EP1723374A2

EP1723374A2 - Solar clothes dryer

Info

Publication number: EP1723374A2
Application number: EP05718849A
Authority: EP
Inventors: Amnon Yogev
Original assignee: Aytec Avnim Ltd
Current assignee: Aytec Avnim Ltd
Priority date: 2004-03-10
Filing date: 2005-03-09
Publication date: 2006-11-22
Also published as: CN1930434A; BRPI0508523A; IL177912A0; WO2005084138A2; EP1723374A4; WO2005084138A3; IL160804A0

Abstract

An apparatus for drying of laundry by use of solar energy, comprising: (i) at least one inner compartment (2) with at least one side containing a solar energy absorbing material on the exterior surface, at least one air inlet at the upper side and at least one air outlet at the lower part, and means for hanging the laundry; (ii) one outer compartment (1) that has at least one transparent side and encloses said inner compartment, thus forming a space (3) between them used as an airway; and (iii) at least one air inlet (4) on the lower part of at least one side and/or at the bottom side of the outer compartment for conveying air from the outside surroundings into the space between the outer and inner compartments, and at least one air outlet on at least one side of the outer compartment. The apparatus may also be foldable or portable.

Description

SOLAR CLOTHES DRYER

FIELD OF THE INVENTION The present invention relates to an apparatus for drying laundry by use of solar energy and, in particular, to such an apparatus comprising at least one inner compartment which is the laundry compartment and one outer compartment enclosing the at least one inner compartment such that a space is formed which serves as airway. Air from the surroundings enters the apparatus and is heated by solar energy, rises through the airway and enters the laundry compartment. The air passing through the laundry enhances evaporation of water; this cools the air and thus increases its specific weight, causing it to descend and to exit the apparatus through air outlets. This continuous flow of hot air dries the clothes.

BACKGROUND OF THE INVENTION The known methods of drying laundry include the use of an electric or gas tumbling dryer or a manual clothesline. The use of a gas or electric dryer is expensive and the tumbling action is detrimental to the clothes. The use of a clothesline is esthetically unappealing and mostly limited to hot sunny weather. Leaving the clothes exposed to sunlight also causes the colors to fade. Henceforth, several attempts have been made to use solar energy to power clothes dryers for drying clothes. Some known solar energy powered clothes dryers include: U.S. Pat. No. 4,514,914 describes an electrical clothes dryer, which may be aided by water heated through a solar plate collector. There is no use of the effect of warm air rising and of air cooled by the laundry falling and thus pulling more warm air. Moreover, in this example, the air cooled by evaporation disturbs the convection process. The air must be forced through the clothes by means of a blower. This dryer also uses tumbling action as in conventional dryers. U.S. Pat. No. 4,279,082 describes a dryer air inlet construction for enabling selection of air inlet to a conventional clothes dryer. The operator may choose between regular air inlet and solar heated air coming through a duct from another part of the house. This system does not use the solar heated air as the primary means for drying clothes but as a supplemental source of hot air assisting in reaching the desired temperature in a regular electrical clothes dryer. It is not portable or foldable. Moreover, there is no use here of the effect of air-cooling by water evaporating from the fabrics for pulling in more hot air. U.S. Pat. No. 5,809,663 describes a portable, solar powered clothes dryer, comprising a dark-colored hamper, and a solar powered motor. The motor rotates the hamper and the clothes within are dried by the heat energy from the sun collected in the dark hamper and the air entering through holes in the hamper's body. Here too, there is no use of the cooling effect for conveyance of the air through the clothes and there is use of tumbling. Australian patent, AU-B 10341/76 describes yet another solar clothes dryer comprising a rotary assembly of horizontal arms used for hanging wet clothes. A cover comprising of a clear plastic pyramid with a vent at the point of the pyramid fits over the horizontal arms. Sunlight travels through the plastic cover and heats the clothes. The fan extracts the moisture to avoid water accumulation. This invention does not use the cooled air for the purpose of airflow.

