The present disclosure relates to a heat exchange structure that performs a heat exchange between two fluids.
The heat-exchange catalytic reactor includes a heat-exchange structure that performs a heat exchange between two fluids. The heat exchange structure includes a heat medium flow channel and a reaction flow channel, which are adjacent to each other. A heat medium flows in the heat medium flow channel. A reaction fluid, which contains a reactive raw material, flows in the reaction flow channel. The heat medium flow channel and the reaction flow channel are thermally coupled to each other through a partition. Therefore, the heat exchange occurs between the heat medium and the reaction fluid between which there is a temperature difference, and the reaction of the reactive raw material is promoted.
A fin structure may be installed in at least one of the heat medium flow channel and the reaction flow channel to improve the overall heat transfer coefficient between the heat medium and the reaction fluid. The fin structure is called corrugated fins or waving fins. It is formed, for example, by bending a metal plate. The fin structure has a number of fins (side surfaces) that stretched or curved in the longitudinal direction of the channel in which the fin structure is installed. In this regard, JP 2017-140591 A discloses a heat transfer promoter as the fin structure. When the aforementioned fin structure is installed in the reaction flow channel, the catalyst may be supported on the fin structure.
Conventional fin structures deflect or disperse fluid along a surface on which the fins are placed. Therefore, when such a fin structure is in in the heat exchange structure described above, the fluid generally flows along the partition. On the other hand, heat to be exchanged between the heat medium and the reaction fluid is transferred through this partition. The heat flux is proportional to the temperature difference (temperature gradient). Therefore, the heat transfer between the fluids is larger closer to the partition where the temperature boundary layer is generated, and is smaller farther from the partition. Accordingly, the farther the fluid is from the partition, the less likely it is to be heated (or cooled). This situation hinders the improvement of the heat transfer rate. In order to sufficiently heat (cool) the fluid everywhere, it can be dealt with by lengthening the flow path of the fluid. In this case, however, the equipment becomes larger, and the manufacturing cost increases.
The present disclosure has been made to provide a heat exchange structure capable of improving the overall heat transfer coefficient between two fluids in a space with a limited length.
An aspect of the present disclosure is a heat exchange structure including: two flow channels stacked in a stacking direction and thermally coupled to each other; and a fin structure detachably installed in at least one flow channel of the two flow channels, wherein the fin structure includes fins arranged in a longitudinal direction of the at least one flow channel in which the fin structure is installed, the fins configured to form openings alternately arranged along the at least one flow channel on one side and the other side of the at least one flow channel in the stacking direction.
The fins may be perpendicular to the longitudinal direction of the at least one flow channel in which the fin structure is installed. The fins may be inclined with respect to the longitudinal direction of the at least one flow channel in which the fin structure is installed. Some of the fins may be arranged at a different pitch from the other of the fins. The fin structure may include a pair of strips configured to support the fins, provided on both sides of the arrangement of the fins in a direction intersecting the stacking direction.
The fin structure may include: a pair of strips provided on both sides of the arrangement of the fins in a direction intersecting the stacking direction; and support portions configured to link the pair of strips, provided between the pair of strips, and connected to a corresponding one of the fins. The fin structure may be integrally formed of a single plate member.
The fin structure may include connection portions supported by the pair of strips, configured to connect the fins so that the fins meander in a direction intersecting the stacking direction. The fins and the connection portions may be integrally formed of a single plate member. A catalyst may be supported on the fin structure.
According to the present disclosure, it is possible to provide a heat exchange structure capable of improving the overall heat transfer coefficient between two fluids in a space with a limited length.
Embodiments according to the present disclosure are described below with reference to the drawings. In the drawings, common parts are denoted by the same symbols and redundant explanations thereof will be omitted.
A basic configuration of a heat exchange structure 50 according to the present embodiment will be described. Hereafter, for convenience of explanation, X, Y and Z directions are defined as three directions perpendicular to one another. As described later, the Y direction is a stacking direction of two flow channels 51 and 52. The Z direction is a longitudinal direction (extending direction) of each channel. The X direction is a width direction of each channel and is also an arrangement direction when multiple channels are provided in parallel.
