US 3908393 A
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[ Sept. 30, 1975 United States Patent 1 Eubank AIR CONDITIONING UNIT CONTAINING CONDENSER WITH EVAPORATIVE SUB-COOLER Primary E.\'aminerWilliam F. ODea Assistant Evamilzer-Ronald C. Capossela Attorney, Agent. or Firm-James C. Fails  ABSTRACT Disclosed herein is an improvement in a conventional  Filed:
[211 App]. 538,105 refrigcrative air conditioning system. The portion of the unit containing a condenser coil seats in a basin containing water to a depth of two to five coils. At-  US. 62/305; 62/506; 62/507 tached to the basin is a conventional apparatus for Int. Cl. controlling level of water nd Said basin is a  Field of Search 62/305, 428, 429, 506,
pump. A conduit extends upwardly from the pump, and its open end terminates in the air stream circulated by the condenser fan after passage through the [5.6] References C'ted condenser coil. The pump pumps water through the UNITED STATE A E end of the conduit, where the hot air stream causes ISSL e? r mo hm m tnmm SIMMO- ww s n a c m ki u de nin .l .wkm F t n 0 mm .m m l d w aow a OO E cl c D m 2 n mt 1 ts m mmm C I mhw e h P mm C mmmfi 8 emmw mw m aa t ame fPh nm m g me 55 0.3 00 80 BB QB M.
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AIR CONDITIONING UNIT CONTAINING CONDENSER WITH EVAPORATIVE SUB-COOLER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to air conditioning systems, and more particularly to improvements in the condensing process by an evaporative sub-cooler.
2. Description of the Prior Art A conventional air conditioner, particularly smaller units for homes, includes an exterior portion including a compressor and condenser coil unit which is positioned outside of the home, and an evaporator and blower unit inside the home. The function of the condenser coil is to remove heat from the compressed refrigerant, which enters in a gas phase, thereby condensing the refrigerant to a liquid phase prior to entry in the evaporator coil. The liquid refrigerant subsequently expands to a cold gas in the evaporator coil, which cools air circulated past.
The air conditioner is more efficient if the refrigerant leaves the condenser coil and enters the evaporator at a cool temperature. Moreover, since various refrigerants normally condense at temperatures within the range of 105l 33F, a given refrigerant may not completely condense into a liquid in extremely hot weather, especially if the condenser is exposed to the sun and unshaded.
Thus it is desirable to keep the condenser coil as cool as possible. One method would be to spray cool water over the coils. However unless the water is continually treated, deposits from the evaporating water will soon clog the ventilation passages through the coils. In addition a means for cooling the water such as a cooling tower would be necessary. Consequently condenser coils for smaller units are normally kept dry and cooled only by circulating air through the ventilation passages.
Accordingly the general object of this invention is to provide an economical device for smaller air conditioners which will improve their efficiency, lowering the temperature of the condenser coil, and obviating the disadvantages of the prior art.
Another object is to cool at least a portion of the coils of the condenser with water, yet avoid deposits from evaporation.
The objects are accomplished in accordance with this invention by providing a water bath that immerses a selected number of lower downstream coils of the condenser. The water is economically cooled by pumping the water through a nozzle positioned in the hot air stream downstream from the condenser, thus causing .evaporation yet avoiding conventional encrustation problems in the air-cooled portion of the condenser.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial isometric and partial schematic view of an air conditioner improved in accordance with this invention, showing an isometric view of an external unit and a schematic view of an internal unit.
FIG. 2 is a top elevational view of the external unit of FIG. I with the top of the unit removed.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring initially to FIG. 1, a typical central air conditioning unit is shown improved in accordance with this invention. The external portion, or unit, includes a compressor 11 for compressing the gaseous refrigerant, and condenser coil 13 for liquifying the compressed gas. Inside the enclosure to be air conditioned such as a mobile home 15, there is an evaporator coil 17 connected with the condenser coil 13 for evaporating the liquified refrigerant in heat exchange relation with, and simultaneously cooling, air that is circulated past, as by the evaporator fan 19.
