US20190078772A1

US20190078772A1 - Heat exchanger for heating water

Info

Publication number: US20190078772A1
Application number: US15/772,178
Authority: US
Inventors: Christopher J. Jacques; Andrew Hodsdon; Jason A. Butler
Original assignee: Laars Heating Stystems Co
Current assignee: Laars Heating Stystems Co; Laars Heating Systems Co
Priority date: 2015-11-20
Filing date: 2016-11-18
Publication date: 2019-03-14
Also published as: WO2017087829A1

Abstract

Aspects of the invention provide a heat exchanger including a shell at least partially defining an interior region; a burner positioned to deliver combustion gases into the interior region; and a plurality of tubes configured to circulate water therein, the plurality of tubes extending through the interior region. The plurality of tubes further including an inner set of tubes and an outer set of tubes, the inner set of tubes being closer to the burner than the outer set of tubes. The inner set of tubes and the outer set of tubes being positioned adjacent to one another such that the outer set of tubes is staggered from the inner set of tubes and tubes of the outer set of tubes are adjacent to tubes of the inner set of tubes. Additionally, baffle segments are annularly positioned in the interior region adjacent the plurality of tubes. Adjacent baffle segments defining gaps for the flow of the combustion gases.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is related to and claims the benefit of U.S. Provisional Application No. 62/258,094, entitled HEAT EXCHANGER FOR HEATING WATER, filed on Nov. 20, 2015, the contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

This disclosure relates to heat exchangers as well as methods and systems using the same.

BACKGROUND OF THE INVENTION

Commercial and residential water heaters typically heat water by generating tens of thousands, and even hundreds of thousands, of BTUs. For many years, manufacturers of heater exchangers, including manufacturers of heat exchangers to be used in residential and commercial applications, have sought to increase the efficiency of the exchange of this heat energy from burned fuel to the water contained in the water heater. Accordingly, maximized heat exchange efficiency has long been an object of commercial and residential water heater manufacturers.
As heat exchange efficiency increases, however, such increased efficiency gives rise to the problems associated with condensation of water vapor from the products of combustion. More specifically, upon burning of a mixture of fuel and air, water is formed as a constituent of the products of combustion. It is recognized that as the temperatures of the combustion gases decrease as the result of successful exchange of heat from the combustion gases to water in the water heater, the water vapor within the combustion gases tends to be condensed in greater quantities. In other words, as the temperatures of the combustion gases decrease as a direct result of increasingly efficient exchange of heat energy to the circulated water, the amount of condensate forming on the heat exchange surfaces also increases.
In many instances, however, purchasers of heat exchangers may have exhaust pipes and vents that are not compatible with condensing heat exchangers. Accordingly, such purchasers are posed with the choice of replacing their exhaust pipes and vents or buying non-condensing heat exchangers. Accordingly, it would be desirable to satisfy the needs of purchasers for maximized heat exchange efficiency and/or non-condensing heat exchangers.

SUMMARY OF THE INVENTION

Aspects of the invention relate to heat exchangers and parts thereof, as well as methods of manufacturing the heat exchangers.
In accordance with one aspect, the invention provides a heat exchanger that includes a shell at least partially defining an interior region; a burner positioned to deliver combustion gases into the interior region; a fuel supply configured to supply fuel to the burner; a controller configured to control the fuel supply; and a plurality of tubes configured to circulate water. The tubes extend through the interior region. The tubes further include an inner set of tubes and an outer set of tubes, the inner set of tubes being closer to the burner than the outer set of tubes. The heat exchanger also includes baffle segments positioned in the interior region adjacent the outer set of tubes. Adjacent baffle segments define gaps for the flow of the combustion gases outwardly relative to the outer set of tubes. Additionally, the heat exchanger includes a condensate drain positioned to receive condensate from the interior region. The heat exchanger is configurable to operate in a condensing mode in which moisture condenses from the combustion gases or a non-condensing mode in which moisture does not condense from the combustion gases. The condensate drain is coupled to receive condensate from the interior region when the heat exchanger is operated in the condensing mode. The heat exchanger is further configurable to operate in the condensing mode or in the non-condensing mode by adjusting the controller.
According to another aspect, the invention includes a heat exchanger having a non-circular shell at least partially defining an interior region; a burner positioned to deliver combustion gases into the interior region; and a plurality of tubes configured to circulate water. The tubes extend through the interior region. Additionally, the tubes include an inner set of tubes and an outer set of tubes, the inner set of tubes are closer to the burner than the outer set of tubes. Baffle segments are positioned in the interior region adjacent the outer set of tubes. Adjacent baffle segments define gaps for the flow of the combustion gases outwardly relative to the outer set of tubes.
In accordance with another aspect, the invention provides a heat exchanger including a shell at least partially defining an interior region; a burner positioned to deliver combustion gases into the interior region; and a plurality of tubes configured to circulate water, the tubes extending through the interior region. The tubes further include an inner set of tubes and an outer set of tubes, the inner set of tubes being closer to the burner than the outer set of tubes. The inner set of tubes and the outer set of tubes are positioned adjacent to one another such that the outer set of tubes is staggered from the inner set of tubes, and tubes of the outer set of tubes are adjacent to tubes of the inner set of tubes. Additionally, baffle segments are annularly positioned in the interior region adjacent the tubes. Adjacent baffle segments define gaps for the flow of the combustion gases.
According to yet another aspect, the invention provides a heat exchanger having a shell at least partially defining an interior region; a burner positioned to deliver combustion gases into the interior region; and a plurality of tubes configured to circulate water, the tubes extending through the interior region. The tubes include an inner set of tubes and an outer set of tubes, the inner set of tubes being closer to the burner than the outer set of tubes. The heat exchanger also includes baffle segments that are annularly positioned in the interior region adjacent the outer set of tubes. Adjacent baffle segments define gaps for the flow of the combustion gases outwardly relative to the outer set of tubes. The heat exchanger further includes a tube sheet positioned at an end region of the shell, the tube sheet being coupled to the tubes. Additionally, the heat exchanger includes a header coupled to the shell, the header and the tube sheet together defining a cavity between the header and the tube sheet. The tube sheet further defines an inner set of apertures in water flow communication with the inner set of tubes and defining an outer set of apertures in water flow communication with the outer set of tubes.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed description when read in connection with the accompanying drawings, with like elements having the same reference numerals. When a plurality of similar elements are present, a single reference numeral may be assigned to the plurality of similar elements with a small letter designation referring to specific elements. When referring to the elements collectively or to a non-specific one or more of the elements, the small letter designation may be dropped. This emphasizes that according to common practice, the various features of the drawings are not drawn to scale unless otherwise indicated. On the contrary, the dimensions of the various features may be expanded or reduced for clarity. Included in the drawings are the following figures:

