Gas and liquid contact apparatus – Contact devices – Porous sheet
Reexamination Certificate
2000-09-12
2002-04-09
Bushey, C. Scott (Department: 1724)
Gas and liquid contact apparatus
Contact devices
Porous sheet
C261SDIG001, C239S553500
Reexamination Certificate
active
06367782
ABSTRACT:
FIELD OF THE INVENTION
This invention relates broadly to apparatus for contacting large surfaces of a liquid, such as water, with a gas, such as air, for the purpose of humidifying air. More particularly, it refers to an improved means for the uniform distribution of water to an evaporative element in such an apparatus.
BACKGROUND OF THE INVENTION
The humidification of dry air normally occurring in buildings during the winter heating season by the evaporation of water therein, depends upon the efficient evaporation of water from the continuously wetted surfaces of an evaporative element or pad as, for example, an interstitial body having extensive surfaces to provide a large area of contact of the air with water. The air to be humidified is forced through the openings of the element where it contacts the wet baffles or fibers of which the evaporative element is composed. Exposure of relatively large water surfaces in this way results in the evaporation of large amounts of the water.
An example of this type of evaporating apparatus is disclosed in the assignee's U.S. Pat. No. 5,211,891 issued May 18, 1993. In this apparatus, the humidifier includes a base portion and a removable cover. An evaporative pad or water panel is removably disposed within the base. A water feed tube is connected to a solenoid valve equipped with a small orifice for controlling the flow of water therethrough and supplies water to a trough-like distribution tray. The water flows by gravity from the distribution tray through openings and down through the water panel. Air is forced through the water panel and the air evaporates water on the water panel and humidified air is delivered to the house, building or heated space. The evaporative water panel is held within a frame mounted in the base portion in order to reduce the air bypass around the water panel, and to contain mineral deposits that build up on the water panel as a result of the evaporative process.
A typical prior art distribution tray is a plastic reservoir 0.875 inches deep which spans the top of a water panel. Within the reservoir are six cylindrical towers with V-shaped metering weirs intended to evenly spread the water to six places on the top of the water panel. The interior of this distribution tray is coated with a spray adhesive and pumice powder in the hopes of improving the evenness of the water metering. This pumice coating process is a very undesirable manufacturing step. It is labor intensive, messy and very hard toontrol, so that the coating evenly cogs all parts. When the coating is not uniform, the metering rate of individual weirs is not equal. By design, the distribution tray must be relatively large to contain an adequate water level for the metering weirs to function. This directly effects the cost of the part and indirectly the cost of the humidifier as a whole since the humidifier must be sized to contain the distribution tray. This larger size effects versatility in installation of the humidifier, since more space is required.
Another critical problem arises during installation. Weir-type metering systems are very sensitive to being mounted level. That is, the plane of the upper surface of the distribution tray should be parallel to the earth's horizon. If mounted at an angle, water will be deeper at one weir than the others and water flow will be uneven. In some cases, all the water may flow out only the lowest weir. Non-uniform shape of the individual metering weirs is another major problem. In manufacture, the weir is effected by molding flash, trimming of flash, warpage of plastic, and uneven coating of pumice. In actual use, mineral deposits may change the shape, cleaning can scrape away some of the pumice coating, or the pumice coating erodes away in some water conditions. When the metering weir is not uniform, water is not evenly distributed to the water panel. Another problem with the prior art distribution tray is its slow response time. When the humidifier turns on, it takes about 30 seconds for enough water to fill the distribution tray for the metering weir to begin supplying water to the water panel. Yet another problem is that the metering forces of a weir design are very low and easily disturbed to cause uneven flow. The operating pressure from the reservoir water level is only about 0.014 psi when all six weirs are functioning. This low pressure is within a realm of molecular water forces such as surface tension and capillary force. The metering rate is thus easily disturbed. When one weir does not start or stops flowing, the reservoir water level rises slightly and flow diverts to the remaining weirs. The pressure increase on the blocked weir is only about 10%, so there is very little force increase to encourage the weir to restart. Even if all but one weir is blocked, the pressure increases to only about 0.033 psi, still not enough to encourage blocked weirs to restart.
All of the above problems degrade the performance of humidifiers. Evaporation from the humidifier water panel is best when it is evenly covered with an adequate supply of water. Uneven distribution of water can lead to loss of wetted surface in the water panel and reduced evaporation.
Most competitor humidifiers are using variations of the weir. Different weir shape, placement, and materials are used. Some use surface textures or die cut wicking materials in place of pumice coating. All of these have the same drawbacks as the systems described above. One design lets the water stream from a single nozzle drop onto a series of ribs which divide the flow and guide each resulting stream to an outlet hole. This method takes up about the same space and has part costs similar to the prior art system. It also has low control forces and flow might easily be made to distribute unevenly. Other competitors avoid the distribution system by dipping the evaporator media in a reservoir. Stationary versions rely on wicking ability of media. These are not currently used on furnaces and performance is weak unless a recirculating pump is added with a high flow rate distributor. Dynamic systems form evaporator media in a wheel or drum shape that rotates through a reservoir to wet out. These are undesirable due to mechanical complexity and added cost.
Accordingly, it is desirable to provide a water distributor for humidifiers or other similar evaporative apparatus which overcomes the numerous problems and drawbacks set forth above. It is also desirable to provide a humidifier which replaces the prior art distribution tray, and provides a better water distribution to the evaporative water panel.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide a water distributor which eliminates the prior art trough-like distribution tray and pumice coating thereof.
It is also an object of the present invention to provide a water distributor which enables a consistent, even flow of water at a desired flow rate therethrough and a quicker response time in which water is delivered to the evaporative water panel.
It is a further object of the present invention to provide a water distributor which is capable of unplugging flow blockages caused by particles in the incoming water flow.
It is an additional object of the present invention to provide a water distributor employing tortuous flow channels designed for high flow resistance.
Another object of the present invention is to provide a water distributor which is improved in unit size, cost and manufacturability.
Yet a further object of the present invention is to provide a water distributor which is insensitive to unlevel mounting angles in the humidifier.
In one aspect of the invention, a water distributor provides a uniform supply of water at a desired flow rate to an evaporative panel held in a frame in an evaporative apparatus. The water distributor includes a base having a plurality of flow channels, each of the flow channels includes an inlet port for receiving water from a source, an outlet port for delivering water to the evaporative panel, and a tortuous path connecting the inlet p
Andrus Sceales Starke & Sawall LLP
Bushey C. Scott
Research Products Corporation
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