A set having a first dryer and a second dryer

Abstract

 The invention relates to a set having a first dryer 11 and a second dryer 31. Each dryer 11, 31 comprises a respective housing 12,32 enclosing a respective interior 13, 33. Each housing 12, 32 comprises a respective front wall 14, 34 and a respective back wall 15, 35, a respective drying chamber 16, 36 disposed within said housing 12, 32, and a respective process air guide 17, 37 for guiding process air through said respective drying chamber 16, 36 for drying articles 18, 38 disposed therein. Each process air guide 17, 37 comprises a respective back channel 19, 39 disposed on said respective back wall 15, 35 outside said respective interior 13, 33, each back channel 19, 39 projecting into said respective interior 13, 33 through a respective first hole 20, 40 and a respective second hole 21, 41 in said back wall 15, 35. Each first hole 20, 40 is placed below each respective second hole 21, 41 with respect to a respective vertical axis 22, 42. Each process air guide 17, 37 is configured for guiding the process air through each respective back channel 19, 39 from said respective first hole 20, 40 to said respective second hole 21, 41, and from said respective second hole 21, 41 into said respective drying chamber 16, 36. In said first dryer 11, said respective process air guide 17, 37 comprises an air-to-air heat exchanger 1 disposed within said respective housing 12, and an electric heater 2 disposed within said respective back channel 19. In said second dryer 31, said respective process air guide 17, 37 comprises a heat sink 3 and a heat source 4, said heat sink 3 and said heat source 4 belonging to a heat pump 3, 4, 5, 6, 7, 9 disposed within said respective housing 32. In said first dryer 11, said respective second hole 21 is a single passage for said respective back channel 19 to project into said respective interior 13. In said second dryer 31, said respective back wall 35 has at least one third hole 8, with said respective back channel 39 projecting into said respective interior 33 through said at least one third hole 8 in parallel to said respective second hole 41, and with said respective process air guide 37 being configured for guiding the process air from said respective first hole 40 to said respective second hole 41 and said at least one third hole 8.

Description

[0001] The invention relates to a set having a first dryer and a second dryer, wherein each dryer comprises a respective housing enclosing a respective interior, each housing comprising a respective front wall and a respective back wall, a respective drying chamber disposed within said housing, and a respective process air guide for guiding process air through said respective drying chamber for drying articles disposed therein, wherein each process air guide comprises a respective back channel disposed on said respective back wall outside said respective interior, each back channel projecting into said respective interior through a respective first hole and a respective second hole in said respective back wall, wherein each first hole is placed below each respective second hole with respect to a respective vertical axis, and wherein each process air guide is configured for guiding the process air through each respective back channel from said respective first hole to said respective second hole, and from said respective second hole into said respective drying chamber, wherein, in said first dryer, said respective process air guide comprises an air-to-air heat exchanger disposed within said respective housing, and an electric heater disposed within said respective back channel, and wherein, in said second dryer, said respective process air guide comprises a heat sink and a heat source, said heat sink and said heat source belonging to a heat pump disposed within said respective housing.

[0002] A known dryer comprises a housing enclosing an interior and comprising a front wall and a back wall, a drying chamber disposed within said housing, and a process air guide for guiding process air through said drying chamber for drying articles disposed therein. The process air guide comprises a back channel disposed on said back wall outside said interior, the back channel projecting into said interior through a first hole and a second hole in said back wall, wherein the first hole is placed below the second hole with respect to a vertical axis, and wherein the process air guide is configured for guiding the process air through the back channel from said first hole to said second hole, and from said second hole into said drying chamber.

[0003] In a known dryer of the kind specified above, which known dryer is particularly known as a condensation-type dryer, the process air guide comprises an air-to-air heat exchanger disposed within the housing and an electric heater disposed the back channel. A drying process in such dryer is effected by heating the process air by the electric heater, passing it through the drying chamber containing the articles to be dried for picking up humidity from the articles, and finally making the humidity condensate by extracting heat from the process air by the heat exchanger. In the heat exchanger, the heat extracted from the process air is transferred to cooling air that exits the dryer, thereby dissipating the heat into the ambient of the dryer without any possibility of recovery.

