US2088390A - Cooling apparatus - Google Patents

Description

Patented July 27, 1937 UNITED STATES COOLING APPARATUS Ernest F. Stalcup, Rutledge, and Paul L. Fetzer, Ridley Park, Pa., assignors to Westinghouse Electric & Manufacturing Company,

East

Pittsburgh, Pa., a corporation of Pennsylvania Application December 23, 1933, Serial No. 703,786

4 Claims.

Our invention relates to cooling apparatus, more particularly to cooling apparatus of the vapor or steam jet type for cooling air or similar fluid, and it has for an object to provide improved apparatus of the character set forth.

A further object is to improve the operation of said apparatus, particularly the efiiciency thereof.

Another object is to provide simplified apparams of the character set forth.

As heretofore constructed, in steam jet refrigcrating apparatus for cooling air, water is cooled by subjecting the same to a reduced pressure, or high vacuum, in an evaporating chamber or cold tank having an ejector connected thereto. The reduced pressure efiects partial evaporation of the water and cooling of the remaining portion, as is well known in the art. The cooled water is then conveyed to a heat exchanger or air cooler, in which it extracts heat from the air to be cooled and is thereby heated to a higher temperature. It is then returned to the evaporating chamber to be recooled. It will be noted that the water must be cooled, in the evaporating chamber, to a temperature which is lower than the average temperature at which it effects cool ing of the air in the air cooler, since the water absorbs heat only as sensible heat.

It is an object of our invention to provide cooling apparatus of the vapor jet type in which the water or other liquid is cooled at substantially the same temperature at which it extracts heat from the air or other similar fluid.

In accordance with our invention, we provide a combined evaporating chamber and air cooler. It includes a group of tubes, the outer surfaces of the tubes being in contact with the air to be cooled. The tubes are preferably provided with fins or other form of extended surface on the exterlor to provide the large area of heat transfer surface required for effectively cooling air. We provide a supply of water or other liquid, preferably in a finely divided state, into the interior of the tubes to wet the inner surfaces thereof. We also provide means, such as an ejector, for'efiecting a reduced pressure in the tubes, whereby the water is partially evaporated within the tubes and cooled at the same time that it cools the air, and at the same temperature. Since it is not necessary. to reduce the temperature of the water below the temperature at which it cools the air, the consumption of steam or other motive fluid of the ejector is considerably reduced.

A further feature of our invention resides in arranging the tubes in vertical position. In this 55 position, the water tends to spread and form a film on the inner surfaces of the tubes, thereby wetting all or a large portion of said inner surfaces and providing effective cooling action.

The above and other objects are effected by our invention, as will be apparent from the following description and claims taken in accordance with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a vertical sectional view of one embodiment of our apparatus;

Fig. 2 is a plan view of the above;

Figs. 3 and 4 are vertical sectional views of other embodiments of our invention;

Figs. 5 and 6 are plan and vertical sectional views, respectively, of a detail of the apparatus shown in Fig. 4; and

Fig. 7 is a vertical sectional view of still another embodiment.

Referring now to the drawings more in detail, we show, in Figs. 1 and 2, a combined evaporating chamber and air cooler designated generally by the reference numeral it). This piece of apparatus, in the form shown in Figs. 1 and 2, includes an upper chamber or header II, a lower chamber or header l2, and a group of vertically disposed tubes l3, whose upper and lower ends communicate with the upper and lower headers and are secured to tube plates and I5 associated with the upper and lower headers, respectively.

In the present embodiment, the headers H and I2 and the interior of the tubes constitute the evaporating chamber, said spaces being in free communication with each other and thereby containing the same reduced pressure. A tube 24 of greater diameter ,than the tubes l3 may be extended, if desired, between the tube plates l4 and Hi, to provide free communication between the upper and lower headers II and I2 and insure full equalization of pressure therein; A shell or casing portion I6 preferably encloses thetubes l3. The shell I6 is provided with an air inlet l8 connected to an air duct l9 which delivers air to the shell 16, and with an air outlet 2| connected to an air duct 22 to which the cooled air is delivered from the heat exchanger portion. The duct 22 conveys the cooled air to the point of use, for example, a room to be air-conditioned. The tubes l3 are preferably provided with heat transfer fins 23 on the exterior thereof, for increasing the exterior air-cooling surface. It will be understood that the apparatus may embody heat exchanger or other improvements which are independent of the present invention.

