Prevention of cooling flow blockage

A fluid cooled cold plate includes a main coolant passage with a first cross-sectional area taken laterally in a direction perpendicular to the flow direction and a finned coolant passage having a second cross-sectional area taken laterally in a direction perpendicular to the flow direction, with the second area smaller than the first area. Fluidly connecting the main coolant passage with the finned coolant passage is a branch oriented such that a fluid is turned 90° or more when passing into the branch from the main coolant passage. Also included is a coolant bypass passage in fluid communication with the main coolant passage and located fluidically parallel to the finned coolant passage.

BACKGROUND

The present embodiments relate to fluid cooled cold plates, and specifically to the prevention of coolant flow passage blockage within fluid cooled cold plates.

Electronic devices, and particularly high power electronic devices, dissipate heat which if not accounted for can cause the electronic devices to overheat and fail. As a result, electronic devices require cooling for reliable operation. Often, cold plates are used to cool electronic devices. A cold plate receives a fluid from a cooling system and passes the fluid through cold plate coolant flow passages, which can have varying sizes and shapes within a single cold plate. The cold plate can be positioned so as to interface with an electronic device to provide convective cooling.

While the use of fluid cooled cold plates to provide cooling to electronic devices is very effective thermally, fluid cooled cold plates can be susceptible to flow passage blockage. Cold plate flow passage blockage can result in insufficient cooling and ultimately failure of the electronic device. Therefore, it is desired to provide a fluidic cooling system which provides suitable cooling flow with a reduced risk of flow blockage.

SUMMARY

One embodiment includes a fluid cooled cold plate having a main coolant passage with a first cross-sectional area taken laterally in a direction perpendicular to the flow direction and a finned coolant passage having a second cross-sectional area taken laterally in a direction perpendicular to the flow direction, with the second area smaller than the first area. Fluidly connecting the main coolant passage with the finned coolant passage is a branch oriented such that a fluid is turned 90° or more when passing into the branch from the main coolant passage. Also included is a coolant bypass passage in fluid communication with the main coolant passage and located fluidically parallel to the finned coolant passage.

Another embodiment includes a method for preventing cooling flow blockage in a fluid cooled cold plate. The method includes passing a fluid with an entrained contaminate through a main coolant passage having a first cross-sectional area taken laterally in a direction perpendicular to the flow direction. The fluid with an entrained contaminate larger than a finned coolant passage is bypassed past a branch that is oriented such that the fluid is turned 90° or more when passing into the branch from the main coolant passage. The branch is in fluid connection with the main coolant passage on a first end and the finned coolant passage on a second end, with the finned coolant passage having a second cross-sectional area taken laterally in a direction perpendicular to the flow direction, where the second area is smaller than the first area. The fluid with the entrained contaminate larger than the finned coolant passage is directed through a coolant bypass passage in fluid communication with the main coolant passage and fluidically parallel to the finned coolant passage.

DETAILED DESCRIPTION

FIG. 1shows a cross-sectional view of a prior art cold plate10. Cold plate10includes inlet12, fluid coolant14(designated by arrows), main coolant passage16, branches18, finned coolant passage sets20each including multiple finned coolant passages21, intermediate coolant passage22, downstream finned coolant passage set23including multiple downstream finned coolant passages24, return coolant passage26, and outlet28.

Cooling system8, which can be, for example, a central cooling system, is in fluid communication with inlet12such that cooling system8provides fluid14in a relatively cold state to cold plate10through inlet12. From inlet12, fluid14passes into main coolant passage16. Branches18are fluidly connected between main coolant passage16and finned coolant passage sets20, such that fluid14is conveyed from main coolant passage16downstream into finned coolant passages21via branches18. Finned coolant passages21(and downstream finned coolant passages24) have smaller areas, taken laterally in a direction perpendicular to the fluid14flow direction, than main coolant passage16. After passing through finned coolant passages21, fluid14re-collects at intermediate coolant passage22and passes through downstream finned coolant passage set23. After exiting downstream finned coolant passages24, fluid14is conveyed by return coolant passage26to outlet28where fluid14can be returned to cooling system8and/or used in another cold plate.

The embodiment of cold plate10as illustrated shows three finned coolant passage sets20fluidically arranged in parallel. However, various configurations of passages16,21,22,24, and26can be used in a given cold plate depending on the specific cooling needs of an electronic device. For example, the number of finned coolant passage sets20, as well as the number of finned coolant passages21that make up each set20, can vary depending on the particular application of cold plate10. Also, finned coolant passage sets20, as well as finned coolant passages21, can vary so as to be in parallel, as shown inFIG. 1, in series, and/or a combination of parallel and series sets20and passages21depending on the particular application of cold plate10.

