US20120192812A1

US20120192812A1 - Water heater with counter-twisted baffle

Info

Publication number: US20120192812A1
Application number: US13/015,790
Authority: US
Inventors: Ramin K. Rahmani; George W. Kraus; Roger D. Veen; Stephen J. Werfel; J. Eric Arnold; John L. Dreher
Original assignee: AO Smith Corp
Current assignee: AO Smith Corp
Priority date: 2011-01-28
Filing date: 2011-01-28
Publication date: 2012-08-02
Also published as: CA2765514A1

Abstract

A water heater including a storage tank, a combustion chamber, a burner for producing products of combustion, the burner positioned in the combustion chamber, a flue extending from the combustion chamber through the storage tank, and a baffle positioned within the flue and directing the flow of the products of combustion through the flue. The baffle includes multiple clockwise twist segments and multiple counterclockwise twist segments.

Description

BACKGROUND OF THE INVENTION

The present invention relates to water heaters, and more particularly to water heaters including flue baffles.
A flue baffle is positioned in the flue tube of a gas-fired water heater. A burner combusts a fuel and air mixture to create products of combustion or exhaust gases. The gases flow through the flue tube to heat the water stored in a tank. The baffle enhances the heat exchange rate between the gases and the water stored in the tank.

SUMMARY OF THE INVENTION

The present invention provides, in one aspect, a water heater including a storage tank, a combustion chamber, a burner for producing products of combustion, the burner positioned in the combustion chamber, a flue extending from the combustion chamber through the storage tank, and a baffle positioned within the flue and directing the flow of the products of combustion through the flue. The baffle includes multiple clockwise twist segments and multiple counterclockwise twist segments.
The present invention provides, in another aspect, a baffle for use in the flue of a water heater to direct the flow of products of combustion through the flue. The baffle includes multiple clockwise twist segments and multiple counterclockwise twist segments.
Other features and aspects of the invention will become apparent by consideration of the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a water heater.

FIG. 2 is a perspective view of a baffle of the water heater of FIG. 1.

FIG. 3 is a front view of the baffle of FIG. 2.

FIG. 4 is a side view of a portion of a sheet used to form the baffle of FIG. 1.

FIG. 5 is a front view of a second embodiment of a baffle.

