GB2160634A

GB2160634A - Heat exchanger

Info

Publication number: GB2160634A
Application number: GB08507410A
Authority: GB
Inventors: Dr Malcolm John Denman
Original assignee: SHEFFIELD METROPOLITAN DISTRIC
Current assignee: SHEFFIELD METROPOLITAN DISTRIC
Priority date: 1984-03-23
Filing date: 1985-03-21
Publication date: 1985-12-24
Also published as: GB8704119D0; GB8507410D0; GB8407575D0; GB2160634B

Abstract

An air-to-air heat exchanger 1 comprises a plurality of spaced apart, parallel plates 2, with adjacent plates 2 secured together by adhesive, and having first and second air flow paths arranged orthogonally with respect to one another. <IMAGE>

Description

SPECIFICATION Heat exchanger and dehumidifier incorporating a heat exchanger This invention relates to a heat exchanger and to a dehumidifier incorporating a heat exchanger, particularly though not exclusively, for domestic use.

Condensation problems in domestic dwellings lead to serious deterioration of the building fabric, rotting of natural materials and the formation of mould on walls. When this occurs on a large scale the financial implications are considerable. As is well known, condensation is encouraged by insufficient heating, poor ventilation, high production of moisture, bad dwelling design, and lack of understanding by designers and householders. Insufficient heating is frequently due to the high running cost of heating systems often installed in the era of low cost energy. Draught stripping can reduce heating losses but a large reduction in ventilation rate can aggrevate condensation problems.Furthermore, with many dwellings it is not possible dry clothes outside, due to lack of space or security problems, and BS 5250: 1975 lists drying of clothes as the largest single item for domestic moisture production.

To alleviate the condensation problem without resorting to massive investment schemes to provide dwellings with sufficient insulation, an efficient heating system or at worst demolition and re-building-it has been proposed to make use of a dehumidifier to remove moisture from the air by passing the moist air over a chilled surface which is at, or below, the dew point temperature of the air.

The prime aim of the dehumidifier is to extract moisture from the air at the most economical rate and thus the output temperature is not controlled, the heat output acting as low level heating. However, currently available dehumidifiers are open to criticism on the grounds of noise of fan, noise when de-icing, size, effectiveness, ice clogging, machine operation, and initial installation costs (250 + ). Furthermore, no currently available machine is of the "advanced type" which has a more efficient thermodynamic cycle and hence is cheaper to run whilst giving enhanced performance, this advanced type incorporating a heat exchanger installed between the evaporator and the condenser, the cold air from the evaporator being used to cool the incoming air so that the evaporator receives saturated air, while the air is subsequently heated before passing over the condenser.However, currently available heat exchangers are of designs that demand substantial capital investment in tooling e.g.

by requiring crimping, folding or other deformation operations and hence are available at prices which reflect these tooling costs.

According to a first aspect of the present invention, there is provided an air-to-air heat exchanger comprising a plurality of spaced apart, parallel plates, with adjacent plates secured together by adhesive.

The construction of heat exchanger in accordance with the first aspect of the invention, preferably embodies a first flow path in a first direction, and a second flow path in a second, orthogonal direction. The adhesive used is conveniently a hot-melt adhesive, preferably of a silicone base type. Most advantageously the plates are sectionalised (as herein defined) with each plate having at each longitudinal edge a laterally extending rib, with an inturned flange, the latter to abut against an adjacent plate and hence the lateral dimension of the rib dictating a plate spacing, while the width of the flange defines the surface area available to receive adhesive.By "sectionalised" is meant a plate than can be produced from sheet metal, with the plate of such dimensions, that sufficient stiffness is imparted to the individual plates by the presence of the ribs and inturned flanges, so that, in contrast with prior art proposals, no stiffening deformations are required by the plates.

Hence the plates comprise a planar wall portion, with ribs along the opposed longitudinal edges of the wall portion. Thus the heat exchanger is advantageously constructed not only from a plurality of plates stacked one on top of the other, but also located end-to-end, to define as many additional stacks as are required for the desired rate of heat transfer/ moisture removal, to give a multi-channel heat exchanger construction. Furthermore, plates with planar wall portions give reduced resistance to air flow compared with prior art proposals, and additionally can be made of thinner gauge metal to give reduced cost, lighter weight, and better heat transfer.

According to a second aspect of the present invention, there is provided a dehumidifer comprising an air-to-air heat exchanger having first and second air flow paths arranged orthogonally with respect to one another, with a fan to induce the airflow.

The dehumidifier in accordance with the second aspect of the present invention, provides, in connection with known machines, a far more compact construction, and hence enables a domestic dehumdifier to be manufactured of relatively small dimensions, and hence of relatively unobtrusive appearance, which is particularly advantageous for domestic use. Thus, the dehumdifier in accordance with the invention is aimed at being wall mounted or free-standing e.g. to be located in the confines of a hall, stairwell, bedroom etc.

With the dehumdifier in accordance with the second aspect, airflow along the second path is preferably preceeded by flow through or over an evaporator, with airflow from the second path being through or over a condenser. The heat exchanger conveniently com prises a plurality of spaced apart, parallel platens, with adjacent plates secured together by adhesive. In detail, the condenser, evaporator and air-to-air heat exchanger are housed in a common container e.g. of synthetic plastics material, conveniently produced by moulding, deep drawing or other convenient process. Such a container may, if required, serve as a reservoir for the condensate, which can either be run into a drainage system or periodically be emptied by the user, through a tap outlet.It is also preferred to incorporate a safety device in the form of a float switch, to switch off the dehumidifier should an overflow condition be sensed. It is also preferred to house the container, as well as the condenser and evaporator, in a box.

