This invention relates to the field of heat exchangers. More particularly, this invention relates to systems, devices for, and methods of utilizing a fluid cooled channeled flat plate fin heat exchange device in an optimal manner.
Each advance in electronic components can cause increases in heat generation in a smaller package size. Due to these factors, there is a need for dissipation of the heat generated by these components. For example, there is a current need to dissipate heat from personal computer Central Processing Units (CPUs) in the range of 50 to 150 W.
Forced and natural convection air cooling methods, used in conjunction with heat sinks and heat pipes, currently serve as the predominant method of cooling electronics. The current conventional air cooling systems that use aluminum extruded or die-casting fin heat sinks are not sufficient for cooling the high heat flux of chip-surfaces or for large heat dissipation with low thermal resistance and compact size. Further, these air-cooled heat sinks require a substantial surface area to effectively function. To be able to transfer the increased heat load, the air-cooled heat sinks have become even larger. This requires the use of larger fans to overcome back-pressures caused by the large heat sinks. In other words, current air-cooled heat sinks require substantial space on the one hand, while blocking airflow entry and escape paths on the other. Thus, current cooling methods are unequal to the task of removing heat.
Moreover, the use of progressively larger fans increases the amount of acoustic noise generated by the cooling system and also increases the amount of electric power drawn by the system. For example, conventional solutions include use of multiple heat pipes to carry the heat to large heat sinks via high airflow. This leads to solution with high noise levels, which are undesirable.
Furthermore, a shortcoming of current traditional fan based heat dissipation methods is that heat is transferred in only one direction because a fan is placed to blow air in one direction over the heat sink. This limitation causes non-uniform temperature gradients across the heat sink and correspondingly, across the electronic component.
Due to these factors, and other shortcomings, there is a need for a more efficient and effective cooling system.
A device, method, and system for a fluid cooled channeled heat exchange device is disclosed. The fluid cooled channeled heat exchange device utilizes fluid circulated through a channel heat exchanger for high heat dissipation and transfer area per unit volume. The device comprises a highly thermally conductive material, preferably with less than 200 W/m-K. The preferred channel heat exchanger comprises two coupled flat plates and a plurality of fins coupled to the flat plates. At least one of the plates preferably to receive flow of a fluid in a heated state. The fluid preferably carries heat from a heat source (such as a CPU, for example). Specifically, at least one of the plates preferably comprises a plurality of condenser channels configured to receive, to condense, and to cool the fluid in the heated state. The fluid in a cooler state is preferably carried from the device to the heat source, thereby cooling the heat source.
The miniaturization of electronic components has created significant problems associated with the heating of integrated circuits. More and more, effective cooling of heat flux levels exceeding 100 W/cm2 from a relatively small surface area is required. Currently, there is a need for compact thermal solutions for electronic devices with high heat (power) density. For example, the upward trend in chip power with shrinking die sizes has lead to extremely high power density in high performance processors for which effective thermal solutions do not exist.
Due to its low density, air has a limited ability to carry heat per pound. In contrast, liquids are capable of carrying a substantially greater amount of heat per pound, due to their greater density. For example, forced-air cooling has an approximate heat-transfer coefficient of 20 W/m2° C., while moving water has an approximate heat-transfer coefficient of 9000 W/m2° C.
By utilizing the current fluid cooled invention, heat may be dissipated with a significant reduction in the amount of surface area required due to the higher heat-transfer rate. In addition, the invention currently disclosed dissipates more heat with considerably less flow volume and acoustic noise. Further, the current invention addresses the need to maintain temperature uniformity in the X-Y direction. The preferred embodiment of the current invention maintains substantial temperature uniformity at the X-Y direction in addition to dissipating heat to the ambient with low thermal resistance.
Embodiments of the fluid cooled channeled heat exchange device presently disclosed provide extremely high heat transfer area per unit volume. The geometric parameters have a significant influence on the convective heat transfer characteristics. Therefore, designs of systems using the present invention preferably optimize key parameters, allowing the fluid cooled channeled flat plate fin heat exchange device to serve as an efficient and economical means to dissipate high heat per unit volume.
Unlike prior art, embodiments of the fluid cooled channeled flat plate fin heat exchange device disclosed in the current invention provide high heat transfer area per unit volume in an optimal manner for use in cooling heat sources including electronic components such as, but not limited to, CPU's, integrated circuits, and microprocessors. Further, the current invention optimizes temperature uniformity in the X-Y direction of the heat exchange device in addition to dissipating heat to the ambient with low thermal resistance—a shortcoming of current traditional heat dissipation methods which only transfer heat in one direction. For example, embodiments of the current invention can dissipate heat fluxes exceeding 100 W/cm2 by utilizing fluid cooled channels etched in silicon or other materials.