In conventional operation, compressor 11 compresses refrigerant gas to a pressure in the range from two to three hundred pounds per square inch, resulting in a substantial temperature increase in the refrigerant. This hot refrigerant gas enters the top of condenser coil 13 via pipe 21. The gas proceeds through numerous copper coils 23, cooling as it proceeds downstream, since ambient air is circulated through ventilation passages 25 adjacent the coils 23 by a motor driven condenser fan 27. The coils 23 and ventilation passages 25 are shown larger than normal for clarity. The air conditioner as illustrated utilizes a condenser fan 27 that draws air through screen 28 past the condenser coil 13, although condenser fans which blow air through the condenser coil are common also. The shield 30 prevents air from being drawn through the opening between the two ends of the condenser coil 13.
The refrigerant condenses into a liquid and exits the bottom of condenser coil 13 via pipe 29 at approximately ambient temperature. The refrigerant then enters the evaporator 17 through expansion valve 31, undergoing a pressure drop, which lowers the boiling point so that the refrigerant vaporizes. This causes a corresponding decrease in temperature, which cools the air circulated past the evaporator in the direction of arrows 32, 34. Low pressure cool refrigerant gas returns to the compressor via pipe 33.
The improving device of this invention is a condenser sub-cooler, which lowers the temperature of a few lowermost downstream coils 23 in the condensing coil 13 in order to further cool the refrigerant after the temperature has already been reduced by circulating air in the upper coils and before it enters pipe 29. The device includes a basin 35 formed by walls 37. Water or a suitable cooling fluid fills the basin 35 to a depth which covers a few of the lower coils 23.
Ideally it is desired to lower the refrigerant to the temperature of the water in the basin, therefore the minimum depth is the height of the number of coils required to lower the exit refrigerant to that temperature considering flow rate, heat transfer coefficients, and temperatures. Preferably by the time the refrigerant reaches the submerged coils, it has already condensed into liquid phase. The maximum depth is governed by the ability of the water cooling means, described below, to maintain a desired temperature. This depends on several factors, including ambient temperature, humidity, and rate of evaporation. The sub-cooler is designed for depths in the range from two to five coils.
The apparatus for maintaining water temperature includes a pump 39 in communication with the water of the basin 35. The pump 39 illustrated is a conventional centrifugal pump comprising a motor 45, shaft 47, im-v peller vanes 49, and intake 51. A conduit 41 is connected to the pump 39 and disposed upwardly in the air stream drawn by the condenser fan 27, downstream from the condenser coil 13. The conduit 41 terminates in a nozzle 43, and the height of the conduit 41 is approximately one-half the height of the condenser coil 13.
The pump rate, in the range from three to five gallons per minute, height of the conduit 41, and nozzle 43 size are designed so that the condenser fan 27 will not entrain appreciable amounts of droplets and blow them out. Nor does the nozzle 43 spray water radially outward far enough such that the coils 23 will become wet, since to avoid deposits of solids or encrustations, it is essential that the upper coils 23 remain dry.
Liquid levelling means including a conventional float 53 and valve 55 are used to replenish water lost from evaporation. The valve 55 is attached to wall 37 and connected to a water source through pipe 56. Water having low dissolved salts is preferred since there is no problem with the build up of scale, film, or undesirable deposits. Otherwise, to alleviate any problem with films forming on the coils adjacent or submerged in the water, any of the conventional methods may be resorted to. For example, the water may be treated with a small amount of conventional additives, such as 1000 parts per million of sodium dichromate or it may be flushed periodically through drain 57.
In operation condensing refrigerant 23 is further cooled by the water in basin 35. The heat transferred by refrigerant to the water is dissipated by evaporation. The evaporation is accomplished by spraying the water through nozzle 43. Hot air drawn by condenser fan 27 passes over the spray, increasing the rate of evaporation, which in turn cools the water as it falls to the basin.
The refrigerants employed may comprise any of the conventional refrigerants, such as tetrafluoromethane, Freon l4; dichlorodifluoromethane, Freon 21; or monochlorodifluoromethane, Freon 22.
Whereas the drawing shows a circular condenser coil curving greater than 270, the condenser sub-cooler device will work with other configurations, such as a flat condenser or ones curved into 180. In addition it is not necessary that the fan discharge upward as shown in the drawing. Moreover the sub-cooler device will work in a single integral unit, rather than having the interior and exterior units as shown. It is only essential that the water spray be downstream of the air stream from the condenser coil, and that the coils of the condenser to be submerged contain exiting refrigerant.