[0004] In another known dryer of the kind specified above, the process air guide comprises a heat sink and a heat source, wherein the heat sink and the heat source belong to a heat pump disposed within the housing. While this type of dryer is also a condensation-type dryer in principle, it comprises a means to recover the heat which is introduced into the process air by the heat source and extracted from the process air by the heat sink. This means is commonly known as a heat pump; its action is basically a transfer of heat that has been charged through the heat sink to the heat source and including any appropriate rise of temperature, for discharging the heat through the heat source at an elevated temperature. A known type of heat pump includes a closed circuit wherein a refrigerant is circulated, the circuit including two heat exchangers as heat source and heat sink, a compressor to compress refrigerant having exited the heat sink in gaseous state, and forward the refrigerant to the heat source. In the heat source, the refrigerant is liquefied to release heat. Behind the heat source, the liquid refrigerant passes a throttle as embodied in a valve, a nozzle, or a capillary, to return to the heat sink at reduced pressure and temperature, to be evaporated upon being charged with heat again, thereby completing the cycle. Other types of heat pumps including a heat pump based on a process of adsorption and desorption and a heat pump basing on the Peltier effect are known.

[0005] It is also known for a manufacturer of dryers to manufacture series of both a condensation-type dryer comprising an electric heater and an air-to-air heat exchanger and a condensation-type dryer comprising a heat pump, establishing a set of the two dryers specified as a basis for mass production by a manufacturer.

[0006] It is an object of the present invention to specify a set of a type as defined in the introduction, wherein both dryers are designed for high structural similarity in spite of their functional differences, to allow use of equal or similar parts for their manufacturing.

[0007] This object is achieved by a set as specified in the independent claim attached hereto. Preferred embodiments of the inventive set are specified in the dependent claims attached hereto. Combinations of such preferred embodiments are also understood to constitute preferred embodiments within the scope of the present invention.

[0008] Accordingly there is specified, in accordance with the invention, a set having a first dryer and a second dryer, wherein each dryer comprises a respective housing enclosing a respective interior, each housing comprising a respective front wall and a respective back wall, a respective drying chamber disposed within said housing, and a respective process air guide tor guiding process air through said respective drying chamber for drying articles disposed therein, wherein each process air guide comprises a respective back channel disposed on said respective back wall outside said respective interior, each back channel projecting into said respective interior through a respective first hole and a respective second hole in said respective back wall, wherein each first hole is placed below each respective second hole with respect to a respective vertical axis, and wherein each process air guide is configured for guiding the process air through each respective back channel from said respective first hole to said respective second hole, and from said respective second hole into said respective drying chamber, wherein, in said first dryer, said respective process air guide comprises an air-to-air heat exchanger disposed within said respective housing, and an electric heater disposed within said respective back channel, and wherein, in said second dryer, said respective process air guide comprises a heat sink and a heat source, said heat sink and said heat source belonging to a heat pump disposed within said respective housing, and wherein, in said first dryer, said respective second hole is a single passage for said respective back channel to project into said respective interior, and that, in said second dryer, said respective back wall has at least one third hole, with said respective back channel projecting into said respective interior through said at least one third hole in parallel to said respective at least one second hole, and with said respective process air guide being configured for guiding the process air from said respective first hole to said respective second hole and said at least one third hole

[0009] Accordingly, the two dryers that constitute the set may be designed and manufactured with a particularly high structural similarity, while retaining advantageous features of each dryer. In particular, the housings and a considerable part of their interior including the drying chambers, control units and condensate collecting devices may be quite equal. However, the first dryer's electric heater is placed at a highly advantageous location for minimizing heat losses at an upside end of the process air guide's back channel on one hand. On the other hand, the second dryer's heat pump may be constructed as a compact unit for placement below the drying chamber in the housing, and space thus saved in the respective process air guide's back channel is utilized to improve the air resistance within the process air guide for better process air throughput by inserting the at least one third hole.

[0010] In accordance with a preferred embodiment of the invention, each said drying chamber is a drum rotatable about a respective rotational axis, wherein each rotational axis placed between said respective first hole and said respective second hole as seen along said respective vertical axis, and wherein, in said second dryer, said at least one third hole is placed between said respective rotational axis and said respective first hole. Thereby, a maximum space is provided in the first dryer's back channel for positioning the electric heater, while a maximum opening for conveying process air into the drying chamber is provided in the second dryer, thus allowing for better operation of the heat pump contained therein. In a more preferred embodiment, said first dryer's electric heater is placed at a common level with said respective rotational axis as seen along said respective vertical axis. Still more preferred, said second dryer's second hole and at least one third hole are arranged within a circle not exceeding a projection of said respective drying chamber onto said respective back wall and parallel to said respective rotational axis. This maximizes the opening in the second dryer, while minimizing heat losses in the first dryer.

