HEAT EXCHANGER HAVING WINDING CHANNELS
A winding channel heat exchanger includes a heat transfer member having winding channels, a manifold, and a cover plate. The channels' winding design is defined by a non-linear flow axis that may include a plurality of short pitch and small amplitude undulations, which cause the flow to change directions, and may also or alternatively include two or more large amplitude bends that cause the flow to reverse direction. In one embodiment, the undulations have varying amplitudes to increase the heat transfer coefficient along the length of the channel. The winding channels allow a user to customize the pressure drop to promote good flow distribution, to achieve improved heat transfer uniformity, and to improve the heat transfer coefficient.
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The present application claims priority under 35 USC §119(e) to U.S. provisional application No. 61/347,949, filed on May 25, 2010, and is a continuation-in-part under 37 CFR §1.53(b) of U.S. application Ser. No. 12/188,859, filed Aug. 8, 2008, the entire contents of all the above applications are herein incorporated by reference in their entirety.
GOVERNMENT LICENSE RIGHTThe U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of Contract No. N65540-06-C-0015 awarded by the U.S. Navy.
TECHNICAL FIELDThis invention relates generally to an apparatus for cooling a heat-producing device and, more specifically, to a liquid cooled heat exchanger having winding, non-linear channels.
BACKGROUNDThe use of heat exchangers for cooling a range of heat producing devices, for example, electronic devices is known in the art. Liquid cooled heat exchangers are generally characterized as having macro-channels, mini-channels, or micro-channels, depending on the size of the channels. The term ‘micro’ is applied to devices having the smallest hydraulic diameters, generally between ten to several hundred micrometers, while ‘mini’ refers to diameters on the order of about 0.5 mm to about 2 millimeters, and ‘macro’ channels are the largest in size, generally greater than about 2 millimeters. An example of a typical macro channel design is the conventional swaged-tube cold plate illustrated in
As shown in
Conventional finned cold plates have a number of closely spaced fins 21 attached to the heat transfer surface 23. The fluid flows through the channels 25 formed by the spaces between the fins. The channels typically have a width between about 1 to 5 mm. Conventional finned cold plates can achieve thermal resistances as low as approximately 1° C./(W/cm2).
The thermal resistance of macro channel cold plates decreases as the flow rate is increased and approaches asymptotically a minimum value at a flow of about 0.1 LPM/cm2. Increasing the flow rate further has not been found to result in an additional reduction in the thermal resistance.
For cooling high heat flux devices, such as solid-state laser diodes, which dissipate heat at a rate of 500-1000 W/cm2, cold plates with substantially lower thermal resistance than that of the swaged-tube cold plates or the machined fin cold plates are needed. In these applications, micro-channel cold plates are generally employed.
There are two primary types of prior art micro-channel cold plates: parallel flow and normal flow. As the name implies, parallel flow micro-channel cold plates have the liquid flowing through the heat transfer passages in a direction parallel to the surface being cooled. In contrast, normal flow micro-channel cold plates (NCP) have the liquid flowing through the heat transfer passages in direction normal to the surface being cooled. The parallel flow cold plates have geometries similar to that of the finned cold plate shown in
One objective in the design of conventional micro-channel cold plates is to minimize the pressure drop consistent with achieving the target thermal performance. Minimizing the flow length and maximizing the flow area of the micro-channels is most often employed to achieve this objective. Conventionally, the flow length is minimized by making the flow axis straight, while making the micro-channel depth large compared to its width maximizes the flow area. As such, prior art parallel-flow micro-channels have a depth that is an order of magnitude larger than the width.
Normal flow cold plates invented by the present inventor, Javier Valenzuela and as described in U.S. Pat. Nos. 5,145,001 and 6,935,411 among other patents, demonstrate excellent heat transfer effectiveness, especially in high heat-flux applications. However, for some systems the highly effective cooling provided by the normal flow design is not required, and the cost of the heat exchanger may not be warranted.
