US3897526A

US3897526A - Evaporative coolers

Info

Publication number: US3897526A
Application number: US365949A
Authority: US
Inventors: Roger Neill Morse; Donald Pescod; John Joseph Kowalczewski
Original assignee: Commonwealth Scientific and Industrial Research Organization CSIRO
Current assignee: Commonwealth Scientific and Industrial Research Organization CSIRO
Priority date: 1972-06-02
Filing date: 1973-06-01
Publication date: 1975-07-29
Anticipated expiration: 1992-07-29
Also published as: JPS4950740A

Abstract

A method of and installation for evaporatively cooling a defined space in which the moisture laden but cooled air into which moisture is evaporated is discharged into the space rather than to the exterior of the space.

Description

United States Patent 1 Morse et a1.

[[ EVAPORATIVE COOLERS [75] inventors: Roger Neill Morse, Caulfield;

Donald Pescod, Balwyn; John Joseph Kowalczewski, East Hawthorn, all of Australia [73] Assignee: Commonwealth Scientific &

Industrial Research Organization, Campbell, Australia [22] Filed: June 1, 1973 [21] Appl. No.1 365,949

[30] Foreign Application Priority Data June 2, 1972 Australia 9205/72 [52] U.S. Cl. 261/152; 98/211; 98/17; 165/42; 261/30; 261/D1G. 4 [51] Int. Cl. B01F3/04 [58] Field of Search 261/161, DIG. 4, 30, 152,

[451 July 29,1975

[56] References Cited UNITED STATES PATENTS 1,986,529 1/1935 Ray 261/161 X 2,257,639 9/1941 Moore 261/D1G. 4 X 2,587,197 2/1952 Mousel 261/D1G. 4 X 2,998,714 9/1961 Bonzer 261/D1G. 4 X 3,606,982 9/1971 Anderson 261/D1G. 4 X 3,738,621 6/1973 Anderson 261/D1G. 4 X

Primary Examiner-Frank W. Lutter Assistant Examiner-William Cuchlinski, Jr. Attorney, Agent, or F irm-Sughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT A method of and installation for evaporatively cooling a defined space in which the moisture laden but cooled air into which moisture is evaporated is dis charged into the space rather than to the exterior of the space.

12 Claims, 4 Drawing Figures PATENTEI] JUL 2 9 I975 SHEET N QI PATENTED JUL29 I975 SHEET EVAPORATIVE COOLERS BACKGROUND OF THE INVENTION This invention relates to cooling installations of the type in which the cooling effect is derived from the evaporation ofa liquid in the path of an air flow. In particular the invention relates to installations of the type in which there are two air flows, a primary air flow and a secondary air flow, and in which moisture is evaporated into the secondary air flow thereby to effect cooling of that flow and by heat exchange of the primary air flow. The required heat exchange occurs between the primary air and the cooled secondary air and/or between the primary air and surfaces from which the moisture has been evaporated in, for example, a plate type heat exchanger.

In one previously proposed installation of the abovementioned type, an air flow is drawn from outside a space to be cooled and split into primary and secondary flows. The primary air flow is passed through a first set of air passageways formed in a heat exchanger and discharged to the interior of the space. The secondary air is passed through a second set of air passageways in the heat exchanger. It is evaporatively cooled as it passes through the heat exchanger and assists in cooling the air in the primary air flow. This air stream is then, according to the prior proposals, discharged outside the space to be cooled.

SUMMARY OF THE INVENTION Although, in the case above described, the secondary air has been used to cool the primary air, it is still nevertheless substantially cooler than the outside air. Hitherto it has been regarded as necessary to discharge this air outside the space to be cooled because of its high humidity. For example, in a typical case, the outside air temperature might have a dry bulb temperature of 37C and a relative humidity of about 25%. The secondary air, after evaporative cooling and heat exchange in the heat exchanger with the primary air might have a dry bulb temperature of 26C but such air, though it is cooler than the outside air, does not provide a comfortable condition because of its high relative humidity, say, 80%. This invention is, however, based on the realization that whilst this moist secondary air flow may not in itself provide a comfortable condition if it is directed at the occupants of the space or is used to provide an overall ambient condition, it can nevertheless, be used to improve the overall cooling effect by being discharged to particular areas of the space separately from the primary air flow. For example, in a vehicle such as a motor-car, bus or truck, use can be made of the relatively lower temperature of this secondary air to improve the net cooling effect obtained in the passanger cabin by directing it against or along the principal heat radiating surfaces of the cabin such as the windscreen and the roof, while the relatively drier and cooler primary air is used to provide what may be termed jet" cooling of the passengers.

