US3662736A - Heat exchange structure for a hot air heater - Google Patents

Abstract

A heat exchange structure for an air heater furnace wherein the cross-over port structure from the first stage of a heat exchanger is an elongated rectangular inlet into the second stage of the heat exchanger, which has a number of spaced flanges therein for guiding the flow of the products of combustion more evenly in their passage to the outlet of the second stage.

Description

United States Patent Tyson et al.

[451 May 16, 1972 HEAT EXCHANGE STRUCTURE FOR A HOT AIR HEATER Thomas L. Tyson; Edward G. Craze, Jr., both of Richmond, Va.

Assignee: Texaco Inc., New York, NY.

Filed: June 1, 1970 Appl. No.2 42,366

Inventors:

US. Cl. ..l26/9l R, 126/106, 126/110 R, 165/155 Int. Cl. ..F24c 3/00, F24h 3/06 FieldofSearch... ..126/90,91, 110, 1108, 116,

References Cited UNITED STATES PATENTS Parrish ..126/110 X 1,334,039 3/1920 Lape ..126/116 2,263,098 11/1941 Muel1er.. ....126/110 3,151,673 10/1964 Strache ....l26/116X FOREIGN PATENTS OR APPLICATIONS 875,975 8/1961 Great Britain ..126/1 10 B Primary ExaminerCharles .1. Myhre Attorney-Thomas H. Whaley and Carl G. Rets [5 7] ABSTRACT A heat exchange structure for an air heater furnace wherein the cross-over portstructure, from the first stage of a heat exchanger is an elongated rectangular inlet into the second stage of the heat exchanger, which has a number of spaced flanges therein for guiding the flow of the products of combustion more evenly in their passage to the outlet of the second stage.

6 Claims, 8 Drawing Figures PATENTEUW 16 m2 SHEET 1 [IF 4 P'A'TENTEnnAY 16 I972 SHEET 2 BF 4 HEAT EXCHANGE STRUCTURE FOR A HOT AIR HEATER BACKGROUND OF THE INVENTION This invention relates generally to hot-air furnace heaters, and particularly to a novel heat exchange structure therefor, prior to venting the combustion products to the exterior.

Hot-air furnaces are used widely in modern homes. Conventionally, such furnaces include a burner gun assembly firing into a combustionchamber which is joined to some form of radiating means for heating air and which serves as a flue for the discharge of the products of combustion. The radiating means provides a circuitous flow of the hot products of combustion so that a two-stage heat exchanger is suited ideally for heating the air. The air to be heated is provided to a distribution conduit which is spaced around the combustion chamber and radiating means, and adjacent thelatter, forms a plenum or distributing space for the ducts leading the heated air to the desired points of reception. Improvements in hot air furnace construction generally are directed to an increase in the efficiency of combustion and/or heat transfer for more even heat distribution and to lower the temperature of the discharged products of combustion.

SUMMARY OF THE INVENTION The invention in general providesfor a more effective heat transfer structure whereby the hot products of combustion are distributed more evenly over the extent of the radiating means or heat exchange surfaces by means of flow dividers therein, which are parallel to the normal gas flow, so that the complexity of the gas flow is minimized. Thus, the pressure loss in the flow passages is not increased materially. Concomitant with the use of the flow dividers is the use of a novel cross-over port structure to aid in the distribution of the products of combustion in the radiating means.

Further, the exterior wall structural member or outside panel of the second stage of the heat exchange surfaces opposite the cross-over port structure between the primary and secondary stages of the heat exchanger is provided with concentric corrugations to overcome the unequal heating and expansion of the panel in this area.

Accordingly, it is an overall object of this invention to provide for more effective heat transfer in a hot-air furnace.

Another object is to provide for a more efficient heat exchanger construction.

