OF MANUFACTURE THEREOF

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. provisional patent application serial number 62/124,235, filed on December 11, 2014, the content of which is included herein by reference in its entirety.

BACKGROUND

(1) Field

[001] This application relates to a tubeless heat exchanger for a fluid heating system, methods of manufacture thereof, and a fluid heating system including the heat exchanger.

(2) Description of the Related Art

[002] Heat exchangers are used in fluid heating systems to transfer heat from a thermal transfer fluid, such as a combustion gas produced by combustion of a fuel such as petroleum or natural gas, to a production fluid. The production fluid can then be used for a variety of commercial, industrial, or domestic applications such as hydronic, steam, and thermal fluid boilers, for example. Because of the desire for improved energy efficiency, compactness, and cost reduction, there remains a need for improved heat exchangers, and fluid heating systems including the same, as well as improved methods of manufacture thereof.

SUMMARY

[003] Disclosed is a heat exchanger including: a heat exchanger core including a casing, a spine disposed on the casing, an inlet on the casing, the spine, or combination thereof, an outlet on the casing, the spine, or combination thereof, wherein the casing and the spine define a flow passage between the inlet and the outlet; a pressure vessel; an inlet member on the inlet for fluidly connecting the inlet to an outside of the pressure vessel; and an outlet member on the outlet for fluidly connecting the outlet to an outside of the pressure vessel.

[004] Also disclosed is a method of manufacturing a heat exchanger core, the method including: providing a casing; disposing a spine the casing; rigidly attaching the spine to the casing; disposing an inlet on the casing, the spine, or a combination thereof; and disposing an outlet on the casing, the spine, or a combination thereof to manufacture the heat exchanger core, wherein the casing and the spine define a flow passage between the inlet and the outlet. [005] Also disclosed is a method of manufacturing a heat exchanger core, the method including: providing a casing; disposing a spine on the casing; rigidly attaching the spine to the casing; disposing a top head on a first end of each of the casing and the spine; disposing a bottom head on a second end of each of the casing and the spine; disposing an inlet on the casing, the spine, or a combination thereof; and disposing an outlet on the casing, the spine, or a combination thereof to manufacture the heat exchanger core, wherein the spine, the casing, the top head and the bottom head define a flow passage between the inlet and the outlet.

[006] Also disclosed is a method manufacturing a heat exchanger, the method including: providing a pressure vessel; and disposing a heat exchanger core in the pressure vessel to manufacture the heat exchanger, wherein the heat exchanger core includes a casing, a spine disposed on the casing, an inlet on the casing, the spine, or a combination thereof, and an outlet on the casing, the spine, or combination thereof, and wherein the spine and the casing define a flow passage between the inlet and the outlet.

[007] Also disclosed is a method of manufacturing a heat exchanger, the method including: providing a shell; disposing a pressure vessel bottom head on the shell; disposing the heat exchanger core in the shell; and disposing a pressure vessel top head on the shell to manufacture the heat exchanger, wherein the pressure vessel top head, the pressure vessel bottom head, the shell, or a combination thereof, includes a pressure vessel inlet, and wherein the pressure vessel top head, the pressure vessel bottom head, the shell, or a combination thereof includes a pressure vessel outlet.

[008] Also disclosed is a method of transferring heat between a first fluid and a second fluid, the method including: providing the heat exchanger; directing a first fluid into a pressure vessel inlet of the pressure vessel; and directing a second fluid into the inlet of the heat exchanger core to exchange heat between the first fluid and the second fluid.

[009] Also disclosed is a heat exchanger including: a pressure vessel including a pressure vessel top head, a pressure vessel bottom head, and a cylindrical shell disposed between the pressure vessel top head and the pressure vessel bottom head, a pressure vessel inlet disposed in the pressure vessel bottom head, the shell, or combination thereof; a pressure vessel outlet disposed in the pressure vessel top head, the shell, or combination thereof; a heat exchanger core including a cylindrical casing, a spine disposed on an outer surface of the casing, an inlet on the casing or the spine, an outlet on the casing or the spine, wherein the spine and the casing define a flow passage between the inlet and the outlet, an inlet disposed on the casing, the spine, or a combination thereof, and an outlet disposed on the casing, the spine, or a combination thereof, an inlet member on the inlet and for fluidly connecting the inlet to an outside of the pressure vessel; and an outlet member on the outlet and for fluidly connecting the outlet to an outside of the pressure vessel, wherein the heat exchanger core is entirely disposed in the pressure vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above and other advantages and features of this disclosure will become more apparent by describing in further detail exemplary embodiments thereof with reference to the accompanying drawings, in which:

[0011] FIG. 1 is a schematic cut-away view of an embodiment of a heat exchanger;

[0012] FIG. 2 is a cross-sectional diagram showing a top view of an embodiment of a casing, a spine, and a pressure vessel;

[0013] FIG. 3 is a cross-sectional view of an embodiment of the heat exchanger;

[0014] FIG. 4 is a schematic cut-away view of another embodiment of the heat exchanger;

[0015] FIG. 5 is a schematic cut-away view of another embodiment of the heat exchanger;

[0016] FIG. 6 is a schematic cut-away view of another embodiment of the heat exchanger; and

[0017] FIG. 7 is a schematic cut-away view of another embodiment of the heat exchanger; DETAILED DESCRIPTION

[0018] Heat exchangers are desirably thermally compact, provide a high ratio of the thermal output to the total size of the heat exchanger, and have a design which can be manufactured at a reasonable cost. This is particularly true of gas-liquid heat exchangers, which can be incorporated into hydronic (e.g., liquid water), steam, and thermal fluid heating systems designed to deliver a hot fluid such as steam for temperature regulation, domestic hot water, or commercial or industrial process applications.

[0019] Tube-and-shell heat exchanger designs suffer a variety of drawbacks. In a tube-and- shell heat exchanger, the heat is transferred from the thermal transfer fluid, e.g., a combustion gas generated by a fuel-fired combustor and driven under pressure through the heat exchanger by a blower, to a production fluid (e.g., liquid water, steam, or another thermal fluid) across the walls of numerous thin-walled fluid conduits, i.e. tubes, having a wall thickness of less than 0.5 centimeters (cm). The tubes are rigidly connected to a tubesheet. Operational factors including thermal stress and corrosion lead to undesirable material failures in the tubes of tube-and-shell heat exchangers, the attachment points of the tubes, and in the tubesheets. Furthermore, when a failure occurs, the fluid heating system is rendered inoperable, and the thin-walled heat exchanger tubes and/or tubesheets are difficult and costly to service or replace, particularly in field installations.

[0020] Tubeless heat exchangers are also used. Tubeless heat exchangers avoid the use of the thin-walled tubes and the tubesheets associated with tube-and shell heat exchangers. Known practical designs for tubeless heat exchangers also have drawbacks. In available tubeless heat exchangers, the pressure vessel outer shell contacts a hot heat transfer fluid, e.g., along the exit path of the flue gas exhaust, resulting in a hot surface on the outside of the pressure vessel. To accommodate the hot outer surface, a refractory barrier outside the pressure vessel is provided, wherein the refractory barrier is separated from the pressure vessel by a gap through which the hot thermal transfer fluid flows, e.g., through an array of longitudinal spines, thereby transferring thermal energy from the thermal transfer fluid into the outside of the shell, and ultimately transferring heat to the production fluid. Such tubeless designs suffer from refractory deterioration and loss of thermal efficiency due to some amount of heat being transferred into and through cracks in the refractory layer, and ultimately into the environment around the boiler. Furthermore, the hot outer surface of the pressure vessel presents safety issues due to the temperature of the skin which overlays the refractory material and due to leaking of thermal transfer fluid (e.g. flue gas) through cracks in the refractory material.

[0021] The disclosed heat exchanger provides a variety of features. For example, in the disclosed heat exchanger there is no direct contact between the thermal transfer fluid and the production fluid. Furthermore, the disclosed heat exchanger avoids use of thin-walled tubing, thereby avoiding the inherent fragility and susceptibility to material failure and corrosion of thin-walled tubing. The disclosed heat exchanger can be provided using metal alloy components having an average wall thickness of 0.5 to 5 cm, for example, as the primary member between the thermal transfer fluid and the production fluid, and thus can avoid the fragility problems associated with thin-walled tubing. In an embodiment, the disclosed heat exchanger can also avoid tight turnabouts in flow passages for both the thermal transfer fluid and the production fluid, thereby avoiding configurations that would be susceptible to fouling, clogging, and corrosion blockage. In addition, the disclosed heat exchanger provides for improved compactness (i.e., energy density, having the units of kilowatts per cubic meter, kW/m ³ ) and improved performance characteristics compared to tube-and-shell heat exchanger alternatives of the same production capability. As is further disclosed herein, in an embodiment of the disclosed heat exchanger all outer surfaces of the heat exchanger core are contacted by the production fluid, thereby fully utilizing the outer surfaces of the heat exchanger core for thermal energy transfer and avoiding thermal stress in the heat exchanger core. The efficiency of the disclosed design provides for reduced material requirements and reduced manufacturing complexity.

