GB2206189A

GB2206189A - Finned heat exchanger tubes

Info

Publication number: GB2206189A
Application number: GB08714776A
Authority: GB
Inventors: Graham Lund
Original assignee: Baxi Partnership Ltd
Current assignee: Baxi Partnership Ltd
Priority date: 1987-06-24
Filing date: 1987-06-24
Publication date: 1988-12-29
Also published as: GB8714776D0

Abstract

A boiler heat exchanger comprises a flueway, a waterway provided through at least one externally-finned heat exchange tube 3, and at least one baffle located in spaced relationship to the fins of the heat exchange tube to guide and constrain hot flue products in the flueway into closer contact with and over a greater surface area of the fins than if the baffle were absent, the battle being of unitary construction and comprising a series of baffle segments 7 which are at least partially located in the spaces between the fins of the heat exchange tube. The provision of the battle improves the efficiency of the heat exchanger. <IMAGE>

Description

HEAT EXCHANGER The present invention relates to heat exchangers for hot water boilers, and particularly to those used in central heating systems.

Heat exchangers for use in such boilers are typically made of at least one cast metal chamber which is provided with a series of fins extending normally from the chamber to increase the outer surface area of same. Hot flue products from the boiler are passed externally over the central heat exchange tube between the fins and water is passed through the chamber to be heated by the hot flue products.

It is the object of the present invention to improve the efficiency of the heat exchanger.

According to the present invention there is provided a heat exchanger comprising a flueway, a waterway provided through at least one externally-finned heat exchange tube, and at least one baffle located in spaced relationship to the fins of the heat exchange tube to guide and contrain hot flue products in the flueway into closer contact with and over a greater surface area of the fins than if the baffle were absent.

Preferably, the baffle is of unitary construction and comprises a series of baffle segments which are at least partially located in the spaces between the fins of the heat exchange tube.

Preferably also, the baffle segments are each provided with an upraised portion with a profile that conforms to the shape of the outer rim of the fin adjacent thereto.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawing, in which: Fig. 1 is a cross-sectional view of part of a heat exchanger according to the present invention; and Fig. 2 is a side view but also in part cross-section of the heat exchanger shown in Fig. 1.

The heat exchanger for use in a central heating system comprises a pair of cast metal heat exchange tubes 1, which are located side by side to define a flueway 2 therebetween. The tubes 1 are hollow and their interiors define waterways 3 so that water flowing through the tubes 1 can be heated by hot flue products from a burner, for example a gas burner, passing through the flueway 2 and around the outside of the tubes 1.

To improve the efficiency of the heat exchange process the tubes 1 are each provided with a series of fins 4. The fins 4 extend outwardly from the central core 5 of the tubes 1 and effectively increase the surface area of the tubes 1.

In order to further improve the efficiency of the heat exchanger, an elongate baffle 6 is located above and between the tubes 1. The baffle 6 is of unitary construction, preferably a casting, and comprises a series of baffle segments 7, which are designed to locate in the spaces 8 between the fins 4. Preferably, as can be seen in the drawing, the tubes 1 are disposed so that the fins 4 on each tube are in line with one another. In this way, the baffle segments 7 can be located so that each segment is disposed between two fins 4 located on each of the tubes 1.

Each baffle segment 7 is also configured so that its profile is such that it conforms to the shape of the rim 9 of the fins 4 adjacent thereto. A segment 7 comprises a body which has its side edges 10 cut away to form a concave rim which conforms to the shape of the core 5 of the underlying heat exchange tube 1. Inwardly of the edges 10 is an upraised portion which defines a finger 11 whose profile 12 conforms to the shape of the outer rim 9 of the adjacent fins 4 of the heat exchanger.

In this way, hot flue products rising through the flueway 2 are constrained into narrow curved channels 13 defined by the edges 10 and the profiles 12 of the baffle segments 7 and the central core 5 and the fins 4 of the tubes 1. The hot flue products are, therefore, constrained to follow a path which brings them into closer contact with the fins 4 and the cores 5 of the tubes 1. In addition, the flue products flow over a greater surface area of the cores 5 and the fins 4 before escaping from the confiner of the heat exchanger than would otherwise be the case if the baffle 6 were not in place. Thus the efficiency of the heat exchanger is improved.

Claims

CLAIMS:

1. A heat exchanger comprising a flueway, a waterway provided through at least one externally-finned heat exchange tube, and at least one baffle located in spaced relationship to the fins of the heat exchange tube to guide and constrain hot flue products in the flueway into closer contact with and over a greater surface area of the fins than if the baffle were absent.

2. A heat exchanger as claimed in claim 1, in which the baffle is of unitary construction and comprises a series of baffle segments which are at least partially located in the spaces between the fins of the heat exchange tube.

3. A heat exchanger as claimed in claim 2, n which the baffle segments are each provided with an upraised portion with a profile that conforms to the shape of the outer rim of the fin adjacent thereto.

4. A baffle for use in a heat exchanger comprising at least one externally-finned heat exchange tube, the baffle comprising a series of baffle segments adapted to be at least partially located in the spaces between the fins of the heat exchange tube.

5. A baffle as claimed in claim 4, in-which the baffle segments are each provided with an upraised portion with a profile that conforms to the shape of the outer rim of the fin adjacent thereto.

6. A heat exchanger, substantially. as hereinbefore described with reference to the accompanying drawing.

7. A baffle for use in a heat exchanger comprising at least one externally-finned heat exchange tube, the baffle being substantially as hereinbefore described with reference to the accompanying drawing.