As shown in
The heat exchange structure 50 may be provided with multiple flow channels 51 and multiple flow channels 52. For example, the flow channels 51 are parallel to each other on a plane parallel to the X-Z, plane, and the flow channels 52 are parallel to each other on the plane parallel to the X-Z plane. The longitudinal directions of the flow channel 51 and the flow channel 52 may be parallel to each other or may intersect with each other. That is, the latter may have a skewed relationship. In both cases, one of the flow channels 51 and 52 is thermally connected to the other of the flow channels 51 and 52 through the partition 55 in most of the sections in the longitudinal directions of the channels.
As shown in
There is a temperature difference ΔT, between fluid 53 and fluid 54. Therefore, when fluid 53 flows through flow channel 51 and fluid 54 flows through flow channel 52, heat is transferred between the fluid 53 and the fluid 54. Specifically, the heat is transferred between the fluid 53 and the fluid 54 due to convection between the fluid 53 and the partition 55, thermal conduction within the partition 55, and convection between the partition 55 and the fluid 54.
In this case, the amount of heat Q per unit time is proportional to the product of the overall heat transfer coefficient (heat transfer rate) U, the heat transfer area A of the partition 55, and the temperature difference ΔT between the fluid 53 and the fluid 54. That is, the relationship among these values is expressed by the following formula (1):
Q=UA (ΔT) (1)
Here, the heat transfer area A is constant. Since the fluid 53 and the fluid 54 flow steadily, the change in the temperature difference ΔT is small. Therefore, it is found that the increase in amount of heat Q is obtained by increasing the overall heat transfer coefficient U.
There is also the following relationship among the overall heat transfer coefficient U, the heat transfer coefficient H1 between the fluid 53 and the partition 55, the heat transfer coefficient H2 between the partition 55 and the fluid 54, and the thermal conductivity K of the partition 55,
1/U=1/H1+1/H2+T/K (2)
where T is the thickness of the partition. 55.
From the formula (2), it is found that the overall heat transfer coefficient U increases when at least one of the heat transfer coefficients H1 and H2 increases.
The heat transfer coefficient H1 increases by accelerating the fluid 53 near the partition 55. This trend is the same for the heat transfer coefficient H2. In the present embodiment, using a fin structure 60, a main flow of at least one of the fluids 53 and 54 is directed to the partition 55. This allows a portion of the main flow to approach or enter the temperature boundary layer near the partition 55, thereby promoting the heat transfer between the main flow and the partition 55. That is, at least one of the heat transfer coefficient H1 and the heat transfer coefficient H2 increases. As a result, the overall heat transfer coefficient U increases, and eventually the amount of heat Q increases. That is, the overall heat transfer coefficient between two fluids can be improved in a space with a limited length.
The fin structure 60 according to the present embodiment is detachably installed in at least one of the flow channels 51 and 52. For convenience of explanation, the fin structure is described below using an example shown in
As shown in
The fin structure 60 includes multiple fins (deflection plates, partition plates) 61. The fin 41 is a substantially rectangular piece of a thin metal plate. The metal plate faces in the Z direction and extends in the X direction. The pitch (interval) P between the two fins 61 and 61 adjacent to each other may be constant or varied. That is, some of the fins 61 may be arranged at a different pitch P from the other of the fins 61. By varying the pitch P, it is possible to vary the local overall heat transfer coefficient along the Z direction.
As shown in
As shown in
As shown in
The fin structure 60 includes a pair of strips 63 and 63. Each of the pair of strips 63 and 63 is provided on both sides of the arrangement of the multiple fins 61 in the direction intersecting the Z direction (e.g., the X direction). The pair of strips 63 and 63 support the multiple fins 61 located between them. However, the fins 61 may be supported by a member linking the pair of strips 63 and 63 (e.g., a support portion 66 shown in
As described above, the openings 62 open toward the Z direction (longitudinal direction) of the flow channel 51 and are alternately arranged along the flow channel 51 on one side and the other side of the flow channel 51 in the Y direction (stacking direction). That is, the openings 62 are arranged zigzag along the Z direction so as to reciprocate in the Y direction. Therefore, the fluid 53 flows in the Z direction while repeating the reciprocation in the Y direction. In other words, the fluid 53 flows in the Z direction with meandering in the Y direction.