[0022] Disclosed is the incorporation of a spine to direct the fluid flow through the heat exchanger to increase the flow path length, thereby facilitating the transfer of heat energy from the thermal transfer fluid to the production fluid. The spine is disposed on a casing of the heat exchanger, and the spine and casing together form a flow passage for conveying the heat transfer fluid. As shown in FIG. 1, the spine may be disposed on an outer surface of the casing. Alternatively, the spine may be disposed on an inner surface of the casing.

[0023] A heat exchanger comprises: a heat exchanger core comprising a casing, a spine disposed on the casing, an inlet disposed on the casing, the spine, or combination thereof; and an outlet disposed on the first casing, the spine, or combination thereof; wherein the spine and the casing define a flow passage between the inlet and the outlet; a pressure vessel; an inlet member on the inlet for fluidly connecting the inlet to an outside of the pressure vessel; and an outlet member on the outlet for fluidly connecting the outlet to an outside of the pressure vessel, wherein casing, and the spine are contained entirely within the pressure vessel. In an embodiment, the spine is disposed on an outer surface of the casing. In an alternative embodiment, the spine is disposed on an inner surface of the casing. Also, if desired, an entirety of the heat exchanger core may be disposed entirely within the pressure vessel so that when the pressure vessel is filled with a production fluid an entire outer surface of the heat exchanger core is contacted by the production fluid.

[0024] In an embodiment the casing can be surrounded by the spine. Alternatively, the spine can be surrounded by the casing. As shown in FIG. 1, a heat exchanger 100 comprises: a heat exchanger core 110 comprising a casing 118; a spine 116 disposed on the casing, wherein an outer surface 118A of the casing 118 is opposite an inner surface 116A of the spine; an inlet 120 on the casing; an outlet 122 on the casing; wherein the spine and the casing define a flow passage between the inlet and the outlet; a pressure vessel 150; an inlet member 152 on the inlet and for fluidly connecting the inlet to an outside of the pressure vessel; and an outlet member 154 on the outlet and for fluidly connecting the outlet to an outside of the pressure vessel. As shown in FIG. 1, the casing and the spine may be contained entirely within the pressure vessel. The inner surface 116A of the spine and the outer surface 118A of the casing are interior to the flow passage defined by the spine 116 and the casing 118. Depending upon the shape of the spine, a heat exchanger core top head 113 or bottom head 114 or both may be used to seal the flow passage at one end or both ends of the casing. As is also shown in FIG. 1, the pressure vessel top head 160, the pressure vessel bottom head 162, and the pressure vessel shell 164 can be disposed between the pressure vessel top head and the pressure vessel bottom head. The pressure vessel top head, the pressure vessel bottom head, or combination thereof may comprise an opening for a conduit (not shown in FIG. 1). The conduit is connected to the inlet member 152, and may pass through the pressure vessel top head 160 and the top head 112 of the heat exchanger core.

[0025] The casing, the inlet, the outlet, the spine, the pressure vessel, the inlet member, and the outlet member can each independently comprise any suitable material. Use of a metal is specifically mentioned. Representative metals include iron, aluminum, magnesium, titanium, nickel, cobalt, zinc, silver, copper, and an alloy comprising at least one of the foregoing. Representative metals include carbon steel, mild steel, cast iron, wrought iron, a stainless steel such as a 300 series stainless steel or a 400 series stainless steel (e.g., 304, 316, or 439 stainless steel), Monel, Inconel, bronze, and brass. Specifically mentioned is an embodiment in which the heat exchanger core and the pressure vessel each comprise steel, specifically mild steel.

[0026] The casing and the outer surface of the spine may be coaxial, and may be concentric. In an embodiment, the casing and the outer surface of the spine are coaxial, as shown in FIGS. 1 and 2. Non-coaxial configurations are also contemplated.

[0027] The casing of the heat exchanger core may have any suitable shape and may have a circular cross-sectional shape, an elliptical cross-sectional shape, an oval cross-sectional shape, a stadium cross-sectional shape, a semicircular cross-sectional shape, a square cross- sectional shape, a rectangular cross-sectional shape, a triangular cross-sectional shape, or combination thereof. An embodiment in which the casing has a cylindrical shape is specifically mentioned.