FIG. 1 is a cross-sectional view of an embodiment of a heat exchanger in accordance with aspects of the present invention;

FIGS. 2A-2C are perspective, top, and side views of a tube subassembly of the heat exchanger of FIG. 1;

FIG. 3A is a cross-sectional top view of the tube subassembly of FIG. 2C;

FIG. 3B is an enlarged view of a portion of the tube subassembly of FIG. 3A;

FIG. 4 is an exploded perspective view of a header subassembly of the heat exchanger of FIG. 1;

FIG. 5A is a top view of the header subassembly of FIG. 4;

FIG. 5B is a cross-sectional side view of the header subassembly of FIG. 5A;

FIG. 6A is a top view of a set of barriers for use in the header subassembly of FIG. 4;

FIG. 6B is a cross-sectional view of the set of barriers of FIG. 6A;

FIG. 6C is a perspective view of an embodiment of a set of barriers formed from multiple segments in accordance with aspects of the present invention;

FIG. 7A is a top view of a set of barriers and a corresponding tube sheet according to aspects of the present invention;

FIG. 7B is an enlarged view of the set of barriers and corresponding tube sheet of FIG. 7A;

FIG. 8 is an exploded view of an embodiment of a header subassembly having an inlet and an outlet in accordance with aspects of the present invention;

FIG. 9A is a top view of the header having an inlet and an outlet of FIG. 8;

FIG. 9B is a cross-sectional side view of the header having an inlet and an outlet of FIG. 9A;

FIG. 10A is a perspective view of a header subassembly of FIG. 8 having a cut out portion;

FIG. 10B is an enlarged view of a portion of the header sub assembly of FIG. 10A;

FIG. 11A is an exploded view of an embodiment of a barrier for use in a header subassembly according to aspects of the present invention;

FIG. 11B is a perspective view of a plurality of barriers of FIG. 11A and a corresponding tube sheet;

FIG. 11C is a top view of the plurality of barriers and corresponding tube sheet of FIG. 11B;

FIG. 12A is a perspective view of an embodiment of a barrier for use in a header subassembly according to aspects of the present invention;

FIG. 12B is a perspective view of an embodiment of a unitary set of barriers in accordance with aspects of the present invention;

FIG. 12C is a perspective view of an embodiment of a set of barriers formed from multiple segments in accordance with aspects of the present invention;

FIG. 13 is a perspective view of an embodiment of a header having a receiving chamber with arrows indicating a flow direction of water;

FIG. 14A is a top view of a head subassembly coupled to the shell of a heat exchanger in accordance with aspects of the present invention;

FIG. 14C is an enlarged view of a portion of the header subassembly of FIG. 14B.

FIG. 15 is a perspective view of a gasket in accordance with aspects of the present invention;

FIG. 16 is an exploded view of an embodiment of a non-circular heat exchanger in accordance with aspects of the present invention;

FIG. 17A is a top view of the non-circular heat exchanger of FIG. 16;

FIG. 17B is a cross-sectional, side view of the non-circular heat exchanger of FIG. 17A;

FIG. 18 is an embodiment of a refractory for a non-circular heat exchanger according to aspects of the present invention;

FIG. 19 is an embodiment of a refractory for an cylindrical heat exchanger in accordance with aspects of the present invention;

FIG. 20A is a perspective view of a condensate drain in accordance with aspects of the present invention;

FIG. 20B is a top view of the condensate drain of FIG. 20A;

