Significant heat fluxes are produced in a wide variety of engineering applications, and there is demand for advanced and efficient heat dissipation systems capable of extracting and dissipating these heat fluxes in order to keep temperatures within acceptable operating ranges.
There is, however, a significant gap between the heat-transfer performance desired by industry and the heat-transfer performance readily available with current systems. Many current methods used in industry are single-phase systems that rely on conduction to transfer heat, such as single-phase liquid cooling.
Overview
Phase change heat transfer devices have potential for efficient thermal management of high heat flux operations. Because such devices can take advantage of the latent heat of evaporation of the working fluid, the potential for heat removal is high. Additionally, phase change heat-transfer can lead to more efficient energy recovery. This is because the liquid and vapor portions of the working fluid may be kept near the saturation temperature. This is because in phase change cooling systems heat transfer occurs over nearly zero temperature gradient. The process of heat transfer in a two-phase heat transfer device is essentially an isothermal one, with no sensible drop in temperature from the heat source to the point of recovery at the heat sink. Thus, the quality of heat acting as input to the energy recovery unit will be higher than it would be for non-phase conductors and more work may be recovered.
Despite these benefits, the vast potential of phase change heat transfer devices has not been realized. Other approaches for such systems mostly rely on pool boiling or porous media evaporation. Both methods are limited by the spatial and temporal randomness of boiling. Boiling is highly unordered, and the developed bubbles of vapor provide tremendous resistance to the flow of working fluid and the heat carried by it or stored in it. Bubbles also create dry areas on the heated surface while the bubble is growing and such dry areas are intermittently inactive, in transferring heat, thus decreasing efficiency.
Another common problem recognized by the inventors is dry-out of the evaporator and overheating damage. In certain approaches to phase change devices, because of high resistance to the flow of liquid, it can be difficult to deliver enough liquid to the evaporation sites to replenish the evaporated mass. When this resistance becomes too great and the amount of liquid provided to the evaporation sites cannot replenish the evaporated mass, dry-out and associated overheating damage will ensue. Design parameters that seek to reduce the occurrence of unordered and disruptive boiling, such as widening of the elongated members of the channels, can reduce the available flow area (i.e., constrict it) and increase resistance to flow of the working fluid. The increased friction can make it difficult to provide enough liquid working fluid to the evaporator to replenish the evaporated mass.
Another problem recognized by the present inventors is the lack of a complete method for estimating the performance of thin-films in general and thin-film evaporators in particular. Certain approaches are limited to solutions for only discrete combinations or channel width and superheat and produce results that are inaccurate by at least a factor of two. (See e.g. H. Wang, S. V. Garimella, and J. Y. Murthy. Characteristics of an evaporating thin film in a microchannel. International Journal of Heat and Mass Transfer, 50(19-20):3933-3942, 2007. H. Wang, S. V. Garimella, and J. Y. Murthy and An analytical solution for the total heat transfer in the thin-film region of an evaporating meniscus. International Journal of Heat and Mass Transfer, 51(25-26):6317-6322, 2008; of which are hereby incorporated by reference herein in their entirety, but are not admitted to be prior art with respect to the present invention by inclusion herein.) Therefore, the present inventors have recognized that there is a need for a more complete method for estimating the performance of a thin-film in general and thin-film evaporators in particular.
An aspect of an embodiment of the present invention provides for, but is not limited thereto, the design of a two-phase heat transfer device that provides enhanced evaporation and cooling capacity. The solution may utilize various conducting materials, working fluids, wetting coatings or substrates, and non-wetting coatings or substrates. The solution may involve repelling of working fluid away from spaces between elongated members of an evaporator to reduce or eliminate bubbling. The solution may involve formation of thin film of working fluid around distal regions of the elongated members such as to facilitate controlled and optimized evaporation. The solution may include a reservoir of working fluid, such as at or adjacent to the far end of the elongated members, such as to reduce pressure drop for liquid flow and to inhibit or prevent drying of the evaporator. The solution may include various patterns of the elongated members to improve vapor flow. The device could be used in high heat flux applications, such as a computer chip, semiconductor device, integrated circuit device, a skin of a hypersonic flying object, a parabolic solar collector, high performance computing system, radio frequency (RF) system, photovoltaic or concentrated photovoltaic operation, hypersonic avionic application, turbine blade, or any other surface or volumetric heat dissipation device or system. It should be appreciated that various embodiments of the present invention device may be applied to and/or be utilized with a wide range of applications as desired, needed or required.