These and other objects, advantages and features of the invention will become more apparent from the following description taken in conjunction with, the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an exposed side view of the furnace assembly with the heat exchanger shown in full outline;

FIG. 2 is an isometric view, partly in section, showing the novel construction of the heat exchanger;

FIG. 3 is a view, partly in section, of the outside panel of the heat exchanger opposite the cross-over port structure;

FIG. 4 is a cross section taken along lines 4-4 of FIG. 3 showing the flow of the flue gases or products of combustion;

FIG.5 is a view showing a support channel between the two stages of the heat exchanger taken along line 5-5 of FIG. 4;

FIG. 6 is a view, partly in section, of the clean-out hole panel of the heat exchanger;

FIG. 7 is a partial section view taken along line 7-7 of FIG. 6 showing the cross-over port structure; and

FIG. 8 is a partial cross section of the corrugated panel of the heat exchanger taken along line 8-8 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIG. 1 of the drawings, a hot-air furnace cabinet assembly is disclosed at 1, comprising the air intake section 2 with the air blower assembly 3, and a control assembly at 4, positioned therein. The air distributing conduit 5 leads from the air intake section 2 and surrounds the combustion chamber 6 and the radiating means or heat exchange construction 10, the latter being a two-stage heat exchanger which is joined to the combustion chamber by V-band clamp means 9.

A burner gun assembly 7 fires into the combustion chamber 6 and supports the fuel pump assembly and combustion air blower 8 thereon.

The heat exchanger '10 comprises the first stage 11 having the transition portion lla where the bottom cylindrical structure, which is connected to the circular combustion chamber 6, is changed to a rectangular structure having a closed top 11b; and the second stage of the exchanger is shown at 12.

Referring specifically to FIG. 2, partially in section, the two stages of a heat exchanger are shown disclosing the manner in which the cross-over port structure and the support flanges hold the two stages together. The cross-over port structure at 13 is a substantially rectangular vertical inlet into the second stage for the products of combustion leaving the first stage and is flared outwardly to join the inside wall of the second stage, as disclosed best in FIG. 7. The outlet from the second stage is disclosed as circular at 14 leading to flue 15 (see FIG. 1). This outlet connection and flanges on the opposite panel joined to the cabinet wall (not shown) support the heat exchanger in the cabinet. An inspection door and control air bleed is at 16, shown more completely in FIG. 1, and clean-out ports are disclosed at 17, the covers therefor having been omitted for clarity in FIG. 2, but are shown figuratively at 17a in FIG. 6.

The directing flanges 18 are generally parallel to the flow of the products of combustion from the inlet 13 to the outlet 14, these flanges being spaced to provide equal or proportional volumes in the second stage as desired and having bent directional portions at 180 adjacent inlet 13 for directing the flow in a controlled manner around the second stage, and are also bent adjacent outlet 14 at 18b. In addition to the flared cross-over port structure at 13, support flanges at 19, one only being shown atthecut-away section, and in cross section in FIG. 5, are used to hold the two stages together. Centrally located, heat expansion corrugations in the panel opposite the cross-over port structure are shown at 20 (also see FIG. 8), these being concentric and having dimensions such that the outer corrugation has a diameter larger than the length of the cross-over port structure or inlet 13, as shown in FIG. 3, to

' compensate for any unequal heat distribution patterns resulting from the flow out of the cross-over port structure.

FIGS. 3 and 4 disclose the interior spacing or inside passage 21 between the first and second stages of the heat exchanger. The proportions of this spacing between these stages and that between the exchanger and the cabinet wherein the pumped air is exposed to the heat of the combustion gases in the furnace can be determined by experiment, and likewise the extent of the surface areas of the heat exchanger, the passages and surfaces being chosen in accordance with heating requirements.

In FIG. 4, the full .arrows disclose the passage of the products of combustion upward from the combustion chamber into the first stage, the flow of somebeing reversed by the top 11b ofthe first stage to join the outward flow along with the other products of combustion into the cross-over port structure at 13, and the dashed arrows show the flow between the directing flanges in the second stage toward the outlet 14.