FIG. 20C is a cross-sectional view of the condensate drain of FIG. 20B; and

FIG. 21A-24B depict configurations for a plurality of tubes with varying amounts of staggering between an outer set of tubes and an inner set of tubes in accordance with aspects of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A detailed description of various, non-limiting embodiments of the invention follows. Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.
Aspects of the present invention advantageously provide heat exchangers that are configured to be operable in both a condensing mode or a non-condensing mode. For example, heat exchangers according to aspects of this invention are configurable to operate in a condensing mode or in a non-condensing mode, depending on the preferences of the manufacturer or user of the heat exchanger. The heat exchangers can be configured by the manufacturer to operate in a condensing mode or in a non-condensing mode prior to shipment from the factory. Also, the heat exchangers can be configured by the installer to operate in a condensing mode or in a non-condensing mode after shipment from the factory but prior to use. Additionally, the heat exchangers can be configured by or for the user to operate in a condensing mode or in a non-condensing mode subsequent to use but before further use.
In another aspect of the present invention, provided are heat exchangers having a reduced size, while maintaining high rates of heat loading (e.g., heat exchange). For example, the heat exchangers can be provided with a smaller “footprint” to occupy less space, yet maintain high efficiency as needed.
In yet another aspect of the invention, commercial heat exchangers capable of entering through standard U.S. doorways are provided. For example, the heat exchangers can be provided with a smaller width to fit through smaller spaces as needed.
Referring generally to non-limiting exemplary embodiments selected for illustration in the figures, heat exchanger 100 includes a shell 110 at least partially defining an interior region 111. The heat exchanger 100 further includes a burner 120 that is positioned to deliver combustion gases into the interior region 111; a fuel supply such as mixture apparatus 122 in fluid communication with the burner 120; a controller 130 configured to control the fuel mixture apparatus 122 and a plurality of tubes 150 configured to circulate water therein. The plurality of tubes 150 extends through the interior region 111 and includes an inner set of tubes 152 and an outer set of tubes 154. The inner set of tubes 152 is closer to the burner 120 than the outer set of tubes 154. Baffle segments 160 are positioned in the interior region 111 adjacent the outer set of tubes 154. Adjacent baffle segments 160 define gaps 161 for the flow of the combustion gases outwardly relative to the outer set of tubes 154. Additionally, heat exchanger 100 also includes a condensate drain 140 positioned to receive condensate from the interior region 111. Preferably, heat exchanger 100 is configurable to operate in a condensing mode in which moisture condenses from the combustion gases or a non-condensing mode in which moisture does not condense from the combustion gases. The condensate drain 140 is coupled to receive condensate from the interior region 111 when the heat exchanger 100 is operated in the condensing mode. Additionally and/or alternatively, the heat exchanger 100 is configurable to operate in the condensing mode or in the non-condensing mode by adjusting the controller 130.
Referring specifically to FIG. 1, heat exchanger 100 includes a shell 110, a burner 120, a fuel mixture apparatus 122, a control 130, and a plurality of tubes 150.
Shell 110 is configured to at least partially define an interior region 111. Shell 110 is not limited to any particular geometrical shape, and thus, may be configured to form any shape that defines an interior region 111 suitable for the features of heat exchanger 100 positioned therein. For example, shell 110 may form a cylinder, an oval cylinder, a cube, a rectangular cube, a pyramid, etc.
Burner 120 is positioned to deliver combustion gases into the interior region 111 defined by shell 110. Although burner 120 is positioned within interior region 111 in FIG. 1, burner 120 may be positioned outside of interior region 111 while in combustion gas flow communication with interior region 111. Preferably, burner 120 is positioned along a longitudinal axis 116 of interior region 111, such as the central axis. Additionally or alternatively, burner 120 may be positioned in an end region 112 a or 112 b of interior region 111. In one embodiment, burner 120 extends from an end region 112 a or 112 b to a center portion 114 of interior region 111. Burner 120 is not particularly limited to any source of combustion material and, thus, may be configured to burn gas fuel, oil, coal, etc.
A fuel mixture apparatus 122 is coupled to be in fluid communication with burner 120. Fuel mixture apparatus 122 provides a fuel mixture of fuel and air/oxygen to burner 120. Fuel mixture apparatus 122 may be a fan, blower, or the like. Preferably, fuel mixture apparatus 122 provides a ratio of air to fuel that enables efficient combustion of the fuel mixture. In one embodiment, fuel mixture apparatus 122 forces air through a venturi, creating a pressure signal to a fuel gas regulator—and thus, as the fuel mixture apparatus 122 increases the delivery of fuel, the pressure changes, and the gas regulator adjusts the amount of fuel provided to the fuel mixture apparatus 122 to maintain the optimal mixture of fuel and air/oxygen in the fuel mixture and optimal energy input to burner 120.
A controller 130 is coupled to fuel mixture apparatus 122 to automatically regulate fuel mixture apparatus 122 and/or enable a user to manually adjust the amount of fuel mixture provided by fuel mixture apparatus 122. Controller 130 may be distinct from fuel mixture apparatus 122 or may be an integral part of fuel mixture apparatus 122, such that fuel mixture apparatus 122 is configured to regulate and/or adjust the amount of fuel mixture provided to burner 120.