In spite of the order of magnitude lower thermal resistances that can be obtained through the use of micro-channels, they are seldom used in large-area cold plates. The principal objections to the use of micro-channels in large area cold plates are: (1) the large pressure drop associated with the flow through long, small-hydraulic-diameter passages, and (2) the relatively high cost of fabricating passages with such small dimensions. The cost of fabrication and large pressure drops can also prevent micro-channels from being used in other applications as well. When micro-channels are not utilized, macro or mini-channels may be utilized and performance is sacrificed for cost, ease of use or other requirements.
There are also other methods of cooling that utilize fluid flowing through channels in order to cool a device. For example, U.S. Pat. No. 6,213,194 discloses the use of a hybrid cooling system for an electronic module which includes refrigeration cooled cold plate and an auxiliary air cooled heat sink. The '194 patent also discloses the use two independent fluid passages embedded in the same cold plate to provide redundancy. A single serpentine passage, akin to that of a swaged tube cold plate, or multiple straight passages feed by headers, akin to a finned cold plate, is used for each one of the redundant systems.
SUMMARYIn accordance with the present disclosure, there is provided a winding channel heat exchanger that includes a heat transfer member having winding channels for cooling a heat-producing device.
The channels' winding design is defined by a non-linear flow axis that, in one embodiment, has a plurality of short pitch and small amplitude undulations, which cause the flow of fluid in the channels to change directions. The winding channels may also include two or more large amplitude bends that cause the flow to reverse direction. The winding channels advantageously allow a user to customize the pressure drop to promote good flow distribution, achieve improved heat transfer uniformity, and increase the heat transfer coefficient.
The heat transfer member includes one or more heat transfer layers, each layer having one or more inlet openings and corresponding outlet openings. Each of the winding channels is in fluid communication with at least one of the inlet openings and at least one of the corresponding outlet openings, such that the cooling fluid enters the inlet openings, flows along the channels, and exits via the outlet openings. In one embodiment, the openings are arranged in rows through each layer, each opening extending from the first surface through to the second surface of each heat transfer layer.
A manifold can supply fluid to each of the inlet openings of the heat transfer member and receives fluid from each of the outlet openings of the heat transfer member. The manifold may distribute and collect the fluid throughout the active heat transfer area in order to promote uniform heat transfer throughout the area.
In alternate embodiments disclosed herein the configuration of the winding channels is modified according to the particular application, but in all embodiments, the winding channel's axis remains non-linear along at least a portion of the length of the channel.
The foregoing and other objects, features and advantages will be apparent from the following description of particular embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of various embodiments of the invention.
The embodiments disclosed herein relate to a heat exchanger having winding channels. As used herein, the term “winding” is used to mean a twisting, serpentine, sinuous path, or the like, which may have a curvature or be angular, and which creates a non-linear path between an inlet and an outlet. As also used herein the term micro-channel is used in the conventional sense with respect to liquid-cooled heat exchanger technology and does not have specific dimensional constraints, but is generally understood to mean channels having the smallest hydraulic diameters, generally between ten to several hundred micrometers, although it is understood that as industry standards change, so too may the dimensions of micro-channels. Likewise, as also used herein the term mini-channel is used in the conventional sense with respect to liquid-cooled heat exchanger technology, and does not have specific dimensional constraints, but is generally understood to mean channels that have diameters on the order of about 0.5 mm to about 2 millimeters, although it is understood that as industry standards change, so too may the dimensions of mini-channels.
Referring initially to
The winding micro-channels 30 according to the present application each include a non-linear flow axis 36, as best shown in
In addition to the one or more pair of reversing bends 40a, 40b, the winding micro-channel 30 may also include one or more undulations 38 that change the direction of the fluid flow, but which do not reverse the direction of the fluid flow. In the present embodiment, the undulations 38 have a smaller amplitude “a” than that of the bends 40a, 40b. These smaller amplitude undulations 38 change the local direction of the fluid flow without reversing the overall direction so that the flow continues in the same overall direction the fluid was traveling before reaching the undulation. It will be appreciated that the number and size of the bends and undulations can be varied depending upon the particular application, and the micro-channels may include both bends and undulations or include only bends or only undulations.