SUMMARY OF THE INVENTION The present invention relates to an apparatus for drying of laundry by use of solar energy, comprising: . (i) at least one inner compartment with at least one side containing a solar energy absorbing material on the exterior surface, said inner compartment comprising at least one air inlet at the upper side and at least one air outlet at the lower part of at least one of the sides, and means for hanging the laundry; (ii) one outer compartment that has at least one transparent side and encloses said at least one inner compartment, thus forming a space between the outer compartment and the at least one inner compartment, wherein said space can be used as an airway; and (iii) at least one air inlet on the lower part of at least one side and/or at the bottom side of the outer compartment for conveying air from the outside surroundings into the space between the outer and the at least one inner compartment, and at least one air outlet on at least one side of the outer compartment for exit of the cooled air coming from the at least one inner compartment. Thus, the present invention is a solar laundry dryer that consists of two parts: an inner and an outer unit. The first unit consists of one or more inner laundry compartments, for drying different types of clothes or tissues. In one embodiment, the apparatus has a sole inner compartment. The exterior surface of at least one of the sides of the inner compartment contains a solar energy absorbing material. This side should be a side that faces the sun and can be the ceiling (upper part) and/or any other side of the inner compartment that faces the sun. Preferably, the at least one side of the at least one inner compartment is made of a thermally insulating material, that can be a multi-layered plastic material and may have cavities between the layers or it can be a plastic foam material. Examples of thermally insulating materials include, but are not limited to, polypropylene, high-density polyethylene and melamine. The plastic thermally insulating material may be black (i.e., contains carbon black) and will then serve also as the solar energy absorbing material, and this constitutes a preferred embodiment of the present invention. In a more preferred embodiment, this material is black polypropylene. Inside the inner compartment there are means for hanging up the laundry, such as retractable clotheslines. The second unit, the outer compartment, is a structure that encloses the one or more inner compartments. The difference in the size of the two units creates a space between them that is used as an air passage. The outer compartment should have at least one side that is made from transparent material and that at least one transparent side should be facing the side on the inner compartment that has the solar energy absorbing material. The transparent side is preferably made of a double-glazing transparent material. Preferably, the double-glazing layers of the transparent plastic material contain air cavities or, alternatively, the two layers are joined together by parallel lines of hollow tubes. This minimizes the heat convection between the two layers. Preferably, the double-glazing consists of two polycarbonate sheets or other lightweight material layers joined together by parallel lines of hollow tubes. It is self-understandable that other transparent materials may be used. In one preferred embodiment, the double-glazing material has a UV- protected surface coating, as commercially available, to protect against outdoor weathering. This UV-surface may be preferably designed to serve as an anti- reflective coating for most of the visible light spectrum. These UV protected double-glazing sheets act as a screen and offer about 80-90% light transmission, thus trapping the heat inside the air passage between the outer and the inner compartment similarly to what occurs in a greenhouse. Not all sides of the outer compartment have to be made from transparent material. Preferably, at least one of the sides that faces the sun is made of transparent material and, more preferably, all sides of the outer compartment are made of transparent material. The outer compartment has one or more air inlets for conveying air from the outside surroundings into the space between the outer and the at least one inner compartment. In one embodiment, the air inlets are located at the lower part of at least one side of the outer compartment. In another embodiment, the air inlets are at the bottom side of the outer compartment. In an additional embodiment, there are air inlets both at the lower part of at least one side and at the bottom side of the outer compartment. In a further embodiment, the outer and / or inner compartments are bottomless. The outer compartment further contains at least one air outlet on at least one side of the outer compartment for exit of the cooled air coming from the at least one inner compartment. The outer compartment can be connected to the inner compartment in a variety of ways known to those skilled in the art. In one embodiment, all sides of the inner and the outer compartment are connected to each other such as creating a space between them for the air passage. In another embodiment, the sides of the inner and outer compartment that are not facing the sun can be connected in such a way that there is no space between the two compartments on that side. In a further embodiment, the inner and the outer compartment are not originally connected to each other, but the apparatus contains means for connecting the two units to each other. According to the present invention, the drying of the laundry occurs by means of air movement resulting from heating of air by the sun and cooling of the hot air by the evaporation of water from the laundry. Thus, air from the outside surroundings enters into the space between the outer and the at