An aspect of an embodiment of the present invention provides a two-phase heat transfer device. The device may comprise: a reservoir configured for containing a working fluid; a base member having a first face and a second face, wherein the first face and the second face are generally opposite each other; the first face of the base member is configured to be in communication with and adjacent to a heat source; elongated members extend distally away from the second face of the base member configured to form passages between the elongated members; the elongated members include a proximal region and a distal region, wherein the distal region is configured to be at least partially inserted into the working fluid; and the passages are configured to accommodate vapor that may be produced from the working fluid so as to define a vapor space. The elongated members may be a protrusion, a wall, a panel, a pin, a post, or a rod; as well as any combination thereof. The base member and the elongated members may be comprised of thermally-conducting non-porous solid such as silicon, diamond, copper, silicon carbide, graphite, silver, gold, platinum, copper or silicon oxide—as well as other materials as desired, needed or required. It should be appreciated that the base member and the elongated members—particularly the distal regions may be comprised of at least in part porous material—although conductivity may be reduced as a result. The working fluid may comprise water, oils, metals, octane, hydrocarbons, Penatane, R-245ca, R-245fa, Iso-Pentane, halogenated hydrocarbons, halogenated alkanes, ketones, alcohols, or alkali metals—as well as other materials as desired, needed or required.
The device may comprise any combination of a wetting coating, a wetting substrate, a non-wetting coating, or a non-wetting substrate to attract working fluid to certain areas of the device and repel working fluid from certain areas of the device. For example, the device may comprise a wetting coating such as hydrophilic coating or lyophilic coating disposed on the distal region of the elongated members to attract working fluid. Alternatively, the distal region of the elongated members may be comprised of a wetting substrate (i.e., material) such as hydrophilic substrate or lyophilic substrate. In another example, the device may comprise a non-wetting coating such as hydrophobic coating or lyophobic coating disposed on the proximal region of the elongated members and the second face of the base member located between the elongated members to repel the liquid working fluid. Alternatively, the proximal region of the elongated members and the second face of the base member located between the elongated members may be comprised of a non-wetting substrate such as hydrophobic substrate (i.e., material) or lyophobic substrate.
The device may comprise the vapor space, defined by the passages, which widen in the direction of vapor flow. For example, the passages may extend radially from a central region, wherein the pathway is radial from the central region. In another example, widening vapor space is formed by reducing the number of the elongated members (e.g., per unit length/area) in the direction of vapor flow. Alternatively, the passage may have a width that is uniform or narrows. Alternatively, the passage may have a width that may provide a combination of widening and narrowing, as well as remaining uniform.
An aspect of an embodiment of the present invention provides a method of making a two-phase heat transfer device. The method may comprise providing a reservoir configured for containing a working fluid; providing a base member configured to be in communication with and adjacent to a heat source; providing elongated members extending distally away from said base member configured to form passages between said elongated members, said elongated members include a proximal region and a distal region; and configuring said distal region of said elongated members to be able to at least partially be inserted or immersed into the working fluid. It should appreciated that for purpose of manufacturing the device that if may be made without providing the actual fluid in the reservoir but rather provided at a later time.
An aspect of an embodiment of present invention provides, but not limited thereto, a two phase heat transfer device. The device may comprise: a reservoir configured for carrying a working fluid; a base member having a first face and a second face, wherein the first face and the second face are generally away from each other, the first face of the base member configured to receive thermal energy from a heat source; elongated members extending distally away from the second face of the base member and configured to define respective passages between adjacent elongated members; the elongated members include a proximal region and a distal region, wherein the distal region is configured to be at least partially inserted into the working fluid; and the passages are configured to accommodate vapor produced from the working fluid so as to define a vapor space.
An aspect of an embodiment of present invention provides, but not limited thereto, a two phase heat transfer device. The device may comprise: a reservoir configured for carrying a working fluid; a base member, the base member configured to receive thermal energy from a heat source; elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members; the elongated members include a proximal region and a distal region, wherein the distal region is configured to be at least partially inserted into the working fluid; and the passages are configured to accommodate vapor produced from the working fluid so as to define a vapor space.
