# Patent

## Title
Cooling apparatuses having sloped vapor outlet channels

## Abstract

Jet impingement and two-phase cooling apparatuses with sloped vapor outlet channels are disclosed. In one embodiment, a cooling apparatus includes a fluid inlet channel, a jet orifice surface having one or more jet orifices fluidly coupled to the fluid inlet channel such that coolant fluid within the fluid inlet channel flows through the one or more jet orifices as one or more impingement jets, and a target surface. The target surface and the jet orifice surface define an impingement chamber where the one or more impingement jets impinge the target surface at an impingement region such that at least some of the coolant fluid changes to a vapor. The cooling apparatus further includes a plurality of sloped vapor outlet channels that are fluidly coupled to the impingement chamber. Coolant fluid flows through the plurality of sloped vapor outlet channels after it impinges the target surface.

## Background
TECHNICAL FIELD
The present specification generally relates to cooling apparatuses for cooling heat generating devices and, more particularly, to jet impingement, two-phase cooling apparatuses having sloped vapor outlet channels.
BACKGROUND
Heat generating devices, such as power semiconductor devices, may be coupled to a heat spreader to remove heat and lower the maximum operating temperature of the heat generating device. In some applications, cooling fluid may be used to receive heat generated by the heat generating device by convective thermal transfer, and remove such heat from the heat generating device. For example, jet impingement may be used to cool a heat generating device by directing impingement jets of coolant fluid onto the heat generating device or a target surface that is thermally coupled to the heat generating device. Additionally, jet impingement may also be combined with two-phase cooling, where the heat generating device is cooled by the phase change of the coolant fluid from a liquid to a vapor. However, vapor bubbles are typically formed within the coolant fluid near the heat generating device. If not properly evacuated, the vapor bubbles will collect, leading to an increase in pressure. The saturation temperature of the coolant fluid increases with increasing pressure, which adversely affects the performance of the two-phase heat transfer.
Accordingly, a need exists for alternative jet impingement, two-phase cooling apparatuses.
SUMMARY
In one embodiment, a cooling apparatus includes a fluid inlet channel, a jet orifice surface having one or more jet orifices fluidly coupled to the fluid inlet channel such that coolant fluid within the fluid inlet channel flows through the one or more jet orifices as one or more impingement jets, and a target surface. The target surface and the jet orifice surface define an impingement chamber where the one or more impingement jets impinge the target surface at an impingement region such that at least some of the coolant fluid changes to a vapor. The cooling apparatus further includes a plurality of sloped vapor outlet channels that are fluidly coupled to the impingement chamber. Each sloped vapor outlet channel slopes in a direction that is both away from the jet orifice surface and opposite from a direction of the one or more impingement jets. Coolant fluid in the form of vapor and/or fluid flows through the plurality of sloped vapor outlet channels after it impinges the target surface.
In another embodiment, a cooling apparatus includes a jet plate manifold, a jet orifice surface within the jet plate manifold, and a vapor manifold coupled to the jet plate manifold. The jet plate manifold includes a tapered portion and a jet plate manifold channel, and is configured to receive a coolant fluid. The jet orifice surface is within the tapered portion of the jet plate manifold, and includes one or more jet orifices. Coolant fluid flows through the one or more jet orifices as one or more impingement jets. The vapor manifold includes a plurality of tapered walls defining an opening such that the tapered portion of the jet plate manifold is disposed within the opening of the vapor manifold. A plurality of vapor outlet channels is located between the plurality of tapered walls of the vapor manifold and the tapered portion of the jet plate manifold. Each vapor outlet channel of the plurality of vapor outlet channels slopes in a direction that is both away from the jet orifice surface and opposite from a direction of the one or more impingement jets. The one or more impingement jets impinge the target surface, wherein at least some of the coolant fluid changes to a vapor, and the vapor and coolant fluid flows through the plurality of vapor outlet channels to exit the cooling apparatus.
In yet another embodiment, a cooling apparatus includes an inlet-outlet manifold, a jet plate manifold, a jet orifice plate, a vapor manifold, and a target surface. The inlet-outlet manifold includes a fluid inlet configured to receive a coolant fluid, an inlet manifold channel fluidly coupled to the fluid inlet, a plurality of outlet manifold channels, and a fluid outlet fluidly coupled to the plurality of outlet manifold channels. The jet plate manifold is coupled to the inlet-outlet manifold and includes an upper portion having a plurality of walls, a plurality of slot channels within the plurality of walls, wherein the plurality of slot channels are fluidly coupled to the plurality of outlet manifold channels, a tapered portion extending from the upper portion, and a jet plate manifold channel extending through the upper portion and the tapered portion. The jet plate manifold channel is fluidly coupled to the inlet manifold channel. The jet plate manifold further includes a seat within the jet plate manifold channel. The jet orifice plate is disposed within the jet plate manifold channel, and includes a flange portion, a jet orifice surface opposite from the flange portion, and a jet channel. The jet orifice plate is disposed within the jet plate manifold channel such that the flange portion is positioned on the seat of the jet plate manifold. The jet orifice surface includes one or more jet orifices. The jet channel is fluidly coupled to the inlet manifold channel, and the coolant fluid flows through the one or more jet orifices as one or more impingement jets. The plurality of tapered walls define an opening, wherein the tapered portion of the jet plate manifold is disposed within the opening of the vapor manifold such that a plurality of vapor outlet channels is located between the plurality of tapered walls of the vapor manifold and the tapered portion of the jet plate manifold. Each vapor outlet channel of the plurality of vapor outlet channels slopes in a direction that is both away from the jet orifice plate and opposite from a direction of the one or more impingement jets. The one or more impingement jets impinge the target surface, wherein at least some of the coolant fluid changes to a vapor, and the vapor and coolant fluid flows through the plurality of vapor outlet channels to exit the cooling apparatus.
These and additional features provided by the embodiments described herein will be more fully understood in view of the following detailed description, in conjunction with the drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
FIG. 1 schematically depicts a cross sectional view of a cooling apparatus according to one or more embodiments described and illustrated herein;
FIG. 2 schematically depicts an exploded view of a cooling apparatus according to one or more embodiments described and illustrated herein;
FIG. 3 schematically depicts a bottom view of the inlet-outlet manifold of the cooling apparatus depicted in FIG. 2 according to one or more embodiments described and illustrated herein;
FIG. 4A schematically depicts a perspective view of a jet orifice plate of the cooling apparatus depicted in FIG. 2 according to one or more embodiments described and illustrated herein;
FIG. 4B schematically depicts a bottom view of the jet orifice plate depicted in FIG. 4A;
FIG. 5A schematically depicts a top view of the jet plate manifold of the cooling apparatus depicted in FIG. 2 according to one or more embodiments described and illustrated herein;
FIG. 5B schematically depicts a bottom view of the jet plate manifold depicted in FIG. 5A;
FIG. 5C schematically depicts a side view of the jet plate manifold depicted in FIG. 5A;
FIG. 6A depicts a top view of the vapor manifold of the cooling apparatus depicted in FIG. 2 according to one or more embodiments described and illustrated herein;
FIG. 6B schematically depicts a bottom view of the vapor manifold depicted in FIG. 6A;
FIG. 6C schematically depicts a side view of the vapor manifold depicted in FIG. 6A;
FIG. 7 schematically depicts a cross sectional, partially transparent perspective view of an assembled cooling apparatus according to one or more embodiments described and illustrated herein; and
FIG. 8 schematically depicts a fluid domain of coolant fluid flowing within the cooling apparatus depicted in FIG. 7.