[0011] In accordance with another preferred embodiment of the invention, said first dryer's air-to-air heat exchanger is placed below said respective drying chamber as seen along said respective vertical axis, and said second dryer's heat pump is placed below said respective drying chamber as seen along said respective vertical axis. Thereby, particularly good use is made of spaces provided in the housings.

[0012] In accordance with a further preferred embodiment of the invention, said second dryer's at least one third hole is two third holes. Still more preferred said two third holes are arranged symmetrically with respect to said respective vertical axis. This makes a particularly good use of space provided on the second dryer's back wall, retaining any necessary or desirable structural stiffness at the back wall.

[0013] Further details and advantages of the invention may be inferred from the subsequent description of preferred embodiments as shown in the drawing attached hereto. In the drawing,

Fig. 1 shows a schematic front view of a set of two dryers;

Fig. 2 shows a schematic side view of a set of two dryers; and

Fig. 3 shows a diagram of a heat pump.

[0014] As to usage of reference numerals in the drawing, it should be noted that similar features in different figures always carry the same reference numeral. Further, reference numerals from 1 to 9 denote features which are present in strictly one dryer of the said only. Reference numerals from 11 to 26 are used to indicate features of the first dryer which have corresponding features in the second dryer, which corresponding features are denoted with reference numerals from 31 to 47.

[0015] Figure 1 exhibits a set having a first dryer 11 and a second dryer 31, each dryer 11 or 31 comprising a housing 12 or 32 enclosing a respective interior 13 or 33. The view according to Figure 1 exhibits principally the back walls 15 and 35, with the process air guides 17 and 37 and the back channels 19 and 39 being denoted only schematically. To indicate the placements of back channels 19 and 39 on each respective back wall 15 or 35 and outside the respective interior 13 or 33, the back channels 19 and 31 are drawn besides of the back walls 15 and 35. Each process air guide 17 or 37 includes a respective blower 25 or 45.

[0016] In the first dryer 11, an air-to-air heat exchanger 1 is provided to extract heat from process air flowing in through the process air guide 17. Such cooling will effect condensation of humidity which has been picked up by the process air from articles to be dried 18 (see Figure 2). Liquid condensate thus formed will be collected and stored for later removal by means not shown in the drawing for simplicity. The cooling is effected by cooling air which is driven through a corresponding cooling channel of the heat exchanger from an ambient of the first dryer 11 by another blower not shown for the sake of simplicity, and returned to the ambient subsequently. Process air exiting the heat exchanger 1 through the process air guide 17 is driven through the back channel 19, to pass the electric heater 2 disposed therein to collect heat prior to passing the articles to be dried 18 again. To allow the process air to exit the interior 13, a first hole 20 which is indicated only schematically is provided in the back wall 15. Process air exiting the back channel 19 will return into the interior 13 through the second hole 21 for entering the drying chamber 16 as shown in Figure 2. In Figure 1, the shape of the drying chamber 16the circle 23, and is also disposed above an axis of rotation 24 which is indicated by the letter x, as seen along a vertical axis 22. This provides some space in the back channel 19 to place the electric heater 2 at a common level with the rotational axis 24, as seen along the vertical axis 22.

[0017] In the second dryer 31 a heat pump 9 replaces both the heat exchanger 1 and the electric heater 2 as present in the first dryer 11. The heat pump 9 is placed below the respective drying chamber 36 (see Figure 2) and constructed as a compact unit. This has the advantage that the retaining of a refrigerant which is material for the functioning of heat pump 9 is easiest. The heat pump 9 includes both the function of cooling process air entering via process air guide 37, and heating the process air after removing condensate formed as detailed for the first dryer 11 prior to exiting through the process air guide 37 towards the blower 35. From the blower 35, the process air exits the interior 33 through first hole 40, to enter the back channel 39 and flow in an upward direction along the vertical axis 42 to the second hole 41. Besides the second hole 41 which is placed in the same way as the second hole 21 in the first dryer 11, two third holes 8 are provided which allow that the process air passing the back channel 39 is branched into three parallel branches, to pass into the interior 33 through the second hole 41 and the third holes 8 in parallel. Thereby, the flow resistance of the process air guide 37 is considerably reduced, easing operation of the heat pump 9. All the second hole 41 and the third holes 8 are contained within the circle 43 which indicates the shape of the rotatable drying chamber 36 as seen in Figure 2, to give a maximum opening for the process air to pass into the drying chamber 36. The circle is drawn around the rotational axis 44 indicated by letter x. While the second hole 41 is placed above the rotational axis 44, the two third holes 8 are placed below the rotational axis 44 and symmetric to the vertical axis 42 as apparent from the drawing.

