US2783616A - Air coolers and dehumidifiers - Google Patents

Description

March 5, 1957 A. Y. DODGE AIR COOLERS AND DEHUMIDIFIERS Filed Nov. 8, 1954 IN V EN TOR.

FIG.I

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Uni fi l w F l -3 AIR COOLERS AND DEHUMIDIFIERS Adiel Y. Dodge, Rockford, .111. Application November 8, 1954, Serial No. 467,250 13 claims. on. 62-4) An object of this invention is to provide a combined dehumidifier and air cooler or an air cooler which produces more dehumidification.

In air coolers, it is common practice to operate the refrigeration elements at a temperature somewhat above the frosting point in order to avoid the frosting of the coils. In my arrangements, I do not avoid frosting but welcome frosting and make good use thereof and provide means for alternately frosting and defrosting.

it is well known that a greater degree of dehumidification can be accomplished by carrying the temperature of refrigeration to a'lower point. p In my co-pending applications Serial Nos. 449,35 "and. also 462,640, I have provided pre-coolingheat exchangers in order that lower temperatures may be readily had in the cold chamber without overchilling the air delivered to the dwelling room. When employing these devices, it becomes increasingly necessary to cope with frosting coils.

To avoid frosting in coolingapparatuses not using my pre-cooler, it was often necessary to make adjustments. This prevented the operation of the equipment in its optimum capacity over a considerable period of its time.

With the arrangement set forth herein, whether using pre-coolers or not, it is no longer necessary to avoid frosting temperatures. To the contrary, frosting temperatures are made use of by allowing one surface to frost while another surface is being defrosted, or alternately frosting and .defrosting one surface, as will be described later. p

Another object of this'invention is to provide means in an air cooler, first. to pre-cool air and later to pass the air over a frosted surface, and still later over a surface being defrosted. Following. this,-the air is tempered to a moderate temperature and delivered to the dwelling. Means to regulate the degree of cooling and the amount of air being blown into the dwelling room is provided, thereby controlling the amount of draft created.

I have found that the ideal comfort range liesat temperatures in the neighborhood of 77 to 81 F., dry bulb temperature, when the humidity is kept between 60 and 80 grains of moisture per pound of air and the air circulation is moderate; that is, below 250 feet per minute. Therefore, one of my chief objec-ts'is to produce an air cooling device which will more nearlymaintain the .above conditions, more particularly when used in connection with one or more-of the inventions set forth in my co-pending patent applications Serial Nos. 449,355; 462,640; and 465,608. l

The enclosed drawing sets forthembodiments of my invention in whichi Figure l is a diagram showing a' cross. section in elevation of my apparatus;

Figure 2 is a diagram showing a detailin fragmentary Figure 3 is a diagram in cross section of a control detail. The air cooler diagrammatically 1. illustrated-in the accompanying drawing is made up bf. morejor'less standard elements in which:

Character 10 indicates a housing for the air cooler elements. Air intake is shown at 11. At 12 is shown a two-speed motor to drive an air circulating fan.

13 indicates the main blades of the centrifugal fan which circulates air through cooler. Auxiliary blades of the centrifugal fan are shown at 14 for recirculating air through tube 19. Hub of fan blades 13 and '14 is shown at 15.

Coils 16 and '17 form one of my pre-coolers and air temperers as fully described in my co-pending applications Serial No. 449,355 and Serial No. 465,608; warm incoming air gives up 'heat to coils 16, and the air is cooled thereby. The heat is'given off at coils "17 to the outgoing air at 18, tempering same.

Cylindrical passage 20 is for swirling air downward; cylindrical passage 21 is for swirling air upward. Air swirls in a vortex while passing therethrough.

Upper inner concave cylindrical chilled surface is shown at 22; lower inner concave cylindrical chilled surface is shown at 23. Lower outer convex cylindrical chilled surface is shown at 24; upper outer convex cylindrical chilled surface is shown at 25.

