GB2142128A

GB2142128A - Laundry drier with moisture condenser

Info

Publication number: GB2142128A
Application number: GB08411392A
Authority: GB
Inventors: Dieter Knopp
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-06-24
Filing date: 1984-05-03
Publication date: 1985-01-09
Also published as: FR2547839B1; IT1176293B; IT8421542A1; GB8411392D0; FR2547839A1; GB2142128B; IT8421542A0; DE8318395U1

Abstract

A laundry drier has an air-cooled heat exchanger for the condensing of moisture carried by recirculated drying air, the heat exchanger comprising a housing (200) and hollow, removable heat exchange plates (21). During operation, the heat exchanger is flowed through substantially in cross-current by cooling air through the plate interiors on the one hand and by drying air through spaces between the plates on the other hand. The plates (21) arranged congruently one above the other and at spacings from each other, form a closed packet removable from the drier and are held on each side of the packet by plate holders (210) rectilinearly guided in withdrawal direction in the housing (200). <IMAGE>

Description

SPECIFICATION Laundry drier The present invention relates to a laundry drier, especially a household drier.

In DE-OS 30 27900 there is disclosed a laundry drier with a heat exchanger having heat exchange plates which can be individually drawn out of a housing, the side walls of which are provided with guide rails for this purpose. These guide rails are provided with sealing strips which seal the laundry drying air against cooling air conducted in the exchanger.

Heat exchanger plates in laundry driers are susceptible to clogging by dust and fluff which, in conjunction with moisture, results in a coating which can be difficult to remove if the plates are not taken out in time. This coating impairs the heat transfer from the drying air to the cooling air. For the removal of dust and fluff, withdrawal of the plates from the heat exchanger is necessary in order to thoroughly clean the plates individually, for example under flowing water.

However, the manipulation of these plates is not particularly simple in the case of individual withdrawal. Moreover,#reinsertion of the plates requires the application of force and careful pushing in so as to ensure that the sealing strips do not detach from the guide rails, push together and/or are displaced and represent an obstacle to the complete insertion of the plates. The tightness and freedom of the flows from obstruction would then no longer be ensured and the efficiency of the heat exchange operation could be impaired.

It would therefore be desirable to improve the tightness between the channels and the flow conditions in the heat exchanger and to facilitate manipulation of the heat exchanger parts before, during and after a cleaning operation.

According to the present invention there is provided a laundry drier provided with a heat exchanger for condensing moisture carried by drying air circulating in the drier, the heat exchanger comprising a housing and a heat exchange unit arranged in the housing to be withdrawable therefrom in a given direction and comprising two plate holders arranged in the housing to extend in the withdrawal direction and a plurality of hollow heat exchange plates arranged at spacings one above the other and each held at two opposite edge portions thereof by the holders, the housing and the heat exchange unit being arranged for the passage of the drying air through the spaces between the plates in one direction and the passage of cooling air through the interiors of the plates in a direction transverse to said one direction.

In a preferred embodiment, the drier comprises an air-cooled heat exchangerfor condensing moisture transmitted into the drying air, wherein the heat exchanger includes hollow plates and during operation is flowed through substantially in cross-current by cooling air passing through the plate interiors on the one hand and by drying air passing through the spaces between the plates on the other hand. The plates, arranged congruently one above the other and at a spacing one from the other, form a closed packet removable from the drier and are shapelockingly connected on each side of the packet with plate holders rectilinearly guided in withdrawal direction in the housing of the heat exchanger.This construction offers the advantage that, before the insertion of the packet, the plates can be conveniently pushed into the holders, for example on a worktop, with full inspection by the operator. As a result, the assembly operation can be monitored and corrected as needed. The plates need to be pushed only transversely over a seal and do not load the seal fastening, so that the plates will lie correctly in the housing and will not provide resistance to the air flows or permit exchange between the flows.

Preferably, the interiors of the plates contain heat transfer elements, for example sinuously extending ribs, as a result of which the interiors are more suitable for guidance of the cooling air than of the drying air, because the dust and fluff proportion is usually greater in the latter than in the former, and such dust and fluff might adhere to the heat transfer elements and impair the heat transfer. Moreover, cleaning would be made more difficult. For these reasons, it is particularly advantageous if the connection of the holders with the plates is at plate edges associated with the openings to the plate interiors.Since household driers are predominantly constructed as front loaders and the drying air flows from the rear forwardly through the drum, flows away at the front and flows from front to rear through the heat exchanger, the cooling air must in these cases flow through the heat exchanger transversely. On the other hand, the plate packet is preferably removable from the front.

Preferably, each of the holders comprises an elongate frame with a plurality of longitudinally extending ribs corresponding in number to the number of spacings between the plates, the width and the length of each rib being at least equal to, respectively, the depth and the length of each such spacing. The arrangement has the advantage that each plate can be inserted tightly into the holders in conspicuous manner outside the drier.