The channels of the preferred embodiment of the fluid cooled channeled heat exchange device comprise channels with a hydraulic diameter below 5 millimeters. In addition to the fluid cooled channels, high aspect ratio fins are necessary to dissipate heat to the ambient with low thermal resistance.
The device for single phase fluid cooled channeled heat exchange 100 is shown in
Specifically,
The flat plate heat exchange device 100 preferably comprises a highly thermally conductive material, preferably with less than 200 W/m-K, such as aluminum. In alternate embodiments, the flat plate heat exchange device 100 comprises semiconducting material. Other embodiments comprise a material with a thermal conductivity value larger than 200 W/m-K.
Fluid carrying heat from a heat source (such as a CPU, for example) enters the device 100 from one side and exits from the opposite side of the device 100. Specifically, fluid enters the device 100 through the fluid inlet 101 in the direction as shown by the arrow 101′. The fluid exits the device 100 through the fluid outlet 102 in the direction as shown by the arrow 102′. The fluid utilized in the cooling process is preferably water, yet in alternative embodiments, the fluid is selected from a group comprising of water, ethylene glycol, isopropyl alcohol, ethanol, methanol, and hydrogen peroxide. In other embodiments, the fluid is selected from one of a liquid and a combination of a liquid and a vapor. While the fluid inlet 101 and the fluid outlet 102 are shown on opposite sides of the device 100, it will be appreciated that they can also be on the same side or adjacent sides as well.
The top plate 103′ (
In alternate embodiments, the condenser channels 104 comprise silicon. Silicon offers an alternate embodiment for the condenser channels 104 due to its reasonably high thermal conductivity (˜120 W/m-K), which allows the heat to conduct effectively up the sidewalls of the channels. In yet other embodiments, materials for the condenser channels 104 include silicon carbide and diamond. Further, in alternate embodiments, the plurality of condenser channels 104 comprises a high aspect ratio micromachining material or precision machined metals or alloys.
In the preferred embodiment of the current invention, the condenser channels 104 have depths in the range of 1 to 6 millimeters and widths in the range of 0.5 to 4 millimeters. These aspect ratios allow large amounts of fluid to be pumped through the fluid cooled channeled heat exchange device with minimal pressure drop, while simultaneously allowing all of the fluid to maintain a high thermal convection coefficient with the channel sidewalls.
In alternate embodiments, the plurality of condenser channels 104 are stamped onto the base plate 103. In yet other embodiments, a conductive fluid proof barrier (not shown) coupled to the base plate 103 and the top plate 103′ (
Still referring to
A plurality of fins 106 are coupled to the base plate 103 of the flat plate heat exchange device. The plurality of fins 106 shown in
The two plate halves of the flat plate heat exchange device 100 (with respective fins) are coupled together as shown in
The plurality of fins 106 and the base plate 103 and the second plurality of fins 106′ (
The preferred embodiment of the current invention is configured to receive a fluid in a heated state from a heat source. Further, the invention is preferably coupled to a pump or other means for supplying fluid (not shown) and to a means for airflow generation such as a fan (not shown) to allow for greater dissipation of heat to the ambient. The fluid in a heated state is received by the device 100 and the heat is dissipated by circulating the heated fluid through the plurality of condenser channels 104. The heated fluid is preferably brought to the heat exchange device by a pump. In alternate embodiments of the current invention, the heat source, such as a microprocessor, is interposed between the components of the device 100. In yet other embodiments of the current invention, the device 100 is otherwise coupled to a heat source directly.
The preferred embodiment of the current invention cools 120 W of heat from a CPU with a water flow rate of 150 ml/min. Unlike prior inventions, the multi-pass arrangement of the current invention for the fluid flow path leads to efficient cooling in a compact volume.
As noted in the discussion of
Fluid enters the device 200 through the fluid inlet 201 in the direction as shown by the arrow 201′. The input fluid is preferably a liquid, but can also be in two phase flow such as a vapor, or vapor and liquid mixture. The fluid exits the device 200 through the fluid outlet 202 in the direction as shown by the arrow 202′. The output fluid is preferably liquid. While the fluid inlet 201 and the fluid outlet 202 are shown on opposite sides of the heat exchange device 200, it will be appreciated that they can also be on the same side or adjacent sides as well.