DETAILED DESCRIPTION
Embodiments of the present disclosure are directed to two-phase, jet impingement cooling apparatuses that may be utilized to cool heat generating devices, such as semiconductor devices. In the embodiments described herein, jet-impingement is provided by directing a jet of coolant fluid at an impingement region of a target surface, which may be a heat generating device or a thermally conductive surface coupled to the heat generating device. Heat is transferred to the coolant fluid as it impinges the target surface. In addition to jet-impingement, embodiments provide two-phase cooling, wherein the coolant fluid changes phase from a fluid to a vapor, thereby removing heat flux from the heat generating device. Accordingly, embodiments are directed to submerged two-phase, jet-impingement cooling devices. Embodiments guide vapor that is formed at the heat source (e.g., at the semiconductor device) due to the boiling of the coolant fluid away from the heat source to prevent the build-up of pressure within the cooling apparatus. More particularly, pitched vapor outlet channels are oriented to take advantage of the buoyancy of vapor bubbles to guide them away from the heat source. Accordingly, the pitched (i.e., sloped) vapor outlet channels resolve the inherent pressure build-up associated with the incomplete evacuation of vapor from the cooling apparatus which causes an increase in the saturation temperature of the coolant fluid and diminishes the effectiveness of heat transfer. Various embodiments of cooling apparatuses having sloped vapor outlet channels are described herein below.
Referring now to FIG. 1, an example cooling apparatus 10 is schematically depicted in cross section. The cooling apparatus 10 generally comprises a fluid inlet 12 that is fluidly coupled to a fluid inlet channel 13, and several fluid outlet channels 14 that are fluidly coupled to one or more fluid outlets 15. In some embodiments, the fluid outlet channels 14 may converge to a single fluid outlet 15. The fluid inlet 12 and the fluid outlets 15 may be fluidly coupled to fluid lines (not shown) that are fluidly coupled to a coolant fluid reservoir (not shown). The coolant fluid may be any appropriate liquid, such as deionized water or radiator fluid, for example. The fluid inlet 12 and the fluid outlets 15 may be configured as couplings, such as male or female fluid couplings, for connecting fluid lines to the fluid inlet 12 and the fluid outlets 15. The fluid inlet channel 13 terminates at a jet orifice surface 26 having one or more jet orifices 25. Coolant fluid 30 flows through the fluid inlet channel 13 and the jet orifices 25. The coolant fluid 30 exits the jet orifices 25 as impingement jets 32 that impinge a thermally conductive target surface 50 that is thermally coupled to a heat generating device, such as a semiconductor device (not shown in FIG. 1). Semiconductor devices may include, but are not limited to, insulated gate bipolar transistors (IGBT), metal-oxide-semiconductor field effect transistors (MOSFET), power diodes, power bipolar transistors, and power thyristor devices. As an example and not a limitation, the semiconductor device may be included in a power electronic module as a component in an inverter and/or converter circuit used to electrically power high load devices, such as electric motors in electrified vehicles (e.g., hybrid vehicles, plug in hybrid electric vehicles, plug in electric vehicles, and the like). In alternative embodiments, the impingement jets 32 impinge the heat generating device rather than an intermediate target surface 50. As described in more detail below, the target surface may further include surface features, such as thermally conductive fins, to further enable heat transfer from the heat generating device to the coolant fluid.
After impinging the target surface 50, which may be configured as a thermally conductive material such as copper or aluminum, the coolant fluid 30 flows away from an impingement region 23 within an impingement chamber 24 defined by the target surface 50 and the jet orifice surface 26. Some of the coolant fluid 30 changes phases from a liquid to a vapor due to the high temperature heat generating device being cooled. This phase change will cause vapor bubbles to form near the impingement region 23 and the heat generating device. Collection of vapor bubbles within the impingement chamber 24 causes the pressure within the cooling apparatus to increase, which further causes an increase in the saturation temperature of the coolant fluid that diminishes the effectiveness of heat transfer.
Body forces from the bulk fluid motion of the coolant fluid alone may not sufficiently remove all of the vapor formed within the impingement chamber 24. Buoyant forces, arising from the lower density of the vapor relative to its surrounding liquid medium, can counteract the body force, thereby leading to the pooling of vapor at the top of the cooling chamber. Because vapor is a gas and is compressive, pressure gradually increases over time as vapor collects, causing an increase in the saturation temperature of the coolant fluid.