For preference, adjacent ones of the ribs are spaced apart by an amount which is greater in regions of the ribs towards the interior of the heat exchange unit than regions of the ribs towards the exterior of the unit, the difference between the spacings of the regions being substantially equal to the wall thickness of the plate associated with those ribs. This offers the advantage that the flow of the cooling air is not made turbulent at additional edges.

Expediently, each plate holder comprises rails extending at the top and bottom in withdrawal direction and - at least at the end face lying at the rear - a rib constructed in the form of the rails, which rib and rails form a labyrinth seal with grooves in the housing of the heat exchanger, the housing being closed by a cover which lies tightly on an end face of the housing.

An additional component, which could make the access to the heat exchanger more difficult, can be dispensed with if the housing is constructed behind the cover as an entry portion for a drying air channel leading out from a drying space and if the cover is removed from the front side of the housing.

In particularly simple manner, the plate packet can be positively located in the housing of the heat exchanger of the plate holders at their front sides have respective detents co-operating with the housing.

The plate packet can be easily removed from a fixed position in the housing if the holders at the front sides have respective handles, which together can be used for withdrawal of the plate packet from the housing.

For enhancement of the cooling air flow, the ribs may each have a flow wedge on a side pointing towards cooling air channel portions. A flow wedge, which has a prismatic shape with leading surfaces in the form of part-cylindrical shells has proved favourable in terms of flow guidance.

An embodiment of the present invention will now be more particularly described byway of example with reference to the accompanying drawings, in which: Figure 1 is a schematic sectional side elevation of a household laundry drier embodying the present invention; Figure 2 is an outside elevation of a plate holder in a heat exchanger of the drier; Figure 3 is a plan view of the holder; Figure 4 is an inside elevation of the holder; Figure is a cross-section, along the line V-V of Figure 4, of the holder; Figure Sis a detail sectional view of the holder, corresponding to the region VI of Figure 5; Figure 7 is a sectional elevation of the heat exchanger, along the line VII-VII of Figure 9; Figure 8 is a front end view of the heat exchanger, with a cover removed; and Figure 9 is a horizontal sectional view of a housing of the heat exchanger.

Referring now to the drawings, there is shown in Figure 1 a laundry drier comprising a casing 10 with an internal drying space 11 formed by, for example, a horizontally mounted laundry drum. Disposed between the drum and the rear wall of the drier is an air feed channel 12, in which the drying air is heated by means of a heater 13 and blown by a blower 14 through a grating wall 15 and into the drum. A charging opening 16 for the loading ofthe laundry to be dried is disposed at the front of the drier and is closable by a door 17.

The circulating drying air, which is blown by the blower 14 through the drum 11 and an annular gap between the door and the outer frame of the opening 16, passes through a lint sieve 18 and into a channel 19, which is connected to an entry portion 20. From there, the drying air passes into an air-cooled heat exchanger 2, which is illustrated partially broken away and which contains highly thermally conductive hollow plates 21. The plates conduct cooling air through their interiors transversely to the drying air.

The drying air is represented on the warm side by a solid arrow and on the cold side by a longitudinally dashed arrow in Figure 1. The warm, moisture-laden drying air gives off heat and moisture at the surfaces of the plates 21 and flows cooled towards the blower 14. The moisture collects at the exit of the heat exchanger and flows towards a condensate collecting container 22, from which the condensate can be pumped away or removed manually. The condensate container could also consist of a flat container, which holds about 3 litres and is arranged underneath the heat exchanger housing.

Also disposed at the front side of the drier casing 10 is a door or flap 23, which can be opened by the operator for the purposes of cleaning the heat exchanger 2. Before cleaning, the plates 21 can be drawn out of the housing of the heat exchanger 2 and cleaned.

The plates of the heat exchanger are constructed to be the same as or similar to those of the DE-OS 30 27 900 and are held, at spacings, laterally by two plate holders 210, as shown in Figures 2 to 6, in the required position in the housing of the heat exchanger 2. The plate holders 210 each consist of an elongate frame 211 with longitudinally extending ribs 213 corresponding to the number (four) of spaces 212 (Figures 1,7 and 8) between the plates.

These ribs are as wide as the spacings between the plates and somewhat longer than these spacings.

A side portion, containing an opening to the plate interior, of a plate fitted between two such ribs 213 is illustrated in chain-dotted lines in Figure 6. It can be seen from this that the spacings A of the ribs on the side of the openings to the plate interior are greater, by the total wall thickness (2 x W) of the hollow plates, than the spacings a on the side of cooling air channel portions.

The ribs 213, on a side facing cooling air channel portions, each have a flow wedge 214 with leading surfaces 215 in the form of a part-cylindrical shell. As a result, the ribs 213 are flowed around smoothly by cooling air and do not form vortices at the transition to the inserted plates, because the surfaces 215 pass over into the internal surfaces of the plates without interruption.

Attheirfront ends, the plate holders 210 have handles 216 with detent lugs 217, which detent into corresponding recesses of the housing as soon as the plate holders have assumed the proper position in the housing. The circumferences of the plate holders 210 are defined by rails 218, which serve for guidance and sealing of the plate holders relative to the heat exchanger housing. The ribs 219 at the rearward ends of the plate holders 210, which have the shape of the rails 218, engage into grooves in the housing and merely serve for sealing between the cooling air channel and the drying air channel.

