US2069359A

US2069359A - Cooling system

Info

Publication number: US2069359A
Authority: US
Publication date: 1937-02-02
Anticipated expiration: 1954-02-02

Description

| DUDLEY m 2,069,359

COOLING SYSTEM Filed Dad. '7, 1955 INVEN 0R. Mun/m In: 001.:Y

W A TTORNEYS.

Patented Feb. 2, 1937 PATENT OFFICE COOLING SYSTEM William Lyle Dudley, Seattle, Wash. Application December 7, 1935, Serial No. 53,364

4 Claims. (Cl. 62-139) 9 This invention relates to cooling systems and more particularly to systems of. that kind wherein cooling is eflected by means of a cooled air stream that is caused to flow about the object or through the area to be cooled and which, in itspassage to the object or to the area, is caused to flow through, or across a heat interchanger, thereby to reduce its temperature to that which is suitable for cooling, and wherein the heat interchanger is kept at a cooling temperature by circulation of a cooled liquid therethrough.

The present invention is in the nature of an improved modification of the system in my 00- pending application, filed on May 13, 1935, under Serial No. 21,229.

It is the principal object of this invention to provide what may be termed a regenerative system, employing a split air stream; one part of which stream is utilized to extract heat from the cooling liquid that is circulated through a heat.

interchanger and anevaporator, while the other part of the stream is caused to be cooled by the heat interchanger in its flow through a cooling circuit.

It is also an object of this invention to provide a relatively simple, inexpensive and efiective means and method of maintaining the cooling liquid at a temperature that is suitable for the particular cooling efiect desired.

A further object of this invention is to utilize the return air in thecooling circuit for a precool ing of the intaken, outside air.

, Other objects of the invention reside in the de tails of construction, in the combination of parts,

and in their mode of use, as will hereinafter be fully described.

In accomplishing these and other objects of the invention, I have provided the improved details of construction, the preferred forms of which are 1 illustrated in the accompanying drawing, wherein- Fig. 1 is a' view diagrammatically illustrating a cooling system employing the split air stream in accordance with the present invention, and

utilizing return air from the cooling circuit f0 precooling the intaken, outside air. Fig. 2 diagrammatically illustrates a modification of the system of Fig. 1.

Fig. 3 diagrammatically illustrates still another cooling system employing the split air stream.

Explanatory to the present invention, it will here be stated that the cooling of any object by air circulation depends upon the interchange of heat between the object and the circulated air, while the rate of cooling depends upon thenature of the surfacetof the object, the quantity of air circulated, and its velocity over the surface to be cooled and the differential of temperatures between that surface and the air stream.

There are two systems of cooling by air now 5 generally in use; namely, the open system and the closed system. In the open system cooling' is obtained by 'humidification of. the air stream in a cooling tower where the air stream is passed over a cold water surface or through a spray. of finely divided water, whereby dust particles are separated from the air and air is cooled by evaporation to approximately the wet bulb temperature of the air. Usually a fan is used to draw or force the cooled air to the points of 15 use. Then the air is discharged to waste after its cooling effect hasbeen utilized.

In the closed system, a closed cooler or a cooling coil is generally used as a heat interchanger with a fan operating to draw or force an air stream thereover and across the objects to be cooled in a closed circuit.

While the open system has the advantage of dust removal from the air stream as well as cooling, it also has the particular disadvantage of water particles being entrained with the air stream and deposited on the objects to be cooled. Y Such free moisture is extremely undesirable in some cooling installations, and therefore recourse must be had to the closed system, which does not have thedust removing advantage unless this feature is applied in the form of filters.

Since there are certain advantages in both of the systems above mentioned, it has been an object of the present invention to provide a practical closed systemthat will retain the advantages of evaporative cooling found in the open system, and at the same time will overcome the objectionable feature of moisture being carried to the object or 'area to be cooled by keeping the cooling stream of air out of contact with water and always above the dew point temperature at which condensation takes place in a saturated mixture of air and water.

