HEAT PIPE WITH LOCALIZED HEATSINK

An apparatus includes a heat pipe, a first fin, and a second fin. The heat pipe includes a first end and a second end. The heat pipe defines a chamber through which a fluid flows. The first fin is coupled to the heat pipe at the first end. The first fin is arranged to absorb heat from the fluid at the first end such that the fluid at the first end flows back towards the second end. The second fin is coupled to the heat pipe between the first fin and the second end. The second fin is arranged to absorb heat from the fluid as the fluid flows from the second end towards the first end.

TECHNICAL FIELD

Embodiments presented in this disclosure generally relate to thermal management. More specifically, embodiments disclosed herein relate to a heat pipe with a localized heatsink.

BACKGROUND

As the power density and power of integrated circuits increases, so does the heat produced by the integrated circuits. Various techniques are used to move the heat away from the integrated circuits, so that the integrated circuits do not overheat. One technique uses heat pipes to carry heat away from the integrated circuits. The performance of the heat pipes, however, suffers in cold ambient conditions (e.g., at or below zero degrees Celsius). Specifically, the heat pipes contain a fluid that evaporates when absorbing heat produced by the integrated circuit. The pressure increase in the fluid causes the fluid to flow towards another end of the heat pipe. The cold ambient condition reduces the pressure of the fluid in the heat pipe, reducing flow. As a result, the heat pipe carries less heat away from the integrated circuit.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Overview

According to an embodiment, an apparatus includes a heat pipe, a first fin, and a second fin. The heat pipe includes a first end and a second end. The heat pipe defines a chamber through which a fluid flows. The first fin is coupled to the heat pipe at the first end. The first fin is arranged to absorb heat from the fluid at the first end such that the fluid at the first end flows back towards the second end. The second fin is coupled to the heat pipe between the first fin and the second end. The second fin is arranged to absorb heat from the fluid as the fluid flows from the second end towards the first end.

According to another embodiment, a method includes absorbing heat into a fluid at a first end of a heat pipe. The heat pipe defines a chamber through which the fluid flows. The method also includes absorbing, using a first fin coupled to the heat pipe at a second end of the heat pipe, heat from the fluid at the second end such that the fluid at the second end flows back towards the first end and absorbing, using a second fin coupled to the heat pipe between the first fin and the first end, heat from the fluid as the fluid flows from the first end towards the second end.

According to another embodiment, a system includes an integrated circuit, a heat pipe, a first fin, and a second fin. The heat pipe contains a fluid arranged to absorb heat produced by the integrated circuit at a first end of the heat pipe. The heat pipe defines a chamber through which the fluid flows from the first end to a second end of the heat pipe. The first fin is coupled to the second end. The first fin is arranged to absorb heat from the fluid at the second end. The second fin is coupled to the heat pipe between the first end and the first fin. The second fin is arranged to absorb heat from the fluid as the fluid flows from the first end towards the second end.

Example Embodiments

This disclosure describes a heat pipe with one or more auxiliary heatsinks that are positioned closer to the heat source (e.g., an integrated circuit) than a primary heatsink. For example, the heat pipe may absorb heat from a heat source at one end of the heat pipe and move that heat towards a primary heatsink at the other end of the heat pipe. The heat pipe may include one or more auxiliary heatsinks positioned between the ends of the heat pipe (e.g., an auxiliary heatsink positioned at the same end of the heat pipe as the heat source or an auxiliary heatsink positioned between the heat source and the primary heatsink). The auxiliary heatsinks absorb heat from a fluid flowing in the heat pipe, which effectively shortens the phase change path within the heat pipe. As a result, the auxiliary heatsinks increase the return of the fluid back to the heat source, which increases the amount of heat removed by the heat pipe during cold ambient conditions (e.g., at or below zero degrees Celsius), in particular embodiments.

The auxiliary heatsinks may increase the Q_max of the heat pipe during cold ambient conditions, and hence the cooling performance of the heat pipe during cold ambient conditions. Without the auxiliary heatsinks, a thermal runaway effect may occur in the heat pipe during cold ambient conditions when a power of a heat source, such as an integrated circuit, reaches 700 Watts. During the thermal runaway effect, the heat pipe removes less heat from the heat source than the heat source generates, which causes the temperature of the heat source to increase until the heat source fails. With the auxiliary heatsinks, the heat source power can reach as high as 800 Watts without thermal runaway during cold ambient conditions. In some embodiments, the maximum cooling capability of the heat pipe at −5 degrees Celsius improves from 500 Watts (without the auxiliary heatsinks) to 800 Watts (with the auxiliary heatsinks). Additionally, the thermal resistance of the heat pipe at −5 degrees Celsius and 500 Watts improves from 0.186 Celsius/Watt to 0.1 Celsius/Watt. Adjustments may be made to the profiles of the auxiliary heatsinks so that the heat source can operate at 950 Watts to 1000 Watts without thermal runaway.