The housing 200 of the heat exchanger (Figures 7 to 9) at the front in the drier has an entry portion 20 for drying air from the drying chamber and at the rear an exit portion 201 for drying air passing to the blower 14. In addition, the housing 200 has a cooling air channel portion 202 (Figure 8), to which a blower 141 for the cooling air is connected, and a channel portion 203 (Figure 9) which is connected with channel components 204 leading out into the open.

The cooling system is so arranged that cooling air is inducted by way of the channel components 204, sucked transversely through the heat exchanger 2 and blown back out into the open by the blower 141.

Alternatively, however, the system can be so arranged that the blower 141 inducts the cooling air from the environment, conducts it through one of the channel portions 202 and 203 to the heat exchanger 2 and conveys it through the respective other channel portion back into the open.

The front region 205 of the housing has a removable cover 206 which is pressed by, for example, a strap closure, and seals 207 onto the end of the otherwise open front region 205.

Disposed at the base of the front region 205 is an outflow opening 208 for condensate, the opening 208 being largely blocked against air exit by means of a tongue 209 of the cover 206. An opening in the tongue 209 is arranged offset from the outflow opening 208, so that condensate can trickle through this opening and the gap between the tongue 209 and the base of the front region 205 to the outflow opening 208.

A further outflow opening 220, which mainly serves for conducting away the condensate arising at the rear side of the heat exchanger, is arranged on the opening portion 201 at the rear of the housing 200. This condensate flows by way of an outflow incline 221 of the collecting container 22 arranged thereunder to an opening 222, which is disposed directly below the outflow opening 208. The condensate collected in the container 22 can be removed from the laundry drier by, for example, a pump or emptied into a separate collecting container. If the collecting container 22 is removably arranged in the drier, then the container can also be emptied by hand.

It is to be noted that the section line for the view of Figure 7 extends, according to Figure 9, in part along a guide groove 231, whereby the rail 218 is visible in Figure 7. The flange-like front portions of the inserted plate holders 210 press on a seal 232, which together with the labyrinth seal formed of rail 218 and groove 231 seals the cooling air channel off from the drying air channel. At the rearward end face of the plate holders 210, the rib 219, which extends uninterruptedly to the guide rail 218, serves for the same sealing purpose in conjunction with a groove 233 arranged at the appropriate place in the housing.

Claims

1. A laundry drier with a heat exchanger for condensing moisture carried by drying air circulating in the drier, the heat exchanger comprising a housing and a heat exchange unit arranged in the housing to be withdrawable therefrom in a given direction and comprising two plate holders arranged in the housing to extend in the withdrawal direction and a plurality of hollow heat exchange plates arranged at spacings one above the other and each held at two opposite edge portions thereof by the holders, the housing and the heat exchange unit being arranged for the passage of the drying air through the spaces between the plates in one direction and the passage of cooling air through the interiors of the plates in a direction transverse to said one direction.

2. A drier as claimed in claim 1, wherein each of said two opposite edge portions of each heat exchange plate is provided with an opening to the plate interior.

3. A drier as claimed in either claim 1 or claim 2, wherein each of the holder comprises an elongate frame with a plurality of longitudinally extending ribs corresponding in number to the number of spacings between the plates, the width and the length of each rib being at least equal to, respectively, the depth and the length of each such spacing.

4. A drier as claimed in claim 3, wherein adjacent ones of the ribs are spaced apart by an amount which is greater in regions of the ribs towards the interior of the heat exchange unit than regions of the ribs towards the exterior of the unit, the difference between the spacings of the regions being substantially equal to the wall thickness of the plate associated with those ribs.

5. A drier as claimed in either claim 3 or claim 4, wherein the frame of each holder comprises an upper and a lower rail extending longitudinally of the frame and a member, corresponding to the shape of the rails, at the rearward end of the frame with respect to the withdrawal direction, the rails and members of the frames co-operating with grooves in the housing to form labyrinth seals for cooling air entry and exit regions of the heat exchange plates, and the housing being provided at one end with an opening which is closed by a cover.

6. A drier as claimed in claim 5, wherein the housing is provided adjacent to the cover with an inlet for drying air, the cover being removable from the housing at a front side of the drier.

7. A drier as claimed in any one of the preceding claims, wherein each of the holders is provided at a front end thereof with detent means locating the holder in the housing.

8. A drier as claimed in any one of the preceding claims, wherein each of the holders is provided at a front end thereof with a handle to facilitate withdrawal of the heat exchange unit from the housing.

9. A drier as claimed in any of claims 3 to 6 or either claim 7 or claim 8 when dependent thereon, wherein each of the ribs of each of the frames has generally wedge-shaped flow-guiding portion pointing outwardly of the housing.

10. A drier as claimed in claim 9, wherein the wedge surfaces of each flow-guiding portion are convex.

11. A laundry drier substantially as hereinbefore described with reference to the accompanying drawings.