It is therefore a principal object of the invention to provide an improved method of and installation for evaporatively cooling a defined space.

According to this invention there is provided a method for cooling a defined space, comprising the steps of:

drawing a primary air flow through a first set of pas sageways formed in a heat exchanger and discharging same into the space;

separating a secondary air flow from the primary air flow after it has passed through the first set of passageways and causing the secondary air flow to pass through a second set of passageways formed in the heat exchangers and to discharge into the space in a stream which is separate from that portion of the primary air flow which is discharged directly into the space and,

supplying a predetermined liquid to the secondary air flow within the second set of passageways,

whereby the liquid is evaporated within the second set of passageway-s thereby to effect cooling of the secondary air flow and to effect cooling of the primary air flow by heat exchange between the respective sets of passageways.

The invention also provides an evaporative cooling installation comprising:

a defined space to be cooled;

a heat exchanger constructed and arranged to define a first set of passageways and a second set of passageways in heat exchange relation with each other;

means to draw a primary air flow through the first set of passageways and to discharge the same into the space;

means to cause a secondary air flow to separate from the primary air flow after it has passed through the first set of passageways and to cause the secondary air flow to pass through the second set of passageways and to discharge into the space in a stream which is separate from that portion of the primary air flow which is discharged directly into the space and;

means to supply a predetermined liquid to the secondary air flow within the second set of passageways;

whereby the liquid is evaporated within the second set of passageways to effect cooling of the secondary air flow and to effect cooling of the primary air flow by heat exchange between the respective sets of passageways.

The heat exchanger is preferably a plate type heat exchanger having spaced apart plates arranged to define the said sets of passageways.

The secondary air flow is preferably separated from the cooled primary air flow before the primary air flow is discharged into the space. This separation may be so arranged that the secondary air flow enters the second set of passageways at the lowest possible wet bulb temperature.

Installations constructed in accordance with the above principles are particularly useful in providing personal cooling, since the relatively dry and cool primary air flow can be so directed as to provide an immediate cooling effect for the occupants of the space, whereas the relatively moister and warmer secondary air flow can be used to cool heat radiating surfaces exposed to the interior of the space. In, for example, a vehicle installation, the secondary air flow should preferably be discharged to the upper part of the vehicle cabin to cool the windscreen and roof of the cabin thereby reducing the amount of heat radiated from these surfaces to the occupants of the vehicle.

The principles of this invention can also be advantageously used to provide an improved cooling effect in a room, particularly where there are large heat radiating surfaces such as extensive glass window areas. In this latter case, the primary air flow would be directed into the space whilst the secondary air flow would be directed over the principal heat radiating window surfaces.

In order that the invention may be better understood examples of its application to a car cooler, to a personal cooler and to a room, will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic sectional side elevation through a cooler as fitted to a motor car, mounted under the dashboard.

FIG. 2 is a diagrammatic sectional side elevation through a cooler of compact design to provide personal jet" cooling within a room.

FIG. 3 is a side elevation ofa larger installation in, for example a room, in which the primary air flow is directed inwardly of the space whilst the secondary air flow is directed over the principal heat radiating surfaces.

FIG. 4 is a portion of a psychometric chart for a cooler according to the arrangement shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates the application of the invention to a motor car using, so far as possible, the existing heater installation as part of the cooling apparatus. In view of this, the installation can, when modified in accordance with the invention, serve a dual purpose as either a cooler or a heater. In the arrangement shown, outside air is taken in through transverse bonnet grating 4 past heater coil 5, which is inoperative when the installation is functioning as a cooler, by means of a fan 6 as in the existing heater arrangement of the vehicle. This air forms a primary air flow 7 at one inlet of a parallel plate type heat exchanger 3 constructed to provide alternating primary and secondary air passageways, the primary air passageways being arranged to be transverse to the secondary air passageways. The air flow passes through the primary air passageways, as indicated by the arrow A in FIG. 1, where it is cooled in a manner hereinafter described and, on leaving these passageways, is directed upwardly through a duct 14. Fromthis duct, a portion P of the cooled air flow is discharged via flexible conduits 17 through register outlets 1 to the interior of the car to provide jet cooling for the front seat passengers. The register outlets are those which normally serve to provide flow-through ventilation of the car interior.