An annular manifold 25 ,is horizontally dis- 55 posed in the upper header H, and spaced above the upper ends of the tubes l3. It is supplied with a suitable fluid under pressure, usually water, and is also provided with a group of downwardlyprojecting nozzles 26, said nozzles being distributed circumferentially around the manifold 25. The nozzles 28 provide a spray of finely divided particles of water which are distributed to the upper ends of the tubes i5. These particles of water pass downwardly through the interior of the tubes and form a thin film of water on the inner surface of the tubes. Due to the vertical position of the tubes, the water tends to distribute itself around the entire circumference of the inner surface. Preferably, a sufficient spray of water is provided to wet the inner surfaces throughout the length of the tubes. The water flows downwardly, under force of gravity, on the inner surface of the tubes, and such portion as is not vaporized, as hereinafter explained, falls into the lower header I2. The latter is formed with an outlet 28 connected to a conduit 29, through which the water flows by gravity to a water circulating pump 3|. The pump 3| forces the water through a conduit 32, by which it is delivered under pressure to the manifold 25.

Make-up water for replacing that portion of the water which is vaporized, is supplied through a valve 34 and a conduit 35 to the conduit 29. The valve 34 is controlledby a float 36 which is responsive to the level of water in the lower chamber I2 and operates the valve 34 to maintain a constant level of water therein, said float moving the valve 34 in opening direction to admit more water when the level drops, and moving it in closing direction when said level rises. The float 36 is disposed in a float chamber 31, which is connected at its upper end to the lower chamber l2 at a point above the water level, and the lower end of which is connected to the conduit 35. The water level in the float chamber 31 is thus the same as the water level in the lower chamber I2.

Suitable means for withdrawing water vapor from the evaporating chamber is provided. This means preferably comprises, as shown, a suitable ejector 38, whose suction inlet is connected to any portion of the evaporating chamber, in this case to a vapor outlet 39 in the upper header ll. Due to the free communication between the headers l l and I2, through the tubes I3 and the larger tube 24, substantially the same low pressure or vacuum produced by the ejector 38 is effected in both headers and the tubes independently of which header the ejector is connected to.

A valve 4| may be interposed between the ejector and the outlet 39. A baflie member 42, as shown, is preferably provided in the upper header ll opposite the vapor outlet 39 but in spaced relation thereto. The lower portion of the baflle 42 extends obliquely to the wall of the upper header ll, so that the vapor must flow upwardly and over the upper edge of the baflle to reach the vapor outlet 39. A horizontal baflle member 43 is preferably provided directly above the outlet 39, to avoid too' short a path for the vapor, which might carry an excessive amount of water particles with it. An opening 40 is preferably formed in the lower portion of the baffle 42 to permit any water collecting between the baffle 42 and the wall to be returned to the upper header.

The operation of the above described apparatus is as follows: Air is delivered through the duct 19 and flows to the left over the exterior surfaces of the tubes l3 to the air duct 22. The

finely divided particles of water delivered by the nozzles 26 provide a thin film of water on the interior surfaces of the tubes. The ejector 38 withdraws vapor from the headers H and I2 and the interior of the tubes and is sufficient to maintain a high vacuum or reduced pressure therein, for example, the ejector may maintain an absolute pressure of 0.1 pound per square inch. This low pressure reduces the boiling point of the water, causing the same to be partially evaporated, the heat of vaporization being extracted from the remaining water and lowering the temperature thereof to said boiling point, as is well understood in the art of steam jet refrigeration. The tubes l3 are thus cooled and extract heat from the air which is in contact therewith. The heat is conveyed from the outer surfaces, through thewalls-of the tubes to the inner surfaces, from which it is delivered to the film of water on said inner surfaces. This heat is immediately absorbed by the water as heat of vaporization by the evaporation of a suflicient quantity of water to absorb said heat. In view of the fact that the heat is immediately converted into heat of vaporization, the water on the inner surfaces of the tubes is maintained at the same temperature at which it cools the air, and it is not necessary to cool the water to a lower temperature, as is necessary in the case in which the water extracts the heat from the air as sensible heat. Accordingly, the ejector is not required to maintain as low an absolute pressure and the steam consumption thereof is substantially reduced.

In order to cover the entire inner surfaces of the tubes with a film of water, as far as possible, a supply of water greater than can be evaporated is delivered to the tubes by the spray, and the unevaporated water collects in the'lower header l2 and is recirculated as described above. The supply of water is sufficiently restricted, however, to prevent the interior of the tubes from being filled with water, since the gravity head of such a body of water would readily raise the boiling point above the temperature of the air being cooled and thus interfere with the cooling action. By restricting the supply of water so that there is a vapor space throughout substantially the entire length of the tubes, the low pressure provided by the ejector 38 is communicated through said vapor to provide cooling by evaporation of water throughout substantially the length of the tubes.