FIG.1illustrates an example system100. As seen inFIG.1, the system100includes a heat transfer block102, one or more heat pipes106, and main fins108and110. Generally, the heat pipes106carry heat from the heat transfer block102to the main fins108and110. The heat is then removed from the system using the fins108and110. For example, air may be circulated on or through the main fins108and110to carry the heat away from the system100.

The heat transfer block102may be a metal block (e.g., a copper block) that absorbs heat produced by an attached circuit or device. For example, a circuit or device may be attached to the underside of the heat transfer block102such that the heat transfer block102absorbs heat produced by the circuit or device. The heat pipes106may be attached to a topside of the heat transfer block102opposite the underside of the heat transfer block102. The heat pipes106absorb the heat from the heat transfer block102. For example, the heat pipes106may contain a fluid that absorbs the heat from the heat transfer block102. The fluid may vaporize as it absorbs heat from the heat transfer block102, which increases the fluid pressure within the heat pipes106. The vapor then flows towards the main fins108and110at an opposite end of the heat pipes106. When the fluid reaches the main fins108and110, the main fins108and110absorb the heat from the fluid. The heat may then be removed from the system100using the main fins108and110. When heat is removed from the fluid, the fluid condenses and flows back towards the heat transfer block102to absorb more heat from the heat transfer block102.

During cold ambient conditions, the fluid pressure within the heat pipes106may be reduced, causing the flow of the fluid in the heat pipes106to also reduce. As a result, less fluid returns to the heat transfer block102and less heat is absorbed from the heat transfer block102. Thus, the efficiency and performance of the heat pipes106suffers during cold ambient conditions.

FIG.2illustrates an example system200. As seen inFIG.2, the system200includes the heat transfer block102, one or more heat pipes106, the main fins108and110, a circuit201, and an auxiliary fin202. Generally, the auxiliary fin202absorbs heat from a fluid204within the heat pipe106as the fluid204moves heat from the heat transfer block102towards the main fins108and110. As a result, a portion of the fluid204condenses before the fluid204reaches the main fins108and110. The condensed fluid204then flows back towards the heat transfer block102to remove additional heat from the heat transfer block102. In this manner, the phase change path within the heat pipe106is shortened, which improves the performance of the heat pipe106during cold ambient conditions, in particular embodiments.

The circuit201is attached to an underside of the heat transfer block102. The heat pipe106is attached to a top side of the heat transfer block102opposite the underside of the heat transfer block102. The circuit201may be any suitable circuit or device. For example, the circuit201may be an integrated circuit. During operation, the circuit201generates heat that should be removed from the circuit201to prevent the circuit201from overheating. The heat transfer block102is attached to the circuit201such that the heat transfer block102removes the heat generated by the circuit201. For example, the heat transfer block102may be a metal block that conducts heat generated by the circuit201away from the circuit201. The heat transfer block102moves the heat generated by the circuit201towards the one or more heat pipes106.

As discussed previously, the heat pipe106absorbs heat from the heat transfer block102and carries the heat towards the main fins108and110. Specifically, the heat pipe106may define an internal chamber203that holds a fluid204. The chamber may extend along the length of the heat pipe106from a first end206to a second end208. The fluid204is contained within the chamber203such that the fluid204may flow within the chamber203between the first end206and the second end208. As a result, the fluid204may absorb heat from the heat transfer block102near the first end206. The fluid204may vaporize as the fluid204absorbs heat from the heat transfer block102. The vapor then flows through the chamber203towards the main fins108and110at the second end208. When heat is removed from the vapor, the vapor condenses and flows back towards the heat transfer block102near the first end206to absorb more heat from the heat transfer block102.

The main fins108and110are attached to the heat pipe106near the second end208of the heat pipe106. The main fin108may be attached to a top side210of the heat pipe106, and the main fin110may be attached to a bottom side212of the heat pipe106. The top side210of the heat pipe106may be opposite the bottom side212of the heat pipe106. The main fins108and110remove heat from the fluid204that has flowed to the second end208of the heat pipe106. When the main fins108and110remove heat from the fluid near the second end208, that fluid204condenses and flows back towards the first end206of the heat pipe106to absorb additional heat from the heat transfer block102. The heat absorbed by the main fins108and110may then be removed from the system200. For example, air may be circulated on or over the main fins108and110to carry the heat absorbed by the main fins108and110away from the system200.

