in the solid lines in Fig. 5, while the second plate B₁, fourth plate D₁, second plate B₂ and fourth plate D₂ are connected in series to one another so as to define a second passage T2 for the second fluid as shown in the broken lines in Fig. 5.
For example, the first passage Tl (solid lines 7 in Fig. 5) in the first plate A₂ extends from the slot 2A of the first plate A₂ to the through-hole 2D of the fourth plate D₁ and then, through the through-hole 2C' of the third plate C₁ into the third flow plate 1C (solid lines 9 in Fig. 5) of the third plate C₁. After passing through the third flow path IC, the first passage Tl extends from the slot 3C of the third plate C to the through-hole 3B of the second plate B and then, through the through-hole 3A' of the first plate A_l into the first flow path 1A (solid lines 10 in Fig. 5) of the first plate A_I. Thus, the first passage Tl of a spiral configuration similar to that of the know spiral two-stack-pipe type heat exchanger shown in Fig. 2 is formed in the heat exchanger Kl.
In the same manner as the first passage Tl, the second passage T2 of a spiral configuration is formed in the heat exchanger Kl.
It will be readily seen from Fig. 5 that the heat exchanger Kl is of a counter flow type in which the first and second fluids flow in opposite directions at every location of the heat exchanger Kl.
Referring to Figs. 6(a) to 6(c), there are shown two kinds of first and second plates a and b of a rectangular shape employed in a spiral stack-plate type heat exchanger K2 for effecting heat exchange between first and second fluids, according to a second embodiment of the present invention.
The first and second plates a and b are, respectively, formed with a first flow path lla for the first fluid and a second flow path llb for the second fluid.
As shown in Fig. 6(a), the first plate a is formed with a groove of a substantially circular shape acting as the first flow path lla for the first fluid such that outer peripheral walls 11A, 11B, 11C and 11D are defined on the first plate a, with the outer peripheral walls 11A and 11C confronting the outer peripheral walls 11B and 11D, respectively. Since the first plate a is formed with a partition wall 12a for intercepting the first flow path lla, which extends from a central portion thereof to the outer peripheral wall 11B, the first flow path lla is formed into a C-shaped configuration. At the central portion of the first plate a, communicating passage portions E₁, E₂, F₁ and F₂for the first and second flow paths lla and llb are formed sequentially in this order in a direction extending from the outer peripheral wall 11C to the outer peripheral wall 11D such that the partition wall 12a is disposed between the communicating passage portions E₁ and E₂. Furthermore, through-holes El and F2 are provided in the communicating passage portions E₁ and F₂, respectively such that the communicating passage portions E₁ and E₂ are brought into communication with the first flow path lla, with the communicating passage portions F₁ and F₂ in communication with each other being held out of communication with the first flow path lla.
In the same manner as the first plate a, as shown in Figs. 6(b) and 6(c), the second plate b is formed with outer peripheral walls 11A', 11B', 11C' and 11D' and a partition wall 12b for intercepting the second flow path llb. At a central portion of the second plate b, communicating passage portions E₁', E₂', F₁' and F₂' for the first and second flow paths lla and llb are formed sequentially in this order in a direction extending from the outer peripheral wall 11C' to the outer peripheral wall 11D' such that the partition wall 12b extends between the communicating passage portions F₁' and F₂'. Furthermore, through-holes E2' and F1' are provided in the communicating passage portions E₂' and F₁', respectively such that the communicating passage portions F₁' and F₂' are brought into communication with the second flow path llb, with the communicating passage portions E1' and E₂' in communication with each other being held out of communication with the second flow path llb.
It will be readily understood that the communicating passage portions E₁, E₂, F₁and F₂ of the first plate a correspond, in position, to the communicating passage portions E₁', E₂', F₁' and F2' of the second plate b, respectively. It is to be noted that the first and second fluids flow in the first plate a in the clockwise direction as shown by the arrow in Fig. 6(a) and in the second plate b in the counterclockwise direction as shown by the arrow in Fig. 6(b), respectively.
When a plurality of the first and second plates a and b are stacked one on another alternately and diffusion bonded to one another, the heat exchanger K2 functions in the same manner as the known spiral two-stack-pipe type heat exchanger shown in Fig. 2. As shown in Fig. 7, a first passage Ul of a spiral configuration for the first fluid extends in a downward direction shown by an arrow 13 and passes through the first flow path lla of an upper first plate a in the clockwise direction. Subsequently, the first passage Ul extends from the through-hole El of the upper first plate a to the communicating passage portion E₁' of the second plate b interposed between the upper first plate a and a lower first plate a and then, through the through-hole E2' of the second plate b into the communicating passage portion E₂of the lower first plate a disposed below the second plate b. After passing through the first flow path lla in the clockwise direction, the first passage Ul extends through the through-hole E1 and further proceeds downwardly as shown by an arrow 14.
