US1933039A - Air conditioning apparatus - Google Patents

Description

1933- s. M. ANDERSON AIR CONDITIONING APPARATUS Filed Dec. 5, 1928 Patented Oct. 31, 1933 UNITED STATES PATENT OFFICE 1,933,039 AIR CONDITIONING APPARATUS Application December 5, 1928. Serial No. 323,951

3 Claims.

The present invention relates to air conditioning apparatus of the general type commonly known as air washers employed for changing the moisture content and temperature condi- 5 tions of atmospheric air. at the same time removing dust and other impurities.

In order to provide a finely divided spray of water with which contact with the air is promoted, the common existing types of air washers employ water nozzles having small orifices through which the water is forced under pressure. These nozzles are inefficient because the spray is not sufficiently atomized to afford the necessary intimate contact with the particles of the air current unless an inordinately large quantity of water is used. In fact, the amount of water vaporized by the air even under the best conditions is only a small fraction of that sprayed through the nozzle.

Another disadvantage of the common spray nozzle is that it affords no provision for regulation of the spray or of the amount of water vaporized by the air. In a nozzle operating under water pressure alone, the volume of the 5 spray and the degree of atomization are both determined by the water pressure, and the pressure must be maintained within fairly close limits to obtain any effective spray whatever. If the water pressure is decreased below its optimum value, the volume of water passing through the nozzle is not only decreased, but the spray effect may be entirely lost, the water being merely forced out in a coherent stream which is useless for purposes of humidification.

The result is that the nozzle must be either on or off, no intermediate spraying conditions being permissible.

Furthermore, the orifice is well situated for the collection of dirt from the water, which still further reduces the efficiency of the spray and the volume of water that can be handled. It is therefore necessary to shut down the equipment frequently or to provide special means for periodically cleaning the nozzles.

One object of the present invention is to provide air conditioning apparatus which is simple and inexpensive in construction, eflicient in operation, and capable of continued use over long periods without necessity for cleaning.

Another object of the invention is to provide air conditioning apparatus and method of operating the same whereby the volume of spray may be nicely regulated to bring about substantially any desired degree of humidification with maximum efiiciency at all times.

With these and other objects in view, as will hereinafter appear, one feature of the invention comprises a spray device of improved construction by which the water is expelled into the air stream in a thoroughly atomized condi tion most effective for maximum vaporization. The spray device includes a water tube to which water is continuously supplied, together with a compressed air nozzle for directing a blast of compressed air across the mouth of the water 5 tube. The water tube and compressed air nozzle are preferably so arranged that the blast of compressed air produces a varying vacuum over the surface of the mouth of the water tube, that is to say, in such fashion that the surface of the water at the end of the tube is subjected to a vacuum gradient. The existence of such a. vacuum gradient is conveniently effected by disposing the axes of the water tube and the nozzle to discharge at an angle less than 90 so that the air stream is not directly across the surface of the tube. The presence of the vacuum gradient causes a turbulent effect in the water near the mouth of the tube, causing a breaking up of the water particles and an expulsion of them 30 into the blast of compressed air which dispels them throughout the air duct in such a finely divided and distributed condition that they vaporize readily in the current of atmospheric air. The apparatus is remarkably simple and 5 efficient, it having been found that for similar degrees of humidiflcation, the present invention requires in some instances less than 10% of the water used by the common forms of spray nozzles.

Another feature of the invention consists in the means and method for accurately regulating the quantity of the spray. According to this feature, water is introduced to the water tube under pressure. This pressure may be a positive pressure or head tending to force the water out through the tube in which case the compressed air blast is called upon only to perform the function of creating turbulence within the tube and dispelling atomized particles throughout the washer. Where smaller quantities of spray are required, the head may be reduced even until it becomes negative in value and in this case, the compressed air blast performs the additional function of applying a suction lift to the water. In either case, the spray operates efiiciently.

Provision for adjusting the pressure or head of the water affords a convenient regulation for the quantity of the spray. The pressure may be varied from a large positive pressure to a large negative pressure and the volume of spray will be correspondingly changed without loss of efficiency and with a high degree of atomization in any case. The volume of spray depends only upon the water pressure and the compressed air pressure, and while the regulation may be effected by a change in either, for mechanical reasons it is preferred to maintain the air pressure constant and to regulate by variations in the head of water.