Controller 130 is configured to place heat exchanger 100 in a condensing mode or in a non-condensing mode by adjusting and/or regulating fuel mixture apparatus 122. For example, controller 130 may direct fuel mixture apparatus 122 to increase or decrease an amount of fuel or fuel mixture provided to burner 120 to increase or decrease the generation of the combustion gases, thereby placing heat exchanger 100 in a condensing mode or a non-condensing mode. To place heat exchanger 100 in a condensing mode, controller 130 directs fuel mixture apparatus 122 to provide an amount of fuel mixture to burner 120 such that the temperature of the surface of the plurality of tubes 150 is below the dew point of the combustion gases. To place heat exchanger 100 in a non-condensing mode, controller 130 directs fuel mixture apparatus 122 to provide an amount of fuel mixture to burner 120 such that the temperature of the surface of the plurality of tubes 150 is above the dew point of the combustion gases, including potential venting materials.
Controller 130 may be configured to regulate and/or adjust fuel mixture apparatus 122 using a single stage process, a modulating process, and/or a multi-stage (step-modulation) process. Using a single stage process, controller 130 either activates fuel mixture apparatus 122 (e.g., directing fuel mixture apparatus 122 to provide a fixed amount and/or rate of fuel mixture to burner 120) or deactivates fuel mixture apparatus 122 (e.g., directing fuel mixture apparatus 122 not to provide fuel mixture to burner 120). The fixed amount of fuel mixture provided to burner 120 may be optimized in conjunction with the pressure drop though heat exchanger 100, the gap 161 between adjacent baffle segments 160 (further discussed below), and/or the plurality of tubes 150. Using a modulation process, controller 130 directs fuel mixture apparatus 122 to provide varying amounts of fuel mixture to burner 120 in response to data received regarding the heat exchanger and/or combustion gases, e.g., the temperature, pressure etc. Using a multi-stage process, controller 130 is configured to direct fuel mixture apparatus 122 to provide fuel mixture to burner 120 at two or more fixed amounts and/or rates. In one embodiment, controller 130 is configured to, during a condensing mode, operate heat exchanger 100 using a modulating process, and during a non-condensing mode, operate heat exchanger 100 using a single stage process.
Referring to FIGS. 1 and 20A-20C, heat exchanger 100 includes a condensate drain 140 positioned to receive condensate from interior region 111. Upon reading this disclosure, one of ordinary skill in the art will appreciate that various condensation drains and/or traps may be suitably employed to remove condensation from heat exchanger 100. Condensate drain 140 is coupled to receive condensate from interior region 111 when heat exchanger 100 is operated in a condensing mode. In one embodiment, condensate drain 140 is coupled to header 170. In another embodiment, condensate drain 140 is coupled to shell 110. Preferably, condensate drain 140 provides an air-lock and/or prevents combustion gases from leaking to the environment.
Referring to FIGS. 2A-2C, heat exchanger 100 also includes a plurality of tubes 150 configured to circulate water therein. The plurality of tubes 150 extends through interior region 111, e.g., from a first end region 112 a of interior region 111 to a second end region 112 b of interior region 111, which may be opposed the first end region 112 a. The plurality of tubes 150 is positioned annularly around burner 120. In one embodiment, the plurality of tubes 150 forms a single annular row of tubes. Preferably, each of the plurality of tubes 150 receives an approximately equal heat load such that, in one embodiment, each tube of the plurality of tubes 150 provides an approximately equal amount of heat exchange between the combustion gases in interior region 111 and the water circulating within the plurality of tubes 150. Additionally or alternatively, the plurality of tubes 150 may include fins, baffles, and/or other features therein that promote heat transfer and/or modify the flow of water circulating within the plurality of tubes 150.
The plurality of tubes 150 includes an inner set of tubes 152 and an outer set of tubes 154. The inner set of tubes 152 is closer to burner 120 than the outer set of tubes 154. The plurality of tubes 150 may be configured such that the water circulating through the inner set of tubes 152 flows in a similar or in a dissimilar direction as the water flowing through the outer set of tubes 154. For example, the water circulating in the plurality of tubes 150 may first travel through the inner set of tubes 152 in a first direction and subsequently travel through the outer set of tubes 154 in a second direction. Preferably, the inner set of tubes 152 and the outer set of tubes 154 have an approximately equal heat load.
Referring to FIGS. 3A and 3B, the inner set of tubes 152 and the outer set of tubes 154 are positioned adjacent to one another such that, e.g., the outer surface 156 of the inner set of tubes 152 is adjacent to the outer surface 158 of the outer set of tubes 154 and/or the fins extending from the outer surface 156 of the inner set of tubes 152 are adjacent to the fins extending from the outer surface 158 of the outer set of tubes 154. As illustrated in FIG. 3B, the outer surface 156 of the inner set of tubes 152 may buttress (e.g., may contact at various points along the tubes) the outer surface 158 of the outer set of tubes 154. In one embodiment, the clearance between outer surface 156 of the inner set of tubes 152 and outer surface 158 of the outer set of tubes 154 is less than 0.05 inches.
