US3726258A

US3726258A - Fin heat exchanger

Info

Publication number: US3726258A
Application number: US00190094A
Authority: US
Inventors: H Reichmann; G Rottmann
Original assignee: Vaillant GmbH
Current assignee: Vaillant GmbH
Priority date: 1970-11-04
Filing date: 1971-10-18
Publication date: 1973-04-10
Anticipated expiration: 1990-04-10
Also published as: ES199992U; BE774428A; NL7114851A; ES199992Y; NL156812B; FR2112438B1; FR2112438A1

Abstract

A plurality of iron tubes are positioned horizontal, parallel and across the top of a combustion chamber. An outer frame holds the tubes and directs the products of combustion about the outer side of the tubes. The interiors of the tubes are connected in series. The tubes are rectangular in cross-section. The first and last tubes of the series have their outer sides abutting and welded to adjacent sides of the frame. On these first and last tubes there are fins extending about only the top and the sides opposite said outer sides. Said fins are welded to the tube and to the frame. On the intermediate tubes there are fins extending about only the vertical sides and top sides of the tubes and being welded thereto.

Description

e 1 ilmte States Patent 1191 1111 3,726,258 Reichmann et al. Apr. 10, 1973 54] FIN HEAT EXCHANGER 780,565 1 1905 Humphrey ..122/367 [75] Inventors: Horst Reichmann, Wuppertal-El- "12233; beffeld; Rtlttmann, Wermel- 1,593,984 7/1926 Murray ..122/235 sklrchen, both of Germany 2,877,000 3/1959 Person ..165/130 x 73 A h. V ill t KG sslgnee Jo a an Primary Examinerl(enneth W. Sprague [22] Filed: Oct. 18, 1971 Attorney-Darbo et al. [21] -Appl.No.: 190,094 ABSTRACT A plurality of iron tubes are positioned horizontal, [30] Foreign Apphcanon Pnonty Data parallel and across the top of a combustion chamber. Apr. 8, 1971 Germany ..P 21 17 222.9 An u r fram h lds the tubes and directs the Nov. 4, 1970 Austria .9940/70 Products of Combustion about the Outer Side Of the tubes. The interiors of the tubes are connected in se- 52 US. Cl. 122/250 R, 122/367 c ries- The tubes are rectangular in eresseeetien- The [51] zz 27/06 first and last tubes of the series have their outer sides 58 Field of Search 122/235 236 250 abutting and Welded to adjacent sides 0f the frame 122/367. 165/136 these first and last tubes there are fins extending about only the top and the sides opposite said outer sides Said fins are welded to the tube and to the frame. On [56] References cued the intermediate tubes there are fins extending about UNITED STATES PATENTS only the vertical sides and top sides of the tubes and being welded thereto. 1,8l2,l98 6/1931 Clayton ..l22/367 X 3,388,692 6/1968 Hale ..,.122/367 7 Claims, 9 Drawing Figures /8 I 7 5 7 8 '4 I 9 5444/ y 1 9 V v 72 s s P7771 n '77) n 77-; [X 7776 73 1e 5' S 711 I z 22 75 20 t 2143 L l PATENTED 3.726258 SHEET 1 OF 3 Fig. 2

GEKNOT FOTTMANN IN V EN TORS FIN HEAT EXCI-IANGER BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to a fin type heat exchanger of rectangular or square shape as seen in a plan view. It comprises a plurality of finned tubes positioned parallel in a common plane. The tubes are connected with each other to form a conduit through which the water being heated flows. The finned tubes are mounted in and enclosed by a sheet metal frame which, throughout its circumference, is in heat-conducting communication with the fin tubes.

The prior art includes fin type heat exchangers which are enclosed by a sheet metal frame (German Pat. application H 1 1,023 X/36e), the frame sections through which the tubes pass being cooled by the tubes soldered to them. The sections of the frame parallel to the fin tubes transmit their heat to the ends of the fin sections of the fin body connected with them for heat conduction as by welding. Moreover, downwardly they merge with the combustion compartment of the gas-heated continuous-flow heater cooled by the heat exchanger coil. The heat exchanger coil is capable of absorbing part of the heat from the sections of the frame parallel to the tin tubes. Nonetheless, in this prior arrangement heat transfer conditions are unfavorable.

Moreover, gas-heated continuous-flow heaters, respectively continuous-flow heaters, have become prior art, which latter operate with an oil gasification burner, and in which the fin body closes off a combustion compartment which iscooled on the outside by the air of combustion passed therepast and does not carry a heat exchanger coil.