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

DETAILED DESCRIPTION

FIG. 1 illustrates a water heater 100 including a base pan 105, a tank 110 supported by the base pan 105 and containing water, an insulating jacket 115 surrounding the tank 110, and a burner 120. A flammable fuel is provided to the burner 120 by a fuel inlet 125 connected to a fuel valve 130. The burner 120 is positioned in a combustion chamber 135 beneath the tank 110. The fuel valve 130 is connected to a fuel supply. The fuel can be, for example, natural gas or propane. The combustion chamber 135 is connected to an air supply, for example, the atmosphere around the water heater 100. A flue tube 140 extends from the combustion chamber 135 through the tank 110. The flue tube 140 includes a central longitudinal axis 145. The products of combustion or exhaust gases created by the burner 120 flow through the flue tube 140 to heat the water stored in the tank 110. A cold water inlet pipe 150 supplies cold water to the tank 110. A hot water supply pipe 155 supplies hot water to an end-use location, for example, a faucet. The water heater 100 as described above is conventional.
As shown in FIG. 1, a baffle 160 is positioned within the flue tube 140. A hanger or cross-bar 165 supports and positions the baffle 160 within the flue tube 140. In some embodiments, other suitable means are used to support and position the baffle 160 within the flue tube 140. The baffle 160 extends longitudinally within the flue tube 140. Preferably, a central longitudinal axis 170 of the baffle 160 is collinear with the longitudinal axis 145 of the flue tube 140. The baffle 160 is positioned within the flue tube 140 to leave a space 172 between the lower end of the baffle 160 and the lower end of the flue tube 140. The space 172 facilitates mounting the flue tube 140 and baffle 160 on a glass coating machine that coats the inside and outside of the flue tube 140 and the baffle 160 with a protective coating to resist degradation or corrosion of the flue tube 140 and baffle 160. Also, the space 172 makes the baffle 160 less likely to be overheated by extreme temperatures in the combustion chamber 135. The space 172 can be, for example, about three inches (7.62 centimeters) in length but such length may vary based on manufacturing parameters. In other embodiments, the lower end of the baffle 160 is flush with the lower end of the flue tube 140.
As shown in FIGS. 2-3, the baffle 160 includes six clockwise twist segments or twists 175 and six counterclockwise twist segments or twists 180 that alternate with each other along the longitudinal axis 170 of the baffle 160 so that each clockwise twist 175 is adjacent to a counterclockwise twist 180. A substantially flat or planar spacer 190 is positioned between each adjacent clockwise twist 175 and counterclockwise twist 180. Each spacer 190 is positioned in a vertical plane that includes the longitudinal axis 170. The length of each spacer 190 along the longitudinal axis 170 can vary as necessary. Preferably, the length of a spacer is 0.36 inches (0.91 centimeters). Preferably, each clockwise twist 175 is a one hundred eighty degree twist and each counterclockwise twist 180 is a one hundred eighty degree twist. That is, a sheet or plate 195 is twisted clockwise one hundred eighty degrees about the longitudinal axis 170 to form a clockwise twist 175 and then the same sheet is twisted counterclockwise one hundred eighty degrees about the longitudinal axis 170 to form a counterclockwise twist 180. The length of each clockwise twist 175 along the longitudinal axis 170 is substantially the same and the length of each counterclockwise twist 180 along the longitudinal axis 170 is substantially the same. In some embodiments, each clockwise twist 175 is twisted more or less than one hundred eighty degrees and each counterclockwise twist 180 is twisted more or less than one hundred eighty degrees. For example, each twist 175 and 180 could be twisted ninety degrees or three hundred sixty degrees. More or fewer twists 175 and 180 can be included as necessary. Preferably, the baffle has a diameter of 3.625 inches (9.207 centimeters) and an overall length of 45.25 inches (114.9 centimeters), the length along the longitudinal axis 170 of each of the twists 175 and 180 is between three inches (7.62 centimeters) and six inches (15.24 centimeters), and the flue tube 140 has a diameter of four inches (10.16 centimeters). In some embodiments, a spacer 190 is not positioned between each adjacent clockwise twist 175 and counterclockwise twist 180. In other embodiments, the spacer 190 is corrugated.
As shown in FIGS. 1-3, the baffle 160 is corrugated. FIG. 4 shows a side view of a portion of the sheet 195 used to form the baffle 160 before the sheet 195 is twisted. The sheet 195 includes an alternating series of peaks 200 and valleys 205 that form the corrugations. Alternatively, the baffle 160 is manufactured from a substantially flat or planar sheet or plate. The sheet 195 can be manufactured of mild (i.e., low carbon) steel, stainless steel, Inconel®, nickel alloy, or other suitable materials. For example, the baffle 160 can be cold formed from a steel sheet 195. However, cold forming a steel sheet 195 limits how short of a twist length can be formed for each of the twists 175 and 180. It is to be understood that other processes and/or methods of processing a material to form the baffle 160 fall within the scope of the invention. For example, the clockwise twists 175 and the counterclockwise twists 180 can be formed individually and then secured together, for example, by welding, brazing, or soldering.
FIG. 5 shows an alternative baffle 360 similar to the baffle 160. Components similar to those of the baffle 160 described above are numbered in a similar fashion plus two hundred. The baffle 360 has a varying pitch so that the length of at least one of the clockwise twists 375 along the longitudinal axis 370 varies with respect to the length of a different one of the clockwise twists 375 and so that the length of at least one of the counterclockwise twists 380 along the longitudinal axis 370 varies with respect to the length of a different one of the counterclockwise twists 380. The baffle 360 includes three groups 210, 215, and 220 of twists 375 and 380. In the first group 210, the lengths of each of the clockwise twists 375 and the counterclockwise twists 380 are a first length. In the second group 215, the lengths of each of the clockwise twists 375 and the counterclockwise twists 380 are a second length different than the first length. In the third group 220, the lengths of each of the clockwise twists 375 and the counterclockwise twists 380 are a third length different than both the second length and the first length. Preferably, the first length is three inches (7.62 centimeters), the second length is four inches (10.16 centimeters), and the third length is five inches (12.7 centimeters). More or fewer groups of twists 375 and 380 of the same length can be used as necessary. The number of twists 375 and 380 in a group can vary and a group can consist of a single twist 375 or 380.
In use, the burner 120 combusts a fuel and air mixture to create products of combustion or exhaust gases. The gases exit the combustion chamber 135 and enter the lower end of the flue tube 140. As the gases encounter the baffle 160, the gases are directed in a circuitous path along the alternating clockwise twists 175 and counterclockwise twists 180. The alternating clockwise twists 175 and counterclockwise twists 180 create tangential and radial movement of the gases which increases both the amount of contact between the gases and the wall of the flue tube 140 and the turbulent kinetic energy of the gases. These in turn increase the heat transfer rate between the gases and the water stored in the tank 110. Additionally, the twists 175 and 180 increase the residence time of the gases within the flue tube 140, which also increases the heat transfer rate. The corrugations of the baffle 160 improve the radiative heat transfer when compared to a non-corrugated baffle. Also, the corrugations increase the amount of turbulent flow in the gases, which increases the convective heat transfer when compared to a non-corrugated baffle. Enhancing the heat transfer rate between the gases and the water stored in the tank 110 improves the energy factor (EF) of the water heater 100. The baffle 160 with alternating clockwise twists 175 and counterclockwise twists 180 significantly increases the heat transfer rate as compared to a baffle with twists all in the same direction. Shorter twist lengths, which result in more twists 175 and 180 for a baffle 160 of a certain length, provide the most heat transfer enhancement. However, the pressure drop caused by the baffle 160 along the flue tube 140 increases as the twists lengths decrease. The baffle 360 with twists 375 and 380 of varying lengths helps to optimize the heat transfer rate in relation to the pressure drop. Also, the length of the spacers 190, 390 can be varied to assist in optimizing the heat transfer rate in relation to the pressure drop. Various features of the invention are set forth in the following claims.