The fin structure 60 has no structure interfering with heat transfer at least in part between the path of the meandering fluid 53 and the partition 55. In other words, the fin structure 60 has a portion (i.e., an opening) which exposes the fluid 53 to the partition 55 in each interval in which the fluid 53 reciprocates in the Y direction. Therefore, part of the fluid 53 can directly approach or enter the temperature boundary layer TB near the partition 55. Accordingly, it is possible to increase the heat transfer coefficient H1 and to improve the heat transfer coefficient between the fluid 53 and the fluid 54. For example, if the temperature of the fluid 53 is higher than the temperature of the fluid 54, the heat flow HF shown in
A similar improvement in overall heat transfer coefficient can also obtained by placing the fin structure 60 in the flow channel 52. That is, the heat transfer coefficient H2 can be increased by installing the fin structure 60 in the flow channel 52. Further, by installing a fin structure 60 in each of the flow channels 51 and 52, the heat transfer coefficient between the fluid 53 and the fluid 54 can be further improved. In any cases, the overall heat transfer coefficient between the fluid 53 and the fluid 54 can be improved by placing the fin structure 60 in a space with a limited length.
The fin structure 60 is formed of a heat-resistant material that can support a catalyst. Such materials include heat-resistant alloys mainly composed of one or more kinds of metals such ah Fe (iron), Cr (chromium), Al (aluminum), Y (yttrium), Co (cobalt), Ni (nickel), Mg (magnesium), Ti (titanium), Me (molybdenum), W (tungsten), Nb (niobium), and Ta (tantalum). For example, the fin structure 60 may be formed by molding a thin-plate structural material made of a heat-resistant alloy such as Fecralloy® or the like.
When a catalyst is supported on the fin structure 60, the catalyst contains as a main component an active metal effective for promoting the progress of chemical reactions. The active metal is, for example, (nickel), Co (cobalt), Fe (iron), Pt (platinum), Ru (ruthenium), Rh (rhodium), and/or Pd (palladium). Only one of these metals may be used, or a combination of several of these metals may be used as long as they are effective in promoting the reaction.
Next, a configuration example of the fin structure 60 will be described.
As shown in
The upper surface 64U and the lower surface 64L are cut and bent toward the inside of the square tube 64 to form multiple fins 61. That is, the multiple fins 61 are bent from the upper surface 64U or the lower surface 64L to be perpendicular to the Z direction while being supported by the upper surface 64U or the lower surface 64L. Note that a height h2 of the fin 61 is approximately equal to a length L1 of an exposed portion 65A in the Z direction.
As a result of the lancing process described above, an exposed portion 65A opens on the upper surface 64U. The exposed portion 65A is located behind (or in front of) the fin 61 in the Z direction and exposes the internal space of the square tube 64, through which the fluid 53 flows, to the partition 55. With this exposure, the overall heat transfer coefficient between the fluid 53 and the fluid 54 is improved.
The fin structure 60A is formed by the lancing process for the square tube 64. That is, the multiple fins 61 are integrally formed with the square tube 64. Since the main processing is only the lancing process, the fin structure 60A can be easily manufactured.
A height of the fin 61 as seen from the Z direction is set to the height h2 described above. Therefore, by tilting the fin 61 with respect to the Z direction, it is possible to set a length L2 of the exposed portion 65B in the Z direction longer than the length L1. That is, it is possible to increase the opening area of the exposed portion 65B than the opening area of the exposed portion 65A. Therefore, at least the overall heat transfer coefficient in the exposed portion 65B can be improved.