Other features of the invention consist in certain novel features of construction, combinations, and arrangement of parts hereinafter described and particularly defined in the claims.

In the accompanying drawing illustrating the preferred form of the invention, Fig. 1 is a sectional elevation of the preferred form of air washer included in a longitudinal section of the air duct, being a section on line l-1 of Fig. 2; Fig. 2 is a section on line 22 of Fig. 1 transversely of the air duct; Fig. 3 is an enlarged detailed sectional view of one of the nozzle sections shown in Fig. 1, being a section on line 3-3 of Fig. 4 looking in the direction of the arrow; and Fig. 4 is a detail plan view of a part of one of the nozzle sections.

The illustrated embodiment of the invention comprises a casing 6 included in or forming a part of the air duct through which the atmospheric air is blown in the direction of the arrow in Fig. 1 by any suitable fan. The casing includes one or more sets of spray devices indicated as two sets at 8 and 10, the former for promoting contact of water with the air in the lower part of the duct and the latter with the air in the upper part.

Each of the sets 8 and 10 comprises a plurality of sections which are of the construction shown in enlarged detail in Fig. 3. Each section includes two flanges 12 at opposite ends which are connected by a water pipe 14 and compressed air pipe 16, the flanges and the two pipes of each section being cast integrally. The sections are bolted together through bolt holes 18 in the flanges and as many sections may be used as are necessary to fill the width of the casing. When bolted together, the pi'pe sections 14 and 16 form respectively continuous water and air pipes extending completely across the casing.

A water tube 20 is fitted in the middle of each water pipe section by an accurately threaded connection 22. Each compressed air pipe section 16 is formed'with an air nozzle 24 having a rounded inlet 26. The mouth of the water tube 20 terminates in the air blast delivered by the nozzle 24. It will be seen that the current of air flowing under high velocity across the mouth of the water tube produces a vacuum which creates conditions of turbulent water flow in the tube, breaking up the water intominute particles, and permitting them to be expelled as a fine mist into the chamber.

It has been found that for maximum eflidisposed that a varying vacuum is produced over ciency the water tube and nozzles should be so difierent portions of the surface of the Water tube. The preferred arrangement is shown in Fig. 3. It will be seen that the axes of the water tube and the air nozzle are disposed with relation to each other at an angle of something less than so that the air current is not blown exactly parallel to the exit surface of the tube. In its best form, the parts are so arranged that the point a which is the point of the internal surface of the water tube extending farthest into the air stream lies in the center line of the nozzle, and the point D which is the diametrically opposite point of the water tube lies on the extended edge of the stream of air leaving the nozzle.

With this construction, the vacuum on the point 27 is a minimum and that on the point a is a maximum, there being a definite gradient between these two points. The result is that although the water fills the tube, it tends to rush toward the point a, thereby creating a turbulent effect at that point. This effect can actually be observed in that the water appears to flow from the upper side of the water tube toward the lower side where it concentrates in an eddy current whirlpool. The concentration of the water particles at the point a together with their high velocity of turbulence, tends to throw them into the compressed air stream in a finely atomized condition; they are then picked up by the stream and carried as a radiating spray in a general direction which is opposed to the flow of fan air, as indicated in Fig. 1, in order that intimacy of contact may be promoted by a considerable relative velocity between the particles of air and the spray. The effect of the nozzle is to throw a cloud of fine mist through the chamber into the atmospheric air, thereby permitting a highly intimate contact of all particles of the air with the atomized particles of water. Furthermore, it has been found that when the water tube and air nozzle have once been properly positioned in angular relation to one another, no change in such relation is necessary or desirable, no matter how the head or pressure of the water may be varied. The amount of water atomized will vary with the head or pressure of the water, but the character of the atomization will remain unchanged.

Compressed air is supplied to the pipe 16 by a compressor of any suitable form connected through a valve 28 with pipes 30 and 32 leading to the compressed air pipes of the spray devices. The compressed air supply is entirely separate from the current of atmospheric air, and preferably is automatically maintained at a uniform pressure.