The auxiliary fin202is attached (e.g., by brazing or an adhesive) to the top side210of the heat pipe106between the first end206and the second end208. As seen inFIG.2, the auxiliary fin202may be attached to the heat pipe106between the first end206and the main fin108. The auxiliary fin202may be any suitable size or shape. For example, the auxiliary fin202may be shorter than, longer than, or the same length as the main fins108and110. The auxiliary fin202absorbs heat from the fluid204as the fluid204flows from the first end206towards the main fins108and110. When the auxiliary fin202absorbs heat from the fluid204, some of the fluid204condenses and flows back towards the heat transfer block102to absorb additional heat from the heat transfer block102. Some of the fluid204may continue flowing past the auxiliary fin202towards the main fins108and110. Thus, the auxiliary fin202reduces the length of the phase change path for some of the fluid204within the heat pipe106. The auxiliary fin202causes some of the fluid204to condense, which increases the flow of fluid204back towards the heat transfer block102. As a result, the auxiliary fin202improves the performance of the heat pipe106during cold ambient conditions, in particular embodiments.

In some embodiments, the auxiliary fin202absorbs additional heat from fluid204that is flowing back from the main fins108and110towards the heat transfer block102. As a result, the fluid204may absorb additional heat from the heat transfer block102when the fluid204reaches the heat transfer block102. In this manner, the auxiliary fin202further improves the performance of the heat pipe106.

FIG.3illustrates an example system300. As seen inFIG.3, the system300includes a heat transfer block102, a heat pipe106, main fins108and110, the circuit201, the auxiliary fin202, and an auxiliary fin302. In particular embodiments, the auxiliary fin302removes additional heat from the fluid204within the heat pipe106before the fluid204reaches the main fins108and110. As a result, the auxiliary fin302causes additional fluid204to condense and flow back towards the heat transfer block102to absorb heat from the heat transfer block102. Thus, the auxiliary fin302further improves the performance of the heat pipe106during cold ambient conditions, in particular embodiments.

Similar to the system200shown inFIG.2, the circuit201is attached to the underside of the heat transfer block102, and the heat pipe106is attached to the top side of the heat transfer block102. The heat transfer block102absorbs heat generated by the circuit201and moves that heat towards the heat pipe106. The fluid204within the internal chamber203of the heat pipe106absorbs the heat from the heat transfer block102, which vaporizes the fluid204. The fluid204then flows towards the main fins108and110to carry the heat towards the main fins108and110. The auxiliary fin202is attached to a top side210of the heat pipe106between the first end206and the main fin108. The auxiliary fin202removes heat from the fluid204as the fluid204flows towards the main fins108and110. When the auxiliary fin202removes heat from the fluid204, some of the fluid204condenses and flows back towards the heat transfer block102to absorb additional heat from the heat transfer block102.

The auxiliary fin302is attached (e.g., by brazing or an adhesive) to a bottom side212of the heat pipe106opposite the top side210. The auxiliary fin302may be a separate structure from the auxiliary fin202. In some embodiments, the auxiliary fin302is positioned opposing the auxiliary fin202. The auxiliary fin302is positioned between the heat transfer block102and the main fin110. The auxiliary fin302may be any suitable size or shape. For example, the auxiliary fin302may be shorter than, longer than, or the same length as the main fins108and110. The auxiliary fin302absorbs heat from the fluid204, as the fluid204flows towards the main fins108and110. When the auxiliary fin302absorbs heat from the fluid204, a portion of the fluid204condenses and flows back towards the heat transfer block102to absorb additional heat from the heat transfer block102. As a result, the auxiliary fin302shortens the phase change path within the heat pipe106and increases the flow of fluid204back towards the heat transfer block102. Thus, the auxiliary fin302improves the performance of the heat pipe106during cold ambient conditions, in certain embodiments.

In some embodiments, the auxiliary fin302absorbs additional heat from fluid204that is flowing back from the main fins108and110towards the heat transfer block102. As a result, the fluid204may absorb additional heat from the heat transfer block102when the fluid204reaches the heat transfer block102. In this manner, the auxiliary fin302further improves the performance of the heat pipe106.