The remaining part of the original primary air flow becomes a secondary air flow 9. The secondary air flow is subsequently directed downwardly through the secondary air passageways, as indicated by the arrow B, water or other liquid being provided by sprays 2 for evaporative cooling of the air flow within the secondary air passageways. Heat necessary to facilitate evaporation of the liquid is derived partly from the secondary air flow itself and partly through transfer of heat through the heat exchanger plates from the primary air flow.

The secondary air flow leaves the heat exchanger at its lower end, is turned upwardly through a duct disposed adjacent and generally parallel to the duct 14 and discharged (arrow S) through a register outlet 13 located in the dashboard of the vehicle to provide general cooling of the windscreen and roof which normally contribute a substantial part of the heat radiated to the vehicle passengers. Water or other liquid which has not been evaporated within the secondary air passages drains under gravity and flows through holes at 16 into a water tank 10 from where it flows via tubing 19 to a sump 18. Water or other liquid for the sprays 2 is circulated from sump 18 by means of a pump (not shown).

It will be observed that although two separate air flows are created only one fan is needed with the arrangement shown. It will also be appreciated that when the car is moving this movement itself will contribute substantially to the flow of air through the apparatus.

It will also be observed that the secondary air flow passes downwardly through the heat exchanger rather than upwardly. Although this serves to appreciably increase the total flow path length, it has been found that an upwardly moving secondary air flow tends to carry a considerable proportion of the water or liquid droplets sprayed at 2 through register 13 onto the windscreen of the vehicle. Thus it is preferred, in order to minimize water or liquid loss, to so arrange the installation that the secondary air flow passes downwardly through the heat exchanger.

It will be appreciated that the installation illustrated in FIG. 1 need not be located forwardly of the passenger compartment. It may indeed be desirable, on converting existing vehicles to incorporate the installation, that at least part of the installation be located in the boot of the vehicle.

The personal cooler shown in FIG. 2 can be similar in basic structure to known personal coolers and can be either portable or fixed in a location such as near a window or a wall. In this arrangement air 23 to be cooled is drawn in at 24 by a fan 25 and cooled as it passes through the primary air passageways of a plate type heat exchanger 26, as indicated by arrow A. A portion P of this primary air flow is discharged at an outlet 27 to provide jet" cooling for the person using the cooler. The remaining portion of the primary air flow becomes a secondary air flow 28, and flows downwardly through the secondary air passageways (arrow B) where it is evaporatively cooled by water or liquid provided by sprays 29. Liquid not evaporated within the secondary air passages drains into a tank 30 from where it is recirculated by a pump 31 which supplies liquid to the sprays 29. The cooled and moist secondary air is turned upwardly through a duct 33 past the heat exchanger and discharged (arrow S) at outlet 32 in a direction upwardly and away from the body of the person using the cooler.

The primary air to be cooled may be drawn from outside the space to be conditioned or from within that space.

In the larger scale installation shown in FIG. 3 a room 40 to be cooled may typically have a large window 41 in an outwardly facing wall 42. The cooler 43 is installed in the lower part of the wall, and may be of the same general type as that shown in FIG. 2. Outside air is drawn into the cooler at 24 and forms the primary air flow as previously described. A portion of the primary air is discharged inwardly to the room through the register 27 and the secondary air S is discharged upwardly over the interior surface of the window 41 thereby cooling that surface and reducing the amount of heat radiated by it to the interior of the room.

The psychometric chart of FIG. 4 depicts the condition of the air at various stages in the cycle of operation of the car cooler of FIG. 1.

Primary air enters the heat exchanger at condition A (a typical summer outdoor condition). The primary air is cooled to condition B without increase in moisture content and a fraction of this air is discharged to the car interior to provide jet cooling as shown in FIG. 1. The remaining fraction of the primary air at condition B then becomes the secondary air, enters the heat exchanger and is discharged through register outlet 13 at condition C. The process from B to C involves the simultaneous evaporative cooling of the secondary air and the heating of it by means of heat transferred from the primary air flow. Similar chart changes can be plotted for the conditions at the various points in FIGS. 2 and 3. Thus in FIG. 3 condition B represents the condition of the laterally discharged air stream P and condition C represents the condition of the secondary air stream S which is discharged over the window surface.