In the present embodiment, a bonded stack of three layers 28 is illustrated and may be varied according the needs of the particular application, as would be known to those of skill in the art. Each one or more layer 28 is generally planar and includes a first surface 10a and a second surface 10b, opposite the first surface. The micro-channels 30 may be formed in the second surface, for example by etching, such that the micro-channels have a depth that is less than the thickness “t” of their corresponding layer. The micro-channels may be formed by alternate methods as would be known to those of skill in the art, and may have a depth equal to the corresponding layer in some embodiments. Unlike the prior art, parallel flow micro-channels; the winding micro-channels 30 of the present invention are characterized by having an aspect ratio close to unity (i.e., the depth of the micro-channels is comparable to the width). The depth of the micro-channels may preferably be between about ½ the size of that of the width to about 1½ the size of that of the width for the depth and width to be comparable. For example, if the width of the channel is 2 mm, the depth may be from about 1 mm to about 3 mm.
As best shown in
In the present embodiment, the functions of distributing and collecting the fluid over the active heat transfer area 17, and transferring the heat between the fluid and the active heat transfer area 17 may be achieved by two separate components: the manifold 12 and the heat transfer member 14, respectively. This separation in functions allows the selection of the flow passage geometry in each component to the benefit of their respective functions.
The manifold 12 may distribute and collect the fluid over the entire heat transfer surface 17 in order to promote uniform heat transfer over the surface. In the present embodiment, the manifold has an interdigitated design as described below. However, alternate manifold designs may be utilized, such as traditional linear manifolds that are not interdigitated and which may include only a single channel. As best shown in
In the winding micro-channel heat exchanger 10, as the fluid is being distributed and collected it is desirable to minimize the pressure drop in the manifold to promote good flow distribution. As discussed in greater detail below, it is also desirable to keep a suitably small separation between the heat transfer member inlet openings 32 and the respective outlet openings 34 to promote uniform heat transfer over the heat transfer area 17. These requirements are conflicting since a small pressure drop would favor large dimensions for the manifold channels 22 and 24, whereas a small separation between the heat transfer member inlet and outlet openings would favor small dimensions for the channels.
The distance between the inlet 32 and outlet openings 34 of the heat transfer member 14 determines the minimum length, and thereby the minimum pressure drop, of the micro-channel passages; and the distance also determines the degree of temperature uniformity (or heat transfer uniformity) which can be achieved throughout the heat transfer member. To make best use of the flow heat transport capacity, and thereby minimize the flow and pressure drop requirements for a given application, it is desirable that the fluid exit temperature be close to the temperature of the surface of the heat transfer member (i.e. high heat exchanger effectiveness). The temperature difference between the fluid and the micro-channel walls is greater near the inlet openings 32 than the outlet openings 34, thereby providing greater heat transfer capability near the inlet openings than near the outlet openings. The variation in heat transfer capability is mitigated by heat conduction in the heat transfer member 14 along a plane parallel to the heat transfer surface. For high thermal conductivity materials, such as copper, this mitigation is most effective when the distance between the inlet and outlet openings is no more than a factor of 5 to 10 times larger than the thickness of the heat transfer member 14. Hence for a member 0.5 mm thick, the distance between inlet and outlet ports should be between about 2.5 to 5 mm.
In some applications it may be desirable to increase the pressure drop if it is unacceptably low. For example, in large area cold plates (larger than about 2×2 cm), it has been determined that at certain flow rates, air bubbles can block linear micro-channels. It has been determined that at the intended water flow rate, the pressure drop through the micro-channel heat transfer member was lower than the bubble point of the micro-channels, and hence insufficient to drive the bubbles out of the micro-channels, an unexpected result of the use of the linear micro-channels in a large-area application. As such, any gas present in the system could block areas of the heat exchanger, resulting in undesirable hot spots. Moreover, since good flow distribution requires that the pressure drop in the manifold be an order of magnitude smaller that in the heat transfer member, such a low pressure drop in the heat transfer member would place undue constraints on the manifold pressure drop, requiring the use of much larger manifold. Thus, contrary to expectations and to the common perception that micro-channels are not desirable because they have too large a pressure drop, the Applicant determined that particularly in large-area applications the opposite was actually true. In particular, that the desired inlet-to-outlet channel spacing, the pressure drop of conventional micro-channels is too low at the typical flow rates employed in large-area cold plates to achieve acceptable performance.