Thus, there has been shown and described how an improved heat exchange structure can be used in a heater to more evenly distribute hot products of combustion to result in an overall increase in heat exchange efficiency to provide for better heating of air and a lowering of flue gas temperatures.

Other modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the'appended claims.

Iclairn:

l. in the combination defining a heater construction for providing heated air and including combustion means, a heat exchanger structure comprising wall members defining a pair of concentrically spaced, interconnected heat exchange chambers, the first or inner of said chambers being connected to the combustion chamber of said combustion means and receiving hot products of combustion directly therefrom, the second or outer of said chambers being joined to the first heat exchange chamber by a cross-over port structure defining an inlet thereinto for receiving said products of combustion from said inner of said chambers, and an outlet located in the exterior wall of said outer of said chambers opposite the exterior wall thereof adjacent said inlet for the discharge of said products of combustion from the second heat exchange chamber, said cross-over port structure being substantially rectangular in configuration and extending vertically at the junction between said chambers whereby the flow of said products of combustion into said second heat exchange chamber is more widely distributed adjacent said inlet and itself provides additional heat exchange surface.

2, In the combination as defined in claim 1, said second chamber having a plurality of flow divider flange strips extending from adjacent said inlet to adjacent said outlet for controlled guidance of the flow of said products of combustion therebetween.

3. In the combination as defined in claim 2, said flange strips being substantially parallel to the normal flow of said products of combustion in said second chamber to minimize the complexity of said flow therein and to keep the pressure loss at a minimum.

4. In the combination as defined in claim 3, the wall member defining the exterior wall of said second heat exchange chamber adjacent said cross-over port structure having a corrugated surface to compensate for unequal heat transfer thereto, said port structure being flared outwardly from said first chamber to its junction with said second chamber.

5. In the combination as defined in claim 4, said surface having a pair of concentric corrugations centered on said wall member, the outer corrugation thereon having a diameter greater than the length of said port structure.

6. In the combination as defined in claim 3, the spacing between said chambers of said heat exchanger structure and the surface areas of said chambers being determined by air heating requirements.

Claims (6)

1. In the combination defining a heater construction for providing heated air and including combustion means, a heat exchanger structure comprising wall members defining a pair of concentrically spaced, interconnected heat exchange chambers, the first or inner of said chambers being connected to the combustion chamber of said combustion means and receiving hot products of combustion directly therefrom, the second or outer of said chambers being joined to the first heat exchange chamber by a cross-over port structure defining an inlet thereinto for receiving said products of combustion from said inner of said chambers, and an outlet located in the exterior wall of said outer of said chambers opposite the exterior wall thereof adjacent said inlet for the discharge of said products of combustion from the second heat exchange chamber, said cross-over port structure being substantially rectangular in configuration and extending vertically at the junction between said chambers whereby the flow of said products of combustion into said second heat exchange chamber is more widely distributed adjacent said inlet and itself provides additional heat exchange surface.

2. In the combination as defined in claim 1, said second chamber having a plurality of flow divider flange strips extending from adjacent said inlet to adjacent said outlet for controlled guidance of the flow of said products of combustion therebetween.

3. In the combination as defined in claim 2, said flange strips being substantially parallel to the normal flow of said products of combustion in said second chamber to minimize the complexity of said flow therein and to keep the pressure loss at a minimum.

4. In the combination as defined in claim 3, the wall member defining the exterior wall of said second heat exchange chamber adjacent said cross-over port structure having a corrugated surface to compensate for unequal heat transfer thereto, said port structure being flared outwardly from said first chamber to its junction with said second chamber.

5. In the combination as defined in claim 4, said surface having a pair of concentric corrugations centered on said wall member, the outer corrugation thereon having a diameter greater than the length of said port structure.

6. In the combination as defined in claim 3, the spacing between said chambers of said heat exchanger structure and the surface areas of said chambers being determined by air heating requirements.

Images