26 and 27 are evaporator chambers. Rotary type refrigerant compressor is shown at 28. Two-speed electric motor 29 drives compressor 28.

Refrigerant condenser is shown at 30. Refrigerant accumulator is shown at 3.1.. Refrigerant return pipe, low side is shown at 32, and refrigerant delivery pipe, high side is shown at 33. Y

34 and 35 show capillary tubes for throttling the refrigerant in lieu of expansion valves. At 36 and 37 are shown thermal bulbs. 38 is a thermal actuated electric switch. 39 is a solenoid to close valve 40.

41 and 42 are wires to feed electricity to solenoids. At 44 is shown a solenoid valve similar to valve 40. 50, 51, and 52 are wires .to feed electricity to motor 12. 53 .is a switch to select oft, low speed, or high speed for fan motor 12. 54, 55, and 56 are similar wires to feed electricity to and control speed of compressor motor 29 g .in a similar manner to above.

Insulation is indicated at 60. -61-and 63 are gutters to catch condensate and melting frost, and 62 and 64 are tubes to carry awaythe above mentioned condensate.

skimming louvres shown at 70 are'to skim off hot humid air from the core of the swirling vortex-as more fully decribed in my Patents 2,519,028 and 2,676,667 and in my patent application Serial No. 462,640.

A solenoid is illustrated at 71. This solenoid actuates a bafiie 72 to direct air awayfrom bulb 36. At 73 is illustrated a bellows to actuate switch 74 in response to changes of pressure in bulb 36.

shows a pressure controlled switch in which pressure of the high side is balanced against a spring 86. This balance is supplemented by the pressure from the low side.

In recent experiments, I have found that air swirling in a vortex will deposit frost on an internal concave cylindrical surface while at the same evaporator temperatures, the swirling air fails to deposit frost-on the outer convexed cylindrical surface.

This is a discovery anduisaprobably dueto laminar conditions set up by centrifugal force. The laminar layer close to the internal wall is relatively well maintained; a minimum of naturalconvection takes place. Due to the cold air being the heavier, it maintains a layer adjacent to the cold inner surface, whereas cold air adjacent the outer cylindrical surface. is carried away by centrifugal force thereby increasing the natural convection.

. .While one cold chamber is sufficient to practice the methods outlined herein, 1 have shown .in Figure 1 two evaporators 26am! 27. Two internal cold surfaces 22 and23 are shown,-a1so two external -cold surfaces 24 and 25. Shut off on expansion valves 40 and 44 are 3 provided such that refrigerant may be shut off and none supplied to one or the other of the evaporators. Said shut off valves are controlled by thermostatic means. The thermal bulbs are located near the inner surfaces which become frosted. Controlled expansion valves may be employed at 40 and 44 instead of shut off valves.

The thermal bulbs 36 and 37 are spaced such that they are kept from chilling due to circulating air until frost has accumulated sufliciently thick to contact one bulb or the other, at which time the bulb is chilled. if the bulb 36 is chilled, the contraction of its charge will cause switch 38 to close its circuit, thereby causing solenoid 39 to close valve 40, after which refrigerant is not furnished to evaporator 26.

Center tube 19 is provided with louvres 70 to skim oif hot humid air seeking the center while it is swirling. Said hot and humid air is drawn upward by auxiliary fan blades 14 and recirculated down through passage 20 for the purpose more fully described in my Patents 2,519,028 and 2,676,667 and in my co-pending application Serial No. 462,640.

*In operation, air enters at 11, being drawn in by fan blades 13. Air is circulated in a helical manner down through chamber 20 contacting coil 16 where the air is pre-cooled as more fully described above and in my copending applications, Serial Nos. 449,355 and 465,608.

