Miniature Heat Exchangers

Abstract

Covers a heat exchanger for use in a boiler or other heating system. The heat exchanger includes one or more boiler sections each having a passage for water or for any other fluid medium, each passage extending vertically throughout the section. One of the walls of each water passage section has a plurality of closely arranged laterally protruding fins formed integrally with the wall of the water passage. The heat exchanger may also be provided with two such sections each equipped with a like plurality of closely arranged laterally protruding fins. The two sections may be arranged opposite each other so that the fins of the two sections extend toward each other. One or more horizontally disposed burners may be positioned below the fins and supplied with gas for heating the fins and the inner walls of the water passages.

Description

This invention relates to boilers such as are employed in central heating systems. The invention also relates to heat exchange elements for incorporation in such boilers.

In our co-pending patent application, Ser. No. 167,763, filed July 30, 1971, of which the present application is a continuation in part, there is disclosed, in or for a boiler, a heat exchange element comprising a boiler section having a passage for water or other fluid medium, extending longitudinally of the boiler section and formed with a multiplicity of parallel flat laterally, protruding fins which, in the assembled boiler, will be located above horizontally disposed burners of the boiler.

In accordance with the present invention, the boiler section may be of tubular form and vertically disposed, and the laterally protruding fins may be arranged either on the outside or on the inside of the tubular section.

The present invention also provides, in or for a boiler, a heat exchange element comprising a vertical section having a passage for water or other fluid medium, extending along the section and provided externally with laterally protruding fins, said fins being disposed at one side only of the section. The latter section may be arranged opposite another similar horizontal section so that the fins of the two horizontal sections extend towards one another, the arrangement providing a boiler assembly of a miniaturized form in which the passages or waterways of the two sections are disposed at the outer sides of the miniaturized boiler so as effectively to form a so-called "wet-sided" heat exchanger.

The heat exchanger may comprise two or more of said horizontal or vertical sections and such sections may be arranged either in series or in parallel to increase the overall heating capacity or the overall heat transmitting capacity of the heat exchanger.

The present invention further provides for a heat exchanger as herein described, or as described in our aforementioned co-pending patent application, and a fan may be provided, if desired, for introducing combustion air or, alternatively, for removing combustion products. Also, the fins may have a lateral extent of about 11/2 to 21/2 times the width of the water passage or waterway, and a mean thickness of about one-sixth to one-tenth the width of the passage or waterway.

For a better and clearer understanding of the invention, embodiments thereof will now be described, merely by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a vertical sectional view schematically illustrating diagrammatically some of the essentials of a boiler incorporating a heat exchanger according to one embodiment of the invention;

FIG. 2 illustrates schematically the principal elements of a boiler employing vertical cylindrical sections intended for domestic hot water central heating installations;

FIG. 3 schematically illustrates another embodiment employing flat waterways in the heat exchanger elements, and;

FIG. 3A represents a cross sectional view of the elements of the boiler of FIG. 3, taken along the line 3A--3A of FIG. 3.

Referring to FIG. 1, the illustrated schematical embodiment comprises a cast-iron boiler section 1 which is of coaxial tubular form and substantially vertically disposed, the boiler section 1 including an annular passage having radially inner and outer walls 3, 4 and forming the waterway 2 of the boiler section 1. In use, the section 1 is intended to be arranged with its waterway extending substantially vertically and is accordingly herein referred to as a vertical section.

The inner and outer walls 3, 4 of the waterway 2 are substantially cylindrical and concentric in form and the outer wall 4 is cast integrally with a plurality of radially arranged outwardly extending flat fins 5, the outwardly extending fins 5 extending over substantially the whole height of the boiler section 1 and being spaced circumferentially and substantially at equal radial angles one from another. The fins 5 are relatively closely spaced so as to provide large heat conducting surfaces.

The heat exchanger just described is mounted in a cylindrical casing 6 surrounding but positioned above a gas burner 7, the latter burner 7 being of circular form of a diameter commensurate with the outer rim of the radial fins 5. The burner is provided with numerous jets 8 located below the finned part of the heat exchanger. The casing 6 has a base part 9 having a circumferential wall formed with louvred openings or inlets 10 for receiving air for the gas combustion. The upper part of the casing 6, i.e., the part above the louvred inlets 10 which surrounds the heat exchanger element 1 and the gas burner 7, incorporates heat insulating material 11 for minimizing heat losses.

The annular forms of the heat exchanger and of the gas burner 7 may provide a central or axial cylindrical space in which may be located gas control means indicated generally at 12, for controlling the supply of gas to the burner 7.

The outer casing 6 is preferably open at its upper end and is so arranged that flue gases, after flowing upwardly over the finned heat exchanger, can pass from the casing 6 through a suitable collector hood to a diverter and thence to a flue outlet (not shown).

