EVAPORATIVE COOLER
An evaporative cooler that includes a frame, a plurality of pads attached to the frame so that the pads substantially enclose an air space to be cooled, a water delivery device positioned at or near the top of the pads to wet the pads, a plurality of drain pans positioned at or near the bottom of the pads to collect water from the pads, and a fan to draw air through the wetted pads, thereby cooling the air by evaporation.
The present invention relates generally to evaporative coolers using cooling pads. More particularly, the present invention relates to evaporative coolers having discrete cooling pads that can be removed and replaced individually.
BACKGROUND AND SUMMARY OF THE INVENTIONAir cooled heat exchangers are commonly used in a wide variety of industries. As the name implies, heat exchangers are devices where two moving fluid streams exchange heat. In an air cooled heat exchanger, a fluid that is circulated through tubes may be cooled by forcing relatively cool ambient air to flow over the exterior of the tubes. As the ambient air passes over the exterior of the tubes, it absorbs heat from the fluid within the tubes, thereby cooling the fluid. As used herein, the term tubes refers to any mechanism for conveying fluid through a heat exchanger, including pipes of any shape, pressure vessels, etc. The lower the temperature of the ambient air, the greater is its capacity to absorb heat. Thus, air cooled heat exchangers are most effective where the ambient air used to cool is at a low temperature.
It stands to reason, therefore, that the performance of air cooled heat exchangers suffers when the heat exchanger is operated in a hot climate or during the summer months when the temperature of the ambient air is relatively high. Under such conditions, air cooled heat exchanger performance deteriorates rapidly. As a result, it is necessary to pre-cool the ambient air prior to its introduction to the heat exchanger.
There are numerous methods and devices for cooling air prior to its initiation to a heat exchanger, such as, for example, subjecting the air to a refrigeration process or an evaporative cooling process. Cooling systems that rely on a refrigeration cycle have disadvantages, including the fact that they typically have high initial and operating costs. Where the climate permits (i.e., where the climate is hot and dry), evaporative cooling may provide a better solution.
Evaporative cooling relies on one simple principle: As water evaporates, heat is absorbed from the surrounding air. As a result, the air is cooled during the process. An evaporative cooler preferably includes porous cooling pads that substantially surround an enclosed space that includes a fan. Moisture is applied to the pads, typically either by dripping water into the top end of the pads, or by spraying the pads with a mister. The fan is arranged to pull ambient air through the pads and into the enclosed space. As the air passes through the pads, the moving air evaporates the water in the pads. This evaporation cools the air as it enters the enclosed space. The fan then expels the cooled air from the enclosed space through an outlet.
One advantage to an evaporative cooler such as that just described is that the water supplied to the cooler does not need to be clean. If water that has impurities or contaminates is provided to the cooling pads, the air passing through the pads will still evaporate the water and be cooled. The contaminates will simply stay in the pads. Thus, in theory evaporative coolers are well suited to use, for example, in heavy applications such as oil production, where the water available may be contaminated with oil.
The practical use of evaporative coolers in industrial or other heavy applications is limited, however, by the size of the coolers required. Some applications require such a large amount of air to be cooled that evaporative coolers having very large air intake surface areas would be required to meet the demand. For example, a typical cooler bank at an oil production facility might require an air intake surface area of around 50,000 square feet or more. The size of the cooling pads that would be needed on a conventional evaporative cooler of that size would be impractical to manufacture, maintain, or replace.
In one embodiment, the present invention provides an evaporative cooler that includes a frame, a plurality of pads attached to the frame so that the pads substantially enclose an air space to be cooled, a water delivery device positioned at or near the top of the pads to wet the pads, a plurality of drain pans positioned at or near the bottom of the pads to collect water from the pads, and a fan to draw air through the wetted pads, thereby cooling the air by evaporation.
In another embodiment, the present invention may also provide an air cooled heat exchanger that includes cooling tubes containing a fluid to be cooled, and a supply of air that flows over the cooling tubes, the air having a lower temperature than the fluid to be cooled so that the air absorbs heat from the fluid, thereby cooling the fluid, and wherein at least a portion of the supply of air is provided by an evaporative air cooler. The evaporative air cooler includes a frame having a plurality of vertical open sides, wherein each side includes two or more stacked cooling sections, a plurality of pads attached to the frame so that the pads enclose the open sides of the frame, each pad corresponding to a cooling section, a plurality of water pipes attached to the cooler and positioned at the top of each cooling section adjacent the top of the pads, the water pipes having apertures arranged to allow water to exit the pipes and wet the pads, a plurality of drain pans positioned at the bottom of each cooling section adjacent the bottom of the pads to collect any water that drips from the pads, and a fan configured to draw air through the wetted pads, thereby cooling the air by evaporation, and provide the cooled air to the heat exchanger.
In one embodiment, the present invention also provides a method of cooling air, the method including the steps of providing a plurality of cooling pads stacked one on top of the other and substantially enclosing an air space to be cooled, wetting the cooling pads at an upper portion thereof, and pulling ambient air through the wetted cooling pads and into the air space to be cooled.