An aspect of an embodiment of present invention provides, but not limited thereto, a two phase heat transfer device. The device may comprise: a reservoir configured for carrying a working fluid; a base member, the base member configured to receive thermal energy from a heat source; elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members; and the elongated members include a proximal region and a distal region, wherein the distal region is configured to be at least partially inserted into the reservoir.
An aspect of an embodiment of present invention provides, but not limited thereto, a two phase heat transfer device. The device may comprise: reservoir configured for carrying a working fluid; a base member, the base member configured to receive thermal energy from a heat source; elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members; and at least some of the elongated members are configured to be at least partially inserted into the reservoir.
An aspect of an embodiment of present invention provides, but not limited thereto, a method of making a two phase heat transfer device. The method may comprise: providing a reservoir configured for carrying a working fluid; providing a base member configured to receive thermal energy from a heat source; providing elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members, the elongated members include a proximal region and a distal region; and configuring the distal region of the elongated members to be able to at least partially be inserted into the working fluid.
An aspect of an embodiment of present invention provides, but not limited thereto, an apparatus that may comprise: a reservoir configured for carrying a working fluid; an integrated circuit (IC) die. The IC die may comprise a heat source and a two phase heat transfer device. And wherein the two phase heat transfer device may comprise: a base member, the base member configured to receive thermal energy from the heat source; elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members; at least some the elongated members configured to be at least partially inserted into the working fluid; and the passages are configured to accommodate vapor produced from the working fluid so as to define a vapor space.
An aspect of an embodiment of present invention provides, but not limited thereto, an apparatus that may comprise: a first reservoir configured for carrying a working fluid; a first integrated circuit (IC) die, the IC die comprises a heat source and a two phase heat transfer device. And wherein the two phase heat transfer device of the first IC die comprises: a base member, the base member configured to receive thermal energy from the heat source; elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members; at least some the elongated members configured to be at least partially inserted into the working fluid; and the passages are configured to accommodate vapor produced from the working fluid so as to define a vapor space. The apparatus further comprises: a second reservoir configured for carrying a working fluid; a second integrated circuit (IC) die, the IC die comprises a heat source and a two phase heat transfer device. And wherein the two phase heat transfer device of the second IC die may comprise: a base member, the base member configured to receive thermal energy from the heat source; elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members; at least some the elongated members configured to be at least partially inserted into the working fluid; and the passages are configured to accommodate vapor produced from the working fluid so as to define a vapor space. Moreover, the first IC die and the second IC operatively coupled together.
An aspect of an embodiment of present invention provides, but not limited thereto, an apparatus that may comprise: a reservoir configured for carrying a working fluid; an integrated circuit (IC) die, the IC die comprises a heat source; a two phase heat transfer device thermally connected to the IC die. And wherein the two phase heat transfer device may comprise: a base member, the base member configured to receive thermal energy from the heat source; elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members; at least some the elongated members configured to be at least partially inserted into the working fluid; and the passages are configured to accommodate vapor produced from the working fluid so as to define a vapor space.
An aspect of an embodiment of present invention provides, but not limited thereto, a computer implemented method for estimating the performance characteristics of a thin-film heat transfer device. The method may comprise: receiving characteristic of the heat transfer device; determining a thickness of a non-evaporating portion of a meniscus formed by a liquid on a surface of channels of the heat transfer device; determining a value for a thickness profile matching parameter; performing a first algorithm to determine a thickness profile of an evaporating portion of the meniscus formed by the liquid on the surface, the first algorithm based on the thickness profile matching parameter and an assumption that the non-evaporating portion of the meniscus has a curved profile; determining that the thickness profile of the evaporating portion is within a threshold range; performing a second algorithm to determine performance characteristics of the heat transfer device; and providing the performance characteristics of the heat transfer device to an output device.
