Patent Description:
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 <CIT>, <CIT>, and <CIT>. 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. Further comparable systems are known from <CIT>.

Generally, the heat transfer coefficient or the Nusselt number (Nu) and pressure drop (ΔP) both increase with increased velocity, but the ratio of Nu/ΔP declines with increased velocity. The patents cited above utilize flow impingement to create high values of Nu/ΔP 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 <NUM>, 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.

In accordance with an embodiment, an apparatus providing enhanced heat transfer is provided. The apparatus includes an inlet, an outlet, a heat transfer surface, and a sheet disposed proximate said 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 <NUM> 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 <NUM>° 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.

According to the invention the sheets provide wall sections that are folded by <NUM>° around a back of the sheet with forming new edges.

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 <NUM> 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 <NUM>° 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.

In another embodiment, the sheet plane is displaced from the plane of the heat transfer surface by an angle of about <NUM>°.

In another embodiment, the angle between the tab planes and the sheet plane is greater than <NUM>°.

In another embodiment, the angle between the tab planes and the sheet plane is about <NUM>°.

In another embodiment the angle between the intersections and the heat transfer surface is between <NUM>° and <NUM>°.

In another embodiment the angle between the channels and the heat transfer surface is less than <NUM>°.

In another embodiment the angle between the channels and the heat transfer surface is between <NUM>° and <NUM>°.

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

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.

In accordance with an 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 <NUM> 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 <NUM>° 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.

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.

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

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 Nu at low superficial velocity and low ΔP.

In particular, it is an objective of the present invention to provide apparatus with a high Nu at low superficial velocity and low ΔP 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.

Certain of the Figures are illustrated in pairs (e.g., <FIG>). 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 area, and the edges of a sheet are shown as thick solid lines.

<FIG> illustrates a sheet viewed from the inlet in accordance with an embodiment. <FIG> shows the sheet of <FIG> viewed from one face of the sheet in accordance with an embodiment. <FIG> illustrates a sheet viewed from the inlet in accordance with an embodiment. <FIG> shows the sheet of <FIG> viewed from one face of the sheet in accordance with an embodiment. Referring to <FIG>, sheet <NUM> having edges <NUM> is cut or blanked along solid lines <NUM>. Dashed lines <NUM> show where the sheet is folded to form tabs, as shown in <FIG>. Lines <NUM> constitute intersections of the sheet and the formed tabs. Referring to <FIG>, portions of the sheet of <FIG> are folded at least <NUM>° and preferably about <NUM>° upward, forming tabs <NUM>. Dashed lines <NUM> show where the sheet is folded to produce the form shown in <FIG>. Referring to <FIG>, the sheet is folded <NUM>° below the plane of the sheet to form wall sections <NUM>. Referring to <FIG>, sections <NUM> of the sheets in <FIG> are shown to be folded an additional <NUM>° or a total of <NUM>° around the back of the sheet. The formed sheet is shown to be placed between heat transfer surfaces or walls <NUM>, which are perpendicular to the sheet shown in <FIG> and are seen from their edges. The newly formed lateral extremities or new edges <NUM> of the formed sheet abut surfaces <NUM>, and gaps <NUM> lie intermittently between the formed sheet and the surfaces. Apparatus <NUM> comprises the formed sheet with its tabs, intersections, edges and gaps, heat transfer surfaces <NUM>, inlet <NUM>, and outlet <NUM>. Fluid passes from the inlet to the outlet through the apparatus. The formed sheets may be welded, brazed, soldered, glued, or otherwise joined or bonded to the surfaces. The fold lines <NUM> 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 <NUM>° and preferably about <NUM>°. The tabs constitute channel walls to direct the flow of a fluid toward the left surface (as perceived by a person viewing <FIG>) as fluid flows through apparatus <NUM> from the inlet <NUM> to the outlet <NUM>.