In Fig. 3, we show a modified form of com- 'bined evaporating chamber and air cooler, which is generally similar to the embodiment shown in Figs. 1 and 2, except that the ejector 38a is connected to the lower header I2a instead of the upper header I la. This arrangement may be somewhat advantageous in that the flow of vapor is downwardly, .in the same direction as the flow of water, thereby tending to assist circulation of particles of water through the tubes 13a. The float valve 34a is arranged slightly differently from the float valve 34 but is essentially the same in operation. It is disposed within the float chamber 31a, and controls flow of water from a supply conduit 30a to a conduit 35a, from which it is admitted to the conduit 29a. The float valve 34a is actuated by a float member 36a and. serves to maintain a constant level in the float I chamber 31a and in the conduit 29a. The circulating pump 3ld is shown in the form of a gear pump.

In Figs. 4, 5, and 6 we show a further modification of the invention in which the water is supplied at the upper ends of the tubes i3 in the form of an annular sheet of water instead of finely divided particles of water. In this case, the upper header Hb is completely filled with water, and a plug 42 is inserted in the upper end of each tube. Each plug has a series of openings 43 extending from the upper face of the plug to a point short of the lower face of the plug, and it is formed with a peripheral surface 44 of reduced diameter adjacent the lower face of the plug, to provide an annular passage between said peripheral surface and the inner surface of the tube l3 for distributing the water from the openings 43 in the form of an annular sheet onto the inner surface of the tube. In other respects, the apparatus shown in Fig. 4 is similar to that shown in Fig. 3.

In Fig. '7 we show an embodiment of our invention in which the tubes are disposed'horizontally. A series of nozzles 260 are disposed within the header He and are designed to direct jets or streams of water directly into the open ends of the tubes I30. The water fiows through the tubes to the right, this flow being assisted by the flow of vapor which is drawn to the right by the ejector 380. Other means, the specified nature of which is not a part of the present invention, may be provided for assisting the flow of water through the tubes in this embodiment.

While we have shown our invention in several forms, it will be obvious to those skilled in the art that it is not so-limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and we desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What we claim is:

1. A combined evaporator and air cooler comprising a plurality of tubes having extended heat transfer surfaces on the exterior thereof, the interior of said tubes being sealed against exterior air pressure, means for conveying air over the exterior of said tubes in contact with said surfaces, means providing a restricted supply of water to the interior of said tubes at one end thereof, said last-mentioned means only partially filling the interior of said tubes with water throughout the length thereof so as to provide a substantially uniform pressure therein, means for withdrawing water vapor from the opposite end of said tubes and effecting a sufi'iciently low absolute pressure in the interior of the tubes to cause partial evaporation and cooling of water therein, and means including a pump for returning unevaporated water to said water supply means for recirculation through the interior of the tubes.

2. A combined evaporator and air cooler comprising a plurality of tubes having extended heat transfer surfaces on the exterior thereof, the interior of said tubes being sealed against exterior air pressure, means for conveying air over the exterior of said tubes in contact with said surfaces, means for directing a spray'of water into the interior of said tubes at one end thereof, said last-mentioned means only partially filling the interior of said tubes with water so as to provide a substantially .uniform pressure along the length of the tubes, means for withdrawing vapor from the interior of said tubes at the opposite end thereof and maintaining a sufficiently low absolute pressure to effect evaporation and cooling of water, and means including a pump for returning the unvaporized water to said water spray means for recirculation through the interior of the tubes. 3. A combined evaporator and air cooler comprising a plurality of vertically disposed tubes having extended heat transfer surfaces on the exterior thereof, the interior of said tubes being closed to external air pressure, means for-conveying air to be cooled over the exterior of said tubes in contact with said surfaces, means for supplying water to the interior of said tubes at the upper end, to wet the inner surfaces-of the tubes, in such restricted quantities as to provide a substantially uniform vapor pressure substantially throughout the interior of the tubes, means for withdrawing water vapor from the interior of the tubes and effecting an absolute pressure therein sufficiently low to cause evaporation and coolingof water therein, and means for returning unevaporated water to said water supply means for recirculation through the interior of the tubes.

4. A combined evaporator and air cooler comprising a plurality of vertically disposed tubes having extended heat transfer surfaces on the exterior thereof, the interior of said tubes being closed to external air pressure, means for conveying air to be cooled over the exterior of said tubes in contact with said surfaces, means for supplying water to the interior of said tubes at the upper end, to Wet the inner surfaces of the tubes, in such restricted quantities as to provide a substantially uniform vapor pressure substantially throughout the interior of the tubes, a header connected to the lower ends of the tubes, an ejector having its suction inlet connected to said header for withdrawing water vapor from the interior of the tubes, said ejector being effective to provide an absolute pressure in the interior of the tubes sufficiently low to cause partial evaporation and cooling of water, and means including a pump for returning unevaporated water from said header to said water supply means for recirculation through the interior of the tubes.

ERNEST F. STALCUP. PAUL L. FE'I'ZER.

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