USRE21917E

USRE21917E - Evaporative cooler

Info

Publication number: USRE21917E
Authority: US
Publication date: 1941-10-07

Description

1941- c. N. DEVERALL EVAPORATIVE COOLER Original Filed Feb. 12, 1'93"! 2 Sheets-Sheet l INVENTOR V 'Oct. 7, 1941. I c. N. DEVERALL Re. 21,917

EVAPORAT IVE COOLER 72 :gENTGR 0(6 ATTORNEYS W Reissuedct7, 1941 v R I UNITED STATES PATENT OFFIC Charles N. Deverall, Buflalo, N. Y., assignor to Niagara Blower Company, New York, N. Y., a corporation of New York Original No. 2,166,397, dated July 18, 1939, Serial No. 125,471, February 12, 1937. Application for reissue August 2, 1940, Serial No. 349,985

10 Claims. (Cl. 257-37) This invention relates to an evaporativecooler dry coils in which the relative amounts of air and is shown as embodied in a condenser for condrawn through the two passages can be convendensing the compressed gas of a refrigeration iently adjusted. system, although it can b employed wherever Another object is to provide an evaporative it is desired to cool a gas or liquid to a point near cooler unit which is so designed as to be capable the wet bulb temperature of the atmosphere. of cooling two or more separate fluids.

One of the principal objects of this invention is Another object is to provide a common header to provide a cooler for cooling and/orcondensing for the wet and dry coils. a gas or liquid, such as compressed superheated Another object of the invention is to provide refrigerant gas, in which the cooling water is resuch an evaporative cooler which is extremely circulated and the cooling effect achieved prin, compact in construction and efficient in operacipally by evaporation of the cooling water on" th pipes through which the gas is conductedj; 1B this means an economy is effected in}v the cost of cooling water and by its use the municipal sewe systems are not overtaxed by the installationo large air conditioning systems,which normall require large amountsotcooling water forcon tion and which can be located at any convenient place; the air being discharged by means of a fan through-a duct which can be arranged to dis- "charge the air as may be desired.

Another object 'of the present invention is to pro'videsuch a condenserwhich has a relatively small'l'amount of cooling coils operating at high 1 v a I .Ieflicienc y and which is comparatively inexpensive Another object of the, presenfllnvention is"tog in construction.

provide such a cooler which isfsuitable' for. use In the'accompanying. drawings:

in cooling fluids having a relatively-high "enter-Q 1 Fig-1 is a fragmentary vertical, section, taken ing temperature. At temperatures above x115? F; generally on line ll, Fig. 2, and showing parts spray water will evaporaterapidly anddep'osit' ,in'elevation.

I scale upon the pipes conducting themedium tobe Fig. 2 is anend elevation thereof.

densing the compressed;'rerrigerant.

cooled. In accordance with the presen't invention i Eigr3iis a vertical section, taken on line 3-3, the temperature of the medium to be cooled-is" Fig; v 1. first reduced to at or below 115 F. by alr cooling' a, .Fig. ,4. is a fragmentary horizontal section,

before being subjected. to evaporative cooling ,so 'taken on line 4-4, Fig. 2. that any deposit which does occur isso soft as to 1 Q In its general organization the evaporative be lmmediatelv washed the P P y the .cooler forming the subject of the present inven- P i 1 tion consists of a casing through which air' is Another object of the present invention is to f n of a fa and which is divided f F such a condenser whichthe fi into two-passages, each passage containing coolcooling stage merely removes sensible heat from, 3 mgpo'flsi'the cooling coils of the two passages ffim i't thififl lilf wfifil3131552355322? mg i In of orative cooling and to remove the balanceof the J :2; zgg ii gg gfiig ifi zggzy gi fi 22:2 2: sensible heat and the latent heat in a second stage by evaporative cooling. By this means the, 9 zi gfgfi gz f i gfii fii g gg g g fig fii 51553 3553353 the heat f x y pi .ranged inthe air passage in which it is cooled below the point at which a scale would form if .'-these coils were sprayed with water. From these Another e t of the present inventioj v provide an evaporative cooler lit-whichxair and l I water is passed over the pipes through whichthe-" cons i l conducted to the coils sprayed with medium to be cooled is conductedand-in which f q other Passage where its temperature the air leaving the cooler is not saturated with reduced and the latent heat removed k moisture, but is relatively dry. By this means f =1 is used as condense!" Means are shouldit be desired to discharge theair through? P v for Preventing the escape of i ed grinwork over a 1 e e w d x g, So -moisture and means are also provided for addanger of the moisture condensing on the grille justmg theproportions 8 8 through the workand. the condensate dripping therefrom. P S EB he headers for thecoils are also so Another obje t is t provide an ,evaporative constructed and connected with one another as cooler having a passage containing dry coils and. oprovide a simpl a d co pact construction a passa e containing wet coils inseries with the and are als Preferably so designed that two or chambers.