least one inner compartment through one or more air inlets on the lower part of at least one side of the outer compartment. The air is heated by contact with the heated exterior surface of the inner compartment's walls containing the solar absorbing material, preferably black propylene, and rises up the airway between the outer and inner compartments. The hot air then enters the laundry inner compartment through the one or more air inlets at the upper side (ceiling) of the inner compartment, passes through the clothes hung in the compartment and enhances evaporation of water. This process cools the air and thus increases its specific weight, causing the cooled air to descend towards the bottom of the inner compartment and to exit through the one or more air outlets located at the lower part of one of the sides of the inner compartment. The air outlet from the inner compartment and the air outlet from the outer compartment are preferably located higher than the air inlet of the outer compartment through which air from the outside surroundings enters the airway between the outer and inner compartment, although any other suitable configuration is also encompassed by the invention. The continuous flow of hot air through the inner laundry compartment causes the clothes to be dried. In one preferred embodiment of the present invention, the ceiling of the inner compartment consists of two separate layers of black slats. There is a gap between the first and second layer. Slats of each layer are spaced from each other by openings, for example, by the width of a slat, wherein preferably in the lower layer the slats are wider than in the upper layer, such that light coming in at an angle will also be absorbed by the slats. In this manner, the hot air enters the inner compartment through the gaps between the layers and is evenly distributed throughout the inner compartment. An access means for the hanging and removing the laundry, such as a door, can be placed on the upper side or on any of the sidewalls of the apparatus. In another preferred embodiment of the present invention, the apparatus further contains means for folding the apparatus. The means for folding the apparatus of the invention may be hinges or any other means that allow the compartments to be folded when not in use, thereby making the apparatus more convenient by taking up less storage space. The folding mechanism for the inner and outer compartment can be made by those skilled in the art to fold together or independently of one another. In one embodiment of the present invention, the apparatus further comprises one or more heaters, which may be electric heaters or water radiators, preferably a radiator using hot water from a domestic solar water heater. These heaters should be preferably installed in the airway between the inner and outer compartments. However, the heater can be placed in the inner compartment as well. The heaters serve as a backup system to heat the air between the outer and inner compartments at nighttime or on cloudy days or whenever the solar radiation is not sufficient. In another embodiment of the present invention, the apparatus contains one or more air fans as a means for controlling the heat inside the inner clothes compartment. The fans are mounted on the upper part of the apparatus between the outer and inner compartments, facing downwards for blowing air into the inner compartment in order to prevent excessive heating of the air that enters the inner compartment. In another embodiment of the present invention, the apparatus comprises at least one thermostat to regulate the temperature of the fans and heaters. When more than one inner compartment is used, separate thermostats can regulate each compartment individually. In a further embodiment of this invention, one or more mirrors are connected, for example, by means of hinges, to the outer compartment of the apparatus to enhance the solar radiation entering the outer compartment. The mirrors can be adjustable or fixed or can be removable from the apparatus. The mirrors can be made from lightweight durable materials such as a metal-coated plastic material. The plastic material is preferably a polycarbonate and the metal is preferably aluminum or silver. In yet another embodiment of this invention, a solar air heater is attached to the air inlet between the inner and outer compartments, in order to increase the temperature of the air entering the apparatus. In another embodiment of this invention, the apparatus comprises means for connecting the apparatus to a wall or railing for easier storage. In another embodiment of this invention, means for making the apparatus portable is provided such as a support frame having a plurality of wheels or wheels that are attached directly to the compartments for maneuvering and aiming the apparatus towards the sun or for moving the apparatus from one desired location to another. The above and other features of the invention will become apparent from the drawings, the description hereinafter and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 illustrates a frontal view of a dryer according to one embodiment of the invention. Fig. 2 illustrates a view looking down on a dryer according to Fig. 1. Fig. 3 illustrates a view on the dryer of Fig. 2 with mirror attachments. Fig. 4 illustrates a side perspective view of a dryer according to one embodiment of the invention. Figs. 5 a-g illustrates one embodiment of a dryer according to the invention and its folding steps. Fig. 6 illustrates a perspective view of two separate layers of black slats of the ceiling of the inner compartment of a dryer according to the invention showing the spaces between the black slates for the hot air inlet to the inner compartment. Fig. 7 illustrates a solar air heater attached to the air inlet, the apparatus itself is mounted on a wheeled cart.