The example cooling apparatus 10 further includes several sloped vapor outlet channels 27 that are fluidly coupled to the impingement chamber 24. The sloped vapor outlet channels 27 take advantage of the buoyancy of the vapor bubbles to guide them away from the impingement region 23. Accordingly, the geometry of the sloped vapor outlet channels 27 accounts for, and utilizes, both body and buoyant forces to drive the vapor away from the impingement region 23 and the heat generating device. Thus, pressure and the saturation temperature of the coolant fluid 30 should remain constant regardless of heat input and vapor generation within the impingement chamber 24 of the cooling apparatus 10. In the illustrated embodiment, the sloped vapor outlet channels 27 transition to vertical vapor outlet channels 28 through which the coolant flows and exits the cooling apparatus 100.
Referring now to FIG. 2, an example cooling apparatus 100 is depicted in an exploded view. Generally, the cooling apparatus comprises an inlet-outlet manifold 110, a jet plate manifold 150 coupled to the inlet-outlet manifold 110, a jet orifice plate 120 disposed within the jet plate manifold 150, a vapor manifold 170 coupled to the jet plate manifold 150, and a target surface 180 disposed within an insulation assembly 190 that is coupled to the vapor manifold 170. Several gaskets may be provided between the various components to prevent fluid from escaping the cooling apparatus 100. For example, a jet plate gasket 130 may be positioned between a flange portion 122 of the jet orifice plate 120 and a seat 131 (see FIG. 7) of the jet plate manifold 150, a jet plate manifold gasket 140 may be positioned between the inlet-outlet manifold 110 and the jet plate manifold 150, and a vapor manifold gasket 160 may be positioned between the jet plate manifold 150 and the vapor manifold 170.
FIG. 3 is a bottom view of the inlet-outlet manifold 110. Referring to FIGS. 2 and 3, the inlet-outlet manifold 110 comprises a fluid inlet 102 at a first surface 101 that is fluidly coupled to an inlet manifold channel 103 within a bulk of the inlet-outlet manifold 110. The inlet manifold channel 103 opens at a second surface 105 of the inlet-outlet manifold 110. In the illustrated body, the inlet manifold channel 103 widens to a larger opening 107 at the second surface 105. A fluid outlet 104 is also present on the first surface 101. The fluid inlet 102 and the fluid outlet 104 may be fluidly coupled to input and output fluid lines, respectively. Coolant fluid is provided to the cooling apparatus 100 through the fluid inlet 102, and is removed from the cooling apparatus 100 through the fluid outlet 104.
Referring to FIG. 3, the second surface 105 of the inlet-outlet manifold 110 also comprises four slot-shaped outlet openings 117 along a perimeter of the inlet-outlet manifold 110. Briefly referring to FIG. 7, each slot-shaped outlet opening 117 is fluidly coupled to an internal outlet manifold channel 114a-114d that is fluidly coupled to the fluid outlet. It is noted that outlet manifold channel 114d is not visible in FIG. 7. The outlet manifold channels 114a-114d are disposed around the inlet manifold channel 103. As described in more detail below, the outlet manifold channels 114a-114d slope upwardly toward the fluid outlet 104 near the first surface 101 of the inlet-outlet manifold 110. Referring once again to FIG. 3, the inlet-outlet manifold 110 further comprises a plurality of through-holes configured to receive a plurality of fasteners (e.g., screws) to maintain the various components of the cooling apparatus 100 in an assembled configuration. It should be understood that, in alternative embodiments, the various components may be coupled together by bonding layers (e.g., solder layers) rather than by mechanical fasteners.
FIG. 4A schematically depicts a perspective view of an example jet orifice plate 120, while FIG. 4B schematically depicts a bottom view of the jet orifice plate 120 depicted in FIG. 4A. Generally, the illustrated jet orifice plate 120 comprises a flange portion 122, and a narrow portion 124 extending from the flange portion 122. A jet orifice surface 126 is provided on an underside surface of the narrow portion 124. A jet channel extends 123 through the flange portion 122 and the narrow portion 124, and is fluidly coupled to the inlet manifold to receive input coolant fluid. The jet orifice surface 126 comprises a plurality of jet orifices 125 through which coolant fluid flows as impingement jets. As shown in FIG. 4B, the plurality of jet orifices 125 may be configured as an array. Any number of jet orifices 125 may be provided in any desirable arrangement, and embodiments are not limited to the number and arrangement of jet orifices 125 depicted in FIG. 4B. Further, the jet orifices 125 may take on any shape, including, but not limited to, round, square, rectangular, star-shaped, lobed, helical, and the like. The jet orifice plate 120 is configured to be disposed within the jet plate manifold 150. In some embodiments, the flange portion 122 further includes through-holes configured to receive fasteners that couple the jet orifice plate 120 to the jet plate manifold 150, or one or more through-holes serving as a pressure relief.