The outer set of tubes 154 is staggered from the inner set of tubes 152. By staggering the outer set of tubes from the inner set of tubes, more heat exchange can be achieved while limiting the distance between the plurality of tubes 150 and the burner 120, thereby minimizing the size and/or “foot print” of heat exchanger 100 while optimizing heat exchange. The staggered configuration may form an angle ϕ between two outer tubes and one inner tube and/or between two inner tubes and an outer tube. Referring to FIGS. 21A-24B, the angle D may be varied to decrease or increase the number of tubes in the plurality of tubes 150. The staggered configuration may form an angle ϕ that is between 180° and 15°. For example, the staggered configuration may preferably form an angle ϕ of between 160° and 20°; more preferably 140° and 25°; more preferably 120° and 30°; more preferably 100° and 35°, more preferably 80° and 40°; more preferably 70° and 45°; and more preferably between 60° and 50°. Preferably, the angle formed by the staggered configuration of the inner set of tubes 152 and the outer set of tubes 154 promotes an approximately equal heat loading of the inner set of tubes 152 and the outer set of tubes 154.
Baffle segments 160 are annularly positioned in the interior region 111 adjacent the plurality of tubes 150. Baffle segments 160 may be adjacent to one or more tubes of the plurality of tubes 150, e.g., one or more tubes of the outer set of tubes 154 and/or one or more tubes of the inner set of tubes 152. In one embodiment, baffle segments 160 extend from a position adjacent to a first tube of the outer set of tubes 154 to a position adjacent to a second tube of the outer set of tubes 154.
Baffle segments 160 have two end portions 164 a and 164 b and a middle portion 162 that extends therebetween. The end portions 164, or a segment thereof, may have a curvature that, e.g., conforms to the curvature of the adjacent tube of the plurality of tubes 150. In one embodiment, first end portion 164 a is positioned adjacent to a first tube of the outer set of tubes 154 and second end portion 164 b is positioned adjacent to a second tube of the outer set of tubes 154. Middle portion 162, or a segment thereof, may extend to be adjacent to a tube of the inner set of tubes 152.
Adjacent baffle segments 160 define gaps 161 for the flow of combustion gases. Gaps 161 may be configured to hinder and/or reduce the amount of combustion gasses flowing therethrough. The size of gaps 161 may be adjusted during manufacturing, during installment, or after use but before subsequent use. For example, the size of gaps 161 may be determined by selecting adjacent baffle segments 160 of a specific size. Additionally or alternatively, the size of gaps 161 may be adjusted after manufacture by way of reducing or enlarging the distance between the end portions 164 of adjacent baffle segments 160 defining the respective gap 161. Preferably, gaps 161 are configured such that the heat load of the plurality of tubes 150 (e.g. the amount of heat transferred from the combustion gasses to the water in the plurality of tubes 150) enables the adjustment of controller 130 and/or fuel mixture apparatus 122 to place heat exchanger 100 in a condensing mode or in non-condensing mode.
Referring to FIGS. 4-5B, 8-9B, and 13-14C one or more headers 170 are coupled to the shell 110 of heat exchanger 100. Header 170 and tube sheet 180 together define a cavity between header 170 and tube sheet 180. Tube sheet 180 is positioned at an end region 112 of shell 110 and coupled to the plurality of tubes 150.
Tube sheet 180 defines an inner set of apertures 181 in water flow communication with the inner set of tubes 152 and defines an outer set of apertures 183 in water flow communication with the outer set of tubes 154. Headers 170 may be configured to redirect water from one set of tubes 152 or 154 to the other set of tubes 152 or 154. Alternatively, one or more of the headers 170 may be employed to collect/disperse water from/into the plurality of tubes 150, e.g., in an embodiment where the water in both the first set of tubes 152 and the second set of tubes 154 flows from a first end of the plurality of tubes 150 to a second end of the plurality of tubes 150.
Referring to FIGS. 8-9B, header 170 may contain an inlet 171 and an outlet 173, as depicted in FIG. 9A, or may contain an inlet 171 on a first header 170 and an outlet 173 on a second header 170. Header 170 may be formed as a single unitary item. Header 170 may also contain one or more O-rings 178 to facilitate a seal between header 170 and tube sheet 180.
Referring to FIG. 13, header 270 is another embodiment that may be employed in a header subassembly of heat exchanger 100. Header 270 includes a receiving chamber 271 defining a receiving cavity for receiving incoming fluid to be heated from inlet 171. Preferably, the receiving chamber 271 forms the receiving cavity with a central portion 182 of tube sheet 180. In one embodiment, the central longitudinal axis (e.g., axis 116) of shell 110 aligns with a center of receiving chamber 271. In another embodiment, receiving chamber 271 is positioned to correspond to a section of tube sheet 180 located closest to burner 120. For example, by employing receiving chamber 271, the incoming fluid, received from inlet 171, removes the heat from central portion 182 of tube sheet 180 such that a refractory 190 is not required to protect central portion 182 of tube sheet 180 from the heat produced by burner 120.
Header 170 contains barriers 172 positioned within the cavity defined by header 170 and tube sheet 180 to direct water flow within the cavity, e.g., by redirecting water flow from one set of tubes 152 or 154 to another set of tubes 152 or 154. For example, barriers 172 may extend between apertures of the outer set of apertures 183 and apertures of the inner set of apertures 181. Although FIGS. 7A-7B and 11B-11C illustrate a configuration of barriers 172 within header 170 wherein each tube of the inner set of tubes 152 is in fluid communication with one tube from the outer set of tubes 154, in at least one embodiment, one or more tubes of the inner set of tubes 152 is in fluid communication with two or more tubes of the outer set of tubes 154, e.g. as illustrated in FIGS. 12B-12C.