[0028] The casing may have a largest outer diameter of 15 centimeters (cm), 25 cm, or 30 cm to 350 cm, 650 cm, or 1,400 cm, wherein the foregoing upper and lower bounds can be independently combined. For example, the casing may have a largest outer diameter of 15 cm to 1,400 cm. An embodiment in which the casing has a largest outer diameter of 30 cm to 350 cm is preferred. Alternatively, the casing may have a largest outer diameter of 50 cm, 100 cm, or 200 cm to 500 cm, 700 cm, or 1,400 cm, wherein the foregoing upper and lower bounds can be independently combined.

[0029] The casing may have a maximum height of 15 cm, 25 cm, or 30 cm to 350 cm, 650 cm, or 1 ,400 cm, wherein the foregoing upper and lower bounds can be independently combined, and wherein the height is determined in a direction of a major axis of the casing. For example, the casing may have a maximum height of 15 cm to 1,400 cm. Alternatively, the casing may have a height of 50 cm, 100 cm, or 200 cm to 500 cm, 700 cm, or 1,400 cm, wherein the foregoing upper and lower bounds can be independently combined.

[0030] An embodiment in which the casing has a largest outer diameter of 30 cm to 350 cm and a height of 50 cm to 1,000 cm is preferred.

[0031] A top head may be disposed on a first end of the casing, and a bottom head may be disposed on the opposite second end of the casing. In an embodiment, depending upon the shape of the spine, the top head and the bottom head may seal the spine to the casing. The top head and the bottom head may each independently be rigidly attached to the casing and the spine by any suitable method, such as by a weld, an adhesive, a fastener, or a combination thereof. An embodiment in which the top head and the bottom head are each welded to the casing and the spine specifically mentioned. As shown in FIG. 1, the top head and the bottom head of the heat exchanger core are distinct members. However, other designs are contemplated. For example, the top head and the bottom head may each independently be formed by providing a weld seam between the casing and the spine. Alternatively, the ends of the casing and the spine may be contacted, e.g., pinched together or rolled, to form the top head and the bottom head. [0032] A thickness, e.g., an average wall thickness, of the top head, the bottom head, the casing, and the spine may be any suitable dimension, and the thickness of the top head, the bottom head, the first casing, and the second casing may each independently be 0.5 cm to 3 cm, e.g., 0.5 cm, 0.6 cm, 0.7 cm, or 1 cm to 5 cm, 4 cm, 3.5 cm, or 3 cm, wherein the foregoing upper and lower bounds can be independently combined. An embodiment in which the top head, the bottom head, the casing, and the spine each independently have a thickness of 0.5 cm to 1 cm is specifically mentioned.

[0033] An outer surface 118A of the casing 118 and an inner surface 116A of the spine 116 define a flow passage between the inlet and the outlet of the heat exchanger core, which comprises, e.g., consists of, the casing, the spine and the top head and the bottom head of the heat exchanger core. It has been surprisingly discovered that certain configurations of the flow passage provide improved performance, including a desirable combination of pressure drop between the inlet and the outlet, and thermal performance. This improvement can be parameterized in terms of an aspect ratio of the flow passage, wherein the aspect ratio of the flow passage is defined as a first inner dimension of the flow passage divided by a second inner dimension of the flow passage, where the first and second inner dimensions are both determined normal to a flow direction and are perpendicular to each other, and wherein the shorter dimension of the first and second inner dimensions is defined at the midpoint of the longer dimension of the first and second inner dimensions. It has been further surprisingly discovered that configurations wherein an aspect ratio of the flow passage is 3 to 500, e.g., 3, 5, 10, 15, or 20 to 80, 100, 200, or 500, preferably 10 to 100, more preferably 20 to 80, provide an improved combination of pressure drop and thermal performance, wherein the foregoing upper and lower bounds can be independently combined.

[0034] Determination of the aspect ratio is illustrated in FIG. 3, which indicates

determination of the height H and the width W of an embodiment of the flow passage. As shown in FIG. 3, the height H can be determined between surfaces of adjacent spines, e.g., between a first spine surface 124A, and a second spine surface 124B when viewed in a cross- sectional dimension, and the width W is determined between and inner surface 116A of the spine 116 and an outer surface 118A of the casing 118. For example, the height H of the flow passage may be 0.6 cm to 600 cm, and may be 0.6 cm, 1 cm, 2 cm, 4 cm, 10 cm, 20 cm, 40 cm, 80 cm, or 160 cm to 600 cm, 550 cm, 500 cm, 450 cm, 400 cm, 350 cm, 300 cm, or 250 cm, wherein the foregoing upper and lower bounds can be independently combined. Also the width may be 0.6 cm to 600 cm, and may be 0.6 cm, 1 cm, 2 cm, 4 cm, 10 cm, 20 cm, 40 cm, 80 cm, or 160 cm to 600 cm, 550 cm, 500 cm, 450 cm, 400 cm, 350 cm, 300 cm, or 250 cm, wherein the foregoing upper and lower bounds can be independently combined. In a preferred embodiment, the height is 20 cm to 60 cm and the width is 1 cm to 4 cm. In a more preferred embodiment, the height is 40 cm to 45 cm and the width is 1.2 cm to 1.9 cm. In another more preferred embodiment, the height is 45 cm to 50 cm and the width is 1.5 cm to 3 cm.