FIG. 5A is a top view of the jet plate manifold 150 depicted in FIG. 2, while FIGS. 5B and 5C are bottom and side views of the jet plate manifold 150, respectively. Referring now to FIGS. 2 and 5A-5C, the jet plate manifold 150 generally comprises an upper portion 152 defined by four walls 158, and a tapered portion 153 extending from the upper portion 152. Four slot channels 157 are provided within the four walls 158 of the upper portion. The slot channels 157 extend from a first surface 151 to a second surface 159 of the jet plate manifold 150, and are positioned such that they are fluidly coupled to the slot-shaped outlet openings 117 and outlet manifold channels 114a-114d of the inlet-outlet manifold 110 when the jet plate manifold 150 is coupled to the inlet-outlet manifold 110. The jet plate manifold 150 may further comprise a plurality of through-holes 155 for receiving fasteners.
The first surface 151 (i.e., the upper surface) has a first opening 154 that extends to a depth D, and then narrows to a second opening 156, thereby defining a seat 131 (FIG. 5C). The exemplary tapered portion 153 comprises four walls that taper downwardly away from the upper portion 152. As described in more detail below, the tapered portion 153 defines sloped vapor outlet channels 176 through which coolant fluid flows.
The first opening 154 and the second opening 156 define a jet plate manifold channel 161 extending from the first surface 151 to the second surface 159. The jet orifice plate 120 is disposed within the jet plate manifold channel 161 of the jet plate manifold 150. As shown in FIG. 7, which is a cross-sectional view of an exemplary cooling apparatus 100, the flange portion 122 of the jet orifice plate 120 is positioned on the seat 131 defined by the transition between the first opening 154 and the second opening 156. In some embodiments, a jet plate gasket 130 may be positioned between the flange portion 122 and the seat 131. The narrow portion 124 of the jet orifice plate 120 is disposed within the second opening 156 and may extend beyond the tapered portion 153, as depicted in FIG. 7.
Referring now to FIGS. 2, 6A-6C and 7, the vapor manifold 170 comprises tapered walls 177 that taper from a first surface 171 toward a second surface 173. The tapered walls 177 define a first opening at 174A at the first surface 171 of the vapor manifold 170. The tapered walls 177 terminate at straight walls 178 that extend to the second surface 173, thereby defining a second opening 174B. The first and second openings 174A, 174B define a vapor manifold opening 172 into which the tapered portion 153 of the jet plate manifold 150 and the narrow portion 124 of the jet orifice plate 120 are disposed. As described in more detail below and depicted in FIG. 7, the tapered walls 177 cooperate with the tapered portion 153 of the jet plate manifold 150 to define the sloped vapor outlet channels 176. The exemplary vapor manifold 170 further comprises through-holes 175, which may be threaded to receive fasteners to couple various components of the cooling apparatus 100 together.
The vapor manifold 170 is coupled to a thermally conductive target surface 180 disposed within an insulation assembly 190, as shown in FIGS. 2 and 7. The target surface 180 also comprises through-holes 185 for receiving fasteners. The target surface 180 may be fabricated from a thermally conductive material, such as copper or aluminum, for example. In the illustrated embodiment, the target surface 180 comprises a plurality of surface fins 182 that orthogonally extend from the target surface 180. The surface fins 182 are arranged to be spaced between rows (or columns) of jet orifices 125, as shown in FIG. 7. The surface fins 182 increase the surface area in contact with the coolant fluid, thereby increasing heat transfer. Further, the surface fins 182 assist in directing the coolant fluid within a impingement chamber 179 defined by the target surface 180, the jet orifice plate 120 and the tapered portion 153 of the jet plate manifold.