The air is further cooled by contacting surfaces 22 and 23. Surface 23 will become frosted first since the air is already cooled before it reaches surface 23. When the frost is sufficiently accumulated on surface 23 to contact thermal bulb 37, valve 44 is closed in a manner similar to that described for valve 40. Air will continue to flow over surface 23. The air so circulating is cooled by the frost until the frost has been melted away. The melting frost is caught in a trap or gutter 63 and carried away through pipe 64.

Air turns the elbow at the bottom of chamber 20 and starts swirling upward through chamber 21, at which time it will contact surfaces 24 and 25 where it will be further cooled more generally, as stated above. However, less extraction of vapor takes place in this passage 21 than took place in passage 20; the moisture having been previously deposited on surface 22 or 23.

The cold air swirls upward and over the coils 17; said air is tempered by coils 17. The air is elevated to a more moderate temperature as set forth in my copending applications Serial Nos. 449,355 and 465,608. After this, the air is discharged at 18, either directly into the dwelling room or into a duct leading to the dwelling room (duct not shown).

During the period when surface 23 is being defrosted, the full capacity of refrigerating equipment may be devoted to evaporator 26 so that the surface 22 is being frosted during the time that 23 is being defrosted. Somewhat after the defrosting of surface 23, frost will have accumulated on surface 22 to contact thermal bulb 36, thereby closing valve 40, as previously described, shutting off refrigerant from evaporator 26 at which time no refrigeration is provided to cool surface'22.

So that the entire surface may be thoroughly frosted, thermal bulb 36 is placed at that part of the surface which tends to frost lastly. When frost has accumulated on this latter frosting surface sufiicient to contact bulb 36, refrigerant is caused to be either throttled by a control expansion valve to a very low point or shut off entirely by solenoid shut off valve previously described. But simultaneously therewith, solenoid 71 shown in Figure 2 is energized to swing baffle 72 into the position shown, thereby to deflect the downward moving air away from bulb 36 so that the frost contacting bulb 36 will not be the first to melt but 'will be the last to melt. In this way, I have assured the cold surface to first become thoroughly frosted and latterly to become thoroughly defrosted over most of its entire surface.

In Figure 3, I have shown a pressure switch 80. Switch 83 is controlled by bellows 81 and 82 working in opposition to spring 86 in the usual manner. Capillary tube 84 is connected to pressure line 95 from compressor while tube 85 may be connected to tube 92. This pressure actuated switch may also be employed in the usual way to shut off the motor 28 when the pressure differential is too high for any reason such as overfrosted evaporator, particularly if only one evaporator is employed. In this case, the switch should be adjusted to cut off only after the cold surface is about completely covered with frost.

The air swirling downward melts the frost off surface 22. The melting is caught in gutter 61 and is carried away in tube 62. It should have been mentioned that when surface 23 became defrosted, thermal bulb 56 caused valve 44 to open so that evaporator 27 may receive the full capacity of the refrigerating equipment. Surface 23 starts to frostwhile surface 22 is being defrosted.

Frosted evaporators present another problem, to wit: the passing of vapor which might be too wet to the compressor. This is to be avoided. To meet this problem, I have shown space in my cold chambers 26 and 27 which is located below the port of the return pipe 32. These spaces will trap condensed refrigerant. (Flooded type cold chambers would be another partial solution instead of the semi-flooded type shown.)

*In addition thereto, I have shown a pro-chilling heat exchanger to exchange heat from the warm condensed liquid to the cold returning vapor. I have positioned this heat exchanger in a manner to form a trap for any condenser refrigerant so that it will be trapped before returning to the compressor.

As further precaution, I have introduced a thermal bulb 91 which may be employed to shut off the motor through a thermal switch (not shown) should a dangerously low temperature be reached. I have also shown a capillary tube 92 communicating with the return pipe 93 which may be employed to actuate a pressure switch (such as is shown at 80 in Figure 3) to shut off the compressor motor 29 should an excessive high pressure he reached. With these precautions, there is little or no danger of returning vapor which is too wet to the compressor even though the cold surfaces are completely frosted.