Referring to FIGS. 6A-6C, barriers 172 may be integrally coupled together, e.g., to form one or more unitary segments. As seen in FIG. 6A, barriers 172 may be integrally connected to form one unitary segment. Alternatively, as seen in FIG. 6B, barriers 172 may be integrally coupled to form three segments, although in other embodiments more than or less than three unitary segments may be formed by the integrally connected barriers 172.
Referring to FIGS. 7A-7B, each of the barriers 172 may be positioned tangential to one of the apertures of the outer set of apertures 183 and tangential to one of the apertures of the inner set of apertures 181. Preferably, barriers 172 do not obstruct and/or hinder the water flow through the outer set of apertures 183 or the inner set of apertures 181. Preferably, barriers 172 are designed to optimize the flow (minimize pressure drop and equalize distribution) of water inside header 170 and the plurality of tubes 150, e.g., as illustrated in FIG. 10A-10B. Barriers 172 may be formed of a deformable material, such as plastics, rubbers, metals, etc., to facilitate a water tight seal between header 170 and tube sheet 180. Preferably, barriers 172 are formed of a material, e.g., polypropylene, that is deformed upon affixing header 170 to shell 110 and/or tube sheet 180. In one embodiment, barriers 172 are configured to define an indent 175, e.g., on the side of barrier 172 configured to buttress tube sheet 180. Indent 175 may, preferably, collapse upon deformation of barrier 172 to further facilitate formation of a seal between header 170 and tube sheet 180. In one embodiment, indent 175 is positioned above the attachment (e.g., welding) of the inner set of tubes 152 to the inner set of apertures 181 and/or the attachment (e.g., welding) of the outer set of tubes 154 to the outer set of apertures 183.
FIGS. 11A-11C illustrate another embodiment of a barrier 272 for use in header 170. Barrier 272 may be formed of one or more materials that are suitable for use with heated water, e.g., rubbers, metals, and plastics that can withstand hot liquids, such as water heated to up to 120° C. Barrier 272 may have an outer section 274 made of metal and an inner section 276 made of deformable rubber. Preferably, inner section 276 has a periphery 277 that extends past the periphery 275 of outer section 274 of barrier 272 such that, e.g., inner section 276 has a height H2 that is larger than the height H1 of outer section 274. In one embodiment, inner section 276 is formed of a deformable material, such as a rubber or plastic, to form a seal between header 170 and tube sheet 180 upon the coupling of header 170 to tube sheet 180 and/or shell 110.
FIGS. 12A-12C illustrate yet another embodiment of a barrier 372 for use in header 170. Barrier 372 may have a thickness T that is approximately equal to the distance between the inner set of apertures 181 and the outer set of apertures 183 of tube sheet 180. As seen in FIG. 12C, barriers 372 may be configured to form a seal with gasket 374. For example, barriers 372 may be affixed (e.g., welded) to one of tube sheet 180 or header 170 while gasket 374 may be affixed to the other of tube sheet 180 or header 170, such that coupling header 170 to tube sheet 180 and/or shell 110 forms a seal between barriers 372 and gasket 374. Gasket 374 contains a lip 376 for attachment to one of the tube sheet 180 or the header 170. Gasket 374 may also contain a receiving slot 375 to receive barriers 372, thereby forming a seal around a periphery 377 of barrier 372.
Referring to FIGS. 14A-14C, headers 170 include a shroud lip 174 that buttresses an inner surface 118 of shell 110. The shroud lip 174 may have a sealing surface 176 that may be affixed to or integrally part of the shroud lip 174. Sealing surface 176 may be formed of a material, such as silicone, to form an air tight seal against the inner surface 118 of shell 110, e.g., to contain the combustion gases within interior region 111.
Referring to FIGS. 16-19, heat exchanger 200 includes a non-circular configuration having a dimension in a first direction (e.g., length) that is different than a dimension in a second direction (e.g., width), the second direction being transverse to the first direction. Additionally or alternatively, the non-circular configuration of heat exchanger 200 may include a dimension in a third direction (e.g., height) that is different than the dimension in the first direction and/or the dimension in the second direction, the third direction being orthogonal to the first and second directions. Although heat exchanger 200 is illustrated in FIGS. 16-19 as having an oval configuration, in other embodiments of the present invention heat exchanger 200 may have, e.g., rectangular, diamond, trapezoidal, or other configurations forming geometrical shapes or, alternatively, non-geometrical shapes. One of skill in the art would understand based on the description herein that various configurations of heat exchanger 200 may be utilized without reducing the advantageous effects of the equal heat loading across each of the plurality of tubes 150.