The water supply system is described as follows: Two closed tanks 34 and 36 are supported by the sides of the casing, each adapted to contain a supply of water maintained at a constant head with respect to the mouths of the spray devices. A pipe 38 connects the water pipe sections 14 to each set of nozzles with the water supply in the tank. The tanks 34 and 36 are maintained at a suitable level by means of a supply tank 40 connected by a pipe 42 with branch pipes 44 and 46, eachleading to one of the pressure tanks and each including a regulating valve 48 and a check valve 50. Each tank is provided with an equalizing pipe 52 which enters the chamber 6 and is turned downwardly as shown in Fig. 2, to prevent splashing of 140 water into it. The purpose of the equalizing pipes is to place the pressure tanks under the same pressure or vacuum as the chamber 6, so that the balanced pressure existing between the tank level and the mouths of the water tubes 145 is not in any way afiected by variations of pressure caused by changes in the velocity of the atmospheric air.

In operation, the water level in each of the tanks 34 and. 36 is maintained at a defimte 150 value relative to the position of the mouth of the water tubes 20. The amount of water which each nozzle supplies in the form of a spray is dependent upon the head of the vwater in the pressure tanks 34 and 36 and also upon the velocity of the compressed air. The head of water on the nozzles may be either positive or negative. As shown in Fig. 2, where the water levels in the pressure tanks are below the mouths of the nozzles, the head is negative and is measured as a suction or lift quantitatively expressed in inches of water. The magnitude of this negative head is indicated at 1;. Under these conditions, the compressed air must produce a suction suflicient to lift the water from the level of the tank to the mouth of the water tubes, as well as to create the vacuum gradient necessary for producing the desired condition of turbulence. If the head is increased, that is, if the lift is decreased, the air pressure remaining constant, the amount of spray will be increased. The water head or pressure may be increased to substantially any desired value up to 10 or 12 inches positive head or even higher.

When the head is positive, the water flows by, gravity through the water tubes and is sprayed by the blast of air as fast as it approaches the mouth of the tube. The same operating conditions take place, except for variations in the density of the spray, when the head or pressure is negative. The valves 48 controlling the flow of water to the pressure tanks will be adjusted to replenish the supply of water as it is used by the sprays and to maintain the head at the proper value to give the desired volume of water atomized.

If the temperature of the water is equal to the wet bulb temperature of the entering atmospheric air, the maximum humidiflcation will occur when the dry bulb temperature of the air leaving the washer is brought down to its wet bulb temperature. In this case, the relative humidity will be Any desired degree of humidification less than the theoretical maximum may be obtained by adjusting the heads in the pressure tanks. If, therefore, after operating to produce a desired humidity and temperature of the air for a certain period, it is desired to change the air conditions, this is conveniently accomplished merely by opening or closing the valves 48 slightly, thereby permitting the water levels in the pressure tanks to rise or fall to different values. will be established under the newly adjusted pressures and the density of spray in the chamber will be changed to suit the new conditions.

The amount of water which is taken by a single nozzle for different heads of water and different velocities of compressed air: may be easily determined, and charts or tables showing the degree of humidification and cooling of the atmospheric air at different volumes of spray may also be established by experiment. With an apparatus employing a given number of nozzles, therefore, the level necessary to be maintained in the pressure tanks may be readily determined for substantially any desired degree of air conditioning. A nicely regulated control of air conditions is obtainable merely by regulating the water pressure applied to the spray water.

A similar control might be obtained by varying the velocity of the compressed air while maintaining the water level constant, and although such control is theoretically as effective as varying the water levels, for mechanical reasons it After a short time equilibrium is preferred to operate the air compressor under constant pressure and to regulate by variation of head.

The casing 6 is provided at opposite sides with filters 5 which permit the air to pass through but which'serve to catch any entrained particles of water. The preferred filters are of metal wool which have a large number of small interstices to permit the air to flow without excessive resistance but which serve effectively to catch any entrained water particles and permit them to run down to the bottom of the chamber. The filter at the inlet side of the apparatus might be omitted but for the fact that upon starting, if the water is turned on before the fan is started, a part of the spray might be blown into the fan. The chamber is formed at the bottom with a conical collecting basin 56 from which the drain water is drawn 011 through a pipe 58.