The insulation assembly 190 is configured to receive the target surface 180. In the illustrated embodiment, the insulation assembly 190 includes a recessed area 194 into which the target surface 180 is disposed. The illustrated insulation assembly 190 further includes a device recess 192 that is configured to accept a heat generating device 197, such as a semiconductor device (see FIG. 7). The target surface 180 is thermally coupled to the heat generating device 197. The insulation assembly 190 may further include a notch 193 that allows electrical connections to pass from the heat generating device 197 out of the cooling apparatus 100. The insulation assembly 190 may also include through-holes or blind bores for receiving fasteners to maintain the various components in an assembled state.
The insulation assembly 190 may be fabricated from any non-electrically conductive material capable of withstanding the high operating temperatures of the heat generating device 197. Exemplary materials include, but are not limited to, solidified polymers (e.g., polyether ether ketone (“PEEK”)), ceramic materials (e.g., aluminum nitride), and the like.
Referring specifically now to FIG. 7, a cross-sectional, partially transparent view of an assembled cooling apparatus 100 is schematically depicted. A heat generating device 197 is positioned in a device recess 192 of the insulation assembly 190. The target surface 180 is positioned within the recessed area 194. A second surface 173 of the vapor manifold 170 is coupled to the insulation assembly 190 and the target surface 180.
The jet plate manifold 150 is coupled to the first surface 171 of the vapor manifold 170. In some embodiments, a vapor manifold gasket 160 is positioned between the jet plate manifold 150 and the vapor manifold 170 to prevent coolant fluid from leaking between the two components. The jet plate manifold 150 is arranged with respect to the vapor manifold 170 such that the tapered portion 153 is disposed within the vapor manifold opening 172. The tapered portion 153 of the jet plate manifold 150 is offset with respect to the tapered walls 177 of the vapor manifold 170 such that the tapered portion 153 and the tapered walls 177 define a plurality of sloped vapor outlet channels 176. The sloped vapor outlet channels 176 slope outwardly away from an impingement region (i.e., a region at the surface fins 182) and upwardly toward the fluid inlet 102 (i.e., opposing gravity). The sloped vapor outlet channels 176 are aligned with, and fluidly coupled to, the slot channels 157. As described above, the sloped vapor outlet channels 176 take advantage of the buoyancy of the vapor bubbles to guide them away from the impingement region.
The jet orifice plate 120 is positioned within the jet plate manifold channel 161 such that the jet orifice surface 126 contacts, or nearly contacts, the surface fins 182 of the target surface 180. It is noted that, in some embodiments, the target surface 180 does not include surface fins 182. Additionally, the surface fins 182 may have a geometric configuration that is different from that depicted in FIGS. 2 and 7. In the illustrated embodiment, the rows of jet orifices 125 are aligned with respect to the surface fins 182 such that the impingement jets exiting the jet orifices 125 are between adjacent surface fins 182.
The narrow portion 124 of the jet orifice plate 120, the tapered portion 153 of the jet plate manifold 150, and the target surface 180 define an impingement chamber 179 into which the coolant fluid flows after impinging the target surface 180, as described in more detail below.
The inlet-outlet manifold 110 is coupled to the jet plate manifold 150. In some embodiments, a jet plate manifold gasket 140 is positioned between the inlet-outlet manifold 110 and the jet plate manifold 150 to prevent coolant fluid from escaping the cooling apparatus 100. The slot-shaped outlet openings 117 of the inlet-outlet manifold are aligned with the slot channels 157 of the jet plate manifold 150, thereby fluidly coupling the outlet manifold channels 114a-114d of the inlet-outlet manifold 110 to the slot channels 157.
The outlet manifold channels 114a-114d are fluidly coupled to the fluid outlet 104. In the illustrated embodiment, the outlet manifold channel 114c that is closest to the fluid outlet 104 has the largest height, and the outlet manifold channel 114a opposite from the fluid outlet 104 has the smallest height. Each of the outlet manifold channels 114a-114d slope upwardly toward the fluid outlet 104. It is noted that outlet manifold channel 114d is not visible in FIG. 7, and that outlet manifold channel 114d is symmetrically similar to outlet manifold channel 114b. The outlet manifold channels 114a-114d surround the inlet manifold channel 103 near the perimeter of the inlet-outlet manifold 110.