Heat exchanger 200 has a length dimension L1, width dimension W1, and height dimension H3 that facilities transportation of heat exchanger 200 into buildings. The aspect ratio of heat exchanger 200, which is the length dimension L1 multiplied by the width dimensions W1 and multiplied by the height dimension H3, is preferably optimized to provide the desired amount of heat loading and/or thermal output. Thus, to reduce the width dimension W1 of heat exchanger 200, while keeping the aspect ratio the same, the length dimension L1 and/or the height dimension H3 of heat exchanger 200 may be increased. Similarly, if the height dimension H3 and/or the width dimension W1 of heat exchanger 200 is to be reduced, the other dimensions of the aspect ratio may be increased to retain the same heat loading and/or thermal output. Additionally or alternatively, if the aspect ratio of heat exchanger 200 is reduced, the heat loading and/or thermal output may be maintained by modifying the configuration of the plurality of tubes 150, the gaps 161 defined by baffle segments 160, and/or other features as disclosed herein.
Preferably, heat exchanger 200 has a width dimension W1 and height dimension H3 configured to be less than the dimensions of a U.S. standard door, e.g., less than seven feet in height and less than three feet in width. Additionally or alternatively, shell 110 may have a non-circular configuration, such as an oval configuration that defines an oval interior region 111.
Preferably, burner 120 is positioned vertically within interior region 111. The plurality of tubes 150 may also be positioned in a vertical configuration annularly around burner 120 to form a non-circular (e.g., an oval, as illustrated in FIG. 16) configuration. For example, the plurality of tubes 150 may extend vertically through the oval interior region 111 from bottom region 112 a or 112 b to top region 112 a or 112 b.
Preferably, each of the plurality of tubes 150 receives approximately an equal amount of heat loading from the combustion gases within the non-circular interior region 111. Heat loading may be approximately equal among each of the plurality of tubes 150 by way of adjusting the flow rates and/or firing rates. Additionally and/or alternatively, gaps 161 defined by baffle segments 160 may be sized such that combustion air more readily passes by tubes that are closer to burner 120 to promote approximately equal heat loading among each of the plurality of tubes 150. Additionally, the angle D produced by staggering the outer set of tubes 154 and the inner set of tubes 152 may be optimized to provide approximately equal heat loading to each tube of the plurality of tubes 150 by way of accounting for the variation in the proximity of each tube to burner 120 (which affects radiant heat exchangers) and the gaps 161 defined by adjacent baffle segments 160 (which affects heat exchange by way of conduction).
Heat exchanger 200 includes a refractory 290 that is formed from one or more segments, e.g., segments 292 a and 292 b. The segments 292 of refractory 290 may be affixed together to form refectory 290. Although refractory segments 292 a and 292 b are configured to be ship-lapped together, refractory segments 292 may have other matting surfaces, which are not directly exposed to burner 120 such as, e.g., angled, beveled, grooved, or similar matting surfaces.
Preferably, each segment 292 of the refractory 290 is configured to fit through the opening 291 for burner 120. For example, as illustrated in FIG. 19, refectory segment 292 a may be inserted into interior region 111 by inserting refectory segment 292 a sideways through the opening 291. One or more retention clips 294 (e.g., corkscrews) may be inserted through one or more segments of refractory 290 to secure refractory 290 to tube sheet 180. The retention clips 294 may be formed of a wire capable of withstanding high temperatures. Preferably the retention clips 294 are in the shape of a corkscrew (e.g., retaining screw with course thread), and may enter through a hole in tube sheet 180 to penetrate refractory 290, thereby holding refractory 290 securely against the tube sheet 180.
According to one aspect of the present invention, heat exchangers, e.g., 100 and/or 200, are operable in a condensing mode in which moisture condenses from the combustion gases or a non-condensing mode in which moisture does not condense from the combustion gases. Heat exchangers 100 and/or 200 may be configurable to operate in the condensing mode or in the non-condensing mode by adjusting controller 130 and/or fuel mixture apparatus 122, by adjusting gaps 161 defined between adjacent baffle segments 160, or by adjusting controller and/or fuel mixture apparatus 122 and adjusting gaps 161 defined between adjacent baffle segments 160. The gaps 161, the controller 130, and/or the fuel mixture apparatus 122 may be adjusted during factory production, during installation, or after use but before subsequent use to place heat exchanger 100 and/or 200 in either a condensing or a non-condensing mode. For example, controller 130 may be adjusted (e.g., adjusting the firmware/programming of an electronic controller) to change the amount of fuel mixture provided by the fuel mixture apparatus 122 and/or to change the process employed by controller 130 to control and/or regulate fuel mixture apparatus 122, e.g., single process, multi-stage (step modulating) or modulation.
Heat exchanger 100 and/or 200 are constructed from materials resistant to high temperatures and above atmospheric pressures, thereby facilitating a long life expectancy (e.g., >20 yrs) for heat exchanger 100 and/or 200. For example, in contrast to typical non-condensing heat exchangers, which may be made from high-carbon steel or cast iron that cannot resist the corrosive effects of condensate, heat exchanger 100 and/or 200, or portions thereof, are preferably constructed of stainless steel that resists the corrosive effects of acidic condensate.
The water and gas openings may be configured to reduce the pressure drop through heat exchanger 100 and/or 200, which may allow for minimal energy usage related to moving the water or gasses within heat exchanger 100 and/or 200. Preferably, heat exchanger 100 and/or 200 is oriented vertically, thereby enabling condensate to drain and be collected by way of gravity, but other orientations are also contemplated and the condensate drain can be positioned or repositioned accordingly.
Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.