[0035] The spine may have any suitable cross-sectional dimensions. In a preferred embodiment in which the spine is rectilinear, a cross-sectional height and width of the spine may be independently selected, and may be 0.3 cm to 600 cm, and may be 0.3 cm, 0.5 cm, 0.6 cm, 1 cm, 10 cm, or 50 cm, to 100 cm, 200 cm, 400 cm, or 600 cm, wherein the foregoing upper and lower bounds can be independently combined and wherein the height is measured in a direction of a major or longitudinal axis of the heat exchanger core and wherein the width is measured in a direction perpendicular to the longitudinal axis of the heat exchanger core. For example, a rectilinear spine may have a height of 0.3 cm to 600 cm and a width of 0.5 cm to 365 cm. The spine may have a semi-circular cross-sectional shape, a semi-annular cross-sectional shape, a semi-elliptical cross-sectional shape, an oval cross-sectional shape, a stadium cross-sectional shape, a semi-square cross-sectional shape, a semi-rectangular cross- sectional shape, a semi-triangular cross-sectional shape, or combination thereof. A spine having a rectilinear or curvilinear cross-section, such as an ell-shape, a semi-circular cross- sectional shape, or a portion of a circle, is specifically mentioned. In an embodiment, the spine may be tubular. A spine having a cross-sectional shape of a portion of a circle having a diameter of 1 cm to 5 cm is specifically mentioned. In an embodiment, a wall thickness of the tubular spine may be 0.1 cm to 1 cm, and may be 0.1 cm, 0.2 cm, or 0.4 cm to 0.6 cm, 0.8 cm, or 1 cm, wherein the foregoing upper and lower bounds can be independently combined.

[0036] In an embodiment the spine is wound around the outside of the casing so that the flow channel is formed by the outer surface of the casing and the inner surface of the spine. In another embodiment, the spine is wound around the inside surface of the casing so that the flow channel is formed by the inner surface of the casing and the inner surface of the spine. In yet another embodiment, a first spine may be disposed on an outer surface of case and a second spine may be disposed on an inner surface of the casing. [0037] The spine may have any suitable cross-sectional shape. In an embodiment, the spine may have a circular cross-sectional shape, an annular cross-sectional shape, an elliptical cross-sectional shape, an oval cross-sectional shape, a stadium cross-sectional shape, a semicircular cross-sectional shape, a square cross-sectional shape, a rectangular cross- sectional shape, a triangular cross-sectional shape, or combination thereof. For example, as shown in FIG. 4, an ell-shaped spine 402 may have an ell ("L") cross-sectional shape wherein a first longitudinal edge is disposed on the casing and a second longitudinal edge is disposed on another surface of the spine. FIG. 5 shows a cross-sectional view of the ell-shaped spine 502 disposed on the casing 508 wherein the spine is welded with a fillet 504 to the casing and welded to the spine to form a flow passage 510 for conveying the thermal transfer fluid. Alternatively, and as shown in FIG. 6, a spine 604 may have a rectangular cross-sectional shape and may be attached by a weld, such as a fillet 602 to the casing 608. In yet another embodiment, as shown in FIG. 7, a spine 704 may be attached by a weld using a fillet 702 to the casing 708 and may have a circular or semi-circular cross-sectional shape.

