ENGINEERED PACKING FOR HEAT EXCHANGE

Field of Invention

[0001] This invention relates generally to the field of heat exchangers and non-adiabatic catalytic reactors and more specifically to systems and methods for constructing an engineered packing for heat exchange.

Background

[0002] Various systems and methods to improve heat transfer between a heat transfer surface and a fluid via an engineered packing that directs the fluid to impinge the surface and thereby break down boundary layers that otherwise impede heat transfer are known. For example, apparatus employing this technique include those taught in US patents 7,566,487, 7,976,783, and 8,257,658. These three patents disclose engineered packing structures that provide advantageous flow patterns created by flow channels that convey a fluid to and from a heat transfer surface at an oblique angle to the surface, which surface is approximately parallel to the general path of the fluid from an inlet to an outlet of a heat exchange device such as for heat transfer inside a tube or annulus or between flat plates.

[0003] Generally, the heat transfer coefficient or the Nusselt number (N _u ) and pressure drop (ΔΡ) both increase with increased velocity, but the ratio of N _U /AP declines with increased velocity. The patents cited above utilize flow impingement to create high values of N _U /AP at relatively low superficial velocity compared to other heat exchangers. These patents permit effective heat transfer between two or more fluids with greater residence time, requiring less primary heat transfer surface area and permitting less expensive heat transfer devices. Extended surfaces are also known in plate and fin heat exchangers, but are only generally useful where the thermal conductivity of the extended surface material far exceeds the conductivity of the fluid transferring heat to or from the secondary surface as is the case with extended surfaces composed of copper, aluminum or noble metals and in the transfer of heat to or from a gas. Aluminum plate and fin heat exchangers enable the construction of compact and inexpensive heat exchangers for noncorrosive fluids at temperatures generally below 200° C, particularly for gases. Extended surfaces are less beneficial where the extended surfaces must be composed of carbon steel, stainless steel, nickel alloys, or other materials of relatively low thermal

conductivity for corrosive or high temperature applications.

Summary

[0004] In accordance with an embodiment, an apparatus providing enhanced heat transfer is provided. The apparatus includes an inlet, an outlet, and a sheet disposed proximate a heat transfer surface, the sheet being oriented in a sheet plane that is displaced from a plane of the heat transfer surface by an angle of at least 10 degrees. The apparatus also includes a plurality of tabs attached to the sheet, the tabs lying in respective tab planes, wherein the tab planes and the sheet plane intersect forming respective intersections, the intersections of the tab planes and the sheet plane are substantially parallel, the intersections of the tab planes and the sheet plane are at an angle of less than 88° to the heat transfer surface, and the plurality of tabs collectively form channels directing a fluid passing from the inlet to the outlet to impinge the heat transfer surface.

[0005] In one embodiment, the apparatus also includes a second sheet disposed proximate a heat transfer surface, the second sheet being oriented in a second sheet plane that is displaced from the plane of the heat transfer surface by an angle of at least 10 degrees, and a plurality of second sheet tabs attached to the second sheet, the tabs lying in respective second sheet tab planes, wherein the second sheet tab planes and the second sheet plane intersect forming respective second intersections, the second intersections of the second sheet tab planes and the second sheet plane are substantially parallel, the intersections of the second sheet tab planes and the second sheet plane are at an angle of less than 88° to the heat transfer surface; and the plurality of second sheet tabs collectively form second channels directing a fluid passing from the inlet to the outlet to flow away from the heat transfer surface.

[0006] In another embodiment, the sheet plane is displaced from the plane of the heat transfer surface by an angle of about 90°.

[0007] In another embodiment, the angle between the tab planes and the sheet plane is greater than 5°.

[0008] In another embodiment, the angle between the tab planes and the sheet plane is about 90°.

[0009] In another embodiment the angle between the intersections and the heat transfer surface is between 5° and 70°.

[00010] In another embodiment the angle between the channels and the heat transfer surface is less than 88°.

[00011] In another embodiment the angle between the channels and the heat transfer surface is between 5° and 70°.

[00012] In another embodiment the tabs are formed from the sheet by blanking and bending operations.

[00013] In another embodiment the apparatus includes one or more gaps between the apparatus and the heat transfer surface through which gaps fluid flowing from the inlet to the outlet passes from the channels to the second channels. [00014] In another embodiment the tabs have a width and are tapered in width to form an arc shaped apparatus and the respective formed sheets are closer together at an inside apparatus diameter than at an outside apparatus diameter.