As in the boiler sections disclosed in our aforementioned co-pending patent application, pump means (not shown) may be provided for forcing water through the water passage 2 to provide a continuous flow of water under pressure through the water passage of the heat exchanger.

The embodiment illustrated in FIG. 2 schematically illustrates a boiler which may be specially suitable for use in domestic hot water central heating installations. The boiler comprises a cast iron section indicated generally at 15 and having an annular or concentric waterway 16 defined by and positioned between inner and outer cylindrical or concentric walls 17, 18. The section 15 is vertically disposed and its inner wall 17 thereof is formed integrally with a series or plurality of equal radially inwardly directed flat fins 18a. Within the boiler section 15, there is arranged at the bottom thereof an annular gas burner 19. Below the gas burner 19, there is provided control means 20 for the supply and control of gas to the gas burner 19, the control means 20 being mounted in a base part 21 of the boiler casing. The cylindrical wall of the base part 21 is provided with louvred openings 22 through which air will be admitted to flow to the burner 19 to aid in the gas combustion.

The radially inner vertical edges of the fins 18a of FIG. 2 define an open tubular passage 23, and the lower edges 24 of the fins 18a are preferably inclined downwardly and radially outwardly to provide a funnel-like entry into the open central tubular passage 23.

In operation, the hot gases from the burner 19 are confined by the cylindrical inner wall 17 of the heat exchanger, the gases passing upwardly and over the surfaces of all of the circumferentially spaced radial fins 18a, whereby heat is extracted from the gases by the fins 18a and the extracted heat is conducted to the vertical waterway 16 for the heating of the water therein as it passes through the vertical waterway 16.

In the described embodiments of FIGS. 1 and 2, the boiler sections may be enclosed within a cylindrical outer casing, and this feature is schematically shown in FIG. 1. In FIG. 1, the outer casing may also be arranged to enclose the insulation 11. In FIG. 2, however, the coaxial or tubular waterway 16 forms in effect a so-called "wet-sided" heat exchanger so that the boiler section has a relatively cool outer wall. Accordingly, the outer casing, such as casing 11 of FIG. 1, may be fitted close to the outer cylindrical wall 18 and additional heat insulation may be obviated. This can effect a real structural,manufacturing and financial saving.

The further embodiment of FIG. 3 schematically illustrates a boiler comprising two substantially flat cast-iron heat exchange sections 26, 27 disposed in face-to-face relation. Each of these sections 26, 27 has a longitudinally extending and vertical elongated waterway 28, each waterway 28 being defined by inner and outer side walls 29, 30, each of these two sections being of substantially rectangular form and thus substantially equivalent to the vertically elongated waterways provided in the constructions disclosed in our aforementioned co-pending patent application. The inner walls 29 of each boiler section 26, 27 is cast integrally with flat parallel laterally projecting fins 31, these being closely spaced from one another along the boiler section. The lower edges 33 of the fins are preferably inclined laterally outwardly and downwardly from the inner edges of the fins 31. The fins 31 may be positioned at any angle to the inner walls 29, but they are preferably perpendicular to the inner wall.

A linear gas burner 34 extends medially between the two sections 26, 27 so that, during operation, hot gases from the burner 34 will pass upwardly and over the surfaces of the fins 31 so that the fins 31 will conduct heat to the water traversing path 28 between walls 29, 30. Control means 35 for the supply of gas to the gas burner 34 may be arranged below the burner 34. Alternatively, the control means 35 may be arranged to one side of the boiler section as indicated by dotted lines 36.

The arrangement of the two sections 26, 27 provides effectively a "wet-sided" heat exchanger, thereby eliminating, as in the embodiment of FIG. 2, the necessity for extensive heat insulation of the outer side walls 30. The gas flue passages are bound and confined by the inner walls 29 through which the hot gases from the burner 34 pass upwardly for discharge to the outlet. Means may be provided at the top of the boiler sections for deflecting the flue gases through a suitable collector hood to a conventional diverter for discharge through a conventional chimney outlet.

The arrangement shown in FIG. 3 is particularly convenient and suitable for incorporation in a combined gas-fire and boiler unit, the boiler sections together with the associated gas burner, or burners, and the control means therefor, all being disposed behind the gas-fire, for fitting into a fireplace opening.

In each of the aforedescribed embodiments, pump means (not shown) may be provided for forcing water through the boiler sections. Any number of sections may be joined together in series or parallel relationship. In operation, the pump ensures a continuous flow of water under pressure through the several sections and the heat-exchange surfaces provided by the multiplicity of closely arranged fins serves to ensure satisfactory heating of the water.