FIG.4illustrates an example system400. As seen inFIG.4, the system400includes a heat transfer block102, a heat pipe106, main fins108and110, the circuit201, the auxiliary fin202, and an auxiliary fin402. Generally, the auxiliary fin402removes heat from the fluid204near the first end206of the heat pipe106(e.g., before the fluid204vaporizes). As a result, the auxiliary fin402removes heat from the fluid204so that the fluid204may absorb additional heat from the heat transfer block102, which improves the performance of the heat pipe106, in particular embodiments.

Similar to the system200shown inFIG.2and the system300shown inFIG.3, the circuit201is attached to the underside of the heat transfer block102, and the heat pipe106is attached to the top side of the heat transfer block102. The heat transfer block102absorbs heat generated by the circuit201and conducts that heat towards the heat pipe106. The fluid204within the chamber203of the heat pipe106absorbs the heat from the heat transfer block102. As the fluid204absorbs heat, the fluid204vaporizes and flows towards the main fins108and110. The auxiliary fin202is attached to the top side210of the heat pipe106between the first end206of the heat pipe106and the main fin108. The auxiliary fin202removes heat from the fluid204as the fluid204flows towards the main fins108and110. When the auxiliary fin202removes heat from the fluid204, a portion of the fluid204condenses and flows back towards the heat transfer block102to absorb additional heat from the heat transfer block102. As a result, the auxiliary fin202shortens the phase change path within the heat pipe106and increases the amount of fluid204flowing back to the heat transfer block102. The auxiliary fin202thus improves the performance of the heat pipe106during cold ambient conditions, in particular embodiments. The main fins108and110remove heat from the fluid204that reaches the main fins108and110. When the main fins108and110remove heat from the fluid204near the second end208of the heat pipe106, the fluid204condenses and flows back towards the heat transfer block102to absorb additional heat from the heat transfer block102.

The auxiliary fin402is attached (e.g., by brazing or an adhesive) to the top side210of the heat pipe106near between the first end206of the heat pipe106and the auxiliary fin202. The auxiliary fin402may be a separate structure from the auxiliary fin202. As seen inFIG.4, the auxiliary fin402is positioned near the heat transfer block102. The auxiliary fin402absorbs heat from the fluid204near the first end206of the heat pipe106. As a result, the auxiliary fin402removes heat from the fluid204near the heat transfer block102. The auxiliary fin402thus removes heat from the fluid204before the fluid204reaches the auxiliary fin202and the main fins108and110. Thus, the fluid204may absorb additional heat from the heat transfer block102before moving towards the auxiliary fin202and the main fins108and110.

In some embodiments, the auxiliary fin402removes heat from the fluid204that is flowing back towards the heat transfer block102from the auxiliary fin202or the main fins108and110. As a result, the auxiliary fin402improves the ability of the fluid204that is flowing back to the heat transfer block102to absorb additional heat from the heat transfer block102. In this manner the auxiliary fin402improves the performance of the heat pipe106during cold ambient conditions, in particular embodiments.

FIG.5illustrates an example system500. As seen inFIG.5, the system500includes a heat transfer block102, a heat pipe106, main fins108and110, the circuit201, the auxiliary fin202, the auxiliary fin302, and the auxiliary fin402. Generally, the auxiliary fins202,302and402remove heat from the fluid204flowing within the internal chamber203of the heat pipe106. As a result, the flow of the fluid204back towards the heat transfer block102increases, which improves the performance of the heat pipe106during cold ambient conditions, in particular embodiments.

The circuit201is attached to the underside of the heat transfer block102, and the heat pipe106is attached to the top side of the heat transfer block102. The heat transfer block102absorbs heat generated by the circuit201and moves that heat towards the heat pipe106. The fluid204within the heat pipe106absorbs the heat from the heat transfer block102, which may cause the fluid204to vaporize and flow towards the main fins108and110.

The auxiliary fin202is attached to the top side210of the heat pipe106between the first end206and the main fin108. The auxiliary fin302is attached to the bottom side212of the heat pipe106between the heat transfer block102and the main fin110. The auxiliary fin402is attached to the top side210of the heat pipe106between the first end206and the auxiliary fin202. The auxiliary fins202,302, and402may be separate structures. The auxiliary fin402may absorb heat from the fluid204near the heat transfer block102, which allows the fluid204to absorb additional heat from the heat transfer block102. As the fluid204flows towards the main fins108and110, the auxiliary fins202and302remove heat from the fluid204. When the auxiliary fins202and302remove heat from the fluid204, a portion of the fluid204condenses and flows back towards the heat transfer block102to absorb additional heat from the heat transfer block102. As a result, the auxiliary fins202and302shorten the phase change path in the heat pipe106, which increases the flow of the fluid204back towards the heat transfer block102. Thus, the auxiliary fins202and302improve the performance of the heat pipe106during cold ambient conditions, in particular embodiments. The main fins108and110remove heat from the fluid204that reaches the main fins108and110. When the main fins108and110remove heat from the fluid204, the fluid204condenses and flows back towards the heat transfer block102to absorb additional heat from the heat transfer block102.