, a lower casing section III of rectangular form,

the botom of which is closed to forms tank or sump II which contains a body of water l2. Removably mounted on the section III is an upper rectangular section l3, the two sections it and I3 being in open communication with one another and the upper section l3 containing a plurality of fan housings ll, the inlets of which are in communication with the interior of the casing l3. A common shaft 16 extends through the several fan housings II and is shown as driven by a motor l6 mounted on a bracket H at one end of the casing l3. Within each fan housing the shaft l3 carries a fan I! of any suitable construction, these fans drawing the air from the interior of the casing l0, I3 and discharging it through an outlet is. v

Air is admitted to the lower part of the lower casing section "I through a side inlet 20 which can be of any suitable construction and is preferably screened as indicated at 2|. It will therefore be seen that air is'drawn through the inlet 20 up through the casing sections Ill and I3 into the fan housings from which .it is discharged through the fan outlets l9. It will be understood that the fan outlets I! are to be connected to a duct (not shown) through which the air is discharged at any desired place.

A vertical partition 26 is provided within the casing l0, this partition dividing the casing into two

passages

26 and 21. The partition 26 preferably extends below the top of the inlet 2|! and to the bottom of this partition is preferably hinged a plate 26, this plate being vertically adjustable, as indicated by the full and dotted lines in Fig. 3. It will be seen that by so adjusting the plate 28 the proportions of air admitted to the

passages

26 and 21 can be adjusted as desired to secure any desired relative flows through these passages.

Mounted in the upper part of the passage 26 is an inlet header 30 which can be of any suitable construction and is shown as being in the form of a hollow casting having an internal partition 3| which divides the header into two separate Each of these chambers is provided with an inlet nipple or connection 32. In the form of the invention shown, one of theinterior chambers of the inlet header 30 communicates with three serpentine cooling'coils or tubes 33 and the other chamber communicates with three similar serpentine cooling coils or tubes 34. These tubes are preferably provided with an extended or fin surface and at their lower ends connect with an intermediate header 36 which extends the full width of the casing In. This header 35 is preferably in the form of a casting and is provided with internal partitions forming four

separate chambers

36, 31, 38 and 39. The tubes 33 communicate with the chamber 36. The tubes 34 communicate with the chamber 31. The chamber 36 is connected by an exterior pipe 40 with the chamber 33 and the chamber 31 is connected by a pipe ll with the chamber 36.

That part of the intermediate header 36 containing' the

chambers

38 and 39 is located alongside the passage 21 and sixserp'entine cooling coils 46 are shown as connecting with the chamber 38,

these coils 66 being located within the second P s ge 21. Similarly, six coils 46 are shown as communicating with the chamber 33, these coils being located in the second passage 21. The

lower ends of the coils l6 and 6 connect with an 21,917 I r outlet header 41, this header being formed with a central partition to provide two chambers, the

and the coils 46 into the other of these chambers. Each of these chambers isprovided with an outlet nipple or connection 48. Preferably only the lower part of the bank of coils l6 and 46 in the second passage 21 are provided with an extended or flu surface, the uppermost turns of these coils v 7 being left bare, as best shown in Fig. 3.

float valve 60 which controls the admission of water from a supply main 5| so that as evaporation takes place the valve 50 will replenish the water supply. The water in the tank II is withdrawn by a centrifugal pump 63 driven by a motor 64 and is discharged through a vertical pipe 63v into a horizontal pipe 66 extending lengthwise through the interior of the casing. This pipe 66 carries a suitable number of branch pipes 51 each of which carries a downwardly discharging nozzle 66. The nozzles 68 are arranged above the bank of coils l6 and 46 and in the second passage 21 so that these coils are constantly flushed with water. The excess water from the coils 45 and I6 falls back into the sump II.

In order to remove any entrained moisture from the air passing upwardly through the second passage 21, eliminator plates 60 are provided, these eliminator plates being arranged across the upper end of the passage 21 and being of such form as to whip the air back and forth and cause any entrained moisture to be deposited on the eliminator plates from which these drip down onto the bank of coils. therebelow. The eliminator plates prevent entrained moisture from being carried over to the high temperature coils in the passage 26 and building up a deposit on these coils.