It is an object of this invention, in a fin heat exchanger of the type indicated hereinbefore, to improve the heat transfer conditions at the sections of the frame parallel to the fin tubes. According to the invention, this object is attained by forming the fin tubes so as to have a cross-section of upright rectangular configuration and by directly connecting these sections of the frame which are parallel to the fin tubes with the outer side walls of the two outer fin tubes.

The embodiment of the invention is particularly advantageous if the frame 'of the fin block extends downwardly like a cap and is placed on the upper rim of a combustion compartment cooled by the air of combustion directed therepast by a blower. The cap type extension of the frame directs the heating gas (products of combustion) to the fin body. The heat absorbed by the cap is transferred to the water in the tubes. From the frame sections through which the fin tubes are passed, the heat can flow to the water through the welded joint between frame and fin tubes. From the sections of the frame parallel to the fin tubes, according to the invention, the heat is transferred to the fin tubes through the shortest possible path in that these frame sections are in fiat heat-conducting communication with the likewise flat outer sides of the two outer fin tubes. This provision is made because the hitherto common end sections of the fins protruding relative to the outer fin tubes and enclosing these tubes, cannot transfer the great heat volume absorbed by the cap additionally to the outer fin tube through their end edges, as in the prior arrangement heating gases still flow through between the frame and the last fin tube and these fin areas are heated anyhow by the heating gas.

Advantageously, the fin of the outer fin tubes fit only about the upper and free side of the tube and the rim of that portion of the fin which extends over the fin tube is connected with the frame and the top side of the fin tube as by welding. The fins of the intermediate tubes have rectangular recesses so that they fit on the fin tubes from above, and the fins extend as far downwardly as the bottom edge of the fin tubes. These fins are connected with the respective tubes as by weldmg.

Another possibility of designing a fin body of the type indicated is to assemble the fin block in unit construction principle from single tube-fin sections and/or double tube-fin sections as well as from single tubeor double tube-end tube-fin sections with tubes terminating on one side with a fin edge. Then, different fin heat exchanger types can be manufactured from standard parts while maintaining the advantageous basic design according to the invention. Thereby, the manufacture and stock keeping is simplified.

A convector is known per se comprising fin blocks including several tubes arranged in one plane in juxtaposed relationship and connected with each other through which the heating water flows, the fin blocks being assembled from single tubeand double tube-fin sections. However, the fin tubes do not have an upright rectangular cross-section and the tin blocks do not have a frame which is directly connected with the outer side walls of the outer fin tubes. It is also not the point to transfer hat to a liquid flowing in the fin tubes. Hence, according to the invention another construction element is added, namely an end fin tube section with a tube terminating on one side with a fin edge.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical section through the fin body of an embodiment of the invention;

FIG. 2 is a top or plan view of the embodiment of FIG. 1;

FIG. 3 is a vertical section through the fin block of another embodiment;

FIG. 4 is a plan view of the fin block of FIG. 3;

FIG. 5 is a section through a single tube-f'm component forming an intermediate tube;

FIG. 6 is a section through a double tube-fm component forming an intermediate tube;

FIG. 7 is a section through a single tube-fin component forming an end tube;

FIG. 8 is a section through a double tube-fin component forming an end tube; and

FIG. 9 is a longitudinal section through a fin tube of a fin block with frame section and its enlargement.

DESCRIPTION OF SPECIFIC EMBODIMENTS The following disclosure is offered for public dissemination in return for the grant of a patent. Although it is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvements. The claims at the end hereof are intended as the chief aid toward this purpose, as it is these that meet the requirement of pointing out the parts, improvements, or combinations in which the inventive concepts are found.

The fin tubes 1 of rectangular cross-section are positioned parallel, in juxtaposed relationship and in a common horizontal plane. The tubes are connected with each other by elbows 2 to form a conduit from an inlet connection 3 to a discharge connection 4. At inlet 3, the water to be heated enters and after being heated it discharges through the connection 4. The tubes 1 are equipped with fins 5. The fins have slots extending upwardly from their bottom edges with tongues 6 between the slots. The slots are of a size to receive the tubes 1. Thus, in effect, the fins are fitted down over the top of the tubes with a part of the fin above the tubes and tongues 6 extending between the tubes. The fins abut the narrow sides 1 of the tubes at the top as at 7. The fins are welded to the tubes. The term welding is used herein to include the procedures sometimes referred to as soldering and brazing. The upper outer ends 8 of the fins fit about the tops of the two outer fin tubes and terminate coplanar with the outer flat sides 9 of the outer fin tubes.

The fin block (formed by the assembly of the tubes 1 and the fins is surrounded by a rectangular sheet metal frame 10. The frame 10 has two opposed sides 11 through which the fin tubes 1 pass. These sides 11 are in heat-conducting communication with the fin tubes as by means of welded joints. The other two frame sides 12 are in face-to-face contact with the flat sides 9 of the outer two fin tubes and are welded to the latter. lso, the ends 8 of the fins 5 are welded to the frame sides 9.

