The present invention relates generally to heat exchangers and more particularly, but not by way of limitation, to a microchannel evaporator (“MCE”).
Machines with moving parts often make use of a fluid (e.g., oil) to lubricate the moving parts and to provide a medium to dissipate some of the heat that is generated from operation of the machine. In some instances, the fluid is circulated through the machine to lubricate moving parts and to dissipate heat from the motor. The dissipation of heat from the machine may be improved by circulating the fluid from the machine to an external cooling apparatus, such as a heat exchanger.
One method for cooling the fluid of the machine is to use a coiled-tube heat exchanger. An example of a coiled-tube heat exchanger is shown in
A microchannel evaporator includes a plurality of microchannels. Each of the plurality of microchannels includes a first end and a second end. A first end-tank is coupled to each first end of the plurality of microchannels and a second end-tank is coupled to each second end of the plurality of microchannels. A second-fluid inlet is coupled to either the first end-tank or the second end-tank and configured to receive a fluid into the microchannel evaporator and a second-fluid outlet is coupled to either the first end-tank or the second end-tank and configured to expel the fluid from the microchannel evaporator. Each microchannel of the plurality of microchannels includes at least one bend along a length thereof.
A heat exchanger system includes a fluid tank that includes a first-fluid inlet to permit a first fluid to enter the fluid tank and a first-fluid outlet to permit the first fluid to exit the fluid tank. A first microchannel evaporator is disposed within the fluid tank and includes a plurality of microchannels. Each of the plurality of microchannels has a first end and a second end. A first end-tank is coupled to each first end of the plurality of microchannels and a second end-tank is coupled to each second end of the plurality of microchannels. A second-fluid inlet is coupled to either the first end-tank or the second end-tank and configured to receive a fluid into the first microchannel evaporator and a second-fluid outlet is coupled to either the first end-tank or the second end-tank and configured to expel the fluid from the first microchannel evaporator. Each of the plurality of microchannels includes a bend along a length thereof.
For a more complete understanding of the present invention and for further objects and advantages thereof, reference may now be had to the following description taken in conjunction with the accompanying drawings in which:
Various embodiments of the present invention will now be described more fully with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
In order to cool the first fluid as it passes through the fluid tank 102, a second fluid is passed through each tube of the flat evaporator 104. The first fluid is circulated between the machine and the fluid tank 102, and may be, for example, oil that is used to lubricate at least one of and cool the machine. In a typical embodiment, the second fluid is circulated between the flat evaporator 104 and a cooling system, and may be, for example, a coolant or refrigerant (e.g., R410A). Any cooling system may be used provided that the cooling system provides enough cooling duty to absorb a desired amount of heat from the first fluid. The term “first fluid” is used throughout to describe a fluid that is to be cooled and the term “second fluid” is used throughout to describe a fluid that is used to absorb heat from the first fluid.
While use of the flat evaporator 104 may be an effective solution to generally remove heat from the first fluid, assembly of the flat evaporator 104 has inherent complications. For example, assembling a single flat evaporator 104 may take up to two hours. In addition, it should be noted that due to the overlapping, compact design of the flat evaporator 104 it may be difficult to clean debris and sediment from fluid that becomes deposited on and around the flat evaporator 104. In addition, as shown in
The MCE 200 includes a second-fluid inlet 216 that receives the second fluid from the cooling system and a second-fluid outlet 218 that directs the second-fluid back to the cooling system. In the embodiment shown in
During operation of the MCE 200, the first fluid surrounds the MCE 200 and is permitted to flow through gaps 230 between the plurality of microchannels 210. As the first fluid moves past the MCE 200, heat is absorbed from the first fluid into the second fluid. In some embodiments, the gaps 230 include fins 232 disposed between adjacent microchannels 210. The fins 232 aid in the transfer of heat from the first fluid to the second fluid within the plurality of microchannels 210 by increasing a surface area that the first fluid comes into contact with. When using a refrigerant as the second fluid, the refrigerant that passes through the MCE 200 may enter the second-fluid inlet 216 as a liquid and exit the second-fluid outlet 218 as a vapor. The phase transformation from liquid to vapor results from the absorption of heat from the first fluid to the refrigerant. In such an embodiment, the second-fluid outlet 218 may have a larger diameter than the second-fluid inlet 216 to compensate for the increased volume of the gas phase relative to the liquid phase.
In some embodiments, the second-fluid inlet 216 may be located on the first end-tank 212 and the second-fluid outlet 218 may be located on the second end-tank 214. In such an embodiment, the baffle 220 is not necessary. With no baffle 220 in place, the second fluid enters the second-fluid inlet 216 and flows into the first end-tank 212. The second fluid is then distributed through the plurality of microchannels 210 to the second end-tank 214 and exits the second-fluid outlet 218. In some embodiments, two or more second-fluid inlets may be used to improve distribution of the second fluid into the MCE 200.
In some embodiments, multiple baffles 220 may be included to cause the second fluid to flow back and forth between the first end-tank 212 and the second end-tank 214 before the second fluid exits the MCE 200. Causing the second fluid to pass back and forth between the first end-tank 212 and the second end-tank 214 increases the length of the flow path of the second fluid within the MCE 200, and thus increases the amount of indirect contact between the second fluid in the plurality of microchannels 210 and the first fluid that flows around the MCE 200.