[0038] The spine may contact the casing and a surface of the spine, may be rigidly attached to one or both of the casing and a surface of the spine, or may be disposed loosely on the casing. For example, the spine may form an interference fit with the inner surface of the first casing, the inner surface of the second casing, or a combination thereof. In another embodiment, the first casing and the spine, the second casing and the spine, or a combination thereof may be rigidly attached at a single point, or at a plurality of points along the length of the spine. The attachment may be provided by any suitable attachment member, such as a weld, an adhesive, a fastener, or combination thereof. Use of a weld, such as a spot or stitch weld, is specifically mentioned. The casing and the spine may rigidly attached by a weld which is disposed on 1% to 100%, 5% to 99%, 10% to 90%, 25% to 75% of a length of the spine. Alternatively, a continuous weld extending the length of the spine may be used. Also, the spine may be rigidly attached to the first casing by a first weld and rigidly attached to the second casing by a second weld, wherein the first weld and the second weld may be the same type of weld or may be different types of welds. The spine may be stitch-welded to the first or second casing anywhere along its length, or continuously welded along its length, to hold the spine in a selected position relative to the first casing, the second casing, or both. For example, as shown in FIG. 7, the spine may be welded to a surface of the casing by a fillet weld 702. [0039] The spine may have a pitch, e.g., a slope, having any suitable angle with respect to a longitudinal axis of the heat exchanger core, the inner casing, or the outer casing. As illustrated in FIG. 1, a pitch Θ may be defined with respect to a tangent direction t, wherein the tangent direction is perpendicular to a longitudinal axis of the outer casing. In an embodiment, a pitch of the spine is 0 degrees to 90 degrees with respect to the tangent direction, and can be 0 degrees, 2 degrees, or 5 degrees to 90 degrees, 50 degrees, or 45 degrees with respect to the tangent direction, wherein the foregoing upper and lower bounds can be independently combined. A pitch of 5 degrees to 45 degrees with respect to the tangent direction is specifically mentioned. In an embodiment, the heat exchanger core comprises a plurality of spines, and a pitch of each spine of the plurality of spines may each independently be 0 degrees to 90 degrees with respect to the tangent direction, and can be 0 degrees, 2 degrees, or 5 degrees to 90 degrees, 50 degrees, or 45 degrees with respect to the tangent direction, wherein the foregoing upper and lower bounds can be independently combined. An embodiment in which the pitch is 5 degrees to 45 degrees with respect to the tangent direction is specifically mentioned.

[0040] In yet another embodiment, the spine may be parallel to an axis, e.g., a longitudinal axis, of the first casing, the second casing, or combination thereof. In an embodiment, the heat exchanger core may comprise a plurality of spines, and each spine may be parallel to a longitudinal axis of the first casing, the second casing, or combination thereof. In an embodiment, the heat exchanger core comprises a spine which provides a serpentine flow passage between the inlet and the outlet. The serpentine flow passage may be defined by a plurality of linear spines, or may be defined by a combination of curved spines and linear spines.

[0041] The casing and the spine of the heat exchanger core are contained entirely within the pressure vessel. In another embodiment, the top head, the bottom head, the casing, and the spine of the heat exchanger core are contained entirely within the pressure vessel. As used with respect to the configuration of the heat exchanger core within the pressure vessel, "entirety" means that the component referred to is fully contained within the pressure vessel. For example, when the pressure vessel is filled with a fluid, an entire outer surface of a component of the heat exchanger core which is contained entirely with the pressure vessel would be contacted by the fluid. Thus in use, e.g., when the pressure vessel is filled with a production fluid, an entirety a surface of the casing, e.g., an inner surface, can be contacted by the production fluid. In yet another embodiment the top head may also be contained entirely within the pressure vessel, in which case when the pressure vessel is filled with a production fluid, the production fluid can contact an entire outer surface of the top head as well. In yet another embodiment, an entirety of the heat exchanger core, i.e., the top head (if present), the bottom head (if present), the casing, the spine, the inlet, and the outlet, is contained entirely within the pressure vessel.

[0042] The heat exchanger further comprises an inlet member 152, which fluidly connects the inlet 120 to an outside of the pressure vessel, e.g. for providing a flow of a thermal transfer fluid, such as a combustion gas, to the inlet of the heat exchanger core. Also, an outlet member 154, which fluidly connects the outlet 122 of the heat exchanger core to an outside of the pressure vessel can be provided. Also, the pressure vessel comprises an inlet 155, and an outlet 156 for providing a flow of a production fluid into and out of the pressure vessel.

[0043] The heat exchanger may be used to exchange heat between any suitable fluids, i.e., a first fluid and the second fluid, wherein the first and second fluids may each independently be a gas or a liquid. Thus the disclosed heat exchanger may be used as a gas-liquid, liquid- liquid, or gas-gas heat exchanger. In a preferred embodiment the first fluid, which is directed through the heat exchanger core, is a thermal transfer fluid, and may be a combustion gas, e.g., a gas produced by fuel fired combustor, and may comprise water, carbon monoxide, carbon dioxide, or combination thereof. Also, the second fluid, which is directed through the pressure vessel and contacts an entire outer surface of the heat exchanger core, is a production fluid and may comprise water, steam, oil, a thermal fluid, or combination thereof. The thermal fluid may comprise an ester, a diester, a glycol, a silicone, water, a petroleum oil, a mineral oil, or a chlorofluorocarbon such as a halogenated fluorocarbon, a halogenated chlorofluorocarbon, or a perfluorocarbon. A combination comprising at least one of the foregoing may be used. A thermal fluid comprising glycol and water is specifically mentioned. For example, the thermal fluid may be formulated from an alkaline organic or inorganic compound and used in diluted form with a concentration ranging from 3 weight percent to 10 weight percent, based on a total weight of the thermal fluid.