The rectangular frame 10 extends downwardly and becomes annular. Thus it is enlarged as at 13 beyond the centers of the frame sections and reduced in the area of the frame comers 14 (see FIG. 2). The annular bearing rim 15 thus formed is supported upon an annular upper rim 16 of a casing 17 with the interposition of a seal 18. The inner wall 19 defining a combustion compartment is cooled by the incoming air of combustion flowing in on all sides thereof to the burner of the heater. Thus, the inner wall 19 is surrounded by two

concentric walls

20 and 17 so as to define two outer

annular channels

21 and 23 closed by an annular cap 22. Through the use of a blower 24, the air flows upwardly in channel 21 and after returns downwardly through annular channel 23 and is supplied to the burner (not shown) in the combustion chamber.

Thus, the

walls

17, 19, 20, 22 define a housing about the combustion chamber which housing has air passageways about the outside of the chamber through which air flows to cool the walls. The cap l0, 13 serves the function to direct the heating gases (products of combustion) from the cylindrical combustion chamber through the rectangular fin block. Due to the abutment of the frame sides 12 with the outer tubes, the heat absorbed by the

cap

10, 13 can be directly transmitted to the outer fin tubes through the shortest possible path. This avoids an overheating of the frame. For use in an oil-heated water heater the fin block and frame is advantageously made of sheet iron. The lifetime of such a fin block and frame exceeds by a multiple that of a fin block made from copper. In the combustion of oil the sulphur proportion is about 10 times the amount occurring in the combustion of petroleum derived gases. Sheet iron is sulphur-resistant as compared to copper.

In FIG. 3 the fin block is assembled from the single, intermediate tube-fin sections 31 and single, end tubefin sections 32. The tube-fin section 31 (see also FIG. 5) is comprised of a fin tube 33 rectangular in crosssection and having fins 34 mounted thereon. The tubefin sections 32 (see also FIG. 7) are identical to each other and are comprised of the fin tube 33 and the end fins 35. The upper outer ends 36 of the fins 35 fit over the inner and top sides of the outer fin tubes and terminate coplanar with the outer fiat sides 37 of the tubes. The fin block is enclosed by a

sheet metal frame

38, 39. The fin tubes 33 pass through the two sides 39 of the frame. These sides 39 are in heat-conducting communication with the fin tubes as by welding. The other two frame sides 38 of the frame abut the fiat sides 37 of the outer fin tubes 33 and are welded to the same. Also, the ends 36 of the end fins 35 are welded to the frame sections 38. The

rectangular frame

38, 39 extends downwardly and becomes annular, i.e. it is enlarged beyond the centers of the frame sides 38 and 39 as at 40 and reduced in the area of the frame comers 41 (see FIG. 4). The bearing rim 42 thus formed serves for placement on an annular upper rim of a cylindrical sheet metal housing (not shown) enclosing the combustion chamber.

The cold water, or in a heating system the return flow water, is introduced at the tube fitting 43 and the hot water (of a domestic water tap or a heating circuit supply) discharged through the fitting 44. Thus, a passageway is formed through the tubes from inlet 43 to outlet 44. To this end, the fin tubes can be connected in pairs by caps 46, whereby the water flowing therethrough is directed from the one fin tube to the other adjacent fin tube. The caps 46 are connected with the frame sections 39 (as by welding) for this purpose. lnstead of two caps 46, one cap 47 can be used. This is welded to the frame sections 39 similarly to the caps 46. It encloses a guide plate 48 which serves to direct the water flow from one tube to the adjacent tube.

According to the invention, fin blocks of different widths can be assembled from fin tube sections. By way of example, two intermediate fin tubes can be formed in pairs as double tube-fin sections (see FIG. 6). Here, the fins 45 fit about the adjacent two tubes and are welded thereto. Likewise, according to FIG. 8, the end tube (one or both) can be joined with the first adjacent intermediate tube to form a double end-tube fin section.

With a single tube cross-section and with four fin shapes, fin blocks of different widths and, using longer tubes. of any desired length can be assembled. Such fin blocks are likewise suitable for combustion chambers of rectangular cross-section.

In FIG. 9 the tube 33 closely extends through the frame side 39 (which fits closely thereabout) and terminates in the cap 47. The guide plate 48 serves to direct the water from one tube to the next. The guide plate 48 need not fully seal the guide path of the water relative to the inner wall of the cap. The frame side 39 extends downwardly into the enlargement 40 which forms the bearing rim 42 to rest upon the jacket of the combustion chamber (not shown). Fuel gas collecting hood 49 is mounted on the upper rim of the frame for discharge of the fuel gases.