A more complete appreciation of the subject matter of the present invention and the various advantages thereof can be realized by reference to the following detailed description in which reference is made to the accompanying drawings in which:
The foregoing aspects, features, and advantages of the present invention will be further appreciated when considered with reference to the following description of preferred embodiments and accompanying drawings, wherein like reference numerals represent like elements. In describing embodiments of the invention illustrated in the appended drawings, specific terminology will be used for the sake of clarity. However, the invention is not intended to be limited to the specific terms used, and it is to be understood that each specific term may include equivalents that operate in a similar manner to accomplish a similar purpose.
Referring now to the drawings,
Each side of the cooler may preferably include a plurality of discrete pads that may be individually removed for cleaning or replacement. One advantage to such a configuration is that individual pads are smaller and may be removed and replaced more easily. As the pads become worn out or saturated with contaminates from water that has been evaporated, such removal of the pads for cleaning or replacement may be needed. A configuration with smaller pads, such as that shown in
In one embodiment, the cooler 10 may include, a plurality of pads 14 that lie horizontally and are stacked one on top of the other as shown in
Any pad that holds water, and allows air to pass through the pad to evaporate the water, may be used in the present invention. The materials that make up the pads and the manner of construction of the pads are not critical. One example of a cooling pad that may be used in one embodiment consists of impregnated and corrugated cellulose paper sheets with different flute angles, one steep (e.g., about 60 degrees) and one shallow (e.g., about 30 degrees), that have been bonded together. This particular design yields a cooling pad with a high evaporation efficiency while still operating with a very low pressure drop. In addition, such a design keeps scaling to a minimum because water is naturally directed to the air inlet side of the pad, where most of the evaporation takes place. In addition, the impregnation procedure for the cellulose paper ensures a strong self-supporting pad, with high absorbance, which is protected against decomposition and rotting. Alternatively, pads may be constructed of other materials, such as, for example, excelsior (wood wool), plastics, and melamine paper.
Referring now to
The frame may be made of any suitable material, which material may vary depending on the requirements of the cooling system, the environment in which the cooling system is operated, and many other factors. In one embodiment, the frame may be constructed of steel. The frame may be constructed so that the cooler is positioned above the ground. For example, in one embodiment, the cooler may be 30 feet or more above the ground. In other embodiments, the cooler may be 10, 15, 20, or 25 feet or more off the ground. The placement of the cooler will depend on the conditions at the site where the cooler is to be installed and the arrangement of components to which the cooler is to be connected, such as a heat exchanger. The size and configuration of the frame will vary depending on factors such as the size of the cooler and the position of the cooler above the ground. For example, a larger cooler will require a larger, more heavy duty frame. Similarly, a cooler that is 30 feet or more above the ground will require a frame structure capable of lifting the cooler to that height while still providing a stable foundation for the cooler to rest on. Accordingly, the size, configuration, and composition of the frame are not critical to the invention.
At the bottom of each pad there is preferably a drain pan 26, 28. All but the bottom most pads are positioned above intermediate drain pans 26. The intermediate drain pans 26 are configured to collect water that drains from the bottom of the pad directly above each intermediate drain pan 26, and deliver that water to the top of the next lower pad. The bottom drain pan 28 is positioned below the bottom most pad. The bottom drain pan 28 may be shaped differently from the intermediate drain pans 26 because the function of the bottom drain pan 28 is not to deliver water to a lower pad, but rather to collect water for reuse either in the cooler or elsewhere, or for disposal according to known methods. A more detailed explanation of the shape and function of the intermediate and bottom drain pans 26, 28 is written below with respect to
In operation, the water delivery pipes 24 deliver water to the tops of pads 14 and the water percolates down through the pads 14 until the pads are wetted. Ambient air is pulled through the pads, as discussed above, by fans 12 into an air intake inside the cooler 10. The direction of motion of the air through the pads is indicated in
There is shown in
The drain pans 26, 28 may be constructed of any suitable material, such as, for example, metal or plastic. Because the function of drain pans 26, 28 is to collect water, they are preferably constructed of a material that will not be adversely affected by contact with water. Furthermore, the shape and configuration of the drain pans in the drawings is merely a representation of one particular embodiment. The shape of the drain pans is not critical to the invention and any shape the allows the drain pans to carry out their intended functions is contemplated.
Referring now to
The arrangement and construction of the water delivery pipes is not critical to the present invention, and the pipes may be constructed of any material suitable for carrying water. For example, the pipes may be constructed of steel or plastic. In addition, while the water may be discharged from the pipes and onto the pads through apertures in the pipes, as discussed above, this configuration is not critical. Other mechanisms for dispersing water from the pipes to the pads may be employed as well. For example, in one embodiment the pipes may be fitted with nozzles that drip or spray the water onto the pads in the form of a mist.