Variations of the elements of the sub-cooler device may be employed. Such variations include replacing the centrifugal pump with another pumping means, such as a slinger-ring, and the float and valve with other liquid levelling means. Since the compressor is hermetically sealed, the wall forming the basin may comprise the entire floor, or the compressor might be placed on a raised stand above the water.
From the foregoing, it is readily apparent that an invention having significant advantages has been provided. The condenser sub-cooler, particularly in hot, dry climates, improves efficiency by lowering the temperature of liquid refrigerant as it passes to the evaporator. Water is used as a cooling agent, yet depositions from evaporation on the coils are avoided since no evaporating water touches the coils. The upper coils remain dry and a few lower coils remain submerged, where normally only slight depositions will occur. The need for a separate cooling tower for the water is obviated by using evaporation which is increased by air heated after being drawn through hot dry condenser coils.
Although this invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit of the scope of this invention.
1. In a combination for supplying conditioned air to an enclosure, the combination including:
an air conditioning unit having a closed system with a refrigerant contained therein and including: a compressor for compressing the refrigerant gas, a condenser coil connected with said compressor for condensing the compressed refrigerant, a condenser fan for circulating ambient air past said condenser coil in heat exchange relationship with said compressed refrigerant, an evaporator coil connected with said condenser coil for evaporating the liquefied refrigerant in heat exchange relationship with air circulated therepast to be conditioned, and an evaporator fan for circulating said air to be conditioned past said evaporator coil, the improvement comprising:
a basin for submerging within water a selected number of lower coils of said condenser coil, said lower coils containing exiting refrigerant;
water in said basin; said refrigerant in said condenser being cooled by the ambient air prior to being cooled by the water in said basim;
liquid levelling means in communication with the water of said basin for maintaining a predetermined water level at a depth which submerges a selected number of lower condenser coils;
pumping means in communication with said water of said basin for pumping said water;
a conduit attached to said pumping means provided with an open upper end and extending upwardly, terminating at a point within the stream of air circulated by said fan after passage through said condenser coil;
whereby water circulated by said pumping means will discharge through said conduit and tend to evaporate as hot air drawn by said condenser fan passes over said discharge.
2. The combination of claim 1 wherein said condenser fan draws ambient air through said condenser coils.
3. The combination of claim 1 wherein said liquid levelling means comprises a float and valve.
4. The combination of claim 1 wherein said liquid levelling means maintains said water level at a depth in the range wherein two to five lowermost downstream coils of said condensing coil are submerged.
5. The combination of claim 1 wherein said pumping means comprises a centrifugal pump.
6. The combination of claim 1 wherein the open upper end of said conduit includes a nozzle for forming a spray of water.
7. The combination of claim 1 wherein said condensing coil is of a circular configuration.
8. In a combination for supplying conditioned air to an enclosure, the combination including:
an air conditioning unit having a closed system with a refrigerant contained therein and including: a
compressor for compressing the refrigerant gas, a condenser coil connected with said compressor for condensing the compressed refrigerant, said refrigerant entering at the top of said condenser coil and exiting at the bottom of said condenser coil, a condenser fan for drawing ambient air past said condenser coil and upward in heat exchange relationship with said compressed refrigerant, said compressor and said condenser coil enclosed in an external unit, an evaporator coil located in an internal unit and connected with said condenser coil for evaporating the liquefied refrigerant in heat exchange relationship with air circulated therepast to be conditioned, and an evaporator fan for circulating said air to be conditioned past said evaporator coil, the improvement comprising:
basin for submerging within water two to five lower coils of said condenser coil;
water in said basin; said refrigerant in said condenser being cooled by the ambient air prior to being cooled by the water in said basim;
a float and valve in communication with said water of said basin for maintaining water level;
a pump in communication with said water of said basin for lifting water;
a conduit attached to said pump extending upwardly from said pump, whose upper end is an open nozzle terminating at a point within the stream of air drawn by said fan after passage through said condenser coil;
whereby water circulated by said pump will discharge through said nozzle and tend to evaporate as hot air drawn by said condenser fan passes over said discharge.