GB2186959A - Dehumidifier incorporating a heat exchanger - Google Patents

Abstract

The dehumidifier 10 comprises an air-to-air heat exchanger 1 having first and second air flow paths 7, 8 arranged orthogonally with respect to one another. Evaporator 11 cools the air, the cool air flow 8 cools the incoming air 7 in the heat exchanger, and the air is heated in condenser 12. The evaporator and condenser are part of a refrigerating circuit 16, 17. Fan 15 assists air flow. The heat exchanger comprises spaced, parallel plates secured together by adhesive. Moulded or drawn plastics container 13 houses the dehumidifier, and contains the condensate whose level is monitored to prevent overflow. <IMAGE>

Description

SPECIFICATION Heat exchanger and dehumidifier incorporating a heatexchanger This invention retatesto a heat exchanger and to a dehumidifier incorporting a heat exchanger, particularly though not exclusivley,for domestic use.

Condensation problems in domestic dwellings lead to serious deterioration of the building fabric, rotting of not ray natural materialsandtheformationofmouldon walls. When this occurs on a large scale the financial implications are considerable. As iswell known, condensation is encouraged by insufficient heating, poor ventilation, high production of moisture, bad dwelling design, and lack of understanding by desig ners 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 to dry clothes outside, due to lackofspace or security problems, and BS 5250:1975 lists drying of clothes as the largest single item for domestic moisture production.

To alleviatethecondensation problem-without resorting to massive investment schemes to provide dwellings with sufficient insulation, an efficient heating system or atworst demolition and re-building -it has been proposed to make use of a dehumidifierto remove moisture from the air by passing the moist air over a chilled surface which is at, orbelow,the dew pointtemperature ofthe air. The prime aim ofthe dehumidifier isto extract moisture from the air atthe most economical rate and thus the output tempera- ture is not controlled, the heat ouput 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 iitial installation costs (250+). Furthermore, no currently available machine is ofthe "advanced type" which has a more efficientthermodynamic cycle and hence is cheaperto run whilst giving enhanced performance, his adv ancedtype incorporating a heatexchangerinstalled between the evaporator and the condenser, the cold airfrom the evaporator being used to cool the incoming air so that the evaporator receives saturated air, whilethe airis subsequently heated before passing overthe 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 reflectthesetooling costs.

According to a first aspect ofthe present invention, there is provided an air-to-air heat exchanger compris- ing a plu rality of spaced apartn parallel plates, with adjacerltplates secu}edtogether by adhesive.

The construction of heat exchanger in accordance with the first aspect of the invention, preferably embodies afirstflow 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 siiicone basetype. 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 latterto abut against an adjacent plate and hence the lateral dimension of the rib dictating a plate spacing, while the width oftheflange defines the surface area availabieto receive adhesive.By "sec tionalised" is meant a plate that can be produced from sheet metal, with the plate of such dimensions,that sufficient stiffness is imparted to the individual plates by the presence ofthe ribs and inturned flanges, so that, in contrastwith prior art proposals, no stiffening deformations are required bythe plates. Hence, the plates comprise a planar wall portion, with ribs along the opposed longitudinal edges ofthewall portion.

Thus,the heat exchanger is advantageously constructed not onlyfrom a plurality of plates stacked one on top oftheother, but also located end-to-end, to define as many additional stacks as are required for the desired rate of heattransferlmoisture removal, to give a multi-channei heat exchanger construction.

Furthermore, plates with planarwall portions give reduced resistanceto airflow compared with prior art proposals, and additionally can be made of thinner gauge metal to give reduced cost, lighter weight, and better heattransfer.

According to a second aspect of the present invention,there is provided a dehumidifiercomprising an air-to-air heat exchanger having first and second airflow paths arranged orthogonally with respectto one another, with afanto inducethe airflow.

The dehumidifier in accordance with the second aspect of the present invention, provides, in connection with known machines, afar more compact construction, and hence enables a domestic dehumidifierto be manufactured of relatively small dimensions, and hence of relatively unobtrusive appearance, which is particularly advantageousfor domestic use. Thus, the dehumidifier 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 dehumidifier in accordance with the second aspect, airflow along the second path is preferably preceded byflowthrough or over an evaporator, with airflowfromthesecond path being through or over a condenser. The heat exchanger conveniently comprises a plurality of spaced apart, parallel plates, 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 reservoirforthe 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 afloat switch, to switch off the dehumidifier should an overflow condition besensed. It is also preferred to housethe container, asweli asthe condenser and evaporator, in a box.