On the other hand, a second passage U2 of a spiral configuration for the second fluid extends in an upward direction shown by an arrow-15 and passes through the through-hole F2 to the communicating passage portion F₁ in the lower first plate a. After extending through the through-hole F1' of the second plate b, the second passage U2 passes through the second flow path llb in the counterclockwise direction. Subsequently, the second passage U2 extends from the communicating passage portion F₂' of the second plate b into the through-hole F2 of the upper first plate a. Then, the second passage U2 proceeds from the communicating passage portion F1 of the upper first plate a upwardly as shown by an arrow 16.
Although it is so arranged that the communicating passage portions E₁, E₂, F₁ and F₂ and the communicating passage portions E₁', E₂', F₁' and F₂' are, respectively, enclosed by the C-shaped first and second flow paths lla and llb in the heat exchanger K2, the heat exchanger K2 is not necessarily required to be of such an arrangement.
By integrally stacking a plurality of the first and second plates a and b one on another, the heat exchanger K2 similar to the spiral two-stack-pipe type heat exchanger shown in Fig. 2 can be manufactured with much ease.
Referring now to Figs. 8(a) to 8(d), there are shown three kinds of first, second and third plates G, H and J of a rectangular shape employed in a spiral stack-plate type heat exchanger K3 for effecting heat exchanger among first, second and third fluids, according to a third embodiment of the present invention. The first, second and third plates G, H and J are, respectively, formed with a first flow path 21G for the first fluid, a second flow path 21H for the second fluid and a third flow path 21J for the third fluid.
It is to be noted here that the heat exchanger K3 correspond to the known spiral three-stack-pipe type heat exchanger shown in Fig. 3.
As shown in Fig. 8(a), the first plate G is formed with a groove of a substantially circular shape acting as the first flow path 21G for the first fluid such that outer peripheral walls 21A, 21B, 21C and 21D are defined on the first plate G, with the outer peripheral walls 21A and 21C confronting the outer peripheral walls 21B and 21D, respectively. At a central portion of the first plate G, communicating passage portions Gl, G2, Hl, H2, Jl and J2 for the first, second and third flow paths 21G, 21H and 21J are formed sequentially in this matter in a direction extending from the outer peripheral wall 21C to the outer peripheral wall 21D. Since a partition wall 22G for intercepting the first flow path 21G extends between the communicating passage portions G₁ and G₂ up to the outer peripheral wall 21B, the first flow path 21G is formed into a C-shaped configuration. Furthermore, through-holes Gl, H2 and J2 are, respectively, provided in the communicating passage portions G₁, H₂ and J₂. Thus, the communicating passage portions G₁ and G₂ are brought into communication with the first flow path 21G as shown by the arrow in Fig. 8(a). Meanwhile, the communicating passage portions H₁ and H₂ in communication with each other and the communicating passage portions J and J₂ in communication with each other are held out of communication with each other and with the first flow path 21G.
In the same manner as the first plate G, as shown in Fig. 8(b), the second plate H is formed with outer peripheral walls 21A', 21B', 21C' and 21D' and a partition wall 22H for intercepting the second flow path 21H. At a central portion of the second plate H, communicating passage portions G₁', G₂', H₁', H₂'_' J₁' and J₂' for the first, second and third flow paths 21G, 21H and 21J are formed sequentially in this order in a direction extending from the outer peripheral wall 21C' to the outer peripheral wall 21D' such that the partition wall 22H extends between the communicating passage portions HI' and H2' up to the outer peripheral wall 21B'. Furthermore, through-holes G2', H1' and J2' are provided in the communicating passage portions G₂', H₁' and J₂', respectively. Thus, the communicating passage portions H1' and H2' are brought into communication with the second flow path 21H as shown by the arrow in Fig. 8(b). Meanwhile, the communicating passage portions G_l' and G₂' in communication with each other and the communicating passage portions J₁' and J₂' in communication with each other are held out of communication with each other and with the second flow path 21H.
Likewise, as shown in Figs. 8(c) and 8(d), the third plate J is formed with outer peripheral walls 21A' ', 21B' ', 21C' ' and 21D' ' and a partition wall 22J for intercepting the third flow path 21J. At a central portion of the third plate J, communicating passage portions G₁' ', G₂' ' , H₁' ', H₂' ', J₁' ' and J₂' ' for the first, second and third flow paths 21G, 21H and 21J are formed sequentially in this order in a direction extending from the outer peripheral wall 21C' ' to the outer peripheral wall 21D' ' such that the partition wall 22J extends between the communicating passage portions J1' ' and J₂" up to the outer peripheral wall 21B". Furthermore, through-holes G2' ', H2' ' and J1' ' are provided in the communicating passage portions G₂' ', H₂' ' and J₁' ', respectively. Thus, the communicating passage portions Jl" and J2" are brought into communication with the third flow path 21J as shown by the arrow in Fig. 8(c). Meanwhile, the communicating passage portions G₁' ' and G₂" in communication with each other and the communicating passage portions H₁' ' and H₂' ' in communication with each other are held out of communication with each other and with the third flow path 21J.