In the two phase cooling embodiment, a unique channel geometry with regions for two phase condensation and single phase fluid cooling are utilized. The two phase condensation region is essentially several two phase channels connected to reduce vapor pressure drop in the two phase region. After condensation, heated single phase fluid travels in a multi-pass condenser channels to exit the heat exchange device at the cold side.
Specifically, the device 200 comprises a top plate (not shown) and a base plate 203 coupled together. The device 200 further comprises a plurality of fins 208 coupled to the bottom plate 203. In the preferred embodiment, the device 200 further comprises a second plurality of fins (not shown) coupled to the top plate. The flat plate heat exchange device 200 and the plurality of fins 208 preferably comprise a highly thermally conductive material, preferably less than 200 W/m-K, such as aluminum. In alternate embodiments, the flat plate heat exchange device 200 and the plurality of fins 208 comprise semiconducting material. Other embodiments comprise a material with a thermal conductivity value larger than 200 W/m-K.
The base plate 203 of the flat plate heat exchange device 200 comprises a single phase region 204 comprising a plurality of two phase channels 204′ configured to permit flow of a fluid comprising either vapor, or liquid and vapor, therethrough, along a first axis. The fluid preferably comprises water, but in alternate embodiments, the fluid is from a group comprising of water, ethylene glycol, isopropyl alcohol, ethanol, methanol, and hydrogen peroxide. In other embodiments, the fluid is selected from one of a liquid and a combination of a liquid and a vapor.
The base plate 203 further comprises a condensation region 205 comprising a plurality of condenser channels 205′ coupled to the plurality of two phase channels 204. The plurality of condenser channels 205′ are configured to permit flow of the fluid therethrough, along a second axis, not parallel to (and preferably perpendicular to) the first axis and reduce vapor pressure drop to promote condensation. Preferably, the plurality of two phase channels 204′ and the plurality of condenser channels 205′ are in a serpentine configuration. The plurality of two phase channels 204′ and the plurality of condenser channels 205′ shown in
In alternate embodiments, the base plate 203 further comprises a second single phase region (not shown) comprising a plurality of single phase channels (not shown) coupled to the plurality of condenser channels 205′. The plurality of single phase channels are configured to permit flow of a fluid therethrough, along the first axis.
In an embodiment of the current invention, the device 200 is coupled to a heat source. The heat source preferably comprises a microprocessor, but includes other electronic component heat sources in alternate embodiments.
As in the single phase embodiment of
Simply stated, the single phase region 204 is the first section and is configured to permit flow of fluid (preferably a liquid, but may also be a vapor or a vapor and liquid mixture in other embodiments) in through the fluid inlet 201 and through the plurality of two phase channels 204′. The condensation region 205 is the second section and is configured to permit flow of single phase fluid through the plurality of condenser channels 205′ and out through the fluid outlet 202. The plurality of fins 208 further dissipate the heat transferred by the fluid in the channels.
Similar to the device shown in
More specifically, fluid enters the single phase fluid cooled channeled heat exchange device 300 through the fluid inlet 301 in the direction as shown by the arrow 301′. The fluid exits the device 300 through the fluid outlet 302 in the direction as shown by the arrow 302′. The device 300 shown in
A first plurality of fins 306 is coupled to the base plate 303 of the flat plate heat exchange device 300. A second plurality of fins (not shown), similar to the first plurality of fins 306, are coupled to the top plate (not shown) of the flat plate heat exchange device. The fins are preferably a series of parallel fins, but in alternate embodiments, include a series of perpendicular fins, pin fins, spiral fins, or radial fins.
The two plate halves of the flat plate heat exchange device 300 (with respective fins) are then coupled. The first plurality of fins 306 and the base plate 303 and the second plurality of fins (not shown) and the top plate (not shown) of the flat plate heat exchange device 300 preferably are coupled by an anodic bonding method and comprise a highly thermally conductive material, preferably with less than 200 W/m-K, such as aluminum. In alternate embodiments, they comprise semiconducting material or a material with a thermal conductivity value larger than 200 W/m-K.
Specifically, cool air flows in the direction into or out of the page of the drawing of
In the preferred embodiment of the current invention, the top plate (not shown) of the flat plate heat exchange device 500 is flat and the base plate 503 comprises a plurality of channels 504 configured to permit flow of a fluid therethrough. The plurality of channels 504 are preferably machined, followed by nickel plating, onto the base plate 504 of the device 500. The plurality of channels 504 have rounded corners 505 and are in a radial configuration.
