GB2307037A

GB2307037A - Heat exchanger baffle element

Info

Publication number: GB2307037A
Application number: GB9522751A
Authority: GB
Inventors: Roy Bratley
Original assignee: CARADON IDEAL Ltd
Current assignee: CARADON IDEAL Ltd
Priority date: 1995-11-07
Filing date: 1995-11-07
Publication date: 1997-05-14
Anticipated expiration: 2015-11-07
Also published as: GB9522751D0; GB2307037B

Abstract

A baffle (1) for use with a heat exchanger, having a passage (16) for the flow of hot gases, is formed from a flat metal sheet by appropriate piercing and pressing operations and has a number of rows of baffle elements (3) which protrude from the plane of the baffle to project between heat exchange fins (14) when the baffle is mounted in the passage. The baffle elements increase the turbulence of the gases in the upper part of the passages, and thus increase the efficiency of the heat exchanger.

Description

HEAT EXCHANGER BAFFLE This invention relates to baffles for use with heat exchangers, and is mainly concerned with baffles for use with heat exchangers for domestic gas boilers.

A known form of heat exchanger has upright passages, through which hot combustion gases from a burner flow, in heat exchange relationship with horizontal conduits through which flows a fluid, namely water, to be heated. A plurality of parallel heat exchange fins are located in the passages and extend longitudinally of the passage to increase the efficiency of the heat exchange between the gas and the fluid.

It is known to increase the heat output of such a known heat exchanger by using a powered flue, i.e. a fan to assist the gas flow, and baffles inserted downwardly into the upper ends of the passages and having a number of horizontal fingers projecting laterally between the heat exchange fins. The baffle fingers increase the turbulence of the gases in the upper part of the passages, and it has been found that the use of such baffles can increase the output of the heat exchanger by as much as one third without loss of efficiency.

However, with ever increasing demands for a reduction in the fuel consumption of boilers, the problem of increasing the output of a heat exchanger for a boiler without loss of efficiency remains.

This invention addresses the above problem and accordingly provides a baffle for use with a heat exchanger having a passage for flow of a gaseous heat exchange medium between entrance and exit ends, the passage having therein a plurality of generally parallel heat exchange fins directed along the passage, wherein the baffle is formed from sheet material and comprises a panel with longitudinal rows of slots, adjacent slots in each row separating a plurality of baffle elements, the baffle elements protruding from the plane of the panel for said baffle elements to project between the fins when the baffle is mounted substantially vertically within the heat exchanger passage.

Compared with the known baffle, a baffle according to this invention further disrupts the flow of air through the heat exchanger passages and allows the performance ofthe heat exchanger to be increased, for example by enchancing the efficiency of the heat exchanger without a reduction of output, or by allowing a greater heat exchange output without loss of efficiency.

The solution provided by the invention to the problem explained above is both simple and inexpensive and as a consequence is economically viable even for domestic gas boilers sold in a very cost sensitive area of the market.

Preferably, two substantially identical baffles are mounted within the passage with the baffle elements of the respective baffles extending laterally outwardly in opposite directions.

Conveniently the baffle elements protrude uniformly from the plane of the baffle panel in a symmetrical vee shape.

Also provided in accordance with this invention is a heat exchanger assembly comprising a heat exchanger having a passage for flow of a gaseous heat exchange medium between an entrance and exit ends, the passage having therein a plurality of generally parallel heat exchange fins directed along the passage, and a baffle mounted adjacent the exit end of the passage and protruding downwardly into the passage, the baffle including rows of baffle elements projecting laterally between adjacent fins.

Advantageously, the rows of baffle elements are spaced apart by a distance not greater than 50 mm.

Further provided in accordance with this invention is a boiler having a heat exchanger with a baffle, as described above.

A clear understanding of the invention will be gained from the following detailed description, reference being made to the accompanying drawings, in which: Figure 1 shows a front elevation of a preferred embodiment of a baffle according to the present invention; Figures 2 and 3 respectively show plan and end views of the baffle of Figure 1; Figure 4 shows a partially sectioned plan view of a heat exchanger suitable for use with the baffle of Figs 1-3 in accordance with this invention; Figure 5 shows a section taken along line A-A in Figure 4; and Figure 6 shows the same section as Figure 5, but with baffles operatively mounted adjacent the exit end of the passage.