An advantage of the present invention is that the water used in the cooler need not be clean, although clean water can be used if desired. In one embodiment, the water used in the cooler may be produced water that has been extracted with oil during an oil production process. In such a case, the water may be contaminated with up to 2 percent oil, and sometimes as high as 3 percent or more. Although such produced water may be filtered prior to use in the cooler, this is not necessary. In some cases, the cooler may be connected directly to an oil producing facility with produced water being fed directly to the cooler.
The reason that the cooler of the present invention can be used with contaminated water is because as the water evaporates from the pads, any contaminates within the water will remain in the pads. The consequence of this is that over time, the contaminates within the pads will increase until air flow through the pads is restricted. However, as discussed above, the design of the cooler allows for individual pads to be removed as needed for cleaning or replacement, thereby allowing continued use of the cooler despite the buildup of contaminates from the water. This provides a benefit over coolers that need clean water to operate.
To better understand the cooling potential of an evaporative cooler, the following example may be considered. In the example, a cooler having a width of 112 feet, a length of 62 feet, and a height of 20 feet is provided. This sides of the cooler are enclosed with cooling pads having a thickness of 2 feet. The pads are provided about 850 gallons of water per minute distributed evenly throughout the pads. The ambient air entering the pads has a dry bulb temperature of 104 degrees Fahrenheit, and a wet bulb temperature of 71 degrees Fahrenheit. After passing through the pads and evaporating the water in the pads, the cooled air will have a temperature of 90 degrees Fahrenheit.
Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention.
Claims
1. An evaporative cooler, comprising:
- a frame;
- a plurality of pads attached to the frame so that the pads substantially enclose an air space to be cooled;
- a water delivery device positioned at or near the top of the pads to wet the pads;
- a plurality of drain pans positioned at or near the bottom of the pads to collect water from the pads; and
- a fan to draw air through the wetted pads, thereby cooling the air by evaporation.
2. The evaporative cooler of claim 1, wherein the pads include a bottom pad and intermediate pads positioned above the bottom pad.
3. The evaporative cooler of claim 2, wherein the drain pans associated with the intermediate pads are configured to deliver the collected water to the lower pads.
4. The evaporative cooler of claim 1, wherein the cooler is configured to recycle the collected water for reuse.
5. The evaporative cooler of claim 1, wherein the water is comprises one or more contaminates.
6. The evaporative cooler of claim 5, wherein the one or more contaminates includes oil.
7. The evaporative cooler of claim 1, wherein the frame has a horizontal face, and the fan is configured to expel the cooled air through the face and out of the cooler.
8. An air cooling bank comprising a plurality of evaporative coolers wherein one or more coolers is as claimed in claim 1, wherein the evaporative coolers are connected together and configured to run simultaneously, thereby increasing the amount of air cooled.
9. The evaporative cooler of claim 1, wherein the water delivery device is a plurality of pipes positioned adjacent the top of the pads.
10. The evaporative cooler of claim 9, wherein the pipes have apertures configured to release water from the pipes onto the pads.
11. A method of cooling air, comprising:
- providing a plurality of cooling pads stacked one on top of the other and substantially enclosing an air space to be cooled;
- wetting the cooling pads at an upper portion thereof;
- pulling ambient air through the wetted cooling pads and into the air space to be cooled.
12. The method of claim 11, wherein the water applied to the cooling pads comprises one or more contaminates.
13. The method of claim 12, wherein the one or more contaminates includes oil.
14. The method of claim 11, further comprising collecting excess water for reuse after it passes through the cooling pads.
15. An air cooled heat exchanger, comprising:
- cooling tubes containing a fluid to be cooled; and
- a supply of air that flows over the cooling tubes, the air having a lower temperature than the fluid to be cooled so that the air absorbs heat from the fluid, thereby cooling the fluid;
- wherein at least a portion of the supply of air is provided by an evaporative air cooler, the evaporative air cooler comprising: a frame having a plurality of vertical sides, wherein each side includes two or more cooling sections; a plurality of pads attached to the frame so that the pads enclose the sides of the frame, each pad corresponding to a cooling section; a plurality of water pipes attached to the cooler and positioned at the top of each cooling section adjacent the top of the pads, the water pipes having apertures arranged to allow water to exit the pipes and wet the pads; a plurality of drain pans positioned at the bottom of each cooling section adjacent the bottom of the pads to collect any water that drips from the pads; and a fan configured to draw air through the wetted pads, thereby cooling the air by evaporation, and provide the cooled air to the heat exchanger.
16. The evaporative cooler of claim 15, wherein the cooler is configured to recycle the collected water for reuse.
17. The evaporative cooler of claim 15, wherein the water is comprises one or more contaminates.
18. The evaporative cooler of claim 17, wherein the one or more contaminates includes oil.
19. An air cooling bank comprising a plurality of evaporative coolers wherein one or more coolers is as claimed in claim 15, wherein the evaporative coolers are connected together and configured to run simultaneously, thereby increasing the amount of air cooled.
Type: Application
Filed: Sep 30, 2011
Publication Date: Apr 4, 2013
Inventor: JOHN D. PENTON
Application Number: 13/250,952
International Classification: F28D 5/00 (20060101);