Operation It will be assumed as an example that the evaporative condenser is used to condense the superheated refrigerant gas from the compressor of a refrigeration system and that this superheated refrigerant gas has a temperature of 210 F. and is under 155 lbs. pressure, its condensing temperature therefore being 86 F. It will also be assumed that the wet bulb temperature of the air entering the evaporative condenser is F. and is at, say, a dry bulb temperature of F.

The superheated refrigerant gas enters one of the nipples 32 of the header 30 and passes, say, through the tubes 33 and into the compartment 36 of the header 35. These tubes 33 are fin surfaced and are cooled by the stream of air drawn up through the passage 26, thi air having an entering temperature of 95 F. Under the outside temperature of 95 F., it is possible to cool the gas to F. in the coils 33. The amount of surface of the coils 33 is such that with the maximum temperature of the outside air, the gas will be cooled in these coils 33 to a temperature below F. Such cooling under the condition assumed will reduce the gas to a substantially saturated vapor near its condensing temperature. Since the coils in the air passage 26 are dry coils a deposit is not formed upon these coils as would be the case if they were sprayed with water. the same time onlythe superheat of the gas is removed in these coils, this superheat constituting only a small part of the total heat to be removed. Under the conditions assumed, a reduc-- tion in temperature of the gas from 210 F. to a liquid at 86 F., the total heat to be removed would be 580 B, t. u. per pound. Of this 80 B. t. u. would be sensible superheat and 500 B. t. u. latent heat.

The partially cooled gas from the chamber-3i at the assumed 100 F.. passes through the pipe 40 in the chamber 39 of the same header I! and from this header enters the six tubes 46 connectdischarge at any desired place. Further, it will be seen that the unit is very flexible, permitting the same unit to be used as a cooler and/or a condenser for one or more media to be cooled. It will further be seen that by the provision of the dry coils to initially bring the temperature of the medium to be cooled below 115 F. the cooler can be used to cool gases or fluids at very high ing with the outlet header 41. These tubes are sprayed with water from the spray nozzles 53,

.but since the temperature of the gas has already been reduced below 115 F., the tubes 46 are not heated to a temperature at which the spray water will form a scale on these tubes. It will further be noted that the upper part of the bank of tubes in the pass 21 are unflnned so that if these tubes should rise to a point slightly above 115 F. the

bare tubes will be kept washed and free from the.

slight deposit which might otherwise tend to form. As is well known, tubes, such as the coils 46, when cooled by a flow of air and recirculated spray water assume the wet bulb temperature of the air and in passing through the tubes 46 the refrigerant is therefore cooled to its condensing temperature, or 86 F. under the pres-' sure assumed, the wet bulb temperature being assumed to have been at 75 F. By proper proportioning of surface and sprays, it is possible in the wet coils to reduce the gas temperature to within 4-5 of the wet bulb temperature so that with the assumed outside wet bulb temperature of- 75 F., the gas is cooled to about 80 F. It. will be understood that a sufliciently high outlet pressure is maintained so that the condensing temperature of the gas is above the most adverse atmospheric wet bulb conditions encountered, The condensed refrigerant from the header 4'! is drawn out through the corresponding nipple 48.

The air drawn up through the passage 21 may be substantially saturated. However, the relative humidityof the air coming up the passage 25 is reduced on being heated by the

coils

33 and 34. Therefore when the two streams of air are mixed on passing through the fan, the air discharged from the fan has an intermediate relative humidity and is not saturated. As a result of the admixture of the heated air from the passage 26 there is less tendency for condensation in the duct or condensation at the discharge outlet, the latter being highly undesirable where the discharge is above a point where people pass.

It will be noted that with the above operation the bank of dry coils 34 and bank of wet coils 45 were assumed to be not in use. that the superheated refrigerant gas from another system can be cooled and condensed in these coils or that all of the coils can be used in cooling and condensing the gas from one system. The form of headers with internal partitions and the use of two or more connections leading to and from the chambers formed by these partitions thereby permits of greater flexibility in the use of the unit.

The air on leaving the sprays 58 is passed through eliminator plates which remove any en-- trained moisture. By this means spray water is prevented from being carried over to and coating the high temperature coils in the passage 26.

From the foregoing it will be apparent that the present invention provides an evaporative condenser which is extremely compact in con-' struction and of large capacity and can also be located wherever desired, connecting the air outlet l9 to discharge into a duct which may in turn It is obvious entering temperatures without danger of coating the tubes while at the same time removing the bulk of the heat, particularly in condensing, in moist coils. It will also be seen that the air leaving the cooler'is not saturated because the air leaving the evaporative passage 21 is mixed with the air heated in the passage 16 and which therefore has a low relative humidity. While the invention has been described as an evaporative condenser for condensing high temperature rescribed, comprising a dry precooling coil, means for passing air over said precooling coil to absorb heat therefrom, means forming a chamber, means for forcing a current of air through said chamber, a secondary cooling coil in the current of air passing through said chamber, means for discharging and distributing water over said secondary coil to wash the exterior of said secondary coil and to evaporate thereon and absorb heat therefrom, means for conducting the fluid to be cooled in series through said precooling and secondary coils, means below said secondary coil for collecting the water, and means for recirculating the collected water through said discharging means.