When cold plate10is positioned so as to interface with an electronic device, cold plate10is capable of providing cooling to the electronic device by means of the flow of fluid14through cold plate10. For example, because finned coolant passage sets20increase surface area for convective thermal energy transfer and thereby promote a greater heat exchange function, finned coolant passage sets20can be positioned within cold plate10so as to interface with areas of the electronic device which require greater cooling. However, prior art cold plates, such as cold plate10, can fail to effectively cool an electronic device when fluid14is prevented from passing through cold plate10from inlet12to outlet28.

Fluid14can be prevented from passing through cold plate10when the coolant passages in cold plate10become blocked. Fluid14supplied by cooling system8to cold plate10often contains entrained contaminates30that are conveyed through inlet12and into main coolant passage16. In many instances contaminates30will pass through the relatively large area of main coolant passage16, but create blockage at an inlet to the relatively smaller area of finned coolant passages21. When contaminates30wholly or partially block one or more finned coolant passages21, for example, cold plate10can be unable to meet the cooling needs of the particular application.

FIG. 2is a cross-sectional view of an embodiment of cold plate40which can prevent blockage of cold plate40, including finned coolant passages21. Cold plate40is similar to that described above for prior art cold plate10, but includes the differences noted below.

Cold plate40has branches18oriented such that fluid14is turned at an angle θ which is 90° or more when fluid14passes into branches18from main coolant passage16. Cold plate40also has coolant bypass passage42in fluid communication with main coolant passage16on one end and return coolant passage26on another end. Coolant bypass passage42is fluidly connected to main coolant passage16such that a continuous, straight (i.e. linear) fluid14passage to return coolant passage26is defined by main coolant passage16and coolant bypass passage42. Coolant bypass passage42is located fluidically parallel to finned coolant passages21, meaning the same fluid14does not pass through both coolant bypass passage42and finned coolant passages21(i.e. one portion of fluid14passes through coolant bypass passage42and the other portion of fluid14passes through branches18).

Cold plate40works to prevent blockage of, for example, finned coolant passages21by using fluid14momentum to carry contaminates30(e.g., solid particulates) entrained in fluid14to coolant bypass passage42, so that contaminates30do not pass to smaller area finned coolant passages21. Orienting branches18such that fluid14is turned at an angle θ which is 90° or more when fluid14passes into branches18from main coolant passage16helps to prevent contaminates30from entering branches18and instead, in combination with fluid14momentum along the straight passage, directs contaminates30along main coolant passage16to coolant bypass passage42. Smaller contaminates30, such as those contaminates30which are smaller than the inlet of finned coolant passages21, will not experience as great of fluid14momentum as larger contaminates30, and thus are more likely to turn 90° or more and be directed into branches18. However, these smaller contaminate30generally will not cause significant blockage, and can safely pass through cold plate40, including finned coolant passages21. As a result, large contaminates30entrained in fluid14flush past branches18, and thus the smaller area finned coolant passages21, preventing or minimizing instances of cold plate40blockage.

In the embodiment illustrated inFIG. 2, coolant bypass passage42includes filter element44. As contaminates30flush past branches18and enter coolant bypass passage42, filter element44allows fluid14to pass into return coolant passage26but retains contaminates30at coolant bypass passage42. Filter element44can have sieves sized such that contaminates30which are as large as or larger than an inlet to finned coolant passages21are prevented from passing through filter element44. Coolant bypass passage42also includes a removable plug46. Removable plug46can allow for service of coolant bypass passage42.

Because fluid14which passes through coolant bypass passages50′ and50″ does not circulate through other passages of cold plates40′ and40″ (i.e. fluid14which passes through coolant bypass passages50′ and50″ enters return coolant passage26and exits cold plates40′ and40″ at outlet28), such as finned coolant passages21, fluid14which passes through coolant bypass passages50′ and50″ does not significantly contribute to the cooling provided by cold plates40′ and40″. In other words, fluid14which passes through coolant bypass passages50′ and50″ is substantially wasted in terms of cooling contribution. In one embodiment, a volume of fluid14which passes through coolant bypass passages50′ and50″ is 10-20% of the total volume of fluid14which is within cold plates40′ and40″ at any one time. Therefore, it is desirable to limit the volume of fluid14which passes through coolant bypass passages50′ and50″, yet still direct enough fluid14towards and through coolant bypass passages50′ and50″ to allow fluid14momentum to flush contaminates30past branches18.

Coolant bypass passages50′ and50″ include flow balance mechanisms52′ and52″ to balance a flow resistance between fluid14which enters coolant bypass passages50′ and50″, and fluid14which enters branches18. This minimizes the flow of fluid14through bypass passages50′ and50″, increasing the cooling effectiveness of cold plates40′ and40″ while reducing or eliminating risk of blockage. Flow balance mechanisms52′ and52″ can be permanent or removable from bypass passages50′ and50″ (e.g. for maintenance). Flow balance mechanism52′ shown inFIG. 3is a converging-diverging nozzle, which balances the flow resistance between fluid14which enters coolant bypass passage50′ and fluid14which enters branches18by restricting a volume of fluid14which can pass through coolant bypass passage50′ at any one time, in turn increasing a volume of fluid14which passes through branches18as compared to coolant bypass passage50′ without flow balance mechanism52′. The particular converging-diverging nozzle dimensions can be optimized depending on the cooling needs of the particular application of cold plate40′.