Claims

What is claimed:

1. A heat exchanger for heating water, the heat exchanger comprising:

a shell at least partially defining an interior region;

a burner positioned to deliver combustion gases into the interior region;

a fuel supply configured to supply fuel to the burner;

a controller configured to control the fuel supply;

a plurality of tubes configured to circulate water therein, the plurality of tubes extending through the interior region, the plurality of tubes including an inner set of tubes and an outer set of tubes, the inner set of tubes being closer to the burner than the outer set of tubes; baffle segments positioned in the interior region adjacent the outer set of tubes, adjacent baffle segments defining gaps for the flow of the combustion gases outwardly relative to the outer set of tubes; and

a condensate drain positioned to receive condensate from the interior region;

wherein the heat exchanger is configurable to operate in a condensing mode in which moisture condenses from the combustion gases or a non-condensing mode in which moisture does not condense from the combustion gases;

wherein the condensate drain is coupled to receive condensate from the interior region when the heat exchanger is operated in the condensing mode; and

wherein the heat exchanger is configurable to operate in the condensing mode or in the non-condensing mode by adjusting the controller.

2. The heat exchanger of claim 1, wherein the controller is configurable to:

during the condensing mode, operate the heat exchanger using a modulating process, and

during the non-condensing mode, operate the heat exchanger using a single stage process.

3. The heat exchanger of claim 1, wherein the baffle segments extend between two or more of the outer set of tubes.

4. The heat exchanger of claim 1, wherein when the heat exchanger is operating in a non-condensing mode, the controller activates or deactivates the fuel supply to provide a set amount of fuel mixture to the burner.

5. The heat exchanger of claim 4, wherein the controller modulates an amount of the fuel or fuel mixture provided by the fuel supply to the burner when the heat exchanger is operating in the condensing mode.

6. The heat exchanger of claim 1, wherein the heat exchanger is configurable to operate in the condensing mode or in the non-condensing mode by adjusting the controller, by adjusting the gaps defined between adjacent baffle segments, or by adjusting the controller and adjusting the gaps defined between adjacent baffle segments.

7. A heat exchanger for heating water, the heat exchanger comprising:

a non-circular shell at least partially defining an interior region;

a burner positioned to deliver combustion gases into the interior region;

a plurality of tubes configured to circulate water therein, the plurality of tubes extending through the interior region, the plurality of tubes including an inner set of tubes and an outer set of tubes, the inner set of tubes being closer to the burner than the outer set of tubes;

baffle segments positioned in the interior region adjacent the outer set of tubes, adjacent baffle segments defining gaps for the flow of the combustion gases outwardly relative to the outer set of tubes.

8. The heat exchanger of claim 7, wherein the non-circular shell defines an oval interior region having a top region and a bottom region.

9. The heat exchanger of claim 8, wherein the plurality of tubes extends vertically through the oval interior region from the bottom region to the top region.

10. The heat exchanger of claim 7, wherein each of the plurality of tubes receives approximately an equal amount of heat loading from the combustion gases within the oval interior region.

11. A heat exchanger for heating water, the heat exchanger comprising:

a shell at least partially defining an interior region;

a burner positioned to deliver combustion gases into the interior region;

the inner set of tubes and the outer set of tubes being positioned adjacent to one another such that the outer set of tubes is staggered from the inner set of tubes and tubes of the outer set of tubes are adjacent to tubes of the inner set of tubes; and

baffle segments annularly positioned in the interior region adjacent the plurality of tubes, adjacent baffle segments defining gaps for the flow of the combustion gases.

12. The heat exchanger of claim 11, wherein the plurality of tubes forms a single annular row of tubes.

13. A heat exchanger for heating water, the heat exchanger comprising:

a shell at least partially defining an interior region;

a burner positioned to deliver combustion gases into the interior region;

baffle segments annularly positioned in the interior region adjacent the outer set of tubes, adjacent baffle segments defining gaps for the flow of the combustion gases outwardly relative to the outer set of tubes;

a tube sheet positioned at an end region of the shell, the tube sheet being coupled to the plurality of tubes; and

a header coupled to the shell, the header and the tube sheet together defining a cavity between the header and the tube sheet, the tube sheet further defining an inner set of apertures in water flow communication with the inner set of tubes and defining an outer set of apertures in water flow communication with the outer set of tubes.

14. The heat exchanger of claim 13, wherein the header further includes barriers extending between apertures of the outer set of apertures and apertures of the inner set of apertures.

15. The heat exchanger of claim 14, wherein each of the barriers is positioned tangential to one of the apertures of the outer set of apertures and tangential to one of the apertures of the inner set of apertures.

16. The heat exchanger of claim 13, wherein the barriers are deformed between the header and the tube sheet, upon affixing the header to the shell.

17. The heat exchanger of claim 13, wherein the header is formed of a single unitary material.

18. The heat exchanger of claim 1, wherein the controller is integrated into the fuel supply.

19. The heat exchanger of claim 1, wherein the controller is separate from and coupled to the fuel supply.