DETAILED DESCRIPTION OF THE PREFERED EMBODIMENTS Referring now to the drawings, Fig. 1 shows a frontal view of a dryer according to one preferred embodiment of the invention. The area 2 is the inner compartment made preferably of dark, lightweight thermal insulating material. The outer compartment 1 fits over the inner compartment 2 creating a space 3 between both compartments. The outer compartment 1 is a larger transparent box, preferably double-glazing, preferably of lightweight plastic material with hollow tubes between the transparent layers for transmission of the solar radiation and for thermal insulation from the surroundings. Such a structure may be made of any transparent plastic material, such as polyacrylic or polystyrene. A preferred plastic due to shatter resistance and good temperature resistance is polycarbonate. A structure as described is available in the market place from the General Electric Company under the trademark Polygal. Laundry is put into the inner compartment 2. Air enters the outer transparent compartment 1 through one or more openings 4 on the lower part of one or more sides of the outer compartment 1. The openings 4 are preferably located lower than the opening on the side of the inner compartment 2. The air is heated in the space 3 by solar radiation absorbed by the exterior black surface of the inner compartment 2, which acts as a solar radiation collector. The hot air then rises to the upper part of the dryer between the tops of the inner compartment 2 and the outer compartment 1 as indicated by ascending arrow on the left and enters the inner compartment 2 through the openings for air inlet (not shown) on its ceiling. The hot air passes through the wet laundry causing the water to evaporate. This transfer of energy cools the air and causes the cooled air to descend as indicated by the descending curved arrow and to exit the inner compartment through an air outlet at its lower part on the side not facing the sun 4a. Referring now to Fig. 2, it shows an embodiment of the dryer of the invention including a heater 5 placed in the space 3 between the two compartments. The heater can be used in situations when there is not enough solar radiation. Also shown is an air fan 6 mounted under the ceiling of the outer compartment and directed downwards to regulate the heat resulting from the heater and/or the hot air. In another embodiment, the fan may be mounted close to the ceiling inside the inner compartment, and also faces downwards. It should be understood that the phenomenon of the continuous movement of the hot air ascending to the upper part of the device and the exit of the cooled air, after passing through the laundry, is by itself independent of heating by solar radiation. Therefore, the embodiment of an apparatus consisting only of backup heaters, without the use of solar energy, is also encompassed by the present invention. Fig. 2 further shows the door 7 through which the user can introduce into or take out the laundry from the inner compartment 2. The door 7 may consist of separate doors of the ceilings of both outer compartment 1 and inner compartment 2 or it may be one door when both compartments are connected. The door 7 can be placed with its hinge situated on the side facing the sun 8 or the side not facing the sun 9. Note: Figure 2 shows the apparatus where the inner and outer compartments are connected without a space between them on the side not facing the sun 9. Fig. 3 shows an embodiment in which removable tilted mirrors 10 are connected to the apparatus depicted in Fig. 2. The mirrors, preferably made of a metal-coated plastic material, more preferably of polycarbonate coated by aluminum or silver, can be attached using hinges to the outer unit and placed at such an angle as to maximize the amount of solar radiation crossing the transparent outer compartment, effectively increasing the solar interface by reflecting more sunlight upon the collector, namely the exterior walls of the inner compartment. Fig. 4 is a side view of a dryer according to the invention, showing more clearly the space 3 formed between the outer compartment 1 and the inner compartments 2. Figs. 5a-5g show one preferred embodiment of a foldable apparatus (not in scale) according to the invention and its folding steps. Fig. 5a shows the foldable dryer fully unfolded. Between the transparent outer compartment and inner compartment are depicted two air fans (round structures facing downwards). In Fig. 5b, the upper side of the compartment is connected to one of the sides comprising of the length of the compartment with the use of a hinge. The hinged connection allows the upper side to open upward. In Fig. 5c, the sides comprising the width of the compartment are connected to the sides comprising the length of the compartment with hinges that fold inward. The sides comprising the width of the compartment themselves are hinged at midpoint so that they themselves can fold onto themselves. Fig. 5d shows the sidewalls of the apparatus fully folded. Figs 5e and 5 f show the top of the compartment, sliding forward and finally folding into the collapsed sides as shown in Fig. 5g. Fig. 6 illustrates one embodiment of the ceiling of the inner compartment 2 consisting of two separate layers 11 and 12 of black, solar energy absorbing slats. The slats of each layer are separated by a space 13 between each two slats, each such space preferably corresponding to the width of a slat. The upper layer 11 will have the slats spaced in the opposite way as the slats in the lower layer 12 in such a way that, when looking from above or from the side, the two layers are superimposed and look as one continuous black surface. Fig. 7 illustrates another embodiment of the invention, wherein a solar air heater 15 is attached to the air inlet of the apparatus. The air heated by the solar air heater 15 rises through the space 3 between the inner 2 and outer compartment 1 of the apparatus and enters into the inner compartment 2. In a further embodiment of the present invention, the apparatus can be mounted on a wheeled cart 18 in order to make the dryer portable, and also to facilitate the turning of the system towards the direction of the sun. The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without undue experimentation and without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology, employed herein is for the purpose of description and not limitation. The means, materials, and steps for carrying out various disclosed functions may take a variety of alternative forms without departing from the invention. Thus the expression "means to..." and "means for...", or any method step language, as may be found in the specification above and/or in the claims bellow, followed by a functional statement, are intended to define and cover whatever structural, physical, chemical or electric element or structure, or whatever method step, which may now or in the future exist which carries out the recited function, whether or not precisely equivalent to the embodiment or embodiments disclosed in the specifications above, i.e., other means or steps for carrying out the same functions can be used; and it is intended that such expressions be given their broadest interpretations.