The present invention commends itself not only because of its simplicity, but also because of its economy of water and its capacity for' accurate control. The volume of water admitted to the water tubes and atomized in the form of a spray is completely determined by the head 100 of water, either positive or negative, and the velocity of the compressed air blast. The amount of water actually vaporized, however, depends somewhat on the condition of the air and upon the degree of humidification which it is desired to impart'to it. In general, it is found that if it is not desired to approach 100% humidity, practically all 01' the spray is vaporized, only a very small portion returning to the drain. For approach to maximum theoretical humidification, an increased volume of water must be employed, and since the air becomes less capable of vaporizing the spray at high humidities, a larger proportion of the water will be returned to the drain. In any case, however, the invention employs only a small proportion of the water required by the usual nozzle for the same degree of conditioning.

The simplicity of the control by which the extent of humidification may be adjusted is apparent. When the air is initially moist, or when it is not required to humidify it completely, a small volume of spray is sufficient, and at this time the water may be maintained at a negative head, that is, at a level below the mouths of the water tubes; but for raising initially dry air to a high humidity, it may be necessary to increasethe head to a positive value. In any case, the control is effected merely by operation of the valves 48. Moreover, when once adjusted, the apparatus operates continuously to maintain the proper air conditions, as distinguished from the intermittent operation of the orifice type of washer nozzle.

As a typical example of operating conditions, with a compressed air velocity of about 10,000 feet per minute through each nozzle, the water level may be varied between a positive head of 10 inches and a) negative head of 10 inches.

It will be seen that inasmuch as the water tube 1'40 is of considerable internal diameter (in the preferred form about of an inch) there is no possibility of its becoming plugged by foreign matter. The spray will, therefore, operate continuously for long periods of time without the necessity of shut-down for repairs 01' cleaning.

Any preferred apparatus for artificially raising or lowering the temperature of the air may be employed either in front of or behind the air washer. For heating purposes, the air may be 150 caused to contact with heated surfaces such as steam coils, and for cooling purposes, either the air may be passed over cool surfaces or the spray water may be refrigerated to a low temperature.

It will be understood that when the water is approximately at the wet bulb temperature of the entering air, the maximum theoretical cooling of the air without additional means will occur when its humidity is raised to 100%, the dry bulb and wet bulb temperatures then being equal. If the water is artificially cooled below the wet bulb temperature of the air, the air will first be cooled to its wet bulb temperature by conversion of sensible heat into latent heat of vaporization of the water, assuming, of course, that a. sufficient volume of spray is employed to eflect substantially 100%humidification. Cooling below the wet bulb temperature is then brought about by. mechanical transfer of heat between the air and the artificially cooled water particles.

The invention having been thus described, what is claimed is:

1. Air conditioning apparatus comprising a chamber through which the air being conditioned flows, a liquid tube, a compressed air nozzle for blowing a blast of air across the mouth of the tube, means for supplying liquid to the tube including a tank connected with the tube, means for maintaining a constant level of liquid in the tank, and means for regulating the liquid level to produce a positive or negative head with respect to the mouth of the tube to control the volume of the spray.

2. Air conditioning apparatus comprising a chamber through which the air to be conditioned flows, a liquid tube, a compressed air nozzle for blowing a blast of air across the mouth of the tube, means for supplying liquid to the tube including a tank connected with the tube, means for maintaining a constant level of liquid in the tank, and means for regulating the liquid level to vary the head with respect to the mouth of the tube to control the volume of the spray, and means for establishing an equalizing connection between the tank above the level of the liquid and the chamber whereby the head is uninfluenced by pressure changes due to the velocity of the air to be conditioned.

3. A spray device for air conditioning apparatus comprising a section having bolting flanges at opposite ends and a water pipe and a compressed air pipe, the compressed air pipe having a nozzle, and a water tube communicating with the water pipe and terminating in the path of air flow directed by the nozzle.

SAMUEL M. ANDERSON.

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