Referring now FIGS. 7 and 8, coolant fluid flow through the cooling apparatus 100 will now be described. FIG. 8 schematically depicts a cross section of the fluid domain 200 of coolant fluid (in the form of liquid and vapor) flowing through the cooling apparatus 100. Coolant fluid enters the fluid inlet 102 and the inlet manifold channel 103 as indicated by arrow 133a, and fluid region 202 of FIG. 8. The coolant fluid may originate from a coolant fluid reservoir. The coolant fluid flows from the inlet-outlet manifold 110 into the jet channel 123, as indicated by arrows 133b and 133c, as well as fluid region 223 of FIG. 8. The coolant fluid then flows through the jet orifices 125 as an impingement jet between adjacent surface fins 182 (represented generically by fluid region 272). The coolant fluid flows between and around the surface fins 182 toward a perimeter of the impingement chamber 179 as indicated by arrows 133d (fluid region 274 of FIG. 8). Due to the high operating temperature of the heat generating device 197, some of the coolant fluid changes from a liquid to a vapor. Accordingly, vapor bubbles form within the impingement chamber. Body forces and buoyant forces direct the coolant fluid (both liquid and vapor bubbles) into the sloped vapor outlet channels 176 as indicated by arrows 133e and 133f (fluid region 276 of FIG. 8). It is noted that coolant fluid flows through all four sloped vapor outlet channels 176, and that only two arrows (arrows 133e, 1330 are depicted for ease of illustration. The sloped vapor outlet channels 176 take advantage of the buoyancy of the vapor bubbles to guide them away from the surface fins 182 and the impingement region.
The coolant fluid then flows from the sloped vapor outlet channels 176 into the slot channels 157 of the jet plate manifold 150 as indicated by arrows 133g and 133f, wherein it flows upward and into the outlet manifold channels 114a-114d of the inlet-outlet manifold 110. Referring to FIG. 8, the coolant fluid flowing within the slot channels 157 and the outlet channels 114a-114d are combined into individual flow regions 290a-290c for ease of illustration. It is noted that a fourth fluid region 290d is not depicted in FIG. 8, and is symmetrically similar to fluid region 290b. 
A top portion of each of the fluid regions 290a-290d slope upwardly toward the fluid outlet. Fluid region 290a is the shortest of the four fluid regions 290a-290d, and slopes upwardly toward fluid region 290b and 290d (not shown). Fluid region 290c is the tallest of the four fluid regions 290a-290d and is closest to the fluid outlet, which is indicated by fluid region 204 in FIG. 8. A bridge channel indicated by bridge fluid region 292 fluidly couples fluid region 290a to fluid region 292b. In other words, outlet manifold channels 114a and 114b are fluidly coupled by an internal bridge channel 118a (FIG. 7). Similarly, outlet manifold channels 114a and 114d are fluidly coupled by a bridge channel (not shown) that is symmetrically similar to internal bridge channel 118a. Coolant fluid flowing through internal bridge channel 118a is indicated by arrow 133h in FIG. 7.
Coolant fluid flowing up within outlet manifold channels 114b and 114d through slot channels 157, as well as coolant fluid entering from outlet manifold channel 114a, flows upwardly toward outlet manifold channel 114c as indicated by arrow 133i. Accordingly, FIG. 8 depicts the fluid region 290b that slopes upwardly toward fluid region 290c. Outlet manifold channel 114b is fluidly coupled to outlet manifold channel 114c by an internal bridge channel 118b. Thus, coolant fluid flows from outlet manifold channel 114b into outlet manifold channel 114c through the internal bridge channel 118b as indicated by arrow 133j. FIG. 8 depicts a bridge fluid region 294 that fluidly couples fluid region 290b to fluid region 290c. It is noted that outlet manifold channel 114d (not shown) is also fluidly coupled to outlet manifold channel 114c by an internal bridge channel that is symmetrically similar to internal bridge channel 118b. 
Coolant fluid flowing from the slot channel 157 aligned with outlet manifold channel 114c, as well as coolant fluid entering outlet manifold channel from the other outlet manifold channels 114b-114d, flow upwardly toward the fluid outlet 104 as indicated by 133k. The coolant fluid then exits the cooling apparatus through the fluid outlet 104. Coolant fluid within the fluid outlet 104 is depicted as fluid region 204 in the fluid domain 200 of FIG. 8.
It should now be understood that embodiments described herein are configured as cooling apparatuses that cool a heat generating device by jet-impingement and two-phase heat transfer with reduced pressure build-up by employing sloped vapor outlet channels that guide vapor bubbles away from an impingement region by taking advantage of the buoyant forces of the vapor bubbles. The sloped vapor outlet channels resolve the inherent pressure build-up associated with the incomplete evacuation of vapor from the cooling apparatus, which causes an increase in the saturation temperature of the coolant fluid and diminishes the effectiveness of heat transfer.
While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications may be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.