This cycle of frosting one surface while defrosting another may be employed in several of my operating conditions, or it may be prevalent only during certain operating conditions. The frosting-defrosting conditions referred to might be brought about by control means for controlling first, the flow of refrigerant through controlled expansion valves in one of the usual ways; second, it might be brought about by controlling the speed of motor 22 which drives compressor 28; or third, by controlling the speed of motor 12 which drives the circulating fan. It is apparent that frosting would be most prevalent when operating the compressor at high speed, and the circulating fan at low speed.

One of the chief objects of this device is to dehumidify; defrosting is a very effective method of dehumidifying. Now there are no longer objections to operating in the manner described herein-alternately frosting and defrosting.

It should be pointed out that the surface which is being defrosted is continuing to absorb heat from the air. In fact very close to the same amount of heat energy which was consumed in freezing the moisture is absorbed by the melting frost or ice from the air being cooled at the time of its melting.

I also wish to point out that the average temperature of the cold surface may be operated at temperatures considerably lower than the average temperatures of coolers or dehumidifiers which attempt to avoid frosting. The temperature of my cold surface during the time of frosting may be as low as 0 F.

eraser-e As another discovery, I wish to point out and explain that due to the surface condition-of the inner surface of a cylinder, 1 have been able to build frost rapidly and at the same time have the average temperature of the swirling air as .high as 68. This, however, was exposing only the internal cylindrical surface to the air. So I have discovered a phenomena which enables me to operate with a very cold surface, with a minimum of overchilling of air or no overchil-ling at all aside from any benefits gained by my tempering means, as just pointed out.

The warmest and'more humid air will seek the center of the swirling mass. A portion of the warmer and more humid air will be skimmed off by louvre '70 and will be drawn upward in tube 19 by auxiliary fan blades 14 and will be re-circulated downward through passage 20.

It is apparent that a single cold surface may be em.- ployed and the means outlined herein used to alternately frost and defrost it. During the defrosting operation, the refrigeration equipment would be shut off. It is likewise apparent that the shape of the air passages might be other shapes than cylindrical passages. They might be the usual rectangular passages with fin type heat exchangers. That is, the evaporators may be of the common rectangle type employed individually or in pairs, to be alternately frosted and defrosted as set forth herein.

The control means as described herein embody several different means which may be employed to bring about frosting and defrosting condition as follows:

Frosting of the cold surfaces can be brought about by increasing the speed of the refrigerant compressor over and above the optimum balance speed or by slowing down the flow of air. Whereas, defrosting may be brought aboutlby'slowing the speed of the compressor or by increasing the speed of the fan or by throttling the amount of refrigerant delivered to the cold chamber, or by shutting off the refrigerant being delivered entirely. Defrosting may also be brought about by stopping the compressor, for which purpose a pressure actuated switch, such as is shown in Figure 3, may be used. Various combinations of these ways and means have been set forth herein to provide means for alternately frosting and defrosting a cold surface, thereby to operate at a lower average temperature for the purpose of dehumidification.

Briefly, summing up the operation of one of mydevices: Warm air is taken in from the dwelling room directly or through a duct (vduct not shown) by means of a fan which also sets up a helical swirl of the air which is passed through concentric cylindrical -ducts, first passing over a pro-cooling heat exchanger-which pre-cools the incoming air and slightly warms the outgoing air. The air continues to swirl downward through the chamber, being exposed to chilled surfaces where frosting takes place, thereby ext-nacting moisture from the air. Frosting alternately takes place on one surface while defrosting another surface. The frosting extracts moisture from the air. Swirling upwards through another cylindrical passage, air is more generally cooled and finally tempered to a moderate temperature and delivered to the dwelling room directly or through a duct (not shown).

Having thus described the principal embodiments of my invention, it is apparent that other arrangements and deviations may be employed; therefore, the scope of this invention is limited only by the following claims.