It will be readily understood that the communicating passage portions G₁, G₂, H₁, H₂, J₁ and J₂ of the first plate G correspond, in position, to the communicating passage portions G₁', G₂', H₁', H₂', J₁' and J₂' of the second plate H and the communicating passage portions G₁' ', G₂' ', H₁' ', H₂' ', J_l" and J₂" of the third plate J, respectively.
When a plurality of sets of the first, second and third plates G, H and J are stacked one on another in a predetermined sequence, the first flow path 21G of the first plate G of a first set is connected, through the communicating passage portions of the second and third plates H and J, in series to the first flow path 21G of the first plate G of a second set which is, in turn, connected in series to the first flow path 21G of the first plate G of a third set or more in the same manner as described above, whereby a first passage Vl of a spiral configuration for the first fluid is formed. Likewise, since the second flow paths 21H of the second plates H are connected in series to one another, a second passage V2 of a spiral configuration for the second fluid is formed. Similarly, since the third flow paths 21J of the third plates J are connected in series to one another, a third passage V3 of a spiral configuration for the third fluid is formed.
For example, in the case where three sets of the third, first and second plates J, G and H arranged in this order are stacked one on another one set by one set sequentially and hot water acting as the first fluid is fed downwardly from a point 23 into the first passage Vl while cold water acting as the second and third fluids is fed upwardly from points 24 and 25 into the second and third passages V2 and V3, respectively as shown in Fig. 9, heat is transferred from the first plates G to the second and third plates H and J in the heat exchanger K3. In the heat exchanger K3, it is so arranged that the second flow path 21H of the second plate H and the third flow path 21J of the third plate J are, respectively, disposed below and above the first plate G. It should be noted that, in Figs. 9 and 10, arcuate arrows 26 and linear arrows 27 denote the C-shaped first, second and third flow paths 21G, 21H and 21J, and the communicating passages in the first, second and third plates G, H and J, respectively.
Meanwhile, in the case where the first, second and third plates G, H and J are stacked one on another in a order of the second plate H, first plate G, third plate J, first plate G, second plate H, first plate G, third plate J, first plate G and so on and hot water acting as the first fluid is fed downwardly from the point 23 into the first passage Vl while cold water acting as the second and third ^! fluids is fed upwardly from the points 24 and 25 into the second and third passages V2 and V3, respectively as shown in Fig. 10, heat is transferred from the first plates G to the second and third plates H and J in the heat exchanger _K3. In the heat exchanger K3, it is so arranged that each of the second flow path 21H of the second plate H and the third flow path 21J of the third plate H is interposed between adjacent ones of the first flow paths 21G of the first plates G.
Thus, by stacking three kinds of the first, second and third plates G, H and J one on another, the first, second and third passages Vl, V2 and V3 can be formed variously.
Referring to Figs. 11(a) and 11(b), there is shown a plate 30 of a circular shape employed in a spiral stack-plate type heat exchanger K4 for effecting heat exchange between first and second fluids, according to a fourth embodiment of the present invention. The plate 30 is formed with a groove of a substantially circular shape acting as a flow path 31. The plate 30 further has communicating passage portions 32, 33 and 34 of an identical shape arranged circumferentially in this order and extending in radial directions thereof. The communicating passage portion 32 is disposed at one end of the flow path 31. It is so arranged that the communicating passage portions 33 and 34 are, respectively, circumferentially deviated from the communicating passage portions 32 and 33 by a predetermined angle θ. Furthermore, through-holes 33' and 34' are provided in the communicating passage portions 33 and 34, respectively.
When a plurality of the plates 30 are stacked one on another as shown in Fig. 12, they are circumferentially deviated from one another sequentially by the angle e.
For example, when six plates 30, i.e. first, second, third, fourth, fifth and sixth plates 30A, 30B, 30C, 30D, 30E and 30F which are, respectively, provided with flow paths 1M, 3N, 2M, 2N, 3M and 1N are stacked one on another sequentially in this order as shown in Fig. 13, the first fluid flows downwardly from an arrow 38 in solid lines into the flow path 1M of the first plate 30A and then, passes through the flow path 1M from the lefthand portion to the righthand portion. Subsequently, the first fluid flows through the communicating passage portion of the second plate 30B into the flow path 2M of the third plate 30C. After passing through the flow path 2M from the lefthand portion to the righthand portion, the first fluid flows through the communicating passage portion of the fourth plate _30D into the flow path 3M of the fifth plate 30^E. After passing through the flow path 3M from the lefthand portion to the righthand portion, the first fluid flows through the communicating passage portion of the sixth plate 30F and further proceeds downwardly as shown by an arrow 39 in sold lines, whereby a first passage Wl of a spiral shape for the first fluid is formed.