First, briefly describing the system illustrated in Fig. 1, A designates the area. that is to be cooled, which, for instance, might be an auditorium, room, or other enclosure. In the present instance, the area A represents an auditorium of a building having an attic space or insulating a conduit 5 into a heat interchanger housing 6. The cooled air stream on leaving the heat interchanger, is split; one part thereof being delivered through a conduit 1 directly into the area A, while the other part of the stream is delivered through a connecting conduit 8 into anevaporating chamber 9. From the chamber 9, the air is conducted through a conduit I0 into a heat interchanger housing H, from which it is delivered through a connecting conduit I2 into a cooling chamber I3 that surrounds a portion of the con duit 2. From the chamber l3 the air is conducted through a conduit I4 into the attic space B from which it is exhausted to atmosphere through an outlet IS. The cooled air from area A is conducted through an outlet pipe or conduit it back into the conduit 2 for mixing with fresh incoming air, for recirculation.

The cooling system for the heat interchangers 6 and II includes in each a cooling pipe coil l1. Cooling liquid is withdrawn from a sump l8 in the base of the evaporating chamber 9 through a pipe I! and is delivered to the coil I! in the interchanger 6, and from this coil flows through a pipe 20 to the coil ll of the heat interchanger II, and from this latter coil is delivered through a pipe 2| to atomizing devices 23 in the evaporating chamber 9. A pump 25 on the piping operates to force the circulation.

Assuming that this system is so constructed, it is apparent that the fan 4 operating in the housing 3 will deliver the air mixture from conduit 2 through the heat interchanger 6 and that the cooled air delivered through the conduit 8 from the latter will operate to cool by evaporation the atomized liquid utilized in the interchanger coils. It is apparent also that the cooled air delivered through the conduit 1 into area A will cool the area A.

Assuming that the air entering conduit I from the outside has a dry bulk temperature of90 and a wet bulb temperature of 60, the dew point temperature under these conditions will be 32, and its total heat content will be 26.2 B. t. 11. per pound. Then, if the liquid in the sump I8 has a temperature of it is apparent that at some time or stage of circulation of air and water, the temperature of air passing through the heat interchanger containing liquid at 50 will be lowered, and the temperature of the liquid in the interchanger will be raised.

Inspection of standard psyohrometric charts will show that the total heat content of air is determined by its wet bulb temperature. Physical illustrations show that liquids assume the wet bulb temperature of the air or gas with which they are in intimate contact, since the interchange oi sensible heat between liquid and air orgas is a function of the vapor tension of the moisture of the gas, the vapor tension of the liquid due toits temperature, and the velocity over the liquid surface or intimacy of contact. The vapor tension of the liquid will be controlled by its temperature which assumes, as stated above, the wet bulb temperature of the air with which it is in contact, and the rate of evaporation is thus determined by the difference of the vapor tensions corresponding to the dew point and wet bulb temperatures.

Thus it is evident that cooling of air or gas by evaporation to lower its dry bulb and wet bulb temperature will result in the lowering of the temperature of any liquid with which it is in contact to the wet bulb temperature of the air or gas providing that the initial temperature of the liquid was greater than the lower wet bulb temperature of the air or gas.

Manifestly, in the present instance, evaporation takes place in the chamber 9 and the result of this, as is well known, and further cooling by wetted coil I! in chamber I I may lower the temperature of the circulated liquid in contact with the air stream by the extraction of heat to change internal state and result in obtaining heat level equilibrium between gas and liquid as in the change of water to water vapor. Thus, the liquid is available to the heat interchanger at its temperature in the sump I8. Each successive passage of cooling air through the cooling circuit and interchangers results in successive decrements of temperature in this air stream; each successive lower temperature approaching the dew point temperature of the entering air as a limit.