Claims

1. An apparatus for drying of laundry by use of solar energy, comprising: (i) at least one inner compartment with at least one side containing a solar energy absorbing material on the exterior surface, said inner compartment comprising at least one air inlet at the upper side and at least one air outlet at the lower part of at least one of the sides, and means for hanging the laundry; (ii) one outer compartment that has at least one transparent side and encloses said at least one inner compartment, thus forming a space between the outer compartment and the at least one inner compartment, wherein said space can be used as an airway; and (iii) at least one air inlet on the lower part of at least one side and/or at the bottom side of the outer compartment for conveying air from the outside surroundings into the space between the outer and the at least one inner compartment, and at least one air outlet on at least one side of the outer compartment.

2. The apparatus according to claim 1 wherein the at least one side containing a solar energy absorbing material is made of a thermally insulating material.

3. The apparatus according to claim 2 wherein said thermally insulating material is a multi-layered plastic material.

4. The apparatus according to claim 3 wherein said multi-layered plastic material has cavities between the layers.

5. The apparatus according to claim 3 wherein said multi-layered plastic material is a plastic foam material.

6. The apparatus according to any one of claims 2 to 5 wherein said thermally insulating material is polypropylene, high-density polyethylene or melamine.

7. The apparatus according to claim 6 wherein said thermally insulating material is black and serves as the solar energy absorbing material.

8. The apparatus according to claim 7 wherein said at least one side of the inner compartment is made of black polypropylene.

9. The apparatus according to any one of claims 1 to 8 wherein the at least one transparent side of the outer compartment is made of a double-glazing transparent material.

10. The apparatus according to claim 9 wherein the double-glazing transparent material consists of two polycarbonate sheets or other lightweight material layers.

11. The apparatus according to claim 9 wherein the transparent double-glazing layers include air cavities or are joined together to form hollow tubes.

12. The apparatus according to any one of claims 9 to 11 wherein the transparent double-glazing material has a UV-protected surface.

13. The apparatus according to claim 12 wherein the UV-protected surface is designed to serve as an anti-reflective coating for most of the visible light spectrum.

14. The apparatus according to any one of claims 1 to 13 wherein all sides of the outer compartment are transparent.

15. The apparatus according to any one of claims 1 to 14 wherein the upper side of the inner compartment contains the solar energy absorbing material.

16. The apparatus according to claim 15 wherein the upper side and at least one other side of the inner compartment contain the solar energy absorbing material.

17. The apparatus according to any one of claims 1 to 16 wherein the inner and the outer compartments are connected to each other.

18. The apparatus according to any one of claims 1 to 16 with means for connecting the inner compartment to the outer compartment.

19. The apparatus according to any one of claims 1 to 18 further comprising at least one backup heater.

20. The apparatus according to claim 19 wherein said at least one heater is an electric heater.

21. The apparatus according to claim 19 wherein said at least one heater is a hot water radiator.

22. The apparatus according to any one of claims 19 to 21 wherein at least one heater is placed in the space between the outer compartment and at least one inner compartment.

23. The apparatus according to any one of claims 1 to 22 further comprising at least one air fan for preventing excessive heating.

24. The apparatus according to claim 23 wherein the at least one fan is mounted under the ceiling of the outer compartment or close to the ceiling inside the inner compartment, and said at least one fan faces downwards.

25. The apparatus according to any one of claims 19 to 24, further comprising at least one thermostat.

26. The apparatus according to claim 25, wherein said thermostat controls the temperature of at least one air fan and / or backup heater.

27. The apparatus according to any one of claims 1 to 26 further comprising at least one mirror, optionally adjustable, to enhance the solar radiation.

28. The apparatus according to claim 27 wherein the at least one mirror is made of metal-coated plastic material.

29. The apparatus according to claim 28 wherein the plastic material is polycarbonate and the metal is aluminum or silver.

30. The apparatus according to any one of claims 1 to 29 further comprising means for making it portable.

31. The apparatus according to claim 30, wherein said means are wheels.

32. The apparatus according to any one of claims 1 to 31 further comprising means for connection to a wall or railing.

33. The apparatus according to any one of claims 1 to 32 further comprising means for accessing the laundry on the top or on one of the sides of the apparatus.

34. The apparatus according to any one of claims 1 to 33, wherein a solar air heater is attached to the air inlet.

35. The apparatus according to any one of claims 1 to 34 further comprising means for folding the apparatus.

36. The apparatus according to any one of claim 35 with means for folding the inner and outer compartment independently of each other.