On the other hand, the second fluid flows upwardly from an arrow 40 in broken lines into the flow path 1N of the sixth plate 30F. After passing through the flow path 1N from the righthand portion to the lefthand portion, the second fluid flows through the communicating passage portion of the fifth plate 30E into the flow path 2N of the fourth plate 30D and then, passes through the flow path 2N from the righthand portion to the lefthand portion. Thereafter, the second fluid flows through the communicating passage portion of the third plate 30C into the flow path 3N of the second plate 30B. After passing through the flow path 3N from the righthand portion to the lefthand portion, the second fluid flows through the communicating passage portion of the first plate 30A and further proceeds upwardly as shown by an arrow 41 in broken lines, whereby a second passage W2 of a spiral shape for the second fluid is formed.
Accordingly, when a plurality of the plates 30 of a single kind are integrally stacked one on another so as to be deviated from one another by the angle θ, the heat exchanger K4 corresponding to the known spiral two-stack-pipe type heat exchanger shown in Fig. 2 can be manufactured.
It should be noted that, in the case where the plate 30 is of a regular polygon having n sides (n=p_ositi_ve integer), the angle θ can be given by the equation:
e = 360°/n
In the heat exchanger K4, the plate 30 is of a circular shape, so that the positive integer n becomes infinity and thus, the angle e can be set at an arbitrary value.
Hereinbelow, a spiral stack-plate type heat exchanger K5 employing plates 60 of a single kind for effecting heat exchange between first and second fluids, according to a fifth embodiment of the present invention will be described with reference to Figs. 14 to 16.
As shown in Fig. 14 and Figs. 15(a) to 15(c), the plate 60 of a rectangular shape is so formed as to be diametrically symmetric with respect to a point disposed at a center of the plate 60. The plate 60 has a U-shaped heat exchange groove 48 extending sidewise in parallel with opposite sides thereof and an elongated bypass groove 47 extending in parallel with one end thereof between the one end and a base portion of the U-shaped heat exchange groove 48 such that two arm portions of the U-shaped heat exchange groove 48 extend towards the other end of the plate 60. A through-hole 43 is formed at one end of the bypass groove 47 so as to be disposed adjacent to one side of the plate 60. Meanwhile, a through-hole 44 is formed at one end of one arm portion of the heat exchange groove 48 so as to be disposed adjacent to the other end of the plate 60 and the one side of the plate 60. A point 45 which is symmetric to the point 43 with respect to the point 42 is provided at one end of the other arm portion of the heat exchange groove 48 so as to be disposed adjacent to the other end of the plate 60 and the other side of the plate 60, while a point 46 which is symmetric to the point 44 with respect to the point 42 is provided at the other end of the bypass groove 47. Thus, the bypass groove 47 extends from the through-hole 43 to the point 46, while the heat exchange groove 48 extends from the through-hole 44 to the point 45.
It is so arranged that, when a plurality of the plates 60 are stacked one on another by rotating the plates 60 about the point 42 through 180° relative to one another sequentially, the heat exchange grooves 48 of the stacked plates 60 are aligned with one another as much as possible such that the through- holes 43 and 46 are, respectively, brought into alignment with the points 45 and 46.
When, for example, four plates 60, i.e., first, second, third and fourth plates 60P, 60Q, 60R and 60S are stacked one on another sequentially in this order by rotating the first, second, third and fourth plates 60P, 60Q, 60R and 60S about the point 42 through 180° relative to one another sequentially as shown in Fig. 16, through-holes P43 and P44 and points P45 and P46 of the first plate 60P, through-holes Q43 and Q44 and points Q45 and Q46 of the second plate 60Q, through-holes R 43 and R44 and points R45 and R46, and through-holes S43 and S44 and points S45 and S46 of the fourth plate 60S act as the through- holes 43 and 44 and the points 45 and 46 of the plate 60, respectively. The first fluid flows downwardly from an arrow 49 in chain lines to the point P45 of the first plate 60P and then, reaches the through-hole P44. After passing through the through-hole P44, the first fluid flows down to the point Q46 of the second plate 60Q and thereafter, reaches the through-hole Q43. After passing through the through-hole Q43, the first fluid flows down to the point R45 of the third plate 60R and subsequently, reaches the through-hole _R44. After passing through the through-hole R44, the first fluid flows down to the point S46 of the fourth plate 60S and then, reaches the through-hole S43. After passing through the through-hole S43, the first fluid further proceeds downwardly as shown by an arrow 50 in chain lines, whereby a downward first passage Xl of a counterclockwise spiral shape for the first fluid is formed.
Likewise, the second fluid flows upwardly from an arrow 51 in chain lines into the through-hole S44 of the fourth plate 60S. After passing through the through-hole S44, the second fluid reaches the point S45 and then, passes through the through-hole R43 of the third plate 60R to the point R46. Subsequently, after passing through the through-hole Q44 of the second plate 60Q, the second fluid reaches the point Q45 and then, passes through the through-hole P43 of the first plate 60P to the point P45. The second fluid further proceeds upwardly as shown by an arrow 52 in chain lines, whereby an upward second passage X2 of a clockwise spiral shape for the second fluid is formed. Accordingly, the heat exchanger K5 is of a counter flow type in which the first and second passages Xl and X2 extend in opposite directions.
As is clear from the foregoing description, in accordance with the present invention, by integrally stacking the plates of at most several kinds or a single kind one on another, the heat exchanger for effecting heat exchange between two fluids (or among three fluids) can be manufactured with much ease.
Hereinbelow, advantageous features of the spiral stack-plate type heat exchanger of the present invention will be described in more details.
Generally, in the stack-plate type heat exchanger, since a great portion of the metallic surfaces of the heat exchanger are used as the heat transfer area, a large heat transfer area can be obtained in a small space as compared with the double pipe type heat exchanger, so that the stack-plate type heat exchanger can be made compact in size and therefore, requires a small amount of materials for manufacture thereof. When a prior art double pipe type heat exchanger for effecting heat exchange between hot water and cold water is manufactured so as to have a flow rate of about 10 liters/min. and a pressure loss of about 0.1 m aq./m, a length of an inner pipe of 5/8 inch in outside diameter and an outer pipe of 1 inch in outside diameter is set at 29.3 m on the assumption that the number of transfer unit (N.T.U.) of heat of the heat exchanger is 5. The pressure losses in the inner pipe and the outer pipe reach 0.11 m aq./m and 0.13 m aq./m, respectively and, in overall length, 3.2 m aq. and 3.8 m aq., respectively. In the case where the double pipe is spirally wound at a winding diameter of 300 mm, the double pipe is wound 31 times and is of 790 mm in height.
On the other hand, in accordance with the present invention, if the flow passage is 3 mm deep and 100 mm wide, the pressure loss of the passage reaches 0.113 m aq./m. Assuming that the N.T.U. of heat of the heat exchanger is 5 as in the case of the above known double pipe type heat exchanger, the passage is of 10.6 m in length, which is equivalent to 36% of that of the double pipe of 29.3 m.
Accordingly, the total pressure loss of the heat exchanger reaches 1.2 m aq. lower than that of the above known double pipe type heat exchanger but may be substantially equal to that of the above known double pipe type heat exchanger in consideration of pressure losses of the communicating passage portions between adjacent ones of the stacked plates.
When the plate is formed into a circular shape of 300 mm in diameter, 17 sets of the first and second plates are required to be stacked one on another alternately, so that the 34 first and second plates in all are.required to be provided therefor. In the case where each of the first and second plates has a thickness of 4 mm, the heat exchanger is of 136 mm in overall height, which is only 17% of that of the double pipe. It will be readily seen from this example that the heat exchanger of the present invention is made remarkably compact in size.
When the constructions of the heat exchanger of the present invention are compared with those of the known plate type heat exchanger, the passages are formed in series with respect to the plates in that heat exchanger of the present invention, while the passages are usually formed in parallel with the plates in the prior art plate type heat exchanger. Accordingly, in the known plate type heat exchanger, since the flow velocity is small, the fluids are of laminar flow, so that the heat exchanger is required to be of a complicated structure for converting the laminar flow into turbulent flow or the depth of the flow paths is required to be reduced to an exceedingly small dimension smaller than 1 mm. Thus, the known plate type heat exchanger has such inconveniences that the heat exchanger is readily adversely affected by stain of the heat transfer areas and the passages are likely to be clogged.
On the contrary, in accordance with the present invention, since the flow velocity is sufficiently large, the heat exchanger can be used in the range of turbulent flow.
Furthermore, in accordance with the present invention the depth of the flow paths is not so excessively small, thus eliminating the possibility that the passages are clogged.
Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be noted here that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications depart from the scope of the invention, they should be construed as included therein.