It follows, then, that at one stage of circulationjwe may assume a cooling of the air to 80 dry bulb and wet bulb, corresponding to a dew point of 32 which corresponds to a lowering of total heat in the air by means of the interchanger from 26.2 B. t. u. to 23 B. t. u. This heat absorbed from the air is transferred to the liquid in' the interchanger circuit, raising its temperature, which is in turn lowered in the evaporating chamber 9 and wetted coil I! in chamber II to the wet bulb air temperature of 55 or lower by reason of intimate contact between the air and the mist of liquid and wetted coil surface. The heat absorbed from the liquid is dissipated from the system at the exit I5 after passing through the area B.

Continued circulation of air in the cooling circuits through the interchangers 6 and I l evaporator chamber 9 will further reduce the air temperature in the cooling circuit. For instance, to 70 dry bulb and 52 wet bulb, still no moisture .will have been absorbed in the cooling circuit corresponding to the original dew point temperature of 32, extracting total heat from the original total heat contents of 26.2 B. t. u. per pound down to a heat content of 21.3 B. t. u. per pound, or a removal of 4.9 B. t. u. per pound of air; the relative humidity of the air or gas increasing from its original 12.8% to its final volume of 33%, the dew point remaining constant.

The temperature of the liquid in the evaporator 9 and its sump l8 assumes, first as explained above, the wet bulb temperature of the air or gas with which it is in intimate contact, which is, in this case, 52, thus constantly making available at the heat interchanger 6 liquid which is cooled progressively to the wet bulb temperature of the air or below passing to exit through the evaporator.

In addition the system as regards the liquid in the interchangers, is regenerative with the dew point temperature of the air or gas as a limit. If this dew point is lower than the temperature of the liquid, it becomes possible to lower the temperature of the liquid to a temperature at, or slightly above, the dew point temperature; the heat absorbed from the water by the air or gas with which it is in contact being dissipated from the system at l5, as before described.

Cooled air heavily saturated and carrying entrained moisture discharged from the evaporator chamber 9 through conduit I0 is further changed in temperature and the liquid of the interchanger system is further cooled by its contact with wetted coil I! in the interchanger II by reason of evaporation at'the surface of the coil; the heat for interchanger 63, thence through a conduit 64 ventilator 50.

coil; this air then being delivered into surfacev contact with conduit 2, in the pre-cooler housing l3, operates to reduce the temperature of the intaken air mixture, and to further lower the temperature of the cooling liquid in coil I] of interchanger II, and consequently that of sump l8.

With reference to the system of Fig. 2, shown in connection with an area A representing an auditorium, or the like, having an attic space B and an underfloor space C which is provided with openings D into the area A, 30 designates a conduit through which outside air, for cooling, enters a fan housing 3| containing a fan 32 operable to deliver intaken, outside air forcibly through a conduit 33 into a heat interchanger housing 34; The air stream delivered through the heat interchanger is then split; one part being conducted through a channel or conduit 35 into the area A, and the other part being conducted by conduit 36 into a conduit 31 whereby the. underflow compartment C is connected with an evaporating chamber 38; The connections described provide that cooled air will be delivered through the conduit 35 into the compartment A and will pass through the openings, Dinto the compartment C, andfrom thelatter will flow through the conduit 31 into the evaporating chamber 38 together with the cooled air coming directly from the heat interchanger through the conduit 36. The heat interchanger 34 in this instance comprises a coil of pipe designated at 40, or any other suitable transmission surface, supplied with cooling liquid, from a sump ll in the base of the vaporating chamber 138, through the mediacy of a pipe connection 42, and a pump 43 that is interposed in the pipe connection. A pipe 45 leads from the water discharge end of the heat interchanger coil back to the top side of the evaporating chamber, and is there equipped with a plurality of atomized sprays 46 from which emanates the spray or mist through which the air stream from the conduit 31 passes through the cooling chamber to an outlet conduit 48. In this particular arrangement, a blower 49 is associated withthe outlet conduit and delivers the air into the attic space B of the auditorium, from which it passes This particular system operates in the same manner as described in connection with the system of Fig. 1, except that the cooling air, after passing through the auditoriumor area'to be cooled, is not recirculated back to the heat interchanger, but passes into the cooling chamber 38 and is then delivered through the attic space B.