A plurality of fins 506 are coupled to the base plate 503. A second plurality of fins (not shown), similar to the plurality of fins 506, are coupled to the top plate (not shown) of the flat plate heat exchange device 500. The fins are preferably in a series of parallel fins, but in alternate embodiments, include a series of perpendicular fins, pin fins, spiral fins, or radial fins. The two plate halves of the flat plate heat exchange device 500 (with respective fins) are then coupled. The plurality of fins 506 and the base plate 503 and the second plurality of fins (not shown) and the top plate (not shown) of the device 500 preferably comprise aluminum and are preferably coupled by an anodic bonding method.
Specifically, cool air flows in the direction into or out of the page of the drawing of
The device 703 is preferably configured to cool a fluid in a heated state to a cooler state. The pump 709 is configured to circulate the fluid in the heated state and the cooler state to and from the device 703. Further, the heat source 701 preferably comprise a microprocessor.
In operation, the path 702 couples the heat source 701 to the device 703. It should be understood that the first path 705 and the second path 707 of the device 703 are contained within the device 703 and are not to be confused with the paths 702, 702′, 704, and 704′. The path 702 is configured to carry the fluid in the heated state from the heat source 701 to first path 705 of the device 703. The fluid in the heated state from the heat source 701 is circulated through the first path 705 and cooled. Following the circulation and cooling, the fluid is in a cooler state and exits the device 703 via the path 702′. The path 702′ couples the device 703 to the pump 709 and is configured to carry the fluid in a cooler state from the device 703 to the pump 709. The path 704 couples the pump to the device 703. The path 704 is configured to carry the fluid in a cooler state from the pump 709 to the second path 707 of the device 703. The second path 707 is preferably separate and distinct from the path 705 and is not coupled to the paths 702 and 702′. The fluid in a cooler state from the pump 709 is circulated through the second path 707 and cooled by the device 703. Following the circulation and cooling, the fluid is in a cooler state and exits the device 703 via the path 704′. The path 704′ couples the device 703 to the heat source 701 and is configured to carry the fluid in a cooler state from the device 703 to the heat source 701, thereby cooling the heat source 701.
The plurality of fluid channel heat exchange devices 703, 703′ and 703″ are configured to cool a fluid in a heated state to a cooler state. Each device 703, 703′ and 703″ comprises at least two fluid paths configured to permit flow of a liquid therethrough, as detailed in
The at least two fluid paths of the plurality of fluid channel heat exchange devices 703, 703′ and 703″ are preferably separated and are configured to carry the fluid in the heated state from the plurality of heat sources 701, 701′ and 701″. In addition, the at least two fluid paths of the plurality of fluid channel heat exchange devices 703, 703′ and 703″ are configured to carry the fluid in the cooler state to the plurality of heat sources 701, 701′ and 701″.
For example, the path 702 couples the heat source 701 to the device 703. It should be understood that the least two fluid paths of the plurality of fluid channel heat exchange devices 703, 703′ and 703″ are contained within the devices 703, 703′, and 703″ and are not to be confused with the paths 702, 702′, 704, 704′, 706, 706′, 708, 708′, 710, 710′, 712, and 712′. The path 702 is configured to carry the fluid in the heated state from the heat source 701 to one of the fluid paths of the device 703. The fluid in the heated state from the heat source 701 is circulated through and cooled by the device 703. Following the circulation and cooling, the fluid is in a cooler state and exits the device 703 via the path 702′. The path 702′ couples the device 703 to the pump 709 and is configured to carry the fluid in a cooler state from the device 703 to the pump 709. The path 704 couples the pump to the device 703. The path 704 is configured to carry the fluid in a cooler state from the pump 709 to a separate fluid path of the device 703 that is not coupled to the paths 702 and 702′. The fluid in a cooler state from the pump 709 is circulated through and cooled by the device 703. Following the circulation and cooling, the fluid is in a cooler state and exits the device 703 via the path 704′. The path 704′ couples the device 703 to the heat source 701 and is configured to carry the fluid in a cooler state from the device 703 to the heat source 701, thereby cooling the heat source 701.