Flow balance mechanism52″ shown inFIG. 4is a converging nozzle (i.e. reduction in area of passage50″ taken laterally in a direction perpendicular to fluid14flow direction) which extends axially until the fluid connection with passage26. Flow balance mechanism52″ ofFIG. 4adds a pressure drop which helps to balance the flow resistance between fluid14which enters coolant bypass passage50″ and fluid14which enters branches18. Similarly, the particular dimensions of the converging nozzle can be optimized depending on the cooling needs of the particular application of cold plate40″.

In other embodiments, flow balance mechanisms52′ and52″ can be any mechanism which assists in balancing the flow resistance between fluid14which enters coolant bypass passages50′ and50″, and fluid14which enters branches18. For example, instead of a converging-diverging nozzle, an orifice can be added to coolant bypass passage50′ (i.e. a plate having a hole which is smaller than the area of passage50′ taken laterally in a direction perpendicular to fluid14flow direction). If contaminates30are desired to be directed out of cold plates40′ and40″, flow balance mechanisms52′ and52″ should have an area, taken laterally in a direction perpendicular to fluid14flow direction, which is greater than a size of contaminates30which can cause blockage. Coolant bypass passages50′ and50″ and/or flow balance mechanism52′ and52″ are structured in a manner such that retrofitting a cold plate with coolant bypass passages50′ and50″ and/or flow balance mechanism52′ and52″ is possible.

Discussion of Possible Embodiments

A fluid cooled cold plate comprising: a main coolant passage having a first cross-sectional area taken laterally in a direction perpendicular to the flow direction; a finned coolant passage having a second cross-sectional area taken laterally in a direction perpendicular to the flow direction, wherein the second area is smaller than the first area; a branch fluidly connecting the main coolant passage with the finned coolant passage, wherein the branch is oriented such that a fluid is turned 90° or more when passing into the branch from the main coolant passage; and a coolant bypass passage in fluid communication with the main coolant passage and located fluidically parallel to the finned coolant passage.

The coolant bypass passage is fluidly connected with the main coolant passage to form a continuous straight passage.

The coolant bypass passage includes a flow balance mechanism.

The flow balance mechanism comprises a converging-diverging nozzle.

The flow balance mechanism comprises a filter element.

The coolant bypass passage includes a removable plug.

The main coolant passage is in fluid communication with a central cooling system.

The finned coolant passage is located downstream of the main coolant passage.

A method for preventing cooling flow blockage in a fluid cooled cold plate, the method comprising: passing a fluid with an entrained contaminate through a main coolant passage having a first cross-sectional area taken laterally in a direction perpendicular to the flow direction; bypassing a fluid with an entrained contaminate larger than a finned coolant passage past a branch, wherein the branch is oriented such that the fluid is turned 90° or more when passing into the branch from the main coolant passage, and wherein the branch is in fluid connection with the main coolant passage on a first end and the finned coolant passage on a second end having a second cross-sectional area taken laterally in a direction perpendicular to the flow direction, and wherein the second area is smaller than the first area; and directing the fluid with the entrained contaminate larger than the finned coolant passage through a coolant bypass passage in fluid communication with the main coolant passage and fluidically parallel to the finned coolant passage.

The method of the preceding paragraph can optionally include, additionally and/or alternatively, the following techniques, steps, features and/or configurations:

Directing the fluid with the entrained contaminate larger than the finned coolant passage through the coolant bypass passage comprises directing the fluid along a continuous straight passage from the main coolant passage.

Passing the fluid with an entrained contaminate smaller than the second area and the fluid substantially free of contaminates through the branch.

Balancing a flow resistance between the fluid that passes through the branch and the fluid that passes through the coolant bypass passage.

The flow resistance between the fluid that passes through the branch and the fluid that passes through the coolant bypass passage is balanced by passing the fluid through a converging-diverging nozzle at the coolant bypass passage.

Collecting contaminates in the fluid at the coolant bypass passage.

Removing a plug on the coolant bypass passage.

Any relative terms or terms of degree used herein, such as “generally”, “substantially”, “approximately”, and the like, should be interpreted in accordance with and subject to any applicable definitions or limits expressly stated herein. In all instances, any relative terms or terms of degree used herein should be interpreted to broadly encompass any relevant disclosed embodiments as well as such ranges or variations as would be understood by a person of ordinary skill in the art in view of the entirety of the present disclosure, such as to encompass ordinary manufacturing tolerance variations, incidental alignment variations, temporary alignment or shape variations induced by operational conditions, and the like.

While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims. For example, features described with respect to any given embodiment can be utilized with respect to any other disclosed embodiment, as desired for particular applications.