[00015] In accordance with another embodiment, an apparatus providing enhanced heat transfer is provided. The apparatus includes an inlet, an outlet, and a plurality of sheets disposed proximate a heat transfer surface, each of the plurality of sheets being oriented in a respective sheet plane that is displaced from a plane of the heat transfer surface by an angle of at least 10 degrees. The apparatus also includes a plurality of tabs attached to the plurality of sheets, the tabs lying in respective tab planes, wherein each respective tab plane and a corresponding sheet plane intersect forming respective intersections, the intersections of the tab planes and the corresponding sheet planes are substantially parallel, the intersections of the tab planes and the corresponding sheet planes are at an angle of less than 88° to the heat transfer surface, and the plurality of tabs collectively form channels directing a fluid passing from the inlet to the outlet to impinge the heat transfer surface.

[00016] These and other advantages of the present disclosure will be apparent to those of ordinary skill in the art by reference to the following Detailed Description and the accompanying drawings.

Brief Description of the Drawings

[00017] Figure 1A illustrates a sheet viewed from the inlet in accordance with an embodiment;

[00018] Figure IB shows the sheet of Figure 1A viewed from one face of the sheet in accordance with an embodiment; [00019] Figure 2A illustrates a sheet viewed from the inlet in accordance with an embodiment;

[00020] Figure 2B shows the sheet of Figure 2A viewed from one face of the sheet in accordance with an embodiment;

[00021] Figure 3 A illustrates a sheet viewed from the inlet in accordance with an embodiment;

[00022] Figure 3B shows the sheet of Figure 3A viewed from one face of the sheet in accordance with an embodiment;

[00023] Figure 4A illustrates a sheet viewed from the inlet in accordance with an embodiment;

[00024] Figure 4B shows the sheet of Figure 4A viewed from one face of the sheet in accordance with an embodiment;

[00025] Figure 5A shows a fully formed sheet viewed from the inlet in accordance with an embodiment;

[00026] Figure 5B shows the sheet of Figure 5A viewed from one face of the sheet in accordance with an embodiment;

[00027] Figure 6A shows a mirror image sheet of the sheet of Figures 5A-5B viewed from the sheet' s inlet in accordance with an embodiment;

[00028] Figure 6B shows one face of the sheet of Figure 6A in accordance with an embodiment;

[00029] Fig. 7 shows an apparatus comprising multiple sheets as viewed from the inlet in accordance with an embodiment; [00030] Fig. 8 shows an apparatus comprising multiple sheets as viewed from the inlet in accordance with another embodiment;

[00031] Fig. 9 shows an apparatus comprising multiple sheets as viewed from the inlet in accordance with another embodiment;

[00032] Fig. 10A shows a sheet at one stage of forming as viewed from one face of the sheet in accordance with an embodiment;

[00033] Fig. 10B shows the sheet Figure 9 A and a different stage of forming as viewed from the inlet in accordance with an embodiment; and

[00034] Fig. IOC shows the sheet of Figures 9A-9B in another configuration as viewed from the inlet in accordance with an embodiment.

Detailed Description of the Invention

[00035] The following detailed description discloses various exemplary embodiments and features of the invention. These exemplary embodiments and features are not meant to be limiting.

[00036] Computational fluid dynamic simulation and finite element analysis of stresses have been used to create the inventive design that is disclosed herein, which provides advantageous flow patterns in a structure that is easier and less expensive to manufacture than the known art for creating desirably high values of N _u at low superficial velocity and low ΔΡ.

[00037] In particular, it is an objective of the present invention to provide apparatus with a high Nu at low superficial velocity and low ΔΡ which can be manufactured in less time and on less expensive machine tools using less expensive dies with improved service life than prior art as in the patents cited above. It is another objective to create such apparatus or substrates with greater geometric surface area (GSA) than is practical with prior art. Increased GSA is useful for promoting chemical reactions in the presence of a catalyst mounted on the GSA of a substrate. Other objects of the present invention will be observed in the reading of this disclosure by one reasonably skilled in the art.

[00038] Certain of the Figures are illustrated in pairs (e.g., Figures 1A and IB). In each pair, the figure labeled as 'A' is a view of a sheet from a top edge. The figure labeled 'B' is a view from one face of the sheet. The upper face of a sheet is shown as a dotted area, the back side of a sheet is shown as a cross hatched areas, and the edges of a sheet are shown as thick solid lines.