[0044] For example, the second fluid may comprise water, and may be used as a production fluid in a domestic, commercial, or industrial heating application. The first fluid, e.g., the thermal transfer fluid, which is directed through the inlet member, through the flow passage of the heat exchanger core, and out the outlet member, does not contact the pressure vessel. As a result, thermal heat energy transfer occurs between the hot first fluid flowing inside the core to the second fluid separately flowing in the pressure vessel. As noted above, the second fluid contacts an entire outer surface of the of the heat exchanger core and at no point does the surface of the pressure vessel contact the first fluid. Because the pressure vessel does not contact the first fluid, which can have a temperature of 10°C to 1800°C, such as 10°C, 50°C, 100°C, 200°C, or 400°C to 1800°C, 1600°C, 1400°C, 1200°C, or 1000°C, wherein the foregoing upper and lower bounds can be independently combined, the exterior surface of the pressure vessel remains relatively cool and use of insulation, e.g., a refractory material, to insulate the pressure vessel can be avoided. An embodiment in which the first fluid has a temperature of 100°C to 1350°C is specifically mentioned.

[0045] The pressure vessel top head, the pressure vessel bottom head, and the pressure vessel shell may each independently have any suitable shape, and may be rectilinear or curvilinear, and may be flat, domed, or spherical. For example, as shown in FIG. 1, the pressure vessel top head and the pressure vessel bottom head may have a flat shape. Alternatively, the pressure vessel top head and the pressure vessel bottom head may have a curved shape. Also, the pressure vessel shell may have any suitable shape, maybe curvilinear or rectilinear, and may be cylindrical as shown in FIG. 1.

[0046] Also disclosed is a method of manufacturing a heat exchanger core, the method comprising: providing a casing; disposing a spine on the casing, e.g., on the outer surface of the casing, on the inner surface of the casing, or both; e.g., wrapping, the spine on a surface of the casing; disposing an inlet on the casing, the spine, or combination thereof; and disposing an outlet on the casing, the spine, or combination thereof to manufacture the heat exchanger core; wherein the spine and the casing define a flow passage between the inlet and the outlet. The flow passage may be defined by an outer surface of the casing and an inner surface of the spine, an inner surface of the casing and an inner surface of the spine, or both. Details of the disposing, e.g., welding, are similar to as disclosed above, and thus repeated description is not included for clarity.

[0047] Also disclosed is an alternative method of manufacturing a heat exchanger core, the method comprising: providing a casing; disposing a spine on the casing e.g., on the outer surface of the casing, on the inner surface of the casing, or both; e.g., wrapping, the spine on a surface of the casing; disposing a top head on an upper end of the casing and an exposed longitudinal edge of the spine; disposing a bottom head on a lower end of the casing and an exposed longitudinal edge of the spine; disposing an inlet on the casing, the spine, or combination thereof; and disposing an outlet on the casing, the spine, or combination thereof to manufacture the heat exchanger core; wherein the spine and the casing define a flow passage between the inlet and the outlet. The flow passage may be defined by an inner surface of the casing and an inner surface of the spine. Details of the disposing, e.g., welding, are similar to as disclosed above, and thus repeated description is not included for clarity.

[0048] In any of the foregoing embodiments, the spine may be disposed on an outer surface of the casing; and/or the spine may be disposed on an inner surface of the casing; and/or the heat exchanger core may be contained entirely within the pressure vessel; and/or top head may be disposed on a first end of the casing, a bottom head may be disposed on the second end of the casing, or a combination thereof, wherein the first end of the casing may be opposite the second end of the casing; and/or the casing and spine may be coaxial; and/or the casing and an outer surface of the spine may be coaxial; and/or the casing and spine may each independently have a circular cross-sectional shape, an elliptical cross-sectional shape, an oval cross-sectional shape, a stadium cross-sectional shape, a semicircular cross-sectional shape, a square cross-sectional shape, a rectangular cross-sectional shape, a triangular cross- sectional shape, or combination thereof; and/or the casing and the spine may each