Claims

1. In a heat exchanger (Kl, K2, K3, K4, K5) including a plurality of plates (A, B, C, D) of a substantially identical shape stacked one on another so as to effect heat exchange between at least first and second fluids, the improvement comprising:

a plurality of flow paths (lA, 1B, 1C, lD) for effecting the heat exchange, which are each formed on one flat face of each of said plates (A, B, C, D) such that some (lA, 1C) of said flow paths (lA, 1B, 1C, 1D) and the other ones (lB, ID) of said flow paths (lA, 1B, 1C, 1D) allow said first and second fluids to flow through said some (lA, 1C) of said flow paths (lA, 1B, 1C, 1D) in a first direction at corresponding positions of said some (lA, 1C) of said plates (lA, 1B, 1C, 1D) and through said other ones (1B, 1D) of said flow paths (lA,lB,lC,lD) in a second direction at corresponding positions of said other ones (lB, ID) of said flow paths (lA, 1B, 1C, 1D), respectively; and

at least first and second communicating passages (3A', 3B, 2C', 2D; 4A, 5B', 5C, 4D') for connecting, wholly or partially in series, said some (lA, 1C) of said flow paths (lA, 1B, 1C, ID) to one another and said other ones (lB, 1D) of said flow paths (lA, 1B, 1C, 1D) to one another, respectively, which are formed on each of said plates (A, B, C, D), whereby at least first and second passages (Tl, T2) of spiral configurations for passing said first and second fluids therethrough, respectively are formed independently of each other in said heat exchanger (Kl, K2, K3, K4, K5).

2. A heat exchanger (Kl) as claimed in Claim 1, wherein said plates (A, B, C, D) include at least one set of first, second, third and fourth plates (A, B, C, D) stacked one on another sequentially in this order and formed with first, second, third and fourth flow paths (lA, 1B, 1C, 1D), respectively,

said first, second, third and fourth plates (A, B, C, D) being, respectively, formed with at least two first grooves (2A, 3A), two second grooves (4B, 5B), two third grooves (3C, 2C) and two fourth grooves (5D, 4D) which are, respectively, communicated with said first, second, third and fourth flow paths (lA, 1B, 1C, 1D),

said first, second, third and fourth plates (A, B, C, D) being, respectively, formed with at least first, second, third and fourth through-holes (4A, 3B, 5C, 2D) which are, respectively, held out of communication with said first, second, third and fourth flow paths (lA, 1B, lC, ID),