In comparison to the flat evaporator 104 of
Another benefit of the MCE 200 over the flat evaporator 104 is that the amount of labor to construct the MCE 200 is greatly reduced in comparison to the flat evaporator 104. Due to the complex geometries involved, manufacturing the parts for the flat evaporator 104 and assembly of the flat evaporator 104 is difficult and expensive compared to the MCE 200. The relative simplicity of the MCE 200 also makes it easy to remove the MCE 200 from a fluid tank in comparison to the flat evaporator 104. The elimination of the numerous connections for the flat evaporator 104 also makes the MCE 200 a more robust system that the flat evaporator 104, which is more likely to develop a leak.
Each microchannel 310 of the plurality of microchannels 310 includes a fluid conduit through which the second fluid may flow.
In a typical embodiment, the each microchannel 310 of plurality of microchannels 310 has a rectangular cross-section. In other embodiments, the plurality of microchannels 310 may have other cross-sectional shapes, such as, for example, square, round, and the like. The plurality of microchannels 310 shown herein are not necessarily drawn to scale. The dimensions of the plurality of microchannels 310 can vary depending on the embodiment. For example, width, height, and length of the plurality of microchannels 310 can be changed in accordance with design preferences. The distance between the plurality of microchannels 310 that defines the size of the gaps 330 between the plurality of microchannels 310 may also be varied as desired.
In some embodiments, fins 532 may be included in a central portion 542 of the MCE 500 and end portions 544 of the MCE 500 closest to end-tanks 512 and 514 may include no fins. Removal of the fins 532 from the end portions 544 makes it easier for the first fluid to pass through the end portions 544. In some embodiments, the fins 532 may extend the entire length of the plurality of microchannels 510. In some embodiments, the MCE 500 may include no fins 532. In some embodiments, the agitator 540 may be used to draw the first fluid from beneath the MCE 500 and expel the fluid laterally through end portions of the MCE 500 or vice versa. For example, arrows 3 illustrate a flow path of fluid being drawn from beneath the MCE 500 and arrows 4 illustrate a flow path of fluid being expelled laterally through end portions of the MCE 500.
Similar to the MCEs 200, 300, 400, and 500, the MCE 600 includes a first end-tank 612 that is connected to a second end-tank 614 by a plurality of microchannels 610. A second-fluid inlet 616 of the first end-tank 612 and a second-fluid outlet 618 of the second end-tank permit the second fluid to circulate through the MCE 600.
To form the ring configuration, the first end-tank 612 and the second end-tank 614 are arranged adjacent to each other. The plurality of microchannels 610 are oriented horizontally and are arranged to generally follow a periphery of the fluid tank to substantially form a ring. A distance between sides of the MCE 600 and a wall of the fluid tank can be increased by reducing lengths of the sides of the MCE 600 (i.e., effectively reducing a diameter of the MCE 600). Increasing the space between the MCE 600 and the walls of the fluid tank can facilitate additional flow of the first fluid through the gaps 630 between the plurality of microchannels 610.
In some embodiments, the MCE 600 may be formed into other shapes according to various design parameters. For example, the MCE 600 may be cylindrically shaped. The number of rows of microchannels 610 may be varied according to various design parameters. Similar to the MCEs 200, 300, 400, and 500 discussed above, fins 632 may be placed in some or all of the gaps 630 between the plurality of microchannels 610 to increase efficiency of heat transfer between the first fluid and the second fluid.
In some embodiments, an agitator 640 may be used to impart energy into the first fluid to increase a flow of the first fluid with through the gaps between the plurality of microchannels 610, thereby increasing the heat transfer efficiency of the MCE 600. Arrows 5 generally illustrate a flow path of the first fluid. The agitator 640 may be any of a variety of agitators. For example, the agitator 640 may be a pump-wheel agitator, an impeller, or a mixer.
The MCEs 200, 300, 400, 500, 600, and 701/702 may be made from various materials. In some embodiments, the MCEs 200, 300, 400, 500, 600, and 701/702 may be constructed out of aluminum. In some embodiments, the MCEs 200, 300, 400, 500, 600, and 701/702 may include a coating to protect the MCEs 200, 300, 400, 500, 600, and 701/702 from the fluid in which it is immersed. For example, an MCE made from Aluminum may be plated with nickel, epoxy, and the like.
Each of the MCEs 200, 300, 400, 500, 600, and 701/702 described above may be made from various materials. In some embodiments, the MCEs 200, 300, 400, 500, 600, and 701/702 may be constructed out of aluminum. In other embodiments, the MCEs 200, 300, 400, 500, 600, and 701/702 may include a protective coating that protects the MCEs 200, 300, 400, 500, 600, and 701/702 from the fluid being cooled. Various types of protective coatings may be used depending on the type of first fluid being cooled. In some embodiments, the protective coating is a nickel coating.
Conditional language used herein, such as, among others, “can,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or states are included or are to be performed in any particular embodiment.
While the above detailed description has shown, described, and pointed out novel features as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the devices or algorithms illustrated can be made without departing from the spirit of the disclosure. As will be recognized, the processes described herein can be embodied within a form that does not provide all of the features and benefits set forth herein, as some features can be used or practiced separately from others. The scope of protection is defined by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
This application is a continuation of U.S. patent application Ser. No. 15/298,720, filed on Oct. 20, 2016. U.S. patent application Ser. No. 15/298,720 is incorporated herein by reference. U.S. patent application Ser. No. 15/298,720 claims priority to and incorporates by reference the entire disclosure of U.S. Provisional Patent Application No. 62/245,387, filed on Oct. 23, 2015.
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Number | Date | Country | |
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Number | Date | Country | |
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Parent | 15298720 | Oct 2016 | US |
Child | 17500024 | US |