The fin structure 60C includes the pair of strips 63 and 63. That is, each of the pair of strips 63 and 63 is provided on both sides of the arrangement of the multiple fins 61 in the direction (e.g., the X direction) intersecting the Z direction. The pair of strips 63 and 63 connect to both ends of the fins 61 in the X direction and support the fins 61 located between the pair of strips 63 and 63.
As same as the third configuration, the fin structure 60D includes the pair of strips 63 and 63. That is, each of the pair of strips 63 and 63 is provided on both sides of the arrangement of the multiple fins 61 in the direction (e.g., the X direction) intersecting the Z direction. The pair of strips 63 and 63 connect to both ends of each fin 61 in the X direction and support the fins 61 located between the pair of strips 63 and 63.
The fin structures 60C and 60D of the third and fourth configuration examples do not have a structure that separates the inner space of the flow channel 51, through which the fluid 53 flows, from the partition 55. Thus, the partition 55 is exposed to the fluid 53 almost throughout the Z direction. Therefore, it is possible to improve the overall heat transfer coefficient between the fluid 53 and the fluid 54 over that in the first and second configuration examples.
The fin structure 60E includes the support portions 66 described above. The support portions 66 are provided between the pair of strips 63 and 63 and link the pair of strips 63 and 63. The support portion 66 is also connected to the corresponding one of the multiple fins 61. The connection between the fin 61 and the support portion 66 constitutes an edge 61a forming the opening 62.
As shown in
As similar to the third and fourth configuration examples, the fin structures 60E and 60F of the fifth and sixth configuration examples do not have a structure that separates the inner space of the flow channel 51, through which the fluid 53 flows, from the partition 55. Thus, the partition 55 is exposed to the fluid 53 almost throughout the Z direction. Therefore, it is possible to improve the overall heat transfer coefficient between the fluid 53 and the fluid 54 over that in the first and second configuration examples.
In the fin structures 60E and 60F, the connection between the fin 61 and the support portion 66 serves as the fulcrum of the fin 61. Therefore, when the fin structures 60E and 60F are attached to or detached from the flow channel 51, even if the fin 61 contacts with the inner circumferential surface (i.e., the partition 55) of the flow channel 51 (in other words, even if the friction increases), the fin 61 can be bent around the fulcrum. That is, it becomes easier to attach and detach the fin structure.
In addition, since the fins 61 can be bent during the attachment and the detachment, the height h2 of the fins 61 can be set as high as possible to suppress leakage between the fin structures 60E and 60F and the inner circumferential surface (i.e., the partition 55) of the flow channel 51 as much as possible. In this case, since the fins 61 may contact the inner circumferential surface (i.e., the partition 55) of the flow channel 51, it is also possible to partially achieve heat conduction between the fins 61 and the inner circumferential surface (i.e., the partition 55) of the flow channel 51.
The fin structure 60E of the fifth configuration example and the fin structure 60F of the sixth configuration example are structurally capable of being formed by punching and bending a single plate member without a connecting process such as welding. For example, the fins 61 and strip 63 are formed by bending a part of a single plate member that becomes the support portion 66. With the aforementioned formation of such a single plate member, the number of components and the number of the machining processes can be reduced.
The bent portion 68 may be formed over the entire range in the Z direction as shown in
As same as the other configuration examples, the edge 61a forms the opening 62 between the edge 61a and the inner circumferential surface (i.e., the partition 55) of flow channel 51. As shown in
As shown in
As shown in
The fin structure 60 can efficiently transfer heat in the direction in which the fluid meanders. For example, assuming a configuration in which an assembly of parallel flow channels 51 and an assembly of parallel flow channels 52 are stacked on each other, heat moves mainly along the Y direction between fluids 53 and 54. Therefore, heat exchange can be improved by using the fin structure 60. The reactor (catalytic reactor) described below is designed with taking into consideration this point.