said first, second, third and fourth plates (A, B, C, D) being, respectively, formed with first, second, third and fourth through-openings (3A', 5B', 2C', 4D') which are, respectively, provided in one (3A) of said two first grooves (2A, 3A), one (5B) of said two second grooves (4B, 5B), one (2C) of said two third grooves (3C, 2C) and one (4D) of said two fourth grooves (5D,4D), whereby said first passage (T1) extends from the other one (2A) of said two first grooves (2A, 3A) to said fourth through-hole (2D) through said first flow path (lA), said first through-opening (3A'), said second through-hole (3B), the other one (3C) of said two third grooves (3C, 2C), said third flow path (lC) and said third through-opening (2C'), while said second passage (T2) extends from said first through-hole (4A) to said fourth through-opening (4D') through the other one (4B) of said two second grooves (4B, 5B), said second flow path (1B), said second through-opening (5B'), said third through-hole (5C), the other one (5D) of said two fourth grooves (5D, 4D) and said fourth flow path (lD).

3. A heat exchanger (K2) as claimed in Claim 1, wherein said plates (A, B, C, D) include at least one set of first and second plates (a, b) stacked one on the other,

a first flow path (lla) of a circular shape being formed on a first flat face of said first plate (a) so as to define a first outer peripheral wall (11A, 11B, 11C, 11D),

two pairs of first communicating passage portions (^E ₁, E₂,; F₁, F₂) being formed on said first flat face contiguously to said first flow path (lla),

a first wall (12a) for intercepting said first flow path (lla) being formed between one pair of said first communicating passage portions (E₁, E₂) so as to extend up to said first outer peripheral wall (11A, 11B, 11C, 11D) such that said first flow path (lla) is formed into a C-shaped configuration,

said one pair of said first communicating passage portions (E₁, E₂) being brought into communication with said first flow path (lla), while the other pair of said first communicating passage portions (F₁, F₂) are separated from said first flow path (lla),

a first through-hole (E1) and a first through-hole (F2) being, respectively, formed on one (E₁) of said one pair of said first communicating passage portions (E₁, E₂) and one (F₂) of said other pair of said first communicating passage portions (F₁, F₂),

a second flow path (11b) of a circular shape being formed on a second flat face of said second plate (b) so as to define a second outer peripheral wall (11A', 11B', 11C', 11D'),

two pairs of second communicating passage portions (E₁', E₂'; F₁', F₂') being formed on said second flat face contiguously to said second flow path (llb),

a second wall (12b) for intercepting said second flow path (llb) being formed between one pair of said second communicating passage portions (F₁', F₂') so as to extend up to said second outer peripheral wall (11A', 11B', 11C', 11D') such that said second flow path (llb) is formed into a C-shaped configuration,

said one pair of said second communicating passage portions (F_I', F₂') being brought into communication with said second flow path (11b), while the other pair of said second communicating passage portions (E₁', E₂') are separated from said second flow path (llb),

a second through-hole (Fl') and a second through-hole (E2') being, respectively, formed on one (F₁') of said one pair of said second communicating passage portions (F₁', F₂') and one (E₂') of said other pair of said second communicating passage portions (E₁', E₂').

said first communicating passage portions (E₁, E₂; F₁, F₂) and said second communicating passage portions (E₁', E₂'; F₁', F₂') being brought into alignment with one another when said first and second plates (a, b) are stacked one on the other, whereby said first and second passages (UI, U2) are formed.

4. A heat exchanger (K3) as claimed in Claim 1, wherein said plates (A, B, C, D) include at least one set of first, second and third plates (G, H, J) integrally stacked one on another in a predetermined sequence,

a first flow path (21G) of a circular shape being formed on a first flat face of said first plate (G),

a first wall (22G) for intercepting said first flow path (21G) being formed on said first flat face such that said first flow path (21G) is formed into a C-shaped configuration,

three pairs of first communicating passage portions (G₁, G₂; H₁, H₂; J₁, J₂) being formed on said first flat face contiguously to said first flow path (21G) and independently of one another,

opposite ends of said first flow path (21G) being, respectively, connected to one pair of said first communicating passage portions (G₁, G₂).