I claim the following as my invention:

1. In an air treating apparatus, the combination of a fan to force air in a vortex swirl through cylindrical passages, a pro-cooling heat exchanger extracting heat from incoming air and delivering it to the treated air, a refrigerating machine, two cylindrical evaporators, in

said cylindrical passages, means to connect sald 'evaporators to the 'refrigeratingmachine to cause the inner cylindrical surface of one of the evaporators to accumulate frost to a predetermined thickness, means to reduce the quantity of refrigerant fed to said one evaporator so said one'surface will later defrost by melting while continuing to cool said air, means to supply'refrigerant to the other evaporator while the supply to said one evaporator is reduced to cause the inner cylindrical surface of the other evaporator to frost while the surface of the said one evaporator is defrosting, and control means to prevent liquid refrigerant from entering the compressor.

2. In an air treating appanatus, the combination of a fan to force air through passages, a precooling heat exchanger and air temperer, a refrigerating machine to cool and dehumidify said .air. having two evaporators'in said passages, means to cause one of the surfaces of one of the evaporators to accumulate frost to a predetermined thickness, means to reduce the quantity of refrigerant fed to said surface so said surface will defrost by melting, means to cause the surface of the second evaporator to frost while the surface of the first evaporator is defrosting, thereby to extract moisture from the said air by freezing.

3. In an air treating apparatus, the combination of a fan to force air througha passage, a refrigerating machine to cool and ldehurnidify said air, an evaporator, means to cause the surface of the evaporator to accumulate frost to a predetermined thickness, means to reduoe the refrigerant effect fed to said surface so said surface will later defrost by melting, means to cause muoh'of the surface .to frost and means to later cause much of the surface to defrost, comprising a movable air baffle to direct air away from a thermal control bulb, andcontl'ol means to move said bathe, said bulb controlling a valve to regulate the flow of refrigerant to said evaporator.

4. The construction of-claim 3 plus means to prevent liquid refrigerant from entering the compressor, comprising traps and a heat exchanger to dry returning vapor plus thermal control means to stop the compressou motor. 1

5. The construction of claim 3 plus means to me vent liquid refrigerant from entering the compressor, comprising pressure control means to stop the compressor motor.

v6. An 'airtreating device comprising a fan to circulate air, a refrigerating machine, a heat exchanger taking heat from incoming air and delivering it to the treated air, an evaporator having a cold surface for removing water'vapor by freezing from the air being circulated to be dehumidified, secondary automatic control means comprising a pressure responsive device responsive 'to re- .frigenant pressures, thereby to prevent liquid refrigerant entering the compressor during frosting by momentarily stopping the refrigerating machine.

7. In an air treating apparatus, the combination of a fan to force air in a vortex swirl through cylindrical passages, a precooling heat exchanger to cool incoming air and to temper air being discharged, a mechanical refrigerating machine including two cylindrical evaporators located in said cylindrical passages, said refrigerating means to chill the surfaces of first one and then the other of the evaporators thereby to accumulate frost, detectors to determine the thickness of the frost comprising thermal bulbs spaced adjacent to but away from the cold surfaces, the bulbs to be contacted by the frost after the frost bridges the gap between the bulb and the cold surfaces, means associated with the bulb to reduce the quantity of refrigerant fed to said first evaporator comprising a valve actuated by said thermal bulb so that said first surface will be defrosted by the circulating air melting the frost while being cooled, similar refrigerating means to cause the surface of the other evaporator to frost while the surface of the first evaporator is being defrosted, said thermally actuated valves lalternately reduce or stop the flow of refrigerant to first one cold surface and the-n the other to alternately chill and defrost one surface and later the other surface while air is continuing to circulate over said surfaces, means to prevent liquid refrigerant from entering the compressor comprising an auxiliary heat exchanger to cool condensed refrigerant while warming the vapor returning to the compressor of said refrigerating machine, and a pressure control switch to stop the compressor momentarily.