Figures 1,2 and 3 show a sheet metal baffle 1 having a substantially rectangular main panel 2 with three longitudinal rows of uniformly spaced, vertically elongated slots defining upright baffle elements 3. The baffle elements 3 are bent to protrude uniformly from the plane of panel 2, with each baffle element having a vee shape, symmetrical with respect to a central right angled apex 4, as shown clearly in Figure 3. A top flange 5 extends horizontally from one the upper edge ofthe panel 2. The flange is provided to facilitate the retention of the baffle on heat exchanger, as will become clear.

An initially flat metal sheet can be readily formed into the described baffle by appropriate piercing and pressing operations.

The heat exchanger shown in Figures 4,5 and 6 is formed as a generally rectangular one piece casting defining three upwardly directed elongate passages 10 for flow of a gaseous heat transfer medium, in particular hot flue gases from the burner of a domestic gas boiler, and four conduits 11, the conduits being adjacent to and in heat exchange relationship with the gas passages for flow of water, to be heated through the heat exchanger between water inlet and outlet ports.

Extending along each gas passage 10, continuously from adjacent a lower entrance end 12 to an upper exit end 13, are laterally opposed pairs of parallel heat exchange fins 14 formed integrally with the walls ofthe passage. Defined between the fins are transverse inter-fin spaces 15.

Figure 6 shows the heat exchanger of Figures 4 and 5, fitted with two baffles each as illustrated in Figures 1-3. The baffles are mounted back to back in the upper portion of a passage 10, the flange 5 of each baffle abutting the top ofthe adjacent fins 14. The panels of the baffles extend downwardly into the gap between the opposed pairs of fins, and the baffle elements project laterally into the spaces between the adjacent fins.

The baffle slots 3 are uniformly spaced at substantially the same pitch as the fins so that respective baffle elements 3 project laterally into the respective inter-fin spaces 15. The width of the baffle elements 3 is suitably approximately equal to half the width of the space between adjacent fins 14.

Although only one passage 10 is shown fitted with baffles in Fig. 6 it will be understood that in use a pair of baffles is preferably inserted in each passage of the heat exchanger.

An integral tongue 6, defined by a pair of notches, is provided medially along the flanges 5, and in combination with a suitable clip (not shown) serves to retain the baffles in position prior to installation of the heat exchanger.

In operation, the turbulence of hot gases rising through passages 10 is increased by the protrusion of baffle elements 3 into the inter-fin spaces, and thereby the performance of the heat exchanger is increased.

Most significant improvements are achieved with the rows of baffle elements 3 spaced not more than 50 mm apart.

Claims

CLAIMS:

1. A baffle for use with a heat exchanger having a passage for flow of a gaseous heat exchange medium between entrance and exit ends, the passage having therein a plurality of generally parallel heat exchange fins directed along the passage, wherein the baffle is formed from sheet material and comprises a panel with longitudinal rows of baffle elements defined by a plurality of slots, the baffle elements protruding from the plane of the panel for said baffle elements to project between the fins when the baffle is mounted substantially vertically within the heat exchanger passage.

2. A baffle according to claim 1, wherein the rows of baffle elements are spaced apart by a distance not greater than 50 mm.

3. A baffle according to claim 1 or 2, wherein the baffle elements protrude uniformly from the plane of the baffle.

4. A baffle according to any one of the preceding claims, wherein a support flange extends substantially horizontally from an upper edge of the panel.

5. A heat exchanger assembly comprising a heat exchanger having a passage for flow of a gaseous heat exchange medium between an entrance and exit ends, the passage having therein a plurality of generally parallel heat exchange fins directed along the passage, and a baffle mounted adjacent the exit end of the passage and extending downwardly into the passage, the baffle including rows of baffle elements projecting laterally between adjacent fins.

6. A heat exchanger assembly according to claim 5, wherein the rows of baffle elements are spaced apart by a distance not greater than 50 mm.

7. A heat exchanger assembly according to claim 5 or 6, wherein the baffle elements protrude uniformly from the plane of the baffle.

8. A heat exchanger assembly according to claim 5, 6 or 7, wherein a support flange extends substantially horizontally from an upper edge of the baffle.

9. A heat exchanger according to any one of claims 5 to 8, wherein the width of the baffle elements is approximately equal to half the width of the space between adjacent fins.

10. A heat exchanger assembly according to any one of claims 5 to 9, wherein two substantially identical baffles are mounted within the passage with the baffle elements of the respective baffles extending laterally outwardly in opposite directions.

11. A heat exchanger assembly substantially as herein described with reference to the accompanying drawings.

12. A boiler having a heat exchanger assembly as claimed in any one of claims 5 to 11.

13. A baffle substantially as herein described with reference to the accompanying drawings.