Hereinafter, a reactor (catalytic reactor) 1 is described as an example to which the heat exchange structure 50 is applied. The reactor 1 includes a heat exchange section 2 as the heat exchange structure 50. As described later, first heat transfer bodies 10 and second heat transfer bodies 20 are stacked in the Y direction, and first flow channels (channels) 11 and second flow channels (channels) 21 extend in the Z direction. In addition, the width direction of each channel is taken as the X direction described above. The X direction is also the alignment direction when multiple first flow channels 11 (second flow channels 21) are provided in parallel.
The reactor 1 heats or cools the reaction fluid R containing a reactive raw material to progress (promote) the reaction of the reaction fluid R. For the heating or cooling, the reactor 1 includes the heat exchange section 2 as the heat exchange structure 50 (see
The first heat transfer body 10 includes channels (hereafter referred to as first channels) 11 through which the heat medium M flows. The second heat transfer body 20 includes channels (hereafter referred to as second channels) 21 through which the reaction fluid R flows. The first heat transfer bodies 10 and the second heat transfer bodies 20 are stacked alternately in the Y direction (i.e., the stacking direction). The lid plate 30 is set on the top of them.
With the stacking described above, the first flow channels 11 and the second flow channels 21 are adjacent to each other through a first partition 13 or a second partition 23 (see
The heat exchange section 2 has a counter-flow type structure in which the reaction fluid R and the heat medium M flow in opposite directions. The fin structure 60 (see
The heat exchange section 2 is formed of at least one set of the first heat transfer body 10 and the second heat transfer body 20. The number of each heat transfer body may also be increased to improve the heat exchange performance. The number of channels formed in each heat transfer body is set depending on the design conditions of the heat exchange section 2, heat transfer efficiency, etc. In addition, a housing or insulation material may cover the heat exchange section 2 to reduce heat loss due to heat dissipation from the heat exchange section 2.
Both ends of the heat exchange section 2, which is a laminated body, are held by fixing members 32, 33.
A heat medium introduction section 34 is attached to the fixing member 32. The heat medium introduction section 34 is a concavely curved lid and forms a space S1 between the section 34 and the heat exchange section 2. First inlet ports 12 of the first flow channels 11 are opened toward the space S1 (see
The heat medium introduction section 34 is detachably or openably set on the fixing member 32. By this attachment and detachment, for example, the operator can insert and remove the fin structures 60 from the first flow channels 11.
The heat medium discharge section 41 is a box-shaped member having one opened face. The heat medium discharge section 41 is attached to the heat exchange section 2 so that the opened face faces the first discharge, ports 18 of the first heat transfer bodies 10. The heat medium discharge section 41 includes a first discharge pipe 42. The first discharge pipe 42 discharges the heat medium M that has passed through the heat exchange section 2.
A reaction fluid introduction section 35 is attached to the fixing member 33. As similar to the heat medium introduction section 34, the reaction fluid introduction section 35 is a concavely curved lid and forms a space S2 between the section 35 and the heat exchange section 2. Second inlet ports 22 of the second flow channels 21 are opened toward the space S2 (see
The reaction fluid introduction section 35 is detachably or openably set on the fixing member 33. By this attachment and detachment, for example, the operator can insert and remove the fin structures 60 from the second flow channels 21.
As similar to the heat medium discharge section 41, the product discharge section 43 is a box-shaped member having one opened face. The product discharge section 43 is attached to the heat exchange section 2 so that the opened face faces the second discharge port 28 of the second heat transfer body 20. The product discharge section 43 includes a second discharge pipe 44. The second discharge pipe 44 discharges the reaction gas G containing products derived from the reaction fluid R.
