GB2308551A - Air humidifier - Google Patents

Description

TITLE Adiabatic cooling and humidifying device.

DESCRIPTION The invention relates to devices for humidification of air and in particular to a compact unit for humidifying air to provide adiabatic cooling of the surroundings.

The principle of adiabatic cooling or obtaining cooling by the means of latent heat of vaporisation of water has been recorded since Egyptian times. The external dampened surface of water filled, permeable earthenware vessels, rapidly evaporated by the movement of the air in their living quarters, caused a lowering of dry bulb temperature and a raising of humidity, although no heat was introduced or removed from the room.

The modern day equivalent to this device is the earthenware milk bottle cooler.

The principle is the utilisation of the enthalpy or total heat content of the air required to change the water from the liquid state to vapour state, without raising the water temperature. This required energy has the effect of lowering the dry bulb temperature, and increasing the humidity of the surrounding air, the wet bulb temperature remaining constant.

The principle is analogous to the air/textile boundary layer on the surface of recently washed clothes drying on the line, where the air is cooled as the moisture on the clothes evaporates.

Although there are latent cooling devices on the market, based on the same principle, but using dampened wood chips, or fine capillary meshes, pumped water circuits, and household electric power supplies, there exists a need for a device that is truly transportable, energy efficient, and operating on a low electrical supply voltage, inherently safe. Some known humidifying units contain both an open reservoir of water and a power supply, which could cause a risk of electric shock if the unit were knocked over.

The invention provides a cooling and humidifying unit comprising a fan for creating a flow of air along an airflow path from an inlet to an outlet through the unit; an array of surfaces of a water-conducting material in the airflow path; a reservoir of water; and conducting means for the controlled supply of water from the reservoir to the array of surfaces.

The Drawings Figs. 1 to 6 illustrate various applications of cooling and humidifying units according to the invention.

Fig. 7 is a cross section on line A-A of Fig. 8.

Fig. 8 illustrates a cooling and humidifying unit according to the invention in front and side elevations and in plan view.

Detailed Description Referring first to Figs. 7 and 8, a supply diffuser lid [a], secured in place by means of an over centre clip fastener [q) on each side of the device, allows access to three reservoirs [b], each of which are filled with water, plus optionally one droplet of biodegradable bacteriostat.

Caps [c], which have a self regulating water seepage function (subject of a separate patent application) are screwed on to the reservoirs (b), which are inverted over the device and lowered into position.

With the lid [a] secured, and device connected and switched on to the electrical supply, air is drawn in through the simple dual reticulated polyurethane foam filter [d], and travels through plenum [e], splittered duct [f), and fan intake chamber [g). The axial fan [h] pressurises the air and it leaves the discharge chamber through three openings [j).

The air under pressure is forced through three airways of the humidifying cassette [k], each of which supports ten strips of a non-woven, perforated, synthetic viscose, spun fibre constructed material held on lateral rods. The ends of the material are secured at the base by longitudinal splints through the material perforations.

Six thin strips of the viscose material leave the base of each cap [c), are in contact with and dampen one of three strips each composed of two layers of the viscose material laid on the internal floor of the device. These layers run under and transmit moisture to the bottom ends of the viscose material held in the cassette, and also vertically up the viscose material into the main air path. The pressurized air supply passes through the perforations of the dampened viscose material, where the moisture is transferred from the fine spun viscose fibres into the airstream.

Alternatively, the sheets of viscose material may be arranged parallel to the airflow through the cassette, so that the air flows between the sheets rather than through the perforations of the material, thereby encountering less resistance.

The air supply leaves the cassette at [1], to turn vertically past the reservoirs [b] into plenum [m], to enter one of the three supply jet diffusers [n], which are adjustable for supply direction and air flow rate by means of pivot and damper arrangement [p], to supply the treated air into the room [r) as desired.

For general maintenance the filter [d] may be removed and vacuum cleaned or washed under running water, shaken dry and replaced. For cassette [k] replacement, or washing under running water to remove pollen and fine dust, diffuser lid [a] is unclipped and removed, top [u] is unscrewed and removed, the filter element [d] is removed, the airways and fan arrangement, constructed of sound insulation [v] and divisions [w] can then be removed vertically once the low voltage electrical conductors serving the fan are released at connection block [x]. It is advised that the cassette be replaced at the beginning of the season of use, together with the three double layer floor strips. If it is desired to switch off the device for an appreciable time, the reservoirs should be removed and the fan left running for thirty minutes in order to dry the internal viscose material.

The 12V 5W electrical conductors ty] leave the device to connect the power source - either a rechargeable battery (with optional 12V 10W solar cell) or the mains voltage adapter (as shown in Fig. 8). The low power and voltage requirements of the unit contribute to both its efficiency and its safety.

It is advisable to use either a fresh air source for the intake air supply, or to ensure that effective natural ventilation occurs in the room.

The supply air dry bulb temperature may be approximated as 105% intake air wet bulb temperature or, conversely, the intake air condition raised to approximately 95% relative humidity.

During periods of high temperature, three extra reservoirs with water tight caps, 90% full of water, may be left in the domestic refrigerator, or if placed upright and caps left loose, in the domestic freezer overnight, in order to gain extra cooling effect during the hottest time of the following day.

For persons suffering from common colds, bronchial, asthmatic or other respiratory conditions, symptoms may be alleviated. Benefit may be derived from the inhalation of oil vapours suited to the ailment, by positioning one or two caps [s] as shown containing a reticulated polyurethane foam filter [t] onto which a few drops of the particular oil are placed. Various fragrant oils may also be used to enhance or create character in a room by pervading the atmosphere.