[0018] Figure 2 exhibits a side view of the two dryers 11 and 31. Each dryer 11 or 31 has a respective front wall 14 or 34 and a respective back wall 15 or 35. Each back wall 15 or 35 has the back channel 19 or 39 placed thereon with a respective first hole 20 or 40 and a respective second hole 21 or 41 to pass the process air through the back wall 15 or 35. Each blower 25 or 45 is placed in the respective back channel 19 or 39. Each interior 13 or 33 contains a drying chamber 16 or 36, constructed as a rotatable drum 16 or 36 to be driven by a drive means not shown for the sake of simplicity. Each drum 16 or 35 is rotatable about a respective rotational axis 24 or 44, and is filled with articles to be dried 18 or 38. Access into the drum 16 or 36 may be had by opening the respective door 26 or 46 placed on the respective front wall 14 or 34.

[0019] As to the first dryer 11, Figure 2 details the placement of the electric heater 2 at a common level with the respective rotational axis 24. As to the second dryer 31, placement of the third holes 8 below the respective rotational axis 44 is noted. To allow the process air to enter, each drum 16 or 36 has a surface positioned against the respective back wall 15 or 35 containing a multiplicity of permeations to allow for the passing of the process air. Means for sealing between each drum 16 or 36 and the respective back wall 15 or 35 will be needed, but such means are not shown in Figure 2 for the sake of simplicity.

[0020] Figure 3 details the heat pump 9 present in the second dryer 31. The drying chamber 36 is shown schematically with the process air guide 37 arranged to pass the process air through the drying chamber 36 in a closed circuit, In this context, "closed" means not a hermetic sealing, but means only exclusion of any uncontrolled substantial exchange of air between the process air guide 37 and its ambient as long as the second dryer 31 is operating. Establishing of an essential pressure difference between the interior of the process air guide 37 and its ambient is neither intended nor desired, absent pressure differences occurring by circulation of the process air through the process air guide 37.

[0021] Upon exiting the drying chamber 36 through the process air guide 37, the process air which is laden with humidity from articles 38 contained in the drying chamber 36 will first pass a fluff filter 47 which is dedicated to filtering particulate matter which is torn from the articles 38 by the process air from that process air. Such particulate matter is usually specified as fluff or lint. Subsequently, the process air enters the heat sink 3 which is a correspondent of the heat exchanger 1 in the first dryer 11. In the heat sink 3, the process air is cooled to condensate the humidity and strip the liquid thus obtained from the process air. After exiting the heat sink 3 through the process air guide 27, the process air enters the heat source 4 which is a correspondent of the electric heater 2 in the first dryer 11. In the heat source 4, the process air is heated again to be returned to the drying chamber 36 by the blower 45, thus completing its cycle through the process air guide 37.

[0022] In the heat pump 9, both the heat sink 3 and the heat source 4 are heat exchangers which exchange heat between the process air and a refrigerant circulating through the refrigerant circuit 5. The refrigerant is an agent that is condensable and evaporable under suitable conditions of pressure and temperature. In particular, the refrigerant may be selected from the group comprising carbon dioxide, propane, fluorinated hydrocarbons R134a and R152a, and compositions of fluorinated hydrocarbons R407C and R407A. The refrigerant enters heat sink 3 in liquid state, and is evaporated by picking up heat from the process air flowing through heat sink 3. After its evaporation, the refrigerant exits the heat sink 3 and passes by refrigerant circuit 5 to the compressor 7. In the compressor 7, the refrigerant is compressed while retaining its gaseous state, and passed to the heat source 4. In the heat source 4, the refrigerant condensates by releasing heat to the process air also passing through the heat source 4. Subsequently, the refrigerant exits the heat source 4 through the refrigerant circuit 5 in liquid state, and passes through a throttle 6 which will reduce the internal pressure as well as the temperature of the refrigerant. The throttle 7 may be embodied as a nozzle, a capillary or a valve. Subsequent to throttle 7, the refrigerant will return to the heat sink 3, thereby completing its cycle. It may be noted that a real heat pump 9 may contain two heat exchangers instead of one composing the heat source 4, possibly to allow for dissipating excess heat generated by action of the compressor 7. Likewise, two heat exchangers may compose the heat sink 3. Such embodiments are known in the art and are not detailed presently.