## Claims

1. A cooling apparatus comprising:
a fluid inlet channel;
a jet orifice surface comprising one or more jet orifices fluidly coupled to the fluid inlet channel such that coolant fluid within the fluid inlet channel flows through the one or more jet orifices as one or more impingement jets;
a target surface, wherein the target surface and the jet orifice surface define an impingement chamber, the one or more impingement jets impinge the target surface at an impingement region, and at least some of the coolant fluid changes to a vapor; and
a plurality of sloped vapor outlet channels fluidly coupled to the impingement chamber, wherein each sloped vapor outlet channel slopes in a direction that is both away from the jet orifice surface and opposite from a direction of the one or more impingement jets, and the coolant fluid in the form of one or more of vapor flows and fluid flows through the plurality of sloped vapor outlet channels after impinging the target surface.

2. The cooling apparatus of claim 1, further comprising a plurality of vertical vapor outlet channels extending from the plurality of sloped vapor outlet channels.

3. The cooling apparatus of claim 1, further comprising an insulation assembly and a semiconductor device coupled to the insulation assembly and the target surface.

4. The cooling apparatus of claim 1, further comprising:
a fluid inlet fluidly coupled to the fluid inlet channel; and
a fluid outlet fluidly coupled to the plurality of sloped vapor outlet channels.

5. A cooling apparatus comprising
a jet plate manifold comprising a tapered portion and a jet plate manifold channel, wherein the jet plate manifold is configured to receive a coolant fluid;
a jet orifice surface within the tapered portion of the jet plate manifold, the jet orifice surface comprising one or more jet orifices, wherein the coolant fluid flows through the one or more jet orifices as one or more impingement jets;
a vapor manifold comprising a plurality of tapered walls defining an opening, wherein:
the tapered portion of the jet plate manifold is disposed within the opening of the vapor manifold such that a plurality of sloped vapor outlet channels is located between the plurality of tapered walls of the vapor manifold and the tapered portion of the jet plate manifold; and
each sloped vapor outlet channel of the plurality of sloped vapor outlet channels slopes in a direction that is both away from the jet orifice surface and opposite from a direction of the one or more impingement jets; and

a target surface, wherein the one or more impingement jets impinge the target surface, at least some of the coolant fluid changes to a vapor, and the vapor and coolant fluid flows through the plurality of sloped vapor outlet channels to exit the cooling apparatus.

6. The cooling apparatus of claim 5, wherein the plurality of tapered walls is substantially parallel to the tapered portion of the jet plate manifold.

7. The cooling apparatus of claim 5, wherein:
the cooling apparatus further comprises a jet orifice plate comprising:
a flange portion; and
an opening on a surface of the flange portion, wherein the jet orifice surface is provided on the jet orifice plate opposite from the flange portion such that a jet channel is located between the opening and the jet orifice surface; and

the jet plate manifold comprises a seat within the jet plate manifold channel, and the jet orifice plate is disposed within the jet plate manifold channel such that the flange portion is positioned on the seat.

8. The cooling apparatus of claim 5, wherein:
the tapered portion of the jet plate manifold extends from an upper portion having a plurality of walls;
a plurality of slot channels are disposed within the plurality of walls of the upper portion; and
the plurality of slot channels are fluidly coupled to the plurality of sloped vapor outlet channels.

9. The cooling apparatus of claim 8, further comprising an inlet-outlet manifold coupled to the jet plate manifold, the inlet-outlet manifold comprising:
a fluid inlet;
an inlet manifold channel fluidly coupled to the fluid inlet and the jet plate manifold channel;
a plurality of outlet manifold channels fluidly coupled to the plurality of slot channels of the jet plate manifold; and
a fluid outlet fluidly coupled to the plurality of outlet manifold channels.