The device may be used in a wide variety of applications, and various benefits derived from its use. For example, with a natural ventilated room air condition in the region of 270Cdb, 180Cwb and 40% saturation, the device can supply air at approximately 18.50Cdb, 180Cwb and 95% saturation, varying slightly with prevailing conditions, effectively giving over 80Cdb cooling. For an arid desert ambient condition of 360Cdb, 200Cwb and 20% saturation, a supply condition of 20.50Cdb, 200Cwb and 95% saturation can be achieved, giving over 15 Cdb cooling and consuming less energy than 10W.

Figure 1 shows a standard arrangement for fresh air intake, with a hit and miss grille [A) and flexible length of ductwork [B], the device being connected via an electrical mains voltage adaptercJ.

Figure 2 indicates a typical set-up for a building in a semi-tropical or arid region and employs the use of a 12V battery [A], which may be re-charged after three days' continual use. The device may be run by means of a high quality, industrial grade, polycrystalline silicon photovoltaic module [B] (a solar cell limited to 13.8V, 10W), which drives the fan and automatically re-charges the battery during daylight hours for continuous duty throughout the night.

Figure 3 indicates a method of obtaining a fresh supply for a household with a fireplace [C]. Air is drawn into the chimney pot [A], down chimney [B], and with a blanking-off sheet [D] having flexible seals around the device, provides a positive air path to the unit.

Figure 4 shows device usage for a typical radiator heated office utilising natural ventilation by means of window [A]. For office buildings with existing central comfort cooling plant installations, ceiling mounted split cassette, or through the wall units, the cooling coils in the units condense a large percentage of the moisture in the recirculated/fresh air mixture. The resultant low temperature supply air is also low in moisture content, low enough to cause unpleasant discharges of static electricity to occur, generated by friction between footwear and synthetic floor coverings. A low moisture content can, when combined with low fresh air ventilation rates, also produce sick building syndrome symptoms of headaches, various sinus problems and respiratory disorders relating to dry throats.

Figure 5 indicates hospital bed usage in countries with high temperatures, dry atmospheres, and low energy electrical power capabilities in the wards. Considerable alleviation of heat stress may be achieved for patients suffering from bone fractures or from diseases requiring cooler and high humidity air conditions than naturally available. A supporting framework [A] is secured to the bed frame and covered with a canopy over the top and access panels [B] of transparent plastic around the sides and foot end. The device is positioned on bracket [C] and a number of devices may be run from one 12V rechargeable battery.

Figure 6 shows an application in a florists, where some potted plants and cut flowers will have a longer shelf life. A bench mounted greenhouse has the device positioned at low level, with fresh air hit and miss grille [A) adjacent to the intake filter. If required this grille may be connected as shown in Figure 1 to give 100% fresh air, in which case the humid air will circulate internally and escape through door crackage [B]. For storage of pot grown tropical orchids etc, a thermostatically controlled heater [C] may be required. In the case of cut flower storage, and when the fresh air intake is not duct connected, a high level hit and miss grille will be required to provide a degree of natural ventilation, in order to keep internal conditions pleasant.

Other uses of the device apart from office, home and workshop, summer comfort and allergy symptom reduction include: during exercise periods in keep-fit, dance, and home gym situations; during boating or caravan holidays; in antique shops preventing furniture drying out and cracking; in musical instrument shops enabling pianos etc to remain in tune for longer periods of time; even to simple uses for example whilst ironing clothes, where a more comfortable environment for the job in hand can be ensured.

Claims (11)

1. A cooling and humidifying unit comprising: a fan for creating a flow of air along an airflow path from an inlet to an outlet through the unit; an array of surfaces of a water-conducting material in the airflow path; a reservoir of water; and conducting means for the controlled supply of water from the reservoir to the array of surfaces.

2. A cooling and humidifying unit according to claim 1, wherein the means for conducting water from the reservoir to the array comprises a layer of water-conducting material that is in contact with the reservoir and with the surfaces of the array.

3. A cooling and humidifying unit according to claim 2, wherein the reservoir is a sealed unit, including a generally planar base in contact with the water-conducting layer; and wherein the base of the reservoir includes at least one aperture, through which is threaded a strip of water-conducting material to provide a path for conducting water from the reservoir to the water-conducting layer.

4. A cooling and humidifying unit according to any preceding claim, wherein the array comprises a plurality of sheets of the water-conducting material arranged generally parallel to the direction of airflow through the array.

5. A cooling and humidifying unit according to any preceding claim, wherein a non-woven fibre fabric is used as the water-conducting material.

6. A cooling and humidifying unit according to claim 5, wherein the fibre of the non-woven fabric is viscose.

7. A cooling and humidifying unit according to any preceding claim, wherein the fan is disposed in the airflow path between the inlet and the array.

8. A cooling and humidifying unit according to claim 7, wherein ducts for conducting air from the inlet to the fan are arranged around the fan to shield the noise of the fan from the outside of the unit.

9. A cooling and humidifying unit according to any preceding claim, wherein the reservoir is disposed in the airflow path between the array and the outlet.

10. A cooling and humidifying unit according to any preceding claim, including means at the outlet for controlling the direction of flow of humidified air from the unit.

11. A cooling and humidifying unit substantially as described herein with reference to the drawings.