8. In an air treating apparatus, the combination of a fan to force air through cylindrical passages, a precoo ling heat exchanger to cool incoming air and to temper air being discharged, a mechanical refrigerating machine including a cylindrical evaporator located in said cylindrical passages, said refrigerating means to intermittently chill the surface of the evaporator thereby to accumulate frost, :a detector to determine the thickness of the frost accumulated comprising a control element spaced adjacent to but away from the cold surface, the element to be contacted by the frost after the frost bridges the gap between the element and the cold surfaces, means associated with the element to reduce the quantity of the refrigerant fed to said evaporator comprising a valve actuated by said element so that said surface will be defrosted by the circulating air melting the frost while said air is being cooled.

9. In an air conditioning apparatus, the combination of a mechanical refrigerating machine having a refrigerant evaporator formed with concave and convex cylindrical cold surfaces to cool said air, fan means to circulate air over said concave cold surface in a helical swirl motion and then over the convex cold surface, skimmer means to skim oif a portion of the core air to be recirculated, means to collect frost on the concave cold surface, said frost forming due to the removal of moisture from the air being conditioned, detector means to detect the thickness of the frost comprising an element adjacent to but spaced away from the cold surface so that circulating air prevents the chilling of said element until frost forms to close the gap between the element and the cold surface, after which said frost acts as a conductor to carry heat away from the element, said element actuating a flow valve, thereby to reduce or stop the flow of refrigerant to the cold surface, thereby to allow the frost to be melted by the circulating air while cooling the air by the convex surface and by the frosted surface.

10. The method of conditioning air which comprises forcing air to be treated in a vortex swirl through a tubular passage, cooling a portion of the wall of the passage to a temperature below the freezing point of water to cause an accumulation of frost on said wall portion, and reducing the cooling after a predetermined amount of frost has accumulated on said wall portion while continuing to force air through the passage to melt the accumulated frost.

11. The method of conditioning air which comprises forcing air to be treated in a vortex swirl through a tubular passage, cooling a portion of the wall of the passage to a temperature below the freezing point of Water to cause an accumulation of frost on said wall portion, reducing the cooling after a predetermined amount of frost has accumulated on said wall portion while continuing to force air through the passage to melt the accumulated frost, and exchanging heat between the air entering and leaving the passage to increase the temperature of the air leaving the passage.

12. The method of conditioning air which comprises forcing air to be treated in a vortex swirl through a tubular passage, cooling a portion of the wall of the passage to 18. temperature below the freezing point of watento-cause an accumulation of frost on said Wall portion, reducing the cooling after a predetermined amount of frost has accumulated on said wall portion while continuing to force air through the passage to melt the accumulated frost, passing the air over an additional cooled surface, and exchanging heat between the air entering the passage and the air leaving said additional cooled surface.

13. The method of conditioning air which comprises forcing air to be treated in a vortex swirl through a tubular passage, cooling a portion of the Wall of the passage to a tempenature below the freezing point of water to cause an accumulation of frost on said wall portion, simultaneously reducing the cooling of said wall portion after a predetermined amount of frost has accumulated thereon and cooling another portion of the wall of the passage to a temperature below the freezing point of water, and alternately cooling and reducing the cooling of said wall portions so that one is accumulating frost as the other is defrosting.

References Cited in the file of this patent UNITED STATES PATENTS 2,008,628 Ruff July 16, 1935 2,072,486 Smith Mar. 2, 1937 2,093,725 Hull Sept. 21, 1937 2,117,104 Rorison May 10, 1938 2,157,145 Ridge May 9, 1939 2,222,240 Philipp Nov. 19, 1940 2,231,628 Knorr Feb. 11, 1941 2,401,233 Kleen May 28, 1946 2,519,028 Dodge Aug. 15, 1950 2,576,663 Atchison Nov. 27, 1951 2,658,355 Katzenberger Nov. 10, 1953 2,676,667 Dodge Apr. 27, 1954

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