As discussed in greater detail below, the winding channel configuration disclosed herein provides a way to regulate the pressure drop in the heat transfer member to a desired value, while at the same time improving both the heat transfer capability and the heat transfer uniformity of the heat exchanger. At the flow rates per unit area typical of large area cold plates, the flow in the micro-channels is laminar (Reynolds number typically less than about 500) and the pressure drop in the micro-channels is proportional to the product of the velocity and the micro-channel length, and inversely proportional to the micro-channel hydraulic diameter. Therefore, increasing the length, increasing the velocity, or decreasing the diameter can all increase the pressure drop. The performance of micro-channel heat exchangers improves as the diameter of the micro-channels is decreased. Hence the diameter is often selected as the minimum diameter consistent with other considerations, such as ease of manufacture, or filtration level requirements. Therefore, for the purpose of comparing different micro-channel configurations, the diameter is not considered a design variable.
As discussed below, the winding channel configuration is advantageous relative to the straight (i.e. linear) channel configurations on two counts: (1) improved heat transfer uniformity; and (2), greater average heat transfer capability. To illustrate the two points, the total length of each channel depicted in
For the winding configurations 5a and 6a the average fluid temperatures alternate between values of 2.3 to 2.7 between the strips. For the linear channel configuration 5b with increased distance between the inlet and exit ports, the average fluid temperatures range from 0 near the inlet port to 5 near the exit port. For linear channel configuration 6b with increased velocity in the channels, the average fluid temperatures alternate between 1 and 4. It will be readily appreciated that the winding configuration disclosed in the present invention aids in providing greater uniformity in fluid temperature, and hence greater uniformity in heat transfer, over the heat transfer surface.
The winding channels of
The following examples are provided as comparisons, are intended to be illustrative in nature, and are not to be considered as limiting the scope of the invention.
Example 1To illustrate the magnitude of the heat transfer coefficient enhancement and pressure drop increase, the ratio of the heat transfer coefficient and pressure drop of a winding micro-channel with a topology similar to that depicted in FIG. 3.b to that of a straight micro-channel of equal length and cross-section were computed using ANSYS, a commercial computational fluid dynamics (CFD) software. The results of this computation are shown in
A heat exchanger according to the first embodiment described above was fabricated and tested. The heat exchanger had a 60×60 mm transfer area and the heat transfer member consisted of a stack of three heat transfer layers fabricated out of 0.25 mm thick copper foil. Winding micro-channels with a width of 0.25 mm and a depth of 0.17 mm were chemically etched into one surface of the heat transfer layers. Inlet and outlet opening with a diameter of 0.75 mm were etched through the heat transfer layers. The distance between the inlet and outlet openings was 4.8 mm. The winding micro-channel topology was similar to that depicted in
A 20×20 mm heat exchanger with winding mini channels having a width of 1 mm and a depth of 0.65 mm was fabricated and tested. The mini channels had amplitude of 0.86 mm and a wavelength of 3 mm. The total length of the mini channels was 20 mm.
The thermal resistance of the winding micro-channel cold plate and winding mini-channel cold plate was measured as a function of the water flow rate per unit area. The measured resistance is shown in
It has also been found that in utilizing winding mini-channels heat transfer uniformity can be improved by varying the amplitude of the undulations of the winding channels along the length, “l” thereof, as illustrated in
The substantial increase in heat transfer coefficient resulting from the winding channel geometry allows the use of mini-channels in some applications formerly requiring the use of micro-channels to achieve the desired heat transfer capacity. The mini-channel design also has the added advantage of wider channels that generally do not require filtration of the cooling liquid prior to entering the winding mini-channels. Filtration is generally required to reduce particulates that can block the small-scale micro-channel passages, impeding performance and sometimes leading to failure of the micro-channel device. As will be appreciated, the elimination of filtration that is generally required with micro-channels reduces the cost, labor and possibility of break down for the mini-channel device as compared to a similar device utilizing micro-channels.