The auxiliary fins202,302and402may remove additional heat from the fluid204that is flowing back towards the heat transfer block102. As a result, the auxiliary fins202,302and402further improve the fluid's204ability to absorb additional heat from the heat transfer block102. For example, the auxiliary fins202and302may absorb heat from the fluid204that is flowing from the main fins108and110back towards the heat transfer block102. As another example, the auxiliary fin402may remove additional heat from the fluid204that is flowing from the auxiliary fins202and302or the main fins108and110back towards the heat transfer block102. In this manner, the auxiliary fins202,302and402further improve the performance of the heat pipe106, in particular embodiments.

FIG.6is a flowchart of an example method600performed in the systems200,300,400, and500ofFIGS.2through5. In particular embodiments, the various components of the systems200,300,400, and500perform the steps of the method600. By performing the method600, the systems200,300,400, and500improve the performance of the heat pipe106during cold ambient conditions.

In block602, the heat transfer block102absorbs heat from the circuit201. The circuit201may be an integrated circuit that produces heat during operation. The circuit201may be attached to the underside of the heat transfer block102such that the heat transfer block102absorbs the heat produced by the circuit201. In block604, the heat transfer block102transfers the heat to the first end206of the heat pipe106. The heat transfer block102may be a metal block that conducts the heat generated by the circuit201towards the heat pipe106. The heat pipe106may be attached to the top side of the heat transfer block102. The heat pipe106may define an internal chamber203that contains a fluid204that absorbs the heat from the heat transfer block102.

In block606, the fluid204transfers the heat towards the second end208of the heat pipe106. As the fluid204absorbs heat from the heat transfer block102near the first end206of the heat pipe106, the fluid204may vaporize and increase the fluid pressure within the heat pipe106. The vapor then flows towards the second end208of the heat pipe106.

In block608, the auxiliary fin202absorbs heat from the fluid204as the fluid204flows towards the second end208. The auxiliary fin202may be attached to a top side210of the heat pipe106between the first end206of the heat pipe106and the main fin108. The main fin108may be attached to the heat pipe106near the second end208of the heat pipe106. When the auxiliary fin202absorbs heat from the fluid204, some of the fluid204condenses and flows back towards the first end206of the heat pipe106to absorb additional heat from the heat transfer block102. As a result, the auxiliary fin202shortens the phase change path within the heat pipe106, which improves the performance of the heat pipe106during cold ambient conditions, in certain embodiments.

In block610, the main fins108and110absorb heat from the fluid204at the second end208of the heat pipe106. When the main fins108and110absorb heat from the fluid204, the fluid204condenses and flows back towards the first end206of the heat pipe106to absorb additional heat from the heat transfer block102. In certain embodiments, the auxiliary fin202absorbs additional heat from the fluid204as the fluid204flows back towards the heat transfer block102, which increases the amount of additional heat that the fluid204may absorb from the heat transfer block102when the fluid204reaches the heat transfer block102. Heat absorbed by the main fins108and110may be removed from the system200,300,400, or500. For example, air may be circulated on or over the main fins108and110to carry the heat absorbed by the main fins108and110away from the systems200,300,400, or500.

In summary, a heat pipe106has one or more auxiliary heatsinks that are positioned closer to the heat source (e.g., an integrated circuit) than a primary heatsink. For example, the heat pipe106may absorb heat from a heat source at one end206of the heat pipe106and move that heat towards a primary heatsink (e.g., main fins108and110) at the other end208of the heat pipe106. The heat pipe106may include one or more auxiliary heatsinks positioned between the ends206and208of the heat pipe106(e.g., an auxiliary fin402positioned at the same end of the heat pipe as the heat source or auxiliary fins202and302positioned between the heat source and the primary heatsink). The auxiliary heatsinks absorb heat from a fluid204flowing in the heat pipe106, which effectively shortens the phase change path within the heat pipe106. As a result, the auxiliary heatsinks increase the return of the fluid204back to the heat source, which increases the amount of heat removed by the heat pipe106during cold ambient conditions, in particular embodiments.

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