With reference to the modification which is illustrated in Fig. 3, the area to be cooled is designated at A, the attic space at B and the basement area at C. Outside air is delivered into the basement area C through an' inlet '60 and is delivered from the basement area by means of a fan or blower 6| through a conduit 62 and heat into the upper portion of the area A; being forced downwardly and out through the outlet 65.. The heat interchanger includes the cooling pipe coil 66 through which a cooling liquid is delivered from a sump 68 in a cooling chamber. through the mediacy of a connecting pipe and pump 11- interposed in the pipe connection.- Cooling liquid from the coil is returned to the evaporating chamber 69 through a .pipe 12 and is delivered into the chamber from the pipe through atomizing devices 15. Outside, cool air is drawn intothe evaporating chamber through an opening to outside air through a I1 and is delivered through an outlet 18 and conduit 79 into the attic space B from which it escapes to outside air through an outlet 80; there beinga fan or blower, as designated at 8| interposed in the conduit" for forcing the flow of air. In this system the fresh air used for cooling the water of the interchanger 63 also cools, the attic space, and fresh air for the auditorium is cooled by its passage through the heat interchanger. Thewater for the heat interchanger in turn is cooled by evaporation in the cooling chamber, as in the system of Fig. 1.

The various systems above described differ from cooling systems heretofore employed in that, although an interchange of sensible heat between the air used for cooling and the cooling liquid takes place by its transmission through the metallic surfaces of a heat interchanger coil, nevertheless, it is believed novel to lower the temperature of the liquid used for cooling in the heat interchanger by evaporation elsewhere until the liquid assumes the wet bulb temperature of the air with which it is in intimate contact, and approaches by progression a limit, cooling to approximately the dew point temperature of the air as a limit.

Furthermore, the cooling air being separated from the air used as a heat carrier in the evaporator does not contain additional moisture or vapor due to evaporation. It is cooled without the addition of-moisture or vapor although evaporation is utilized to lower the temperature of the cooling liquid to approximately the wet bulb temperature of the air. The utilization of a combination of .an air stream as a heat carrier,

tain this wet bulb temperature in the cooling liquid used in an air or gas heat interchanger is believed to be new and not used in any methods of cooling or drying now practiced.

In each system, proper air proportion as between that passing through the evaporators and that to the area to be cooled, may be under control ot'suitable dampers placed in the conduits, and these might be automatically or manually regulated.

Having thus described my invention, what I claim as new therein and desire to secure by Letters Patent is- 1. A cooling system for an enclosed area comprising heat interchange devices in series in a circulating system that is common to both and througlrwhich a cooling liquid is continuously recirculated; said circulating system including, at one place in its path of circulation, means for efiecting a temporary atomization of the liquid, means for causing fresh air to flow'through one of said interchange devices for cooling thereby, means for dividing the cooled air stream and for directing one part through the area to be cooled and the other part through the area of atomized liquid to extract heat from the latter, thence through the other interchange device for cooling of the liquid'therein.

2. A cooling system for an enclosed area comprising heat interchange devices in series ina one of said heat interchange devices for additional cooling; means for dividing the cooled stream of air and for directing one part through the area to be cooled and the other part through the area of atomized liquid to extract heat from the latter, thence through the other heat interchange device for cooling of the liquid therein, and finally through the precooler housing for the initial cooling of intaken fresh air.

3. A system as in claim 1 wherein means is provided for delivering the cooling air from the cooled area back to the entering fresh air stream.

4. A cooling system for an enclosed area, comprising heat interchange devices in series in a common circulating system through which a cooling liquid is continually recirculated; said circulating system at one point being open for atmospheric contact with the liquid, means for causing air to flow through one of the inter- WILLIAM LYLE DUDLEY.