In addition to the potential for improved heat exchanger performance discussed above, the present disclosure provides an inexpensive approach for fabricating winding channel heat exchangers to meet a wide range of applications. For example, the winding channels can be fabricated inexpensively by laser machining, chemical milling, or the like. In the chemical milling process, photosensitive resist layers are laminated to both sides of a metal foil and a photomask is employed to pattern the winding channel geometry onto the resist. After development, the resist is removed from the areas that will be etched. The winding channels may be made by etching the metal from only one side; thereby obtaining a partially etched feature that does not extend through the thickness of the layer 28. The inlet and outlet openings 32, 34 may be made by etching the metal from both sides, until all the metal is dissolved and a through feature is obtained that connects the first surface 10a to the second surface 10b.
The present construction also simplifies the fabrication of heat exchangers having a range of heat transfer capabilities. The heat transfer capability of the heat exchanger is proportional to the flow rate, and to maintain the same thermal effectiveness, the product of the winding channel wall area and the winding channel heat transfer coefficient must be proportional to the flow rate. In the heat exchanger of the present disclosure, this can be easily accomplished by increasing the number of layers in the heat transfer member in proportion to the required flow for the target application. In addition, the present embodiment also allows for inexpensive tailoring of the heat transfer capability over the surface of the heat exchanger. In some applications it may be desirable to provide a greater heat transfer capability (lower thermal resistance) in one area of the heat exchanger and a smaller heat transfer capability (higher thermal resistance) in another. For example, if hot spots are disposed in one area greater heat transfer capability in that area would be desired. This can be easily accomplished by using the heat exchanger of the present disclosure. For example, a flow restrictor plate 44 can be inserted between the manifold 12 and the heat transfer member 14. As illustrated in
Alternatively, the same effect could be achieved by grouping the winding channels so as to vary the heat transfer capability in certain areas of the heat transfer member. For example, the number of winding channels per unit area could be varied over the active area of the heat transfer member, with some groupings being denser than others so as to increase the heat transfer capability in the areas with a greater density of winding channels. Likewise, the winding channels could also be grouped according to the size of the undulations and/or bends, with similar amplitude winding channels being grouped together. In this manner, the amplitudes of the undulations could be varied between groups of winding channels over the heat transfer member so as to vary the thermal resistance over an active area of the heat transfer member.
Yet another fabrication advantage of the heat exchanger of the present disclosure is that the flow distribution and heat transfer functions are confined to different components. The heat transfer capacity depends primarily on the geometry and material properties of the heat transfer member and high thermal conductivity materials, such as copper or aluminum, need only be used in the fabrication of the heat transfer member. The manifold could be fabricated out of lower cost materials such as a temperature resistant polymer. The manifold could also be a stamping made out of a lower cost metal. Accordingly, the present invention provides for a device that can be readily tailored to a variety of needs in an inexpensive and readily achievable manner.
It will be apparent to those skilled in the art, that there are many variations in the winding channel geometry that can be used to advantage to meet the requirements of different applications. As shown in
It will be understood that various modifications may be made to the embodiments disclosed herein. For example, the dimensions and geometric shapes may be modified, as would be known to those of skill in the art. In addition, the winding channels may find use in normal flow cold plates as well as parallel flow cold plates in which case the directional examples would be modified. In addition, the number and size of the small amplitude undulations and reverse bends can be varied depending upon the application, and some applications may only have bends that reverse the direction of the fluid flow, while others may only have undulations that change the direction of the fluid flow and some may have both. In addition, the winding channel's axis may remain non-linear along only a portion of the length of the winding channel. Likewise, the examples provided are not to be construed as limiting, but as projected outcomes of exemplary embodiments. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope, spirit and intent of the invention.