We claim:

1. In a heat exchanger comprising a series of generally parallel tubes communicating with each other, said tubes being elongated with the length of said tubes being substantially in excess of their transverse cross-sectional dimensions, said tubes having fins positioned transversely to said length, a sheet metal frame for directing a heated fluid across said finned tubes, said frame having sides in heat-conducting communication with said finned tubes, the improvement comprismg:

said tubes being rectangular in transverse cross-section, one of said sides of said frame being immediately adjacent the first of said series of tubes and being directly connected thereto, and another of said sides of said frame being immediately adjacent the last of said series of tubes and being directly connected thereto.

2. In a heat exchanger comprising a series of generally parallel tubes communicating with each other, said tubes having fins, a sheet metal frame for directing a heated fluid across said finned tubes, said frame having sides in heat-conducting communication with said finned tubes, the improvement comprising:

said tubes being rectangular in transverse cross-section, one of said sides of said frame being immediately adjacent the first of said series of tubes and being directly connected thereto, and another of said sides of said frame being immediately adjacent the last of said series of tubes and being directly connected thereto, said one side being in face-to-face contact with a side of said first tube and is welded thereto, and said other side is in face-to-face contact with a side of said last tube and is welded thereto.

3. In a heat exchanger as set forth in claim 2, wherein said frame being in the form of a cap with a downwardly extending rim.

4. The combination of a heat exchanger as set forth in claim 3 and a housing defining a combustion chamber, said housing having an upper edge, said cap being seated on said upper edge, said housing having peripheral walls with air passageways thereto leading to the point of combustion, and a blower connected to cause an air flow through said passageways to said point for the purpose of cooling said walls.

5. In a heat exchanger comprising a series of generally parallel tubes communicating with each other, said tubes having fins, a sheet metal frame for directing a heated fluid across said finned tubes, said frame having sides in heat-conducting communication with said finned tubes, the improvement comprising:

said tubes being rectangular in transverse cross-section, one of said sides of said frame being immediately adjacent the first of said series of tubes and being directly connected thereto, and another of said sides of said frame being immediately adjacent the last of said series of tubes and being directly connected thereto, said tubes having two vertical sides and two horizontal sides, the fins of the two outside tubes of said series fitting about only one vertical and the top horizontal sides of said tubes and being welded to the sides of the frame adjacent thereto and being welded to the 6. iii zfh eat exchanger as set forth in claim 5, wherein the fins of the intermediate tubes of said series fit about only the top and the two vertical sides of said intermediate tubes and are welded thereto.

7. In a heat exchanger as set forth in claim 1, wherein said tubes, said fins and said frame are iron.

* =0 III l

Claims

1. In a heat exchanger comprising a series of generally parallel tubes communicating with each other, said tubes being elongated with the length of said tubes being substantially in excess of their transverse cross-sectional dimensions, said tubes having fins positioned transversely to said length, a sheet metal frame for directing a heated fluid across said finned tubes, said frame having sides in heat-conducting communication with said finned tubes, the improvement comprising: said tubes being rectangular in transverse cross-section, one of said sides of said frame being immediately adjacent the first of said series of tubes and being directly connected thereto, and another of said sides of said frame being immediately adjacent the last of said series of tubes and being directly connected thereto.

2. In a heat exchanger comprising a series of generally parallel tubes communicating with each other, said tubes having fins, a sheet metal frame for directing a heated fluid across said finned tubes, said frame having sides in heat-conducting communication with said finned tubes, the improvement comprising: said tubes being rectangular in transverse cross-section, one of said sides of said frame being immediately adjacent the first of said series of tubEs and being directly connected thereto, and another of said sides of said frame being immediately adjacent the last of said series of tubes and being directly connected thereto, said one side being in face-to-face contact with a side of said first tube and is welded thereto, and said other side is in face-to-face contact with a side of said last tube and is welded thereto.

5. In a heat exchanger comprising a series of generally parallel tubes communicating with each other, said tubes having fins, a sheet metal frame for directing a heated fluid across said finned tubes, said frame having sides in heat-conducting communication with said finned tubes, the improvement comprising: said tubes being rectangular in transverse cross-section, one of said sides of said frame being immediately adjacent the first of said series of tubes and being directly connected thereto, and another of said sides of said frame being immediately adjacent the last of said series of tubes and being directly connected thereto, said tubes having two vertical sides and two horizontal sides, the fins of the two outside tubes of said series fitting about only one vertical and the top horizontal sides of said tubes and being welded to the sides of the frame adjacent thereto and being welded to the tubes.

6. In a heat exchanger as set forth in claim 5, wherein the fins of the intermediate tubes of said series fit about only the top and the two vertical sides of said intermediate tubes and are welded thereto.