An aspect of an embodiment of present invention provides, but not limited thereto, a computer implemented method for estimating the performance characteristics of a thin-film heat transfer device. The method may comprise: receiving characteristics of the heat transfer device; determining a thickness of a non-evaporating portion of a meniscus formed by a liquid on a surface of channels of the heat transfer device; determining a value for a thickness profile matching parameter; performing a first algorithm to determine a thickness profile of an evaporating portion of the meniscus formed by the liquid on the surface, the first algorithm based on the thickness profile matching parameter an assumption that the non-evaporating portion of the meniscus has a curved profile; determining that the first thickness profile of the evaporating portion is not within a threshold range; choosing a second value for the thickness profile matching parameter; performing the first algorithm to determine a second thickness profile of an evaporating portion of the meniscus based on the second value for the thickness profile matching parameter; determining that the second thickness profile of the evaporating portion is within the threshold range; performing a second algorithm to determine performance characteristics of the heat transfer device; and providing the performance characteristics of the heat transfer device to an output device.
An aspect of an embodiment of present invention provides, but not limited thereto, a non-transitory computer readable medium including instructions executable by a processor for estimating the performance characteristics of a thin-film heat transfer device. The instructions may comprise: receiving characteristics of heat transfer device; determining a thickness of a non-evaporating portion of a meniscus formed by a liquid on a surface of channels of the heat transfer device; determining a value for a thickness profile matching parameter; performing a first algorithm to determine a thickness profile of an evaporating portion of the meniscus formed by the liquid on the surface, the first algorithm based on the thickness profile matching parameter and an assumption that the non-evaporating portion of the meniscus has a curved profile; determining that the thickness profile of the evaporating portion is within a threshold range; performing a second algorithm to determine performance characteristics of the heat transfer device; and providing the performance characteristics of the heat transfer device to an output device.
An aspect of an embodiment of present invention provides, but not limited thereto, an apparatus that may comprise: one or more processors; and a memory containing instructions that, when executed by the one or more processors, cause the one or more processors to perform a set of steps. The set of steps may comprise: receiving characteristics of a heat transfer device; determining a thickness of a non-evaporating portion of a meniscus formed by a liquid on a surface of channels of the heat transfer device; determining a value for a thickness profile matching parameter; performing a first algorithm to determine a thickness profile of an evaporating portion of the meniscus formed by the liquid on the surface, the first algorithm based on the thickness profile matching parameter and an assumption that the non-evaporating portion of the meniscus has a curved profile; determining that the thickness profile of the evaporating portion is within a threshold range; performing a second algorithm to determine performance characteristics of the heat transfer device; and providing the performance characteristics of the heat transfer device to an output device.
An aspect of an embodiment of present invention provides, but not limited thereto, a. A computer implemented method for determining the performance characteristics of a heat transfer device. The method may comprise: receiving the heat transfer device characteristics; receiving the heat source characteristics; receiving any ancillary characteristics; determining the performance characteristics of the heat transfer device; determining whether the determined performance characteristics of the heat transfer device are acceptable. And wherein if the performance characteristics of the heat transfer device: are acceptable, then providing such performance characteristics of the heat transfer device; or are not acceptable, then revising the heat transfer device characteristics or provide additional data, and then providing such performance characteristics of the heat transfer device.
An aspect of an embodiment of present invention provides, but not limited thereto, a computer implemented method for determining the heat transfer device characteristics. The method may comprise: receiving the heat transfer device performance characteristics; receiving the heat source characteristics; receiving any ancillary characteristics; determining the heat transfer device characteristics; determining whether the determined heat transfer device characteristics are acceptable. And wherein if the determined heat transfer device characteristics of the heat transfer device: are acceptable, then providing such heat transfer device characteristics; or are not acceptable, then revising the performance characteristics of the heat transfer device or provide additional data, and then providing such heat transfer device characteristics.
An aspect of an embodiment of present invention provides, but not limited thereto, a two phase heat transfer device. The device may comprise: a reservoir configured for carrying a working fluid; a base member, the base member configured to receive thermal energy from a heat source; elongated members having at least one wall, the elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members; wherein the elongated members include a proximal region and a distal region, wherein the distal region is configured to be at least partially inserted into the working fluid; a recess topography disposed on the at least one wall of the elongated members, wherein the recess topography is configured to accommodate the working fluid; and the passages are configured to accommodate vapor produced from the working fluid so as to define a vapor space.