As shown in
The first flow channels 11 are grooves formed on one surface (e.g., the upper surface in the present embodiment) of the first heat transfer body 10. Each groove has a rectangular cross section having a width w3 and a height h3 (see
The first flow channels 11 linearly extend from the first inlet ports 12 located on the side of the fixing member 32 toward the fixing member 33. As shown in
The first heat transfer body 10 includes a first partition 13, two first sidewalls 14, multiple first intermediate walls 15, and a first end wall 16. The first sidewalls 14, the first intermediate walls 15 and the first end wall 16 are provided on one side of the first partition 13. That is, they are provided on the same surface as the surface on which the first sidewall 14, etc. is provided for the first partition 13. The first partition 13 is a rectangular wall and defines the overall shape of the first heat transfer body 10. The first sidewall 14 are wall parts provided on both sides of the extending direction of the first flow channels 11. The first intermediate walls 15 are located between the two first sidewalls 14 and are wall parts provided in parallel with each first sidewall 14.
The first end wall 16 is provided on the opposite side of the first inlet ports 12 across the first flow channels 11. The first end wall 16 is a wall extending in the alignment direction of the first flow channels 11. The first end wall 16 blocks the inflow of the heat medium M toward the space S2.
The first heat transfer body 10 includes a first connection flow channel 17 extending along the first end wall 16. The first connection flow channel 17 is connected with all the first flow channels 11 and the first discharge port 18.
As shown in
The second flow channels 21 are grooves formed on one surface (the upper surface in the present embodiment) of the second heat transfer body 20. Each groove has a rectangular cross section having a width w3 and a height h3 (see
The second heat transfer body 20 includes a second partition 23, two second sidewalls 24, multiple second intermediate walls 25, and a second end wall 26. The second sidewalls 24, the second intermediate walls 25 and the second end wall 26 are provided on one side of the second partition 23. The second partition 23 is a rectangular wall and defines the overall shape of the second heat transfer body 20. The second sidewalls 24 are wall parts provided on both sides of the extending direction of the second flow channels 21. The second intermediate walls 25 are located between the two second sidewalls 24 and are wall parts provided in parallel with each second sidewall 24.
The second end wall 26 is provided on the opposite side of the second inlet ports 22 across the second flow channels 21. The second end wall 26 is a wall extending in the alignment direction of the second flow channels 21. The second end wall 26 blocks the inflow of the reaction gas G toward the space S1.
The second heat transfer body 20 includes a second connection flow channel 27 extending along the second end wall 26. The second connection flow channel 27 is connected with all the second flow channels 21 and the second discharge port 28. As similar to the first flow channel 11, the second connection flow channel 27 is a fluid channel, and there is no substantial difference between the two.
The heat exchange section 2 can be used as any of a liquid-liquid heat exchanger, a gas-gas heat exchanger and a gas-liquid heat exchanger. The reaction fluid R may be any of a gas and a liquid. The heat medium M may be any of a gas and a liquid. In addition, the reactor 1 of the present embodiment enables chemical synthesis through various thermal reactions such as endothermic and exothermic reactions. Examples of such syntheses by thermal reactions include endothermic reactions such as the steam reforming reaction of methane represented by formula (3), the dry reforming reaction of methane represented by formula (4), the shift reaction represented by formula (5), the methanation reaction represented by formula (6), and the Fischer-Tropsch synthesis reaction represented by formula (7). Note that the reaction fluid R in these reactions is a gas.
Ch4+H2O→3H2+CO (3)
CH4+CO2→2H2+2CO (4)
CO+H2O→CO2+H2 (5)
CO+3H2→CH4+H2O (6)
(2n+1)H2+nCO→CnH2n+2+nH2O (7)
It is desirable that the heat medium M is a substance that does not corrode the components of the reactor 1. When a heated gas is used as the heat medium M, gaseous materials such as a combustion gas and a heated air can be used. The heat medium M may be a liquid substance such as water or oil, for example.
It should be noted that the present disclosure is not limited to the embodiments described above, but is indicated by the claims, and further includes all modifications within and meaning equivalent to the scope of the claims.
This application is a continuation application of International Application No. PCT/JP2020/030883, now WO 2022/034683 A1, filed on Aug. 14, 2020, the entire contents of which are incorporated by reference herein.
Number | Date | Country | |
---|---|---|---|
Parent | PCT/JP2020/030883 | Aug 2020 | US |
Child | 18087123 | US |