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

The two aspects ofthe present invention will now be described, in greater detail, by way of example, with reference to the accompanying drawings, in which 1 Figure 1 is a side elevation ofa heat exchanger in accordance with the first aspect ofthe invention; Figure2 a plan view of Figure 1; Figure3isan end elevation of Figure 1; Figure 4 is an enlargement of a portion of Figure2; and Figure 5 is a diagrammaticsideelevationofa dehumidifierinaccordancewith asecondaspectof the invention, incorporating the heat exchanger of Figures 1 to 4.

on the drawings, an air-to-airheatexchangerl,of the cross-flow, parallel plate type is constructed from a plurality of secionalised plates 2. Each plate comprises a planar, rectangularwall portion 3 provided along opposed, longitudinal edges 4,with a rib 5 carrying an inturned flange 6.As can be appreciated from Figures 1 to 4, a plurality of plates 2 are sandwiched together, in alternating manner such thatplateswhich will ensure a first airflow path in a first direction, indicated byarrow7 in Figure 1, are adjacent plateswhich will ensure a second airflowin a second, orthogonal direction, indicated by arrows 3, 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 bestseen in Figure4.

As indicated in Figures, a dehumidifier 10 comprises a heat exchanger 1 oftheform shown in Figures 1 to 4, beneathwhich is is located an evaporatorli 1 fora refrigerant, and above which is located a condenser 12 forthe refrigerant, the heat exchanger 1, evaporator 11 and condenser 12 being located within a common container 13 of synthetic plastics material, the containerserving as a reservoirfor condensate, which may be periodically drawn offthrough a tap outlet 14in a base of the container 13.Air circulation through the dehumidifier is as indicated by arrows 7 and 8, with air at room temperature being conveyed through the heat exchanger 1 in the direction of arrows 7,forthis airthen to pass through the evaporator 11, and in so doing to be cooled, such cooled airthen being passed again through the heat exchanger 1, in the direction of arrow 8, so asto havea cooling effectontheincoming air, the airthen passing through the condenser 4to be heated,to be passed back into the room etc., where the dehumidifier 10 is located. Air circulation through the dehumidifier 10is effected by an electricfan 15, two alternative posifionsforthefan being illustrated in Figure 5. Refrigerantsupplyand return lines 16,17 extend from both the evaporator and condenserto a compressor (notshown).

Claims (15)

1. A dehumidifier comprising an evaporator and a condenser of a refrigeration circuit, an air-to-air heat exchanger having first and second airflow paths arranged orthogonally with respectto one another with a fan to induce the airflow.

2. A dehumidifier as claimed in Claim 1, wherein airflow along the second path is preceded by airflow through or over an evaporator, and airflowfromthe second path being through orovera condenser.

3. A dehumidifier as claimed in Claim 1 or Claim 2, wherein the heatexchanger comprises a plurality of spaced apart, parallel plates, with a-cfjacentplates secured together by adhesive.

4. A dehumidifier as claimed in Claim or Claim 3, wherein the condenser, evaporator and afr-to-air heat exchanger are housed in a common container.

5. Adehumidifierasclaimed in Claim 4, wherein the container is of synthetic plastics material.

6. A dehumidifier as claimed in Claim 4, wherein the container is produced by moulding.

7. A dehumidifier as claimed in Claim 4, wherein the container is produced by deep drawing.

8. A dehumidifieras claimed in any one of Claims4 to 7,wherein the container serves as a reservoirforthe condensate.

9. Adehumidffierasclaimed in Claim 7, wherein the container is connected to a drainage system.

10. A dehumidifier as claimed in Claim7,wherein the container is provided with a tap outlet

11. Adehumidifieras claimed in any one of Claims 8to 10, wherein the container incorporates a safety device to switch off dehumidifiershould an overflow condition be sensed.

12 Adehumidifieras claimed in Claim 1 1,wherein the safety device is afloatswitch.

13. A dehumidifier as claimed in any one of Clairns 1 to 11, wherein the container, condenser and evaporator are housed in a box.

14. Adehumidifier as claimed in any preceding claim, wherein the evaporator and condenser are of theconventionalfin andtubetype.

15. Adehumidifier substantially as hereinbefore described with reference to the accompanying drawings. ~~~~~~~~~~~~~~~~~~~~