There has been described above three constructions and applications according to this invention. It will be understood, however, that other constructions and applications may be made without departing from the spirit and scope of the invention.

We claim:

1. A method for cooling a defined space, comprising the steps of:

drawing a primary air flow through a first set of passageways formed in a heat exchanger and discharging same into the space;

separating a secondary air flow from the primary air flow after it has passed through the first set of passageways and causing the secondary air flow to pass through a second set of passageways formed in the heat exchanger and to discharge into the space in a stream which is separate from that portion of the primary air flow which is discharged directly into the space and,

supplying a liquid to the secondary air flow within the second set of passageways,

whereby the liquid is evaporated within the second set of passageways thereby to effect cooling of the secondary air flow and to effect cooling of the primary air flow by heat exchange between the respective sets of passageways,

said secondary air flow being so discharged into the space as to be directed onto or along a surface therein which radiates heat into the space whereby to effect cooling of the surface.

2. The method according to claim 1 wherein the primary air flow is discharged into a zone of the space which is occupied or to be occupied, whereby to effect cooling of the zone.

3. The method according to claim 1, wherein the secondary flow is separated from the cooled primary air flow before the primary air flow is discharged into the space.

4. The method according to claim 3, wherein the primary air flow is discharged into a zone of the space which is occupied or to be occupied, whereby to effect cooling of the zone.

temperature.

6. An evaporative cooling installation comprising:

a defined space to be cooled;

means to cause a secondary air flow to separate from the primary air flow after it has passed through the first set of passageways and to cause the secondary air flow to pass through the second set of passageways and to discharge into the space in s stream which is separate from that portion of the primary air flow which is discharged directly into the space, means to direct said secondary air flow onto or along a surface therein which radiates heat into the space whereby to effect cooling of the surface and;

means to supply a liquid to the secondary air flow within the second set of passageways;

7. The installation according to claim 6 and further comprising means to direct said primary air flow into a zone of the space which is occupied or to be occupied, whereby to effect cooling of the zone.

8. The installation according to claim 6, wherein the heat exchanger is a plate type heat exchanger having spaced apart plates arranged to define the said sets of passageways.

9. The installation according to claim 6, wherein the means to cause the secondary air flow to separate from the primary air flow is such that the secondary air flow separates from the primary air flow before the primary air flow is discharged to the space.

10. The installation according to claim 9, wherein the primary air flow is discharged into a zone of the space which is occupied or to be occupied, whereby to effect cooling of the zone.

11. The installation according to claim 9, wherein the means to cause the secondary air flow to separate from the primary air flow is such that the secondary flow enters the secondary set of passageways at the lowest possible wet bulb temperature.

12. A vehicle comprising:

a passenger cabin;

a heat exchanger arranged to define a first set of passageways and a second set of passageways in heat exchange relation with each other;

means to draw a primary air flow from the exterior of the vehicle through the first set of passageways and to discharge the same into a zone of the cabin which is occupied or to be occupied;

means to cause a secondary air flow to separate from the primary air flow after it has passed through the first set of passageways but before it has been discharged into the cabin, and to cause the secondary air flow to pass through the second set of passageway and to discharge into the cabin in a stream which is separate from that portion of the primary air flow which is discharged directly into the space 5 and which stream is directed onto or along the interior surface of the vehicle windscreen and/or cabin roof; and

3,897,526 7 8 means to supply a liquid to the secondary air flow dary air flow and to effect cooling of the primary within the second set of passageways; air flow by heat exchange between the respective whereby the liquid is evaporated within the second set of passageways. set of passageways to effect cooling of the secon-

