PHASE CHANGE MATERIAL HEAT SINK
A phase change material heat sink includes a sealed enclosure containing a phase change material. A fluid passage element is in contact with the sealed enclosure and includes a thermal exchange layer in thermal contact with the top and that directs fluid in a first flow direction and a shunt passage element in thermal contact with at least one of the sides or the bottom and that directs fluid in a second flow direction.
Latest HAMILTON SUNDSTRAND CORPORATION Patents:
The subject matter disclosed herein relates generally to the field of heat sinks and, in particular, to phase change material heat sinks
DESCRIPTION OF RELATED ARTPhase change material (PCM) heat sinks utilize PCM's such as water, wax, or other materials with desirable melting points to store and release heat energy associated with the solid-liquid phase change. The energy associated with such a change is generally referred to as the latent heat of fusion. One type of PCM heat sink uses a heat transport fluid to carry thermal energy into and out of the heat sink. The fluid flows through a fluid passage element that bring the fluid into thermal contact with the PCM to allow heat transfer to occur while keeping the fluid isolated from the PCM.
BRIEF SUMMARYAccording to one embodiment, a phase change material heat sink includes a sealed enclosure containing a phase change material and that includes a top, a bottom and sides. The phase change material heat sink of this embodiment further includes a fluid passage element in contact with the sealed enclosure that includes a thermal exchange layer in thermal contact with the top and that directs fluid in a first flow direction and a shunt passage element in thermal contact with at least one of the sides or the bottom and that directs fluid in a second flow direction. In this embodiment, the fluid passage element is configured to direct the fluid through the shunt passage element before it is directed to the thermal exchange layer.
According to another embodiment, a phase change material heat sink includes a sealed enclosure containing a phase change material and including a top, a bottom and sides. The phase change material heat sink of this embodiment also includes a fluid passage element in contact with the sealed enclosure, the fluid passage element including a thermal exchange layer in thermal contact with the top and that directs fluid in a first flow direction and a shunt passage element passing between the top and bottom that directs fluid in a second flow direction. In this embodiment, the fluid passage element is configured to direct the fluid through the shunt passage element before it is directed to the thermal exchange layer.
According to yet another embodiment a phase change material heat sink includes a sealed enclosure containing a phase change material and including outer walls. The phase change material heat sink of this embodiment also includes a fluid passage element in contact with the outer walls, the fluid passage element including a thermal exchange layer in thermal contact with one side of the outer walls that directs fluid in a first flow direction and a shunt passage element in thermal contact with another side of the outer walls that directs fluid in a second flow direction. In this embodiment, the fluid passage element is configured to direct the fluid through the shunt passage element before it is directed to the thermal exchange layer.
Other aspects, features, and techniques of the invention will become more apparent from the following description taken in conjunction with the drawings.
Referring now to the drawings wherein like elements are numbered alike in the several FIGURES:
The PCM heat sink 100 also includes a fluid passage element 101. A heat transmission fluid enters (e.g., Freon or water, for example) an end 103 of the fluid passage element 101 via inlet passage (e.g., pipe) 102 and exits it via outlet passage 114. The fluid generally traverses the fluid passage element 102 in the direction shown by arrow A. The fluid passage element 101 illustrated in
The PCM heat sink 100 also optionally include a heat release element 111. As illustrated, the heat release element 111 includes heat diffusion fins 113 and a top 112. In some cases, the heat release element 111 can be brought into thermal contact with the sealed chamber 106 to dissipate heat stored therein. For example, in the context of a satellite, heat may be stored in the sealed chamber 106 until the satellite is not in line-of-sight with the sun. At that time, the bottom 108 of the sealed chamber 106 can be brought into contact with the top 112 of the heat release element 111 and the heat can be released via fins 113 into space.
A problematic aspect of a PCM heat sink such as that illustrated in
The prior art has proposed several different solutions to the above problem. One is to utilize a movable accumulator to account for the volume change. Another approach is to contain the pressure within a structure that can withstand the forces that develop. Yet another approach is to immobilize the PCM in a substrate, such as a fiber or foam structure. When the PCM is immobilized, the void spaces become evenly distributed within the chamber 106 so that there is no volume change on the macroscopic scale. This eliminates the high pressures that can develop within the chamber 106. However, such an approach adds complexity to the manufacturing approach and, also, limits processing that can be performed on the enclosure 106 itself.
The sealed enclosure 206 is formed at least partially of metal in one embodiment and can optionally be braised. While not illustrated, it shall be understood that the embodiments shown in
As illustrated, the sealed enclosure 206 includes a PCM 120 and is formed such that a void space 110 exists therein. In
In this embodiment, the PCM heat sink 200 also includes a fluid passage element 201. The fluid passage element 201 includes a thermal exchange layer 222 and one or more shunt passage elements 202. Generally, the thermal exchange layer 222 directs fluid from a first end 226 to a second end 228. As the fluid passes through the fluid passage element 201, a bottom side 229 thereof allows heat to be transferred between the fluid and the top 207 of the sealed enclosure 206 to transfer heat to/from the liquid from/to the PCM 120.
In contrast to the prior art, the fluid passage element 201 causes fluid to be directed in a first direction (arrow A) and a second direction (shown by arrow B) that is different than the first direction. In one embodiment, the first and second directions represent counter-flow directions. In a particular embodiment, the first and second directions are anti-parallel to one another. The counter-flow arrangement, as explained further below, causes shunt passages 204 of liquid PCM to be created in the PCM to allow liquid phase PCM 109 to reach and flow into the void space 110 regardless of the location of the void space 110.
In one embodiment, the shunt passage elements 202 (e.g, pipes) are in thermal contact with the sides 230 of the enclosure 206. In one embodiment, the shunt passage elements 202 could be repositioned to contact a bottom 232 of the enclosure 206. A fluid is received into the fluid passage elements 202 that is travelling in the direction B. The heat of that fluid causes shunt passages 204 of liquid PCM to form in the PCM.
As illustrated, two shunt passage elements 202 are provided. Of course, any number of shunt passage elements greater than or equal to one could be included. Regardless, the fluid passing through the shunt passage elements 202 is collected in and redirected an end 205 of the shunt passage elements 202. At end 205, the fluid is transferred into the first end 226 of the thermal exchange layer 222 and then travels in direction A towards the second end 228 of the thermal exchange layer 222. Generally, the change of direction is shown by linking direction C where the fluid flow direction translates from direction B to direction A but, as one of ordinary skill will realize, other end configurations and direction reversal mechanisms could be employed than those illustrated in
It shall be understood that, while not illustrated, the sealed enclosure 302 could be cylindrical in shape. In such a case, the shunt passage elements 306 can be located on an external wall of the cylinder and the thermal transfer layer 322 can be located on an internal wall of the cylinder or vice versa. Operation of