Water distribution tray

A water distribution tray having an improvement comprising a first downwardly inclined surface therein commencing at a base of a water impingement pedestal within a first of a plurality of channels and ending at a corresponding first of a plurality of discharge apertures, wherein the first downwardly inclined surface has a first declension angle associated therewith, and a second downwardly inclined surface commencing at the base within a second of the plurality of channels and ending at a corresponding second of the plurality of discharge apertures, wherein the second downwardly inclined surface has a second declension angle associated therewith different from the first declension angle. A method of manufacturing is also provided.

TECHNICAL FIELD OF THE INVENTION

The present invention is directed, in general, to humidifiers and, more specifically, to a water distribution tray for use in a pad-type humidifier.

BACKGROUND OF THE INVENTION

In cold climates, particularly where occupied spaces must be heated, air in these spaces tends to have low relative humidity. This is uncomfortable, encourages static electricity discharges and is sometimes even unhealthy. Humidifiers are routinely used in heating, ventilation and air conditioning (HVAC) systems to add moisture to the air being conditioned to enhance the comfort of the occupants of the conditioned air space. The current relative humidity and the temperature of the air being conditioned dictate the amount of moisture added.

Humidifiers have a variety of different designs. There are small stand-alone units intended for a single room. Larger units are designed for permanent installation as a component of a central heating/HVAC system. These add moisture to the stream of heated air passing through the furnace duct to the conditioned space. The latter type of humidifier will hereafter be referred to as an “in-duct” humidifier. The humidifier whose description follows is an improvement to one common type of in-duct humidifier.

There are a number of different designs for in-duct humidifiers. The kind which is presently of interest has an air-permeable pad, typically made from a number of similarly-sized layers of thin, expanded aluminum sheet stacked to a thickness of perhaps 1.5 in. The layers of aluminum sheet are bonded to each other so as to create a pad structure having a rectangular box-like shape. The pad is placed in or near the furnace duct so that air warmed by the furnace can flow through the pad. Water is caused to drip onto the top surface of the pad at a rate which keeps the pad moist from top to bottom when humidity is demanded. The warm air passing through the pad evaporates water in the pad, adding humidity to the air and thereby raising the relative humidity.

The water flows onto the pad from what is known as a water distribution tray, or simply a tray. The tray extends along the top surface of the pad and has a reservoir for directing water flow over the pad. Water is fed to the tray from the building water supply and flow is controlled by a solenoid valve. Apertures spaced along the tray bottom permit the water flowing into the tray to fall onto the top of the pad. By properly selecting the rate at which water is added to the tray, the pad can be kept moist from top to bottom. The pad, the tray, and a frame supporting the pad and tray in the proper spatial relationship comprise the most important elements of an in-duct humidifier. It is very important, for efficient operation, that the tray evenly distributes water across the entire width of the pad.

There are water distribution trays now known which have a number of apertures spaced apart along the length of the tray and that use individual ducts, or channels, for conducting water to each aperture. Ideally, sizing and positioning the individual channels to conduct water to the apertures allows each aperture to receive an equal measure of the water; thereby assuring that the pad is evenly soaked across its width in accordance with the water demanded. These designs do not always fully realize these goals and indeed may sometimes cause further problems. For example, problems may arise that still prevent uniform saturation of the pad. This may happen if the tray is not perfectly level, thereby preventing an equal amount of water from flowing to each part of the pad's top surface. This is a fairly common problem as there is generally little need to accurately level other elements of the heating/HVAC system. Thus, when the humidifier is installed, it will usually be only as level as the air duct at that location. Water distribution will then likely favor one end of the tray over the other end.

It is also very important for all of the water in the tray to promptly drain onto the pad when the water flow stops. This eliminates un-drained pools of water standing in the tray which will evaporate leaving behind minerals, originally dissolved in the water, pooled on the tray surfaces. Over time, these mineral deposits can build up to a level which interferes with the operation of the tray itself. The use of a number of individual channels to supply water to individual holes tends to exacerbate this problem.

Accordingly, what is needed in the art is a water distribution tray that does not suffer the limitations of the prior art.

SUMMARY OF THE INVENTION

To address the above-discussed deficiencies of the prior art, the present invention provides a water distribution tray having an improvement comprising a first downwardly inclined surface therein commencing at a base of a water impingement pedestal within a first of a plurality of channels and ending at a corresponding first of a plurality of discharge apertures, wherein the first downwardly inclined surface has a first declension angle associated therewith, and a second downwardly inclined surface commencing at the base within a second of the plurality of channels and ending at a corresponding second of the plurality of discharge apertures, wherein the second downwardly inclined surface has a second declension angle associated therewith different from the first declension angle. A method of manufacturing is also provided.

DETAILED DESCRIPTION

Referring initially toFIG. 1, illustrated is a plan view of one embodiment of an in-duct, humidifier water distribution tray100constructed according to the principles of the present invention. The tray100comprises a centerline101, first and second outer walls110a,110b, a bottom113, a central water-impingement pedestal120, a plurality of channels130a-130h, a corresponding plurality of discharge apertures140a-140h, a plurality of continuous inner vertical walls150a-150h, and first and second end walls111,112. It should be noted that although the continuous vertical walls150a-150hare so named, this does not mean that the faces of the walls are necessarily vertical with respect to the bottom113. The walls150a-150hmay taper slightly as distance from the bottom increases for manufacturability. Nonetheless, a core line of the continuous vertical walls150a-150hwill remain perpendicular to the bottom113. Vertical for the purpose of this discussion will be defined as normal to the bottom113.

The plurality of discharge apertures140a-140hare each associated with the plurality of channels130a-130h. Each of the plurality of channels130a-130his defined by one or more of the continuous vertical walls150a-150hin combination or combined with at least a portion of the first and second outer walls110a,110b, or the end walls111,112. For example, the eighth channel130his defined as the area bounded by: inner vertical wall150h, first outer wall110a, second end wall112, second outer wall110band inner vertical wall150g. At the central water-impingement pedestal120, each of the plurality of channels130a-130hcomprises corresponding equal angles131a-131hof about 45°.

Referring now toFIG. 2, illustrated is a sectional view of the water distribution tray100ofFIG. 1along plane2-2. Commencing from the central water-impingement pedestal120and proceeding along the centerline101toward a first end102, there is shown discharge apertures140a-140d, in order. Similarly, commencing from the central water-impingement pedestal120and proceeding along the centerline101toward a second end103, there is shown discharge apertures140e-140h, in order. Associated with the first discharge aperture140ais a downwardly sloping surface160athat comprises channel130a. Examining the area on either side of the first discharge aperture140a, it can be seen that the slope on each side leading to the aperture140ais identical and is represented by a first declension angle170ameasured from a vertical normal to the bottom113. That is, downwardly sloping surface160a(i.e., channel130a) has a constant slope in all 360° around the first discharge aperture140a. This surface160acan be likened to the inside surface of a funnel except that the surface160aterminates when it intersects inner vertical walls150a,150b, or the central water-impingement pedestal120. In a preferred embodiment, the first declension angle170ais about 125° measured from the vertical.

Associated with the second discharge aperture140bis a second downwardly sloping surface160bthat comprises channel130b. Around the second discharge aperture140b, it can again be seen that the slope on each side of the second discharge aperture140bis identical and is associated with a second declension angle170bmeasured from the vertical. That is, the second downwardly sloping surface160b(i.e., channel130b) has a constant slope in all 360° around the second discharge aperture140b. In a like manner as with the first downwardly sloping surface160a, the second downwardly sloping surface160bterminates when it intersects inner vertical walls150a,150b,150h, the outer wall110a, or the central water-impingement pedestal120. The second declension angle170bis less than the first declension angle170a. In a preferred embodiment, the second declension angle170bis about 104.3°.

One who is of skill in the art will take notice that the third discharge aperture140cis surrounded by a third downwardly sloping surface160cthat comprises the third channel130c. The third downwardly sloping surface160cterminates when it intersects inner vertical walls150bor150c, the outer wall110a, or the central water-impingement pedestal120. The slope on each side of the third discharge aperture140cis identical and is associated with a third declension angle170cmeasured from the vertical. The third declension angle170cis less than the second declension angle170b. In a preferred embodiment, the third declension angle170cis about 98.8°.

Furthermore, the fourth discharge aperture140dis surrounded by a fourth downwardly sloping surface160dthat comprises the fourth channel130d. The fourth downwardly sloping surface160dterminates when it intersects inner vertical walls150c,150d, the outer walls110aor110b, the first end wall111, or the central water-impingement pedestal120. The slope on each side of the fourth discharge aperture140dis identical and is associated with a fourth declension angle170dmeasured from the vertical. The fourth declension angle170dis less than the third declension angle170c. In a preferred embodiment, the fourth declension angle170dis about 96.0°.

In a like manner, fifth through eighth discharge apertures140e-140hare arrayed from the central water-impingement pedestal120along the centerline101toward the second end103. It should be apparent to one who is of skill in the art that the fifth through eighth discharge apertures140e-140hand their corresponding channels130e-130hare analogous to the first through fourth discharge apertures140a-140dand their corresponding channels130a-130d. The fifth declension angle170eis substantially equal to the first declension angle170a. The sixth declension angle170fis substantially equal to the second declension angle170b; and the seventh declension angle170gis substantially equal to the third declension angle170c. The eighth declension angle170his substantially equal to the fourth declension angle170d.

With the channel angle131a-131hfor each channel130a-130hbeing equal, water impinging on the water impingement pedestal120and flowing to the channels130a-130hshould be substantially equal within each channel130a-130h. Therefore, a substantially equal volume of water is being distributed to each channel130a-130h. Because the first and fifth discharge apertures140a,140eare closest to the water impingement pedestal120, the first and fifth channels130a,130ehave the largest declension angles170a,170e. Because the second and sixth discharge apertures140b,140fare closer to the water impingement pedestal120than the third and seventh discharge apertures140c,140g, declension angles170b,170ffor channels130b,130fare less than declension angles170a,170e, but greater than declension angles170c,170g. In a like manner, declension angles170c,170gfor channels130c,130gare less than declension angles170b,170f, but greater than declension angles170d,170h.

The present invention was successfully tested against the prior art upon which it was based. The general plan design for the present invention is essentially that as disclosed in U.S. Pat. No. 4,125,576 to Kozinski which is incorporated herein by reference. Relationship of the water distribution tray to other elements of the humidifier, e.g., frame, water-retaining pad, etc., may be gleaned from Kozinski and are therefore not included here. However, Kozinski did not employ downwardly sloping channels, but rather a flat bottom surface throughout the tray. Both trays were tested in three conditions: level, 2° of tray tilt (¼ bubble of a carpenter's bubble level), and 3.5° of tray tilt (1 full bubble), simulating installation of the humidifier in normal and abnormal positions. It should be noted that to install a heating duct at one full bubble off of level would likely be an extreme case, although it would likely not affect the functioning of the heating system itself.

Referring now toFIG. 3, illustrated is a table of comparative results testing a conventional water distribution tray versus the present invention as shown inFIGS. 1 and 2. Flow through discharge apertures1-8was collected over a 10 minute period for each tray at a level condition, at 2° of tilt and at 3.5° of tilt. Actual flow was then normalized by converting actual flow for each aperture into percent of the total flow. Percentages may not total 100 percent for a tray because of data rounding. The standard deviation was calculated as a measure of how evenly water was distributed by the tray in question. As can be seen inFIG. 3, with both trays level, the standard deviation between discharge apertures of the prior art tray was 11.8% of the flow over 10 minutes; while the standard deviation between discharge apertures of the present invention was only 1.3% of the flow. Similarly at 2° of tilt, the standard deviation between discharge apertures of the prior art tray was 7.55% of the flow; while the standard deviation between discharge apertures of the present invention was only 2.3% of the flow. Therefore, the present invention is a significant improvement over the prior art. This can be attributed to two features of the present invention: (a) each channel is downwardly inclined toward the discharge apertures from all 360° around the discharge apertures thereby eliminating pooling caused by tray tilt, and (b) the downwardly inclined channels have varying declension angles in order to efficiently dispense the water accumulated from the water-impingement pedestal. Even with up to 3.5° (one bubble) of tray tilt from level, there exists a downward slope of 0.5° in the fourth and eighth channels toward the discharge apertures, and significantly larger downward slopes in the other six channels, thus ensuring emptying of each channel and no pooling. It is unlikely that a humidifier with associated water distribution tray would be installed more than one-half bubble (2°) off of level.

Thus, an improved humidifier water distribution tray has been described that provides downwardly sloping surfaces at varying angles of declension to efficiently and reliably deliver water to a humidifier pad for evaporation. Testing shows that the present invention more evenly delivers the water across the width of the humidifier pad and eliminates pooling.