[00039] Figure 1A illustrates a sheet viewed from the inlet in accordance with an embodiment. Figure IB shows the sheet of Figure 1A viewed from one face of the sheet in accordance with an embodiment. Figure 2A illustrates a sheet viewed from the inlet in accordance with an embodiment. Figure 2B shows the sheet of Figure 2A viewed from one face of the sheet in accordance with an embodiment. Referring to Fig. 1A and IB, sheet 1 having edges 2 is cut or blanked along solid lines 3. Dashed lines 4 show where the sheet is folded to form tabs, as shown in Figures 2A-2B. Lines 4 constitute intersections of the sheet and the formed tabs. Referring to Figs. 2A-2B, portions of the sheet of Fig. 1A and IB are folded at least 10° and preferably about 90° upward, forming tabs 5. Dashed lines 6 show where the sheet is folded to produce the form shown in Figs. 3A-3B. Referring to Figs. 3A-3B, the sheet is folded 90° below the plane of the sheet to form wall sections 7. Referring to Fig. 4A-4B, sections 7 of the sheets in Fig. 3A and 3B are shown to be folded an additional 90° or a total of 180° around the back of the sheet. The formed sheet is shown to be placed between heat transfer surfaces or walls 9, which are perpendicular to the sheet shown in Figures 4A and 4B and are seen from their edges. The newly formed lateral extremities or new edges 10 of the formed sheet abut surfaces 9, and gaps 11 lie intermittently between the formed sheet and the surfaces.

Apparatus 12 comprises the formed sheet with its tabs, intersections, edges and gaps, heat transfer surfaces 9, inlet 13, and outlet 14. Fluid passes from the inlet to the outlet through the apparatus. It is not necessary for the formed sheets to be joined to or touch the surfaces, but the formed sheets are preferably as close to the surfaces as possible and most preferably abut the surfaces. The formed sheets may be welded, brazed, soldered, glued, or otherwise joined or bonded to the surfaces. The fold lines 4 of the tabs constitute intersections between the sheet and the tabs in the apparatus and are substantially parallel to each other. The tabs are preferably folded through the same fold angle of at least 10° and preferably about 90°. The tabs constitute channel walls to direct the flow of a fluid toward the left surface (as perceived by a person viewing Figures 4A-4B) as fluid flows through apparatus 12 from the inlet 13 to the outlet 14.

[00040] Fig. 5A and Fig. 5B are two respective views of the formed sheet of Figures 4A- 4B, where sheet 15 is the formed sheet viewed from the inlet as in Fig. 4A, and Fig. 5B is a lateral view of the formed sheet corresponding to the view in Fig. 4B. Left and right heat transfer walls 9 are shown. Referring to Fig. 6A, a second formed sheet 16 corresponding to sheet 15 of Fig. 5A is shown, and Fig. 6B is a view of the second sheet corresponding to the view of Fig. 5B where the formed sheet of Fig. 6A-6B are the mirror image left to right of the formed sheet of Fig. 5A-5B. The structures of Figures 5A-5B and 6A-6B have inlets 13 and outlets 14. The formed sheets of Figures 5A-5B and 6A-6B are bounded by left and right heat transfer surfaces 9. Whereas the formed sheet of Figures 5A-5B causes fluid flowing through the structure from the inlet to the outlet to impinge, or impact, left surface 9 and flow away from right surface 9, the formed sheet of Figures 6A-6B causes fluid to impinge, or impact, right surface 9 and flow away from left surface 9. [00041] Referring to Figures 7, 8, and 9, the structures 15 and 16 of formed sheets in Figures 5A-5B and 6A-6B, respectively, are inserted in alternating sequence between left and right flat surfaces 9 in Figure 7, next to a single flat surface 9 in Figure 8, and between left and right curved surfaces 9 in Figure 9. The surfaces 9 may be straight as shown in Fig. 7 or curved as shown in Figure 9 as viewed from the respective inlets. The volume between the curved surfaces 9 in Figure 9 constitutes an annulus. Alternatively, the volume to the left of a single concave surface 9 would constitute part of the interior of a tube or of the exterior of a tube. The tabs may be cut from their respective sheets in a tapered fashion as shown in Fig. 9 such that the width or short dimension of the tabs is shorter on the left end of the tabs than on the right end of the tabs as shown in the Fig. 9 to cause the apparatus to be curved or arc shaped with the respective formed sheets be closer together at an inside radius of the apparatus than at an outside radius of the apparatus. The curved or arc shaped embodiment may be placed within or around a tube or in an annulus, where the tube or annulus walls are the heat transfer surface 9. The assembled formed sheets, inlet, outlet and at least one heat transfer surface constitute engineered packings 18.

[00042] Referring to Fig. 10B, a single sheet having flat sections 19, 20, and 21 is folded at locations 22 and 23 as shown. From flat sections 19, tabs are blanked and folded to form columns or elements 15 and 16, which are in form the same as those elements in all other drawings.