Claims

1. A water heater, comprising:

a storage tank;

a combustion chamber;

a burner for producing products of combustion, the burner positioned in the combustion chamber;

a flue extending from the combustion chamber through the storage tank; and

a baffle positioned within the flue and directing the flow of the products of combustion through the flue, the baffle including a plurality of clockwise twist segments and a plurality of counterclockwise twist segments.

2. The water heater of claim 1 wherein the baffle further includes a longitudinal axis and wherein the clockwise twist segments alternate with the counterclockwise twist segments along the longitudinal axis.

3. The water heater of claim 1 wherein each of the clockwise twist segments twists one hundred eighty degrees and wherein each of the counterclockwise twist segments twists one hundred eighty degrees.

4. The water heater of claim 1 wherein the baffle is corrugated.

5. The water heater of claim 1 wherein the baffle further includes a longitudinal axis and wherein the length along the longitudinal axis of at least one of the clockwise twist segments varies with respect to the other clockwise twist segments and wherein the length along the longitudinal axis of at least one of the counterclockwise twist segments varies with respect to the other counterclockwise twist segments.

6. The water heater of claim 2 wherein each of the clockwise twist segments twists one hundred eighty degrees and wherein each of the counterclockwise twist segments twists one hundred eighty degrees.

7. The water heater of claim 6 wherein the baffle is corrugated.

8. The water heater of claim 7 wherein the length along the longitudinal axis of at least one of the clockwise twist segments varies with respect to the other clockwise twist segments and wherein the length along the longitudinal axis of at least one of the counterclockwise twist segments varies with respect to the other counterclockwise twist segments.

9. The water heater of claim 6 wherein the length along the longitudinal axis of at least one of the clockwise twist segments varies with respect to the other clockwise twist segments and wherein the length along the longitudinal axis of at least one of the counterclockwise twist segments varies with respect to the other counterclockwise twist segments.

10. The water of claim 9 wherein a spacer is positioned between an adjacent clockwise twist segment and counterclockwise twist segment, wherein the clockwise twist segments are corrugated, and wherein the counterclockwise twist segments are corrugated.

11. The water heater of claim 2 wherein the baffle is corrugated.

12. The water heater of claim 2 wherein the length along the longitudinal axis of at least one of the clockwise twist segments varies with respect to the other clockwise twist segments and wherein the length along the longitudinal axis of at least one of the counterclockwise twist segments varies with respect to the other counterclockwise twist segments.

13. The water heater of claim 2 wherein a spacer is positioned between an adjacent clockwise twist segment and counterclockwise twist segment.

14. The water heater of claim 13 wherein the clockwise twist segments are corrugated and wherein the counterclockwise twist segments are corrugated.

15. A baffle for use in the flue of a water heater to direct the flow of products of combustion through the flue, the baffle comprising:

a plurality of clockwise twist segments;

and a plurality of counterclockwise twist segments.

16. The baffle of claim 15, the baffle further comprising a longitudinal axis and wherein the clockwise twist segments alternate with the counterclockwise twist segments along the longitudinal axis.

17. The baffle of claim 16 wherein each of the clockwise twist segments twists one hundred eighty degrees and wherein each of the counterclockwise twist segments twists one hundred eighty degrees.

18. The baffle of claim 15 wherein each of the clockwise twist segments twists one hundred eighty degrees and wherein each of the counterclockwise twist segments twists one hundred eighty degrees.

19. The baffle of claim 15 wherein the baffle is corrugated.

20. The baffle of claim 15 the baffle further comprising a longitudinal axis and wherein the length along the longitudinal axis of at least one of the clockwise twist segments varies with respect to the other clockwise twist segments and wherein the length along the longitudinal axis of at least one of the counterclockwise twist segments varies with respect to the other counterclockwise twist segments.