As in the embodiments disclosed in our co-pending Patent Application, the construction shown, for example, in FIGS. 3 and 3A has fins which extend over substantially the whole vertical height of the waterways, and the relative dimensions of the fins and waterways, including the spacings, reinforcements, saw-cuts or gaps, etc., may be as specified or described in our co-pending application. In particular, the constructions of our co-pending application and also the construction shown in the accompanying FIG. 3 of the present application, may have fins which at the, or each, side of the waterway, have a lateral extent of 11/2 to 21/2 times the width of the waterway and a mean thickness of each fin may be about one-sixth to one-tenth times the width of the waterway. Moreover, the constructions of the co-pending application and those described above, may have the heating capacity thereof increased, as already noted, by employing a number of sections, these being arranged either in series or in parallel relationship.

While the constructions shown in FIGS. 1 to 3 of this application include vertical waterways and vertically arranged flat fins, horizontal sections of equivalent constructions may be provided and organized, if desired. The arrangement of FIG. 3 of the present invention may employ, for example, horizontal flat waterways and horizontal flat juxtaposed fins, and a corresponding similar gas burner positioned beneath the fins.

While this invention has been shown and described in certain particular arrangements merely for illustration and explanation and while certain particular dimensions and proportions have been recited for aiding in understanding the significant parameters of the miniaturized heat exchange elements of this invention and of the boiler in which such elements may be embodied, it should be clearly understood that this invention may be embodied in other and widely varied organizations without departing from the spirit and scope of this invention.

Claims

What is claimed is:

1. A heat exchange structure for a boiler or the like, comprising a cylindrical water passage having two spaced inner and outer coaxial walls between which water is to be transmitted so as to be raised in temperature, and a plurality of substantially flat closely and uniformly spaced metallic fins integrally formed with the outer wall of the water passage and protruding radially from said outer wall and extending along said outer wall substantially throughout its length, the metallic fins being directly exposed to heated gases for transmitting heat to the water within the water passage.

2. A heat exchange structure according to claim 1, including means for transmitting water through said passage, and a burner having its jets positioned beneath the fins for supplying heat directly to the fins, such heat to be conducted by the fins to the water within said passage.

3. A heat exchange structure according to claim 2 in which the fins are integrally formed with the outer wall of the water passage and extending for a distance short of the jets of the burner.

4. A heat exchange structure according to claim 2 in which the fins are integrally formed with the outer wall of the water passage and are positioned at substantially equal angles from the axis of the water passage.

5. A heat exchange structure according to claim 3 in which the water passage and its fins are vertically oriented and the burner is positioned so that its jets are beneath the fins but within heating range of the fins.

6. A heat exchange structure according to claim 4 in which the water passage and its fins are vertically oriented and the fins are within heating range of the burner and reach to positions closely adjacent to the outer wall of the structure.

7. A heat exchange structure according to claim 5 including an exterior casing of insulating material coaxially arranged about the coaxial walls of the water passage and closely adjacent the outer wall.

8. A heat exchange structure for a boiler or the like according to claim 6 including a casing of insulating material coaxially arranged about the outer tips of the fins and embodying louvred air inlets.

9. A heat exchange structure for a boiler or the like comprising two spaced substantially equal parallel flat substantially vertical water passages each having two substantially vertical walls between which water may flow, each of the walls facing each other and having a plurality of parallel heat conducting continuous fins substantially perpendicular to said walls, the outermost walls of the two water passages forming the external walls terminating the structure, said fins extending substantially throughout the vertical length of said waterways, the sides of said fins farthest from said walls being spaced from each other so as to form a flue space directly exposed to the heated flue gases.

10. A heat exchange structure according to claim 9 including a burner positioned beneath said fins for supplying to said fins heat to be conducted to the respective water passages.

11. A heat exchange structure according to claim 10 including also a casing of insulation enclosing said water passages and positioned closely adjacent to the outer walls of said water passages.

12. A heat exchange structure according to claim 11 in which each of the fins has a substantially horizontal upper edge and each of the fins has its lower edge at a substantial predetermined angle with respect to the horizontal plane.

13. A heat exchange structure according to claim 12 including pumping means for pressurizing the water to be fed into the water passages.

14. A heat exchange structure according to claim 13 in which the burner is linearly aligned substantially midway between and parallel to the two water passages.

15. A heat exchange structure according to claim 14 in which the casing of insulation includes louvred openings to admit air for adding fuel combustion.

16. A boiler comprising two parallel linear water passages each of which is formed between two linear substantially equal walls, the adjacent walls of the two water passages each having a plurality of flat continuous parallel closely spaced fins integrally formed with the respective adjacent inner walls of the water passages and perpendicularly oriented with respect to said adjacent walls, the fins of one inner wall being pointed toward the fins of the adjacent inner wall, a burner having its jets positioned beneath the fins and aligned so as to be located midway between the walls of the two water passages, an insulated casing fitted about the walls of the two water passages and the burner, said casing having louvered openings to receive air for aiding fuel combustion.

17. A boiler according to claim 16 including a plurality of pairs of water passages coupled to each other and having integrally formed fins as specified in claim 16.