An aspect of an embodiment of present invention provides, but not limited thereto, a method of making a two phase heat transfer device (or portions thereof). The method may comprise: providing a reservoir configured for carrying a working fluid; providing a base member configured to receive thermal energy from a heat source; providing elongated members having at least one wall, the elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members, wherein the elongated members include a proximal region and a distal region; configuring the distal region of the elongated members to be able to at least partially be inserted into the working fluid; and providing a recess topography disposed on the at least one wall of the elongated members, wherein the recess topography is configured to accommodate the working fluid.
An aspect of an embodiment of present invention provides, but not limited thereto, an apparatus that may comprise: a reservoir configured for carrying a working fluid; an integrated circuit (IC) die, wherein the IC die comprises a heat source and a two phase heat transfer device. The two phase heat transfer device may comprise: a base member, the base member configured to receive thermal energy from the heat source; elongated members having at least one wall, the elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members; wherein at least some the elongated members configured to be at least partially inserted into the working fluid; a recess topography disposed on the at least one wall of the elongated members, wherein the recess topography is configured to accommodate the working fluid; and the passages are configured to accommodate vapor produced from the working fluid so as to define a vapor space.
An aspect of an embodiment of present invention provides, but not limited thereto, an apparatus that may comprise: a first reservoir configured for carrying a working fluid; a first integrated circuit (IC) die, wherein the IC die comprises a heat source and a two phase heat transfer device; wherein the two phase heat transfer device of the first IC die comprises: a base member, the base member configured to receive thermal energy from the heat source; elongated members having at least one wall, the elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members; at least some the elongated members configured to be at least partially inserted into the working fluid; a recess topography disposed on the at least one wall of the elongated members, wherein the recess topography is configured to accommodate the working fluid; and the passages are configured to accommodate vapor produced from the working fluid so as to define a vapor space. The apparatus may further comprise: a second reservoir configured for carrying a working fluid; a second integrated circuit (IC) die, wherein the second IC die comprises a heat source and a two phase heat transfer device; wherein the two phase heat transfer device of the second IC die comprises: a base member, the base member configured to receive thermal energy from the heat source; elongated members having at least one wall, the elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members; at least some the elongated members configured to be at least partially inserted into the working fluid; a recess topography disposed on the at least one wall of the elongated members, wherein the recess topography is configured to accommodate the working fluid; and the passages are configured to accommodate vapor produced from the working fluid so as to define a vapor space; and the first IC die and the second IC operatively coupled together.
An aspect of an embodiment of present invention provides, but not limited thereto, an apparatus that may comprise: a reservoir configured for carrying a working fluid; an integrated circuit (IC) die, wherein the IC die comprises a heat source; a two phase heat transfer device thermally connected to the IC die. And the two phase heat transfer device may comprise: a base member, wherein the base member configured to receive thermal energy from the heat source; elongated members having at least one wall, the elongated members extending distally away from the base member and configured to define respective passages between adjacent elongated members; at least some the elongated members configured to be at least partially inserted into the working fluid; a recess topography disposed on the at least one wall of the elongated members, wherein the recess topography is configured to accommodate the working fluid; and the passages are configured to accommodate vapor produced from the working fluid so as to define a vapor space.
A device and related method that provides, but is not limited thereto, a two-phase heat transfer device with unique combination of enhanced evaporation and increased cooling capacity. An advantage associated with the device and method includes, but is not limited thereto, increased cooling capacity per unit area, controlled and optimized evaporation, prevention of boiling, and prevention of drying of the evaporator. An aspect associated with an approach may include, but is not limited thereto, using a recess topology to increase suction of working fluid in the direction toward the heat source. An aspect associated with an approach may include, but is not limited thereto, using a non-wetting coating or structure to keep working fluid away from the spaces between elongated members of an evaporator and using a wetting coating or structure to form thin films of working fluid around the distal region of the elongated members. For example it can be used to cool a computer chip, a skin of a hypersonic flying object, parabolic solar collector, turbine or engine blade, or any other heat source that requires high heat flux.
These and other objects, along with advantages and features of various aspects of embodiments of the invention disclosed herein, will be made more apparent from the description, drawings and claims that follow.