independently have an average wall thickness of 0.5 centimeters to 5 centimeters; and/or an aspect ratio of the flow passage may be between 10 and 100, wherein the aspect ratio is a ratio of a height of the flow passage to a width of the flow passage, wherein the height of the spine is a greatest inner dimension of the spine and is measured parallel to a longitudinal axis of the casing, and wherein the width of the flow passage is a greatest inner dimension measured from an inner surface of the first casing to an inner surface of the spine; and/or the heat exchanger may comprise a plurality of spines; and/or the spine may have a helical shape, a rectilinear shape, a curvilinear shape, a shape of segment of a square, a shape of a segment of a circle, a shape of a segment of a rectangle, the shape of a segment of a polygon, shape of a segment of a circle, a shape of a segment of a ellipse, or a combination thereof; and/or the spine may have a circular cross-sectional shape, an annular cross-sectional shape, an elliptical cross-sectional shape, an oval cross-sectional shape, a stadium cross-sectional shape, a semicircular cross-sectional shape, a square cross-sectional shape, a rectangular cross- sectional shape, a triangular cross-sectional shape, or combination thereof; and/or the spine may have a semi-circular cross-sectional shape, a semi-annular cross-sectional shape, a semi- elliptical cross-sectional shape, an oval cross-sectional shape, a stadium cross-sectional shape, a semi-square cross-sectional shape, a semi-rectangular cross-sectional shape, a semi- triangular cross-sectional shape, or combination thereof; and/or the spine may be rigidly attached to the casing; and/or the casing and the spine, or any section thereof, may be rigidly attached by a weld; and/or the casing and the spine may be rigidly attached by a weld which is disposed on 1% to 100% of a length of the spine, and wherein the weld is a spot weld, a stitch weld, a butt weld, a fillet weld, or a combination thereof; and/or a pitch of the spine may be between 0 degrees and 90 degrees, wherein the pitch is determined with respect to a tangent direction, wherein the tangent direction is perpendicular to a longitudinal axis of the second casing; and/or the pitch of the spine may be parallel to a longitudinal axis of the casing; and/or the heat exchanger core may comprise a plurality of spines, and a pitch of each spine of the plurality of spines is independently between 0 degrees and 90 degrees with respect to the tangent direction; and/or a pitch of the spine may be parallel to a longitudinal axis of the casing; and/or the heat exchanger core may comprise a plurality of spines, and wherein a pitch of each spine of the plurality of spines may be parallel to a longitudinal axis of the casing; and/or the pressure vessel may comprise a pressure vessel top head, a pressure vessel bottom head, and a shell disposed between the pressure vessel top head and the pressure vessel bottom head, wherein the pressure vessel top head, the pressure vessel bottom head, the shell, or a combination thereof comprises a pressure vessel inlet, and wherein the pressure vessel top head, the pressure vessel bottom head, the shell, or combination thereof comprises a pressure vessel outlet; and/or the pressure vessel inlet may be disposed in the pressure vessel bottom head, and wherein the pressure vessel outlet may be disposed in the pressure vessel top head; and/or the spine and the casing may define a helical flow passage; and/or optionally further comprising welding the spine to the casing; and/or wherein the disposing of the spine on the casing may comprise disposing the spine on an outer surface of the casing.

[0049] The invention has been described with reference to the accompanying drawings, in which various embodiments are shown. This invention may, however, be embodied in many different forms, and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout. [0050] It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may be present there between. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. Also, the element may be on an outer surface or on an inner surface of the other element, and thus "on" may be inclusive of "in" and "on."

[0051] It will be understood that, although the terms "first," "second," "third," etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer or section. Thus, "a first element,"

"component," "region," "layer," or "section" discussed below could be termed a second element, component, region, layer, or section without departing from the teachings herein.

[0052] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms, including "at least one," unless the content clearly indicates otherwise. "Or" means "and/or." As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises" and/or "comprising," or "includes," and/or "including" when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

[0053] Furthermore, relative terms, such as "lower" or "bottom" and "upper" or "top," may be used herein to describe one element's relationship to another element as illustrated in the Figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. For example, if the device in one of the figures is turned over, elements described as being on the "lower" side of other elements would then be oriented on "upper" sides of the other elements. The exemplary term "lower," can therefore, encompasses both an orientation of "lower" and "upper," depending on the particular orientation of the figure. Similarly, if the device in one of the figures is turned over, elements described as "below" or "beneath" other elements would then be oriented "above" the other elements. The exemplary terms "below" or "beneath" can, therefore, encompass both an orientation of above and below.

[0054] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0055] Exemplary embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features.

Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims.