Air treating apparatus

C. D. GRAHAM

AIR TREATING APPARATUS

May 31, 1949.

Filed June 8-, 1946

2,472,011

Sheets-Sheet 1

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104

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May 31, 1949.

2,472,011

C. D. GRAHAM

AIR TREATING APPARATUS

Filed June 8, 1946

Sheets-Sheet 2

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INVENTOR.

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Patented May 31,1949

2,472,011

UNITED STATES PATENT OFFICE

2,472,011

AIR TREATING APPARATUS

Charles D. Graham, Oakwood, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware

Application June 8,1946, Serial No. 675,363

Claims.

This invention relates to refrigerating apparatus and more particularly to an improved system for conditioning and sterilizing air.

It is an object of this invention to provide a simple and inexpensive system for conditioning air for comfort purposes.

It has long been known that various air-borne diseases interfere greatly with one’s comfort and productive effort and as a result of this knowledge various methods and apparatus have been used to destroy bacteria in the air with varying degrees of success. One of the most effective and practical ways of destroying air-borne bacteria Is to introduce a glycol vapor into the air.

It is an object of this invention to provide an improved method and apparatus for vaporizing germicidal agents such as the glycols which have a high boiling point and which in the undiluted state are difficult to vaporize except at objectionably high temperatures.

It is another object of this invention to eliminate the need for adding water as such to the heated glycol solution in a glycol vaporizing unit.

Another object of this invention is to provide an improved arrangement for injecting the glycol vapor or other germicidal agent into the conditioned airstream.

Still another object of this invention is to provide an improved control arrangement for the vaporizing apparatus.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 of the drawing is a somewhat diagrammatic vertical sectional view showing a self-contained air conditioning unit embodying features of my invention: and

Fig. 2 is a diagrammatic view, partly in section, showing an improved arrangement for injecting a germicidal vapor into a central type of air conditioning system; and

Fig. 3 is a vertical sectional view, partly diagrammatic, showing a modified type of vaporizing unit.

Although all glycols possess air sterilizing value in varying degrees, propylene glycol, C3He(OH)2 and triethylene glycol CeHi2O2(OH)2 are the two which seem to have the most desirable properties for widespread use. Of these two, triethylene glycol seems to have the more desirable properties and requires the smallest degree of concentration for effectiveness. Thus, concentra(Cl. 21—74) tions of .005 mgm. of triethylene glycol per liter of air is very effective in destroying air-borne bacteria. At this concentration, the air remains odorless and is non-toxic.

₅ Referring now to Fig. 1 of the drawing, reference numeral 10 designates a conventional enclosure within which there is mounted an air conditioning unit generally designated by the reference numeral 12. This unit comprises an ID outer casing 14 which is provided with a return air inlet 16, a fresh air inlet 18, and a conditioned air outlet 20 all arranged as shown. A blower 22 is mounted^- within the cabinet and serves to circulate air in over the Alter 24, the cooling ' ₁₅ coil 26, and the heating coil 28 and to discharge the air out through the outlet 20 in accordance with well-known practice. The cooling coil may be supplied with a cooling medium from any convenient source such as a volatile refrigerant 20 liquefying unit (not shown) which may be mounted either directly within the cabinet 12 or at some remote location. The heating coil 20 is used for heating the air whenever heating is required and is adapted to be supplied with a ₂₆ heating medium from any convenient source (not shown).

In the lower portion of the cabinet 14 there is mounted an insulated vaporizer tank 30 which is adapted to contain a solution of water and glycol. 3Q (The term “glycol” is used throughout the speciAcation and claims in its generic sense and is intended to include all of the glycols such as ethylene glycol, diethylene glycol, triethylene glycol and propylene glycol.) A perforated steam ₃₅ supply pipe 32 is provided adjacent the bottom of ° the vaporizer tank 30 and is adapted to supply dry steam at a pressure such that its temperature is at least 10° above the desired liquid temperature in the vaporizer tank. Although liquid tempera₄₀ tures between 270° and 300° F. will cause satisfactory vaporization, other temperatures may be maintained. By increasing the operating temperatures the rate of evaporation for a given concentration is obviously increased and vice versa. ₄5 The Aow of steam to the perforated steam supply pipe 32 is controlled by means of a valve 36 which may be of the manually controlled type or which may be of the automatic type operable/either in response to the temperature of the solution with50 in the vaporizer tank, the degree of concentration of the solution within the vaporizer tank or the degree of concentration of glycol vapor within the conditioned space.

A steam heating coil 38 has also been provided 55 within the vaporizer tank 30 for adding auxiliary

9,479,011 heat to the solution at such times when the heat supplied by the steam released from the perforated steam supply pipe 12 is not sufficient to vaporize.an adequate supply of glycol. The flow of steam through the coil 21 is controlled by 5 means of a valve 40 which is arranged as shown and which is controlled by the thermostat 42 disposed so as to respond to the temperature of the solution within the vaporizer tank 30. A conventional steam trap 44 is provided in the return io line 46 as shown.

The vapor leaves the tank through the outlet 40 and is discharged directly into the inlet opening 50 of the blower 22 so as to be thoroughly mixed with the air before it leaves the fan chamber. By virtue of this arrangement, the blower serves to reduce the pressure within the tank 30 and, consequently, increases the rate of vaporization.

Since the boiling temperature of water is 212° F. and the boiling temperature of triethylene glycol is 548° F., it is obvious that the water in the solution will vaporize more rapidly than the triethylene glycol. The vapor leaving the tank 30 for a given setting of the controls may contain over 95% water vapor and the rest glycol vapor. It has been found that this percentage does not constitute a disadvantage since the glycol vapors are more effective, at relative humidities ranging from 30 to 50%. Thus the water vapor or steam which is discharged into the main air stream serves a useful purpose.

The steam discharged into the solution in the tank 30 through the steam supply pipe 32 is relied upon for supplying the necessary makeup water to the solution within the tank 30. Since only a very small amount of gylcol is vaporized from time to time, it is apparent that very little gylcol need be supplied to the tank. A glycol supply tank 52 has been provided within the cabinet 14 as shown and serves as a storage reservoir from which glycol may be added to the solution in the tank 30. The glycol enters the tank 30 through the pipe 54 within which there is placed a control valve 56. The valve 56 may be a manually controlled valve or it may be an automatically controlled valve which serves to supply the proper amount of glycol solution to the varporizer tank. Thus the valve 56 may be a time controlled valve adapted to allow a given amount of glycol to flow at predetermined time intervals or it may be a valve controlled in response to changes in temperature of the solution within the vaporizer tank or in response to the degree of concentration of glycol vapor within the conditioned space. It is apparent that the temperature within the vaporizer tank will be affected by the rate of vaporization which in turn depends in part upon the degree of concentration within the vaporizer tank.

In Fig. 2 of the drawing I have shown a modified arrangement for supplying glycol vapor in a central air conditioning system. Reference numeral 6Ό designates a building having a plurality of rooms such as 62 and 64. A conventional duct system 66 having an air conditioning chamber 68 is provided for supplying conditioned air to the rooms 62 and 64. A centrifugal blower 78 is provided adjacent the outlet of the conditioning chamber 68 for causing circulation of air through the duct system in accordance with established practice. Fresh air may be added from time to time through the damper controlled fresh air inlet 72. A conventional filter 74, a cooling coil 76, and a heating coil 78 are provided within the chamber 68. The supply of cooling medium to the cooling coils 76 from a source (not shown) is controlled by the valve &gt;0 which in turn is controlled by the thermostat 02 located in the return air stream. The flow of heating medium to the coil 78 from a source (not shown) is controlled by the valve 84 which is similarly controlled by a thermostat 86. The thermostats 82 and 86 are arranged so as to cause cooling medium to flow through the coil 76 when the temperature of the return air exceeds a predetermined value and to cause a heating medium to flow through the coil 78 when the temperature of the return air falls below a predetermined value indicating that heating is required.

Vaporized glycol is supplied to the conditioning chamber 68 by the vaporizing unit generally designated by the reference numeral 90. The construction and operation of the vaporizing unit 90 is the same as that of the vaporizer shown in Fig. 1 2Q and, consequently, needs no further description.

The same reference numerals have been used to designate the corresponding parts of the vaporizing apparatus shown in Figs. 1 and 2.

A slightly modified form of vaporizing unit has 2₆ been shown in Fig. 3 of the drawing wherein reference numeral 100 designates a glycol supply tank within which there is disposed a steam pipe 102 through which live steam under pressure is supplied to the steam jet 104 disposed within the ,θ venturi-like nozzle 106. The construction is such that glycol, either in the undiluted form or in a diluted form, will be pulled up from the glycol supply in the bottom of the tank 100 through the feed line 10-8. The flow of steam through the jet ₃5 104 will serve to atomize and vaporize the glycol fed into the escaping steam. The flow of steam through the pipe 102 is controlled by the valve 110 which may be a manually controlled valve or an automatically controlled valve. Since the ₄₀ ratio of water vapor to glycol vapor may be very high for the reasons explained hereinabove, a larger portion or all of the glycol leaving the nozzle 106 will be vaporized by the hot steam leaving the nozzle 104. The unvaporized glycol, if ₄₅ any, will be highly atomized and will serve effectively to kill the air-borne bacteria carried by the air. Some or all of the atomized glycol entering the air stream will be vaporized by the air. Makeup solution may be added to the tank 50 through the opening 112.

Units of the type shown in Fig. 3 may be used for discharging glycol or other types of germicidal or deodorant materials directly into the conditioned space or they may be used in conjunction. ₆₅ with air conditioning apparatus of the type shown in Figs. 1 and 2 in which case the nozzle 106 would preferably be arranged to discharge into the conditioned air stream ahead of the blower.

Whereas the apparatus disclosed herein is pri_fl0 marily designed for use in comfort air conditioning systems, it is obvious that the apparatus could be used in other types of installations.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, 65 it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.