' 2. An evaporative cooler of the character described, comprising a dry precooling coil, means for passing air over said precooling coil, means forming a chamber, means for forcing a current means below said secondary coil for collecting the water, means for recirculating the collected water through said discharging means and means for adjusting the relative amounts of air passing over said precooling and secondary coils.

3. An evaporative cooler of the character described, comprising means forming a chamber, means for forcing a current of air through said chamber, a cooling coil in the current of air passing through said chamber and conducting the fluid to be cooled, means for discharging water to wash the exterior of said coil and evaporate thereon, means below said coil for collecting the water, means for recirculating the collected water through said discharging means, means for mixing a current of dry air with the current of moist air leaving said coils, and means for heat: ing said current of dry air before admixture with said current of moist air.

4'. An evaporative cooler of the character described,- comprising means forming a chamber, an inlet for air in the lower part of said chamber, a fan housed within the upper part of said chamberand withdrawing air from said chamber and discharging it through an outlet in the upper part of said chamber thereby to create an upward current of air in said chamber, a cooling 'coil in the current of air passing through said chamber and conducting the fluid to be cooled, means for discharging water to wash the exterior of said coil, means below said coil for collecting the water, means for recirculating the collected water through said discharging means, means for by-passing a currentof air from said inlet to said fan inlet and around said coils and discharging means, and means for heating said by-passed air.

5. An evaporative cooler of the character described, comprising means providing two currents of air, a cooling coil in one of said currents of air, a second cooling coil in the other current of air and connected in series with said first coil, means for discharging water to wash the exterior of said second coil and evaporate thereon, means below said second coil for collecting the water, means for recirculating the collected water, means for admitting the fluid to be cooled to said first coil and withdrawing it from said second coil, and means for mixing said currents of air after passing said coils.

6. An evaporative cooler of the character described, comprising means forming a chamber, a partition arranged centrally in said chamber and dividing it into two passages, an inlet at one end 01' said chamber and an outlet at the other end of said chamber, means for forcing a current of air into said inlet, through said passages, and out of said outlet, a cooling coil arranged in one of said passages, a second cooling coil in series with said first cooling coil and arranged in the other of said passages, means for discharging water to wash the exterior of said second coil, means below said second coil for collecting the water, means for recirculating the collected water through said discharging means and means for admitting the fluid to be cooled to said first coil and withdrawing the cooled fluid from said second coil.

7. An evaporative cooler of the character described, comprising means forming a chamber, a partition in the central part of said chamber and dividing it into two passages, an inlet and an outlet at the opposite ends of said chamber, b

means for forcing a current of air into said inlet, through said passages and out through said outlet, a cooling coil arranged in one of said passages, a second cooling coil arranged in the other lecting the water and means for recirculating the collected water through said discharging means; 8. An evaporative cooler of the character de-.

scribed, comprising means forming a chamber, a primary and a secondary coil in said chamber, means'for passing the fluid to be cooled in series first through said primary coil and then through said secondary coil, means for passing a stream of air over the exterior of said coils, means for discharging water over the exterior of said secondary coil to evaporate thereon and means for isolating said discharging means and secondary coil to prevent entrained water from being carried over to the primary coil including means in the path of the air leaving said secondary coil and removing the entrained water therefrom.

9. An evaporative cooler of the character described, comprising means forming a primary and a secondary chamber, a primary coil in said primary chamber, a secondary coil in said secondary chamber, means for passing the fluid to be cooled in series first through said primary coil and then through said secondary coil, means for passing a stream of air over the exterior of said coils, means for discharging water into said air stream and bringing said water into contact with one of said coils and eliminator plates in the path of the air leaving said discharging means and interposed between said chambers to remove entrained water therefrom and prevent such entrained water from being-carried over to the other coil.

10. An evaporative cooler of the character described, comprising a dry precooling coil, means for passing air over said precooling coil, means forming a chamber, means for forcing a current of air through said chamber, a secondary cooling coil in the current of air passing through said chamber, means for discharging water to wash the exterior of said secondary coil, means for conducting the fluid to be cooled in series through said precooling and secondary coils, means below said secondary coil for collecting the water and means for recirculating the collected water through said discharging means.

CHARLES N. DEVERALL.