<FIG> are two respective views of the formed sheet of <FIG>, where sheet <NUM> is the formed sheet viewed from the inlet as in <FIG>, and <FIG> is a lateral view of the formed sheet corresponding to the view in <FIG>. Left and right heat transfer walls <NUM> are shown. Referring to <FIG>, a second formed sheet <NUM> corresponding to sheet <NUM> of <FIG> is shown, and <FIG> is a view of the second sheet corresponding to the view of <FIG> where the formed sheet of <FIG> are the mirror image left to right of the formed sheet of <FIG>. The structures of <FIG> have inlets <NUM> and outlets <NUM>. The formed sheets of <FIG> are bounded by left and right heat transfer surfaces <NUM>. Whereas the formed sheet of <FIG> causes fluid flowing through the structure from the inlet to the outlet to impinge, or impact, left surface <NUM> and flow away from right surface <NUM>, the formed sheet of <FIG> causes fluid to impinge, or impact, right surface <NUM> and flow away from left surface <NUM>.

Referring to <FIG>, , the structures <NUM> and <NUM> of formed sheets in <FIG>, respectively, are inserted in alternating sequence between left and right flat surfaces <NUM> in <FIG>, next to a single flat surface <NUM> in <FIG>. The surfaces <NUM> are straight as shown in <FIG>.

Referring to <FIG>, a single sheet having flat sections <NUM>, <NUM>, and <NUM> is folded at locations <NUM> and <NUM> as shown. From flat sections <NUM>, tabs are blanked and folded to form columns or elements <NUM> and <NUM>, which are in form the same as those elements in all other drawings.

Referring to <FIG>, the sheet of <FIG> is further folded to <NUM>° bends at locations <NUM> and to <NUM>° bends at locations <NUM>. The formed sheet is disposed between two heat transfer surfaces <NUM>.

<FIG> 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 <NUM>, <NUM>, and <NUM> can be seen in relation to fold lines <NUM> and <NUM>. Instead of two flat sections <NUM> between consecutive flat sections <NUM>, other numbers of flat sections <NUM> may be disposed between consecutive flat sections <NUM> 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. 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.

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 <NUM> 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 <NUM>° 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.

In another embodiment, the angle between the intersections and the heat transfer surface is between <NUM>° and <NUM>°.

In another embodiment, the angle between the channels and the heat transfer surface is less than <NUM>°.

In another embodiment, the angle between the channels and the heat transfer surface is between <NUM>° and <NUM>°.

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

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.

Claim 1:
An apparatus providing enhanced heat transfer, the apparatus comprising:
an inlet (<NUM>);
an outlet (<NUM>);
a heat transfer surface (<NUM>);
a sheet (<NUM>) disposed proximate said heat transfer surface (<NUM>), the sheet (<NUM>; <NUM>) being oriented in a sheet (<NUM>; <NUM>) plane that is displaced from a plane of the heat transfer surface (<NUM>) by an angle of at least <NUM> degrees; and
a plurality of tabs (<NUM>) attached to the sheet (<NUM>; <NUM>), the tabs (<NUM>) lying in respective tab (<NUM>) planes, wherein:
the tab (<NUM>) planes and the sheet (<NUM>; <NUM>) plane intersect forming respective intersections (<NUM>);
the intersections (<NUM>) of the tab (<NUM>) planes and the sheet (<NUM>; <NUM>) plane are substantially parallel;
the intersections (<NUM>) of the tab planes and the sheet (<NUM>; <NUM>) plane are at an angle of less than <NUM>° to the heat transfer surface (<NUM>); and
the plurality of tabs (<NUM>) collectively forms channels directing a fluid passing from the inlet (<NUM>) to the outlet (<NUM>) to impinge the heat transfer surface (<NUM>),
characterized in that
the sheet (<NUM>; <NUM>) provides wall sections (<NUM>) that are folded by <NUM>° around a back of the sheet (<NUM>) with forming new edges (<NUM>)
and that the tabs (<NUM>) are formed by cutting or blanking the sheet (<NUM>; <NUM>) having edges (<NUM>) along lines (<NUM>) and by folding portions of the sheets at least <NUM>° upward,
the intersections (<NUM>) between the respective tab (<NUM>) plane and the sheet (<NUM>; <NUM>) plane are the lines (<NUM>) where the sheet (<NUM>; <NUM>) is folded to form the tabs (<NUM>)
with the edge (<NUM>) of the formed sheet abuts said heat transfer surface (<NUM>) and gaps (<NUM>) lie intermittently between the formed sheet (<NUM>; <NUM>) and the heat transfer surface (<NUM>).