Similarly, the path 706 couples the heat source 701′ to the device 703′. The path 706 is configured to carry the fluid in the heated state from the heat source 701′ to one of the fluid paths of the device 703′. The fluid in the heated state from the heat source 701′ is circulated through and cooled by the device 703′. Following the circulation and cooling, the fluid is in a cooler state and exits the device 703′ via the path 706′. The path 706′ couples the device 703′ to the pump 709′ and is configured to carry the fluid in a cooler state from the device 703′ to the pump 709′. The path 708 couples the pump 709′ to the device 703′. The path 708 is configured to carry the fluid in a cooler state from the pump 709′ to a separate fluid path of the device 703′ that is not coupled to the paths 706 and 706′. The fluid in a cooler state from the pump 709′ is circulated through and cooled by the device 703′. Following the circulation and cooling, the fluid is in a cooler state and exits the device 703′ via the path 708′. The path 708′ couples the device 703′ to the heat source 701′ and is configured to carry the fluid in a cooler state from the device 703′ to the heat source 701′, thereby cooling the heat source 701′.
In the embodiment shown in
In addition to the embodiments disclosed above, various methods for manufacturing a channeled flat plat heat exchange device is also disclosed. First, a method for manufacturing a soldered fin flat plate heat exchanger is disclosed. This method comprising machining fluid channels into each of two plate halves. Fins are soldered onto each of the two plate halves next. The fluid channels are then nickle or copper plated. Finally, the two halves are coupled such that the fluid channels of each of the two plate halves mate and form a leakproof fluid path.
Specifically,
The two halves are preferably coupled by a soldering method. The soldering method comprises utilizing a solder paste applied by stencil screen printing onto each of the two plate halves to form a bonding interface resulting in a hermetic seal. This ensures a consistent and uniform application of solder, resulting in a hermetic seal of the two halves. Further, in other embodiments, the soldering method comprises a step soldering process for multiple soldering operations. In the alternate embodiments, various allots of solder paste are used. For example, it may be necessary to solder the two halves at a higher temperature followed by a tube attachment soldering step at a lower temperature.
An alternate method for manufacturing involves the manufacture of an extruded fin flat plate heat exchanger. This method first comprises manufacturing a first finned extrusion. A second fined extrusion is next fabricated. Complementary fluid channels are machined onto the first and second finned extrusions. Finally, the first finned extrusion is coupled to the second fined extrusion such that the fluid channels of the first and second finned extrusions mate and form a leakproof fluid path. The method of coupling the first finned extrusion to the second finned extrusion may be either a soldering method or an epoxy method (both described above).
Finally, a method for manufacturing a skived fin flat plate heat exchanger is disclosed. This method comprises manufacturing a first finned halve by a skiving method followed by manufacturing a second finned halve by a skiving method. Next, complementary fluid channels are machined onto the first and second finned halves. Finally, the first finned halve is coupled to the second fined halve such that the fluid channels of the first and second finned halves mate and form a leakproof fluid path. The method of coupling the first finned halve to the second finned halve may be either a soldering method or an epoxy method (both described above).
The current invention provides a more efficient and effective cooling system that offers substantial benefits in heat flux removal capability compared with conventional cooling devices. The fluid cooled invention disclosed dissipates heat while also providing a significant reduction in the amount of surface area required due to a higher heat-transfer rate. In addition, the current invention dissipates more heat with considerably less flow volume and acoustic noise. Further, the current invention maintains substantial temperature uniformity at the X-Y direction in addition to dissipating heat to the ambient with low thermal resistance.
The present invention has been described in terms of specific embodiments incorporating details to facilitate the understanding of the principles of construction and operation of the invention. Such reference herein to specific embodiments and details thereof is not intended to limit the scope of the claims appended hereto. It will be apparent to those skilled in the art that modifications may be made in the embodiment chosen for illustration without departing from the spirit and scope of the invention.
This Patent Application claims priority under 35 U.S.C. 119 (e) of the now abandoned U.S. Provisional Patent Application, Ser. No. 60/423,009, filed Nov. 1, 2002 and entitled “METHODS FOR FLEXIBLE FLUID DELIVERY AND HOTSPOT COOLING BY MICROCHANNEL HEAT SINKS” which is hereby incorporated by reference. This Patent Application also claims priority under 35 U.S.C. 119 (e) of the now abandoned U.S. Provisional Patent Application, Ser. No. 60/442,383, filed Jan. 24, 2003 and entitled “OPTIMIZED PLATE FIN HEAT EXCHANGER FOR CPU COOLING” which is also hereby incorporated by reference. In addition, this Patent Application claims priority under 35 U.S.C. 119 (e) of the now abandoned U.S. Provisional Patent Application, Ser. No. 60/455,729, filed Mar. 17, 2003 and entitled MICROCHANNEL HEAT EXCHANGER APPARATUS WITH POROUS CONFIGURATION AND METHOD OF MANUFACTURING THEREOF”, which is hereby incorporated by reference.
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