Claims
1. A heat exchanger comprising:
- a heat transfer member including at least one heat transfer layer;
- one or more inlet openings disposed in the heat transfer member;
- one or more outlet openings disposed in the heat transfer member;
- at least one winding channel disposed in each of the at least one heat transfer layers and constructed and arranged to carry a fluid, the at least one winding channel having a length and a non-linear flow axis, the non-linear flow axis defining a non-linear path between the one or more inlet openings and the one or more outlet openings;
- at least one undulation having an amplitude constructed and arranged to increase the heat transfer coefficient of the fluid as it passes there through and further being constructed and arranged to change the direction of the flow of the fluid as it travels along the non-linear flow path;
- wherein during use fluid flows through the one or more inlet opening in the heat transfer member, into the at least one winding channel, and flows into the at least one undulation, the amplitude of the undulation increasing the heat transfer coefficient as the fluid passes there through, and wherein the fluid continues to move toward the outlet opening after changing direction and passing through the at least one undulation.
2. The heat exchanger of claim 1, wherein the at least one undulation comprises a plurality of undulations, and wherein the amplitude of the undulations are constant along the length of the at least one winding channel.
3. The heat exchanger of claim 1, wherein the at least one undulation comprises a plurality of undulations, and wherein the amplitude of the undulations vary along the length of the at least one winding channel.
4. The heat exchanger of claim 3, wherein the amplitude of the plurality undulations increases along the length of the at least one winding channel moving in a direction from the one or more inlet openings toward the one or more outlet openings.
5. The heat exchanger of claim 1, wherein the at least one winding channel comprises a plurality of winding channels, the plurality of winding channels each having one or more undulations, and wherein winding channels having undulations of similar amplitude are grouped together, the amplitudes of the undulations varying between groups of winding channels over the heat transfer member so as to vary the thermal resistance over an active area of the heat transfer member.
6. The heat exchanger of claim 1, further comprising a manifold including an inlet port and an outlet port constructed and arranged to distribute fluid to and collect fluid from the heat transfer member.
7. The heat exchanger of claim 1, wherein the at least one winding channel comprises mini-channels.
8. The heat exchanger of claim 1, wherein the at least one winding channel comprises micro-channels.
9. The heat exchanger of claim 1, wherein the non-linear flow path of the at least one winding channel includes an inlet side adjacent a corresponding inlet opening and an outlet side adjacent a corresponding outlet opening, the non-linear path further including at least one pair of bends, each pair having:
- a) a first bend constructed and arranged to reverse the direction of the flow of the fluid as it travels between the corresponding inlet opening and the corresponding outlet opening such that the fluid flows toward the inlet side after passing through the first bend;
- b) a second bend constructed and arranged to reverse the direction of the flow of the fluid as it travels between the corresponding first opening and the corresponding second opening such that the fluid flows toward the outlet side after passing through the second bend; and
- wherein during use fluid flows from the manifold, through the corresponding inlet opening in the heat transfer member, into the at least one winding channel and travels along the non-linear path toward the outlet side of the non-linear channel and flows into the first bend which reverses the direction of the fluid flow toward the inlet side of the channel, the fluid thereafter flowing into the second bend which reverses the direction of the fluid flow toward the outlet side of the channel, the flow of fluid traveling along the non-linear path to the outlet opening.
10. The heat exchanger of claim 9, wherein the first bend, the second bend and the at least one undulation each have an arcuate shape.
11. The heat exchanger of claim 1, wherein the depth of the at least one winding channel is substantially equal to the width of the at least one winding channel.
12. The heat exchanger of claim 1, wherein the at least one heat transfer layer comprises a bonded stack of at least two laminations.