[0023] As a conclusion, the present invention defines two dryers constituting a set, which dryers may be designed and manufactured with a particularly high structural similarity but retaining advantageous features of each dryer.

Reference Numerals

[0024] 

1

Air-to-air heat exchanger

2

Electric heater

3

Heat sink

4

Heat source

5

Refrigerant circuit

6

Throttle

7

Compressor

8

Third hole

9

Heat pump

11

First dryer

12

Housing

13

Interior

14

Front wall

15

Back wall

16

Drying chamber

17

Process air guide

18

Articles to be dried

19

Back channel

20

First hole

21

Second hole

22

Vertical axis

23

Circle on back wall

24

Rotational axis

25

Blower

26

Door

31

Second dryer

32

Housing

33

Interior

34

Front wall

35

Back wall

36

Drying chamber

37

Process air guide

38

Articles to be dried

39

Back channel

40

First hole

41

Second hole

42

Vertical axis

43

Circle on back wall

44

Rotational axis

45

Blower

46

Door

47

Fluff filter

Claims

1. A set having a first dryer (11) and a second dryer (31), wherein each dryer (11, 31) comprises a respective housing (12, 32) enclosing a respective interior (13, 33), each housing (12, 32) comprising a respective front wall (14, 34) and a respective back wall (15, 35), a respective drying chamber (16, 36) disposed within said housing (12, 32), and a respective process air guide (17, 37) for guiding process air through said respective drying chamber (16, 36) for drying articles (18, 38) disposed therein, wherein each process air guide (17, 37) comprises a respective back channel (19, 39) disposed on said respective back wall (15, 35) outside said respective interior (13, 33), each back channel (19, 39) projecting into said respective interior (13, 33) through a respective first hole (20, 40) and a respective second hole (21, 41) in said respective back wall (15, 35), wherein each first hole (20, 40) is placed below each respective second hole (21, 41) with respect to a respective vertical axis (22, 42), and wherein each process air guide (17, 37) is configured for guiding the process air through each respective back channel (19, 39) from said respective first hole (20, 40) to said respective second hole (21, 41), and from said respective second hole (21, 41) into said respective drying chamber (16, 36), wherein, in said first dryer (11), said respective process air guide (17, 37) comprises an air-to-air heat exchanger (1) disposed within said respective housing (12), and an electric heater (2) disposed within said respective back channel (19), and wherein, in said second dryer (31), said respective process air guide (17, 37) comprises a heat sink (3) and a heat source (4), said heat sink (3) and said heat source (4) belonging to a heat pump (3, 4, 5, 6, 7; 9) disposed within said respective housing (32), characterized in that, in said first dryer (11), said respective second hole (21) is a single passage for said respective back channel (19) to project into said respective interior (13), and that, in said second dryer (31), said respective back wall (35) has at least one third hole (8), with said respective back channel (39) projecting into said respective interior (33) through said at least one third hole (8) in parallel to said respective second hole (41), and with said respective process air guide (37) being configured for guiding the process air from said respective first hole (40) to said respective second hole (41) and said at least one third hole (8).

2. The set according to claim 1, wherein each said drying chamber (16, 36) is a drum (16, 36) rotatable about a respective rotational axis (24, 44), wherein each rotational axis (24, 44) placed between said respective first hole (20, 40) and said respective second hole (21,41) as seen along said respective vertical axis (22, 42), and wherein, in said second dryer (31), said at least one third hole (8) is placed between said respective rotational axis (42) and said respective first hole (40).

3. The set according to claim 2, wherein, in said first dryer (11), said electric heater (2) is placed at a common level with said respective rotational axis (24) as seen along said respective vertical axis (22).

4. The set according to one of claims 2 and 3, wherein, in said second dryer (31), said second hole (41) and said at least one third hole (8) are arranged within a circle (43) not exceeding a projection of said respective drying chamber (36) onto said respective back wall (35) and parallel to said respective rotational axis (42).

5. The set according to one of the preceding claims, wherein, in said first dryer (11), said air-to-air heat exchanger (1) is placed below said respective drying chamber (16), as seen along said respective vertical axis (22), and wherein, in said second dryer (31), said heat pump (3, 4, 5, 6, 7; 9) is placed below said respective drying chamber (36) as seen along said respective vertical axis (42).

6. The set according to one of the preceding claims, wherein, in said second dryer (31), said at least one third hole (8) is two third holes (8).

7. The set according to claim 6, wherein said two third holes (8) are arranged symmetrically with respect to said respective vertical axis (42).

Drawing