first through-holes (G₁, H2, J2) being formed on one (G₁) of the pair of said first communicating passage portion (G₁, G₂), one (H₂) of the pair of said first communicating passage portions (H₁, H₂) and one (J₂) of the pair of said first communicating passage portions (J₁, J₂),

a second flow path (21H) of a circular shape being formed on a second flat face of said second plate (H),

a second wall (22H) for intercepting said second flow path (21H) being formed on said second flat face such that said second flow path (21H) is formed into a C-shaped configuration,

three pairs of second communicating passage portions (G₁', G₂'; H₁', H₂'; J₁', J₂') being formed on said second flat face contiguously to said second flow path (21H) and independently of one another so as to correspond, in position, to said first communicating passage portions (G₁, G₂; H₁, H₂; J₁, J₂), respectively,

opposite ends of said second flow path (21H) being, respectively, connected to one pair of said second communicating passage portions (H₁', H₂') so as to be different, in position, from those of said first flow path (21G),

second through-holes (G2', Hl', J2') being formed on one (G₂') of the pair of said second communicating passage portions (G₁', G₂'), one (H₁') of the pair of said second communicating passage portions (H₁', H₂') and one (J₂') of the pair of said second communicating passage portions (J₁', J₂') such that two (G2', H1') of said second through-holes (G2', Hl^l, J2') are different, in position, from two (Gl, H2) of said first through-holes (Gl, H2, J2),

a third flow path (21J) of a circular shape being formed on a third flat face of said third plate (J),

a third wall (22J) for intercepting said third flow path (21J) being formed on said third flat face such that said third flow path (21J) is formed into a C-shaped configuration,

three pairs of third communicating passage portions (G₁", G₂", H₁", H₂", J₁", J₂") being formed on said third flat face contiguously to said third flow path (21J) and independently of one another so as to correspond, in position, to said first communicating passage portions (G₁, G₂; H₁, H₂; J₁, J₂), respectively,

opposite ends of said third flow path (21J) being, respectively, connected to one pair of said third communicating portions (J₁", J₂") so as to be different, in position, from those of said first flow path (21G) and those of said second flow path (21H),

third through-holes (G2", H2", Jl") being formed on one (G₂") of the pair of said third communicating passage portions (G₁", G₂"), one (H₂") of the pair of said third communicating passage portions (H₁", H₂") and one (J₁") of the pair of said third communicating passage portions (J₁", J₂") such that two (G2", Jl") of said third through-hole (G2", H2", Jl") are different, in position, from two (Gl, J2) of said first through-holes (Gl, H2, J2), with two (H2", Jl") of said third through-holes (G2", H2", Jl") being different, in position, from two (H1', J2') of said second through-holes (G2', HI', J2'), whereby first, second and third passages (Vl, V2, V3) are formed independently of one another for first, second and third fluids, respectively so as to be brought into thermal contact with one another.

5. A heat exchanger (K4) as claimed in Claim 1, wherein said plates (A, B, C, D) include at least two plates (30) each formed with a C-shaped flow path (31) of a circular shape extending about a central axis thereof,

first, second and third communicating passages (32, 33, 34) being formed between opposite ends of said flow path (31) so as to be angularly spaced from one another by an angle 6 = m x 360°/n (m, n = positive integer) about said central axis,

said first and third communicating passages (32, 34) being brought into communication with said flow path (31),

said second communicating passage (33) being disposed between said first and third communicating passages (32, 34) and extending through said plate (30),

said plate (30) being of a regular polygon having n sides,

said two plates (30) being stacked one on the other so as to be angularly deviated from each other by the angle 0, whereby said first and second passages (Wl, W2) are formed.

6. A heat exchanger (K5) as claimed in Claim 1, wherein said plates (A, B, C, D) include at least two plates (60) each having a shape symmetric with respect to an axis extending at right angles to one flat face thereof,

first and second through-holes (43, 44) and first and second recesses (45, 46) are formed on said flat face such that said first and second through-holes (43, 44) are symmetric, in position, to said first and second recesses (45, 46) with respect to said axis, respectively,

a groove (48) being formed on said flat face so as to extend between said second through-hole (44) and said first recess (45) such that said groove (48) is substantially symmetric with respect to said point,

a slot (47) being formed on said flat face so as to extend between said first through-hole (43) and said second recess (46) such that said slot (47) does not intersect with said groove (48),

said two plates (60) being integrally stacked one on the other so as to be angularly deviated from each other by an angle of 180° about said axis, whereby said first and second passages (Xl, X2) are formed.