10. The cooling apparatus of claim 9, wherein coolant fluid flows upwardly and outwardly through the plurality of sloped vapor outlet channels into the plurality of slot channels disposed within the plurality of walls of the upper portion of the jet plate manifold, and flows into the plurality of outlet manifold channels of the inlet-outlet manifold before exiting the cooling apparatus through the fluid outlet.

11. The cooling apparatus of claim 9, wherein:
the plurality of outlet manifold channels is defined by a first outlet manifold channel, a second outlet manifold channel, a third outlet manifold channel, and a fourth outlet manifold channel, wherein the first through fourth outlet manifold channels are fluidly coupled;
the fluid outlet is positioned above the first outlet manifold channel, and the fourth outlet manifold channel is opposite from the first outlet manifold channel;
the fourth outlet manifold channel has a height that is shorter than the first outlet manifold channel; and
the second outlet manifold channel and the third outlet manifold channel slope upwardly toward the first outlet manifold channel and the fluid outlet.

12. The cooling apparatus of claim 9, wherein the plurality of outlet manifold channels is disposed around the inlet manifold channel.

13. The cooling apparatus of claim 5, wherein the target surface comprises a plurality of surface fins at an impingement region where the one or more impingement jets impinge the target surface.

14. The cooling apparatus of claim 5, further comprising an insulation assembly and a semiconductor device coupled to the insulation assembly and the target surface.

15. A cooling apparatus comprising
an inlet-outlet manifold, the inlet-outlet manifold comprising:
a fluid inlet configured to receive a coolant fluid;
an inlet manifold channel fluidly coupled to the fluid inlet;
a plurality of outlet manifold channels; and
a fluid outlet fluidly coupled to the plurality of outlet manifold channels;

a jet plate manifold coupled to the inlet-outlet manifold, the jet plate manifold comprising:
an upper portion comprising a plurality of walls;
a plurality of slot channels within the plurality of walls, wherein the plurality of slot channels are fluidly coupled to the plurality of outlet manifold channels;
a tapered portion extending from the upper portion;
a jet plate manifold channel extending through the upper portion and the tapered portion wherein the jet plate manifold channel is fluidly coupled to the inlet manifold channel; and
a seat within the jet plate manifold channel;

a jet orifice plate disposed within the jet plate manifold channel, the jet orifice plate comprising:
a flange portion, wherein the jet orifice plate is disposed within the jet plate manifold channel such that the flange portion is positioned on the seat; and
a jet orifice surface opposite from the flange portion, wherein the jet orifice surface comprises one or more jet orifices; and
a jet channel, wherein the jet channel is fluidly coupled to the inlet manifold channel, and the coolant fluid flows through the one or more jet orifices as one or more impingement jets;

a vapor manifold comprising a plurality of tapered walls defining an opening, wherein:
the tapered portion of the jet plate manifold is disposed within the opening of the vapor manifold such that a plurality of sloped vapor outlet channels is located between the plurality of tapered walls of the vapor manifold and the tapered portion of the jet plate manifold; and
each sloped vapor outlet channel of the plurality of sloped vapor outlet channels slopes in a direction that is both away from the jet orifice plate and opposite from a direction of the one or more impingement jets; and

a target surface, wherein the one or more impingement jets impinge the target surface, at least some of the coolant fluid changes to a vapor, and the vapor and coolant fluid flows through the plurality of sloped vapor outlet channels to exit the cooling apparatus.

16. The cooling apparatus of claim 15, wherein coolant fluid flows upwardly and outwardly through the plurality of sloped vapor outlet channels into the plurality of slot channels disposed within the plurality of walls of the upper portion of the jet plate manifold, and then flows into the plurality of outlet manifold channels of the inlet-outlet manifold before exiting the cooling apparatus through the fluid outlet.

17. The cooling apparatus of claim 16, wherein:
the plurality of outlet manifold channels is defined by a first outlet manifold channel, a second outlet manifold channel, a third outlet manifold channel, and a fourth outlet manifold channel, wherein the first through fourth outlet manifold channels are fluidly coupled;
the fluid outlet is positioned above the first outlet manifold channel, and the fourth outlet manifold channel is opposite from the first outlet manifold channel;
the fourth outlet manifold channel has a height that is shorter than the first outlet manifold channel; and
the second outlet manifold channel and the third outlet manifold channel slope upwardly toward the first outlet manifold channel and the fluid outlet.

18. The cooling apparatus of claim 16, wherein the plurality of outlet manifold channels is disposed around the inlet manifold channel.

19. The cooling apparatus of claim 15, wherein the target surface comprises a plurality of surface fins at an impingement region where the one or more impingement jets impinge the target surface.

20. The cooling apparatus of claim 15, further comprising an insulation assembly and a semiconductor device coupled to the insulation assembly and the target surface.