[00043] Referring to Fig. IOC, the sheet of Fig. 10B is further folded to 180° bends at locations 22 and to 90° bends at locations 23. The formed sheet is disposed between two heat transfer surfaces 9. [00044] Fig. 10A shows a view of a sheet from one face after blanking and forming of the tabs, not shown, in which the blanked shapes of flat sections 19, 20, and 21 can be seen in relation to fold lines 22 and 23. Instead of two flat sections 20 between consecutive flat sections 19, other numbers of flat sections 20 may be disposed between consecutive flat sections 19 to provide additional GSA, and the sheet could be coated with a suitable catalyst for use in a catalytic reactor, particularly a non-adiabatic catalytic reactor. Surfaces 9 may be straight or curved as viewed in Figure IOC such that the one or more surfaces 9 are a tube wall. The catalytic reactor may be a steam methane reformer for converting a hydrocarbon and at least one of steam and carbon dioxide to a gas containing hydrogen.

[00045] Thus, in accordance with an embodiment, an apparatus providing enhanced heat transfer is provided. The apparatus includes an inlet, an outlet, and a sheet disposed proximate a heat transfer surface, the sheet being oriented in a sheet plane that is displaced from a plane of the heat transfer surface by an angle of at least 10 degrees. The apparatus also includes a plurality of tabs attached to the sheet, the tabs lying in respective tab planes, wherein the tab planes and the sheet plane intersect forming respective intersections, the intersections of the tab planes and the sheet plane are substantially parallel, the intersections of the tab planes and the sheet plane are at an angle of less than 88° to the heat transfer surface, and the plurality of tabs collectively form channels directing a fluid passing from the inlet to the outlet to impinge the heat transfer surface.

[00046] In one embodiment, the apparatus also includes a second sheet disposed proximate a heat transfer surface, the second sheet being oriented in a second sheet plane that is displaced from the plane of the heat transfer surface by an angle of at least 10 degrees, and a plurality of second sheet tabs attached to the second sheet, the tabs lying in respective second sheet tab planes, wherein the second sheet tab planes and the second sheet plane intersect forming respective second intersections, the second intersections of the second sheet tab planes and the second sheet plane are substantially parallel, the intersections of the second sheet tab planes and the second sheet plane are at an angle of less than 88° to the heat transfer surface; and the plurality of second sheet tabs collectively form second channels directing a fluid passing from the inlet to the outlet to flow away from the heat transfer surface.

[00047] In another embodiment, the sheet plane is displaced from the plane of the heat transfer surface by an angle of about 90°.

[00048] In another embodiment, the angle between the tab planes and the sheet plane is greater than 5°.

[00049] In another embodiment, the angle between the tab planes and the sheet plane is about 90°.

[00050] In another embodiment, the angle between the intersections and the heat transfer surface is between 5° and 70°.

[00051] In another embodiment, the angle between the channels and the heat transfer surface is less than 88°.

[00052] In another embodiment, the angle between the channels and the heat transfer surface is between 5° and 70°.

[00053] In another embodiment, the tabs are formed from the sheet by blanking and bending operations.

[00054] In another embodiment, the apparatus includes one or more gaps between the apparatus and the heat transfer surface through which gaps fluid flowing from the inlet to the outlet passes from the channels to the second channels. [00055] In another embodiment, wherein the tabs are tapered in width to form an arc shaped apparatus and the respective formed sheets are closer together at an inside apparatus diameter than at an outside apparatus diameter.

[00056] In accordance with another embodiment, an apparatus providing enhanced heat transfer is provided. The apparatus includes an inlet, an outlet, and a plurality of sheets disposed proximate a heat transfer surface, each of the plurality of sheets being oriented in a respective sheet plane that is displaced from a plane of the heat transfer surface by an angle of at least 10 degrees. The apparatus also includes a plurality of tabs attached to the plurality of sheets, the tabs lying in respective tab planes, wherein each respective tab plane and a corresponding sheet plane intersect forming respective intersections, the intersections of the tab planes and the corresponding sheet planes are substantially parallel, the intersections of the tab planes and the corresponding sheet planes are at an angle of less than 88° to the heat transfer surface, and the plurality of tabs collectively form channels directing a fluid passing from the inlet to the outlet to impinge the heat transfer surface.

[00057] Although the present invention has been described in terms of several embodiments, various features of separate embodiments can be combined to form additional embodiments not expressly described. Moreover, other embodiments within the scope of the present invention will be apparent to those skilled in the art. The only limitations on the scope of the invention are those expressly set forth in the claims which follow.