Conveniently, the evaporator and condenser may be of the conventional fin and tube type as are used extensively for refrigeration.

The two aspects of the present invention will now be described, in greater detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a heat exchanger in accordance with the first aspect of the invention; Figure 2 is a plan view of Fig. 1; Figure 3 is an end elevation of Fig. 1; Figure 4 is an enlargement of a portion of Fig. 2; and Figure 5 is a diagrammatic side elevation of a dehumidifier in accordance with a second aspect of the invention, incorporating the heat exchanger of Figs. 1 to 4.

In the drawings, an air-to-air heat exchanger 1, of the cross4low, parallel plate type is constructed from a plurality of sectionalised plates 2. Each plate comprises a planar, rectangular wall portion 3 provided, along opposed, longitudinal edges 4, with a rib 5 carrying an inturned flange 6. As can be appreciated from Figs. 1 to 4, a plurality of plates 2 are sandwiched together, in alternating manner such that plates which will ensure a first air flow path in a first direction, indicated by arrow 7 in Fig. 1, are adjacent plates which will ensure a second air flow in a second, orthogonal direction, indicated by arrows 8, the heat exchanger 1 being assembled by securing adjacent plates together with a hot-melt, silicone base adhesive 9 between adjacent ribs 5, inturned flanges 6 and wall portions 3, as best seen in Fig. 4.

As indicated in Fig. 5, a dehumidifier 10 comprises a heat exchanger 1 of the form shown in Fig. 1 to 4, beneath which is located an evaporator 11 for a refrigerant, and above which is located a condenser 1 2 for the refrigerant, the heat exchanger 1, evaporator 11 and condenser 1 2 being located within a common container 1 3 of synthetic plastics material, the container serving as a reservoir for condensate, which may be periodically drawn off through a tap outlet 14 in a base of the container 1 3. Air circulation through the dehumidifier 10 is as indicated by arrows 7 and 8, with air at room temperture being conveyed through the heat exchanger 1 in the direction of arrows 7, for this air then to pass through the evaporator 11, and in so doing to be cooled, such cooled air then being passed again through the heat exchanger 1, in the direction of arrow 8, so as to have a cooling effect on the incoming air, the air then passing through the condenser 4 to be heated, to be passed back into the room etc., where the dehumidifier 10 is located. Air circulation through the dehumidifier 10 is effected by an electric fan 15, two alternative positions for the fan being illustrated in Fig. 5. Refrigerant supply and return lines 16, 1 7 extend from both the evaporator and condenser to a compressor (not shown).

Claims

1. An air-to-air heat exchanger comprising a plurality of spaced apart, parallel plates, with adjacent plates secured together by adhesive.

2. A heat exchanger as claimed in Claim 1, comprising a first flow path in a first direction, and a second flow path in a second, orthogonal direction.

3. A heat exchanger as claimed in Claim 1 or Claim 2, wherein the adhesive is a hot-melt adhesive.

4. A heat exchanger as claimed in Claim 3, wherein the adhesive is a silicone base adhesive.

5. A heat exchanger as claimed in any preceding Claim, wherein the plates are sectionalised (as hereinbefore defined) with each plate having at each longitudinal edge a laterally extending rib, with an inturned flange, the latter to abut against an adjacent plate and hence the lateral dimension of the rib dictating a plate spacing, while the width of the flange defines the surface area available to receive adhesive.

6. A heat exchanger as claimed in Claim 5, wherein the plates comprise a planar body portion with ribs along the longitudinal edges.

7. A heat exchanger as claimed in any preceding Claim constructed not only from a plurality of plates stacked one on top of the other, but also located end-to-end, to define as many additional stacks as are required for the rate desired heat transfer/moisture removal, to give a multi-channel heat exchanger construction.

8. A dehumidifier comprising an air-to-air heat exchanger having first and second air flow paths arranged orthogonally with respect to one another a fan to induce the airflow.

9. A dehumidifier as claimed in Claim 8, wherein airflow along the second path being preceeded by flow through or over an evaporator, and airflow from the second path being through or over a condenser.

10. A dehumidifier as claimed in Claim 8 or Claim 9, wherein the heat exchanger comprises a plurality of spaced apart, parallel plates, with adjacent plates secured together by adhesive.

11. A dehumidifier as claimed in Claim 9 or Claim 10, wherein the condenser, evaporator and air-to-air heat exchanger are housed in a common container.

1 2. A dehumidifier as claimed in Claim 11, wherein the container is of synthetic plastics material.

1 3. A dehumidifier as claimed in Claim 11, wherein the container is produced by moulding.

14. A dehumidifier as claimed in Claim 11, wherein the container is produced by deep drawing.

1 5. A dehumidifier as claimed in any one of Claims 11 to 14, wherein the container serves as a reservoir for the condensate.

1 6. A dehumidifer as claimed in Claim 14, wherein the container is connected to a drainage system.

17. A dehumidifier as claimed in Claim 14, wherein the container is provided with a tap outlet.

1 8. A dehumidifier as claimed in any one of Claims 1 5 to 1 7, wherein the container incorporates a safety device to switch off the dehumidifier should an overflow condition be sensed.

1 9. A dehumidifier as claimed in Claim 18, wherein the safety device is a float switch.

20. A dehumidifier as claimed in any one of Claims 8 to 18, wherein the container, condenser and evaporator are housed in a box.

21. A dehumidifier as claimed in any one of Claims 8 to 20, wherein the evaporator and condenser are of the conventional fin and tube type.

22. A heat exchanger substantially as hereinbefore described with reference to the accompanying drawings.

23. A dehumidifier substantially as hereinbefore described with reference to the accompanying drawings.