13. The heat exchanger of claim 1, wherein the at least one heat transfer layer comprises a single heat transfer layer.
14. A heat exchanger comprising:
- a heat transfer member including at least one heat transfer layer, the at least one heat transfer layer having a first surface and a second surface and including a thickness extending between the first surface and the second surface;
- a manifold including an inlet port and an outlet port constructed and arranged to distribute fluid to and collect fluid from the heat transfer member;
- one or more inlet openings disposed in the heat transfer member and in fluid communication with the manifold;
- one or more outlet openings disposed in the heat transfer member and in fluid communication with the manifold;
- at least one winding channel disposed in each of the at least one heat transfer layers, the at least one winding channel having a non-linear flow axis, the non-linear flow axis defining a non-linear path between the one or more inlet openings and the one or more outlet openings, the non-linear flow path having an inlet side adjacent a corresponding inlet opening and an outlet side adjacent a corresponding outlet opening, the non-linear path further including at least one pair of bends, each pair having:
- a) a first bend constructed and arranged to reverse the direction of the flow of the fluid as it travels between the corresponding inlet opening and the corresponding outlet opening such that the fluid flows toward the inlet side after passing through the first bend;
- b) a second bend constructed and arranged to reverse the direction of the flow of the fluid as it travels between the corresponding first opening and the corresponding second opening such that the fluid flows toward the outlet side after passing through the second bend;
- wherein during use fluid flows from the manifold, through the corresponding inlet opening in the heat transfer member, into the at least one winding channel and travels along the non-linear path toward the outlet side of the non-linear channel and flows into a first bend which reverses the direction of the fluid flow toward the inlet side of the channel, the fluid thereafter flowing into the second bend which reverses the direction of the fluid flow toward the outlet side of the channel, the flow of fluid traveling along the non-linear path to the outlet opening.
15. The heat exchanger of claim 14, wherein the at least one winding channel comprises mini-channels.
16. The heat exchanger of claim 14, wherein the at least one winding channel comprises micro-channels.
17. The heat exchanger of claim 14, wherein reversing the direction of the fluid flow toward the inlet side and back toward the outlet side of the non-linear path results in substantially uniform thermal resistance throughout the heat transfer member.
18. The heat exchanger of claim 14, further comprising at least one undulation constructed and arranged to change the direction of the flow of the fluid as it travels along the non-linear flow path, without reversing the direction of the flow of the fluid, wherein if the fluid is moving toward the outlet side before passing through the at least one undulation, the fluid continues to move toward the outlet side after passing through the at least one undulation and wherein if the fluid is moving toward the inlet side before passing through the at least one undulation, the fluid continues to move toward the inlet side after passing through the at least one undulation.
19. The heat exchanger of claim 18, wherein the first bend, the second bend and the at least one undulation each have an arcuate shape.
20. The heat exchanger of claim 14, wherein the depth of the at least one winding channels is substantially equal to the width of the winding channel.
21. The heat exchanger of claim 14, wherein the at least one heat transfer layer comprises a bonded stack of at least two laminations.
22. The heat exchanger of claim 14, wherein the at least one heat transfer layer comprises a single heat transfer layer.
23. The heat exchanger of claim 14, further comprising a flow restrictor plate disposed between the manifold and the heat transfer member, the flow restrictor plate including a body having a plurality of openings disposed there through that are configured, dimensioned and positioned to vary the flow to the winding channels according to the heat transfer requirements.
24. The heat exchanger of claim 23, wherein the body of the flow restrictor plate is constructed and arranged to selectively block the fluid flow to the winding channels in sections of the heat transfer member
25. The heat exchanger of claim 14, wherein the at least one winding channel comprises a plurality of winding channels, the plurality of winding channels being disposed over an active area of the heat transfer member in grouping of two or more, the number of winding channels per unit area varying between groups so as to vary the thermal resistance over the active area of the heat transfer member.
Type: Application
Filed: May 25, 2011
Publication Date: Sep 22, 2011
Applicant: MIKROS MANUFACTURING, INC. (Claremont, NH)
Inventor: Javier A. Valenzuela (Portsmouth, RI)
Application Number: 13/115,956
International Classification: F28F 13/12 (20060101); F28F 9/02 (20060101);