Claims

1. A METHOD FOR COOLING A DEFINED SPACE, COMPRISING THE STEPS OF: DRAWING A PRIMARY AIR FLOW THROUGH A FIRST SET OF PASSAGEWAYS FOMED IN A HEAT EXCHANGER AND DISCHARGING SAME INTO THE SPACE, SEPARATING A SECONDARY AIR FLOW FROM THE PRIMARY AIR FLOW AFTER IT HAS PASSED THROUGH THE FIRST SET OF PASSAGEWAYS AND CAUSING THE SECONDARY AIR FLOW TO PASS THROUGH A SECOND SET OF PASSAGEWAYS FORMED IN THE HEAT EXCHANGER AND TO DISCHARGE INTO THE SPACE IN A STREAM WHICH IS SEPARATE FROM THAT PORTION OF THE PRIMARY AIR FLOW WHICH IS DISCHARGED DIRECTLY INTO THE SPACE AND, SUPPLYING A LIQUID TO THE SECONDARY AIR FLOW WITHIN THE SECOND SET OF PASSAGEWAYS, WHEREBY THE LIQUID IS EVAPORATED WITHIN THE SECOND SET OF PASSAGEWAYS THEREBY TO EFFECT COOLING OF THE SECONDARY AIR FLOW AND TO EFFECT COOLING OF THE PRIMARY AIR FLOW BY HEAT EXCHANGE BETWEEN THE RESPECTIVE SETS OF PASSAGEWAYS, SAID SECONDARY AIR FLOW BEING SO DISCHARGED INTO THE SPACE AS TO BE DIRECTED ONTO OR ALONG A SURFACE THEREIN WHICH RADIATES HEAT INTO THE SPACE WHEREBY TO EFFECT COOLING OF THE SURFACE.

5. The method according to claim 3, wherein the secondary air flow is separated such that it enters the second set of passageways at the lowest possible wet bulb temperature.

6. AN EVAPORATIVE COOLING INSTALLATION COMPRISING: A DEFINED SPACE TO BE COOLED, A HEAT EXCHANGER CONSTRUCTED AND ARRANGED TO DEFINE A FIRST SET OF PASSAGEWAYS AND A SECOND SET OF PASSAGEWAYS IN HEAT EXCHANGE RELATION WITH EACH OTHER, MEANS TO DRAW A PRIMARY AIR FLOW THROUGH THE FIRST SET OF PASSAGEWAYS AND TO DISCHARGE THE SAME INTO THE SPACE, MEANS TO CAUSE A SECONDARY AIR FLOW TO SEPARATE FROM THE PRIMARY AIR FLOW AFTER IT HAS PASSED THROUGH THE FIRST SET OF PASSAGEWAYS AND TO CAUSE THE SECONDARY AIR FLOW TO PASS THROUGH THE SECOND SET OF PASSAGEWAYS AND TO DISCHARGE INTO THE SPACE IN S STREAM WHICH IS SEPARATED FROM THAT PORTION OF THE PRIMARY AIR FLOW WHICH IS DISCHARGED DIRECTLY INTO THE SPACE, MEANS TO DIRECT SAID SECONDARY AIR FLOW ONTO OR ALONG A SURFACE THEREIN WHICH REDIATES HEAT INTO THE SPACE WHEREBY TO EFFECT COOLING OF THE SRFACE AND, MEANS TO SUPPLY A LIQUID TO THE SECONDARY AIR FLOW WITHIN THE SECOND SET OF PASSAGEWAYS, WHEREBY THE LIQUID IS EVAPORATED WITHIN THE SECOND SET OF PASSAGEWAYS TO FFECT COOLING OF THE SECONDARY AIR FLOW AND TO EFFECT COOLING OF THE PRIMARY AIR FLOW BY HEAT EXCHANGE BETWEEN THE RESPECTIVE SETS OF PASSAGEWAYS.

12. A vehicle comprising: a passenger cabin; a heat exchanger arranged to define a first set of passageways and a second set of passageways in heat exchange relation with each other; means to draw a primary air flow from the exterior of the vehicle through the first set of passaGeways and to discharge the same into a zone of the cabin which is occupied or to be occupied; means to cause a secondary air flow to separate from the primary air flow after it has passed through the first set of passageways but before it has been discharged into the cabin, and to cause the secondary air flow to pass through the second set of passageway and to discharge into the cabin in a stream which is separate from that portion of the primary air flow which is discharged directly into the space and which stream is directed onto or along the interior surface of the vehicle windscreen and/or cabin roof; and means to supply a liquid to the secondary air flow within the second set of passageways; whereby the liquid is evaporated within the second set of passageways to effect cooling of the secondary air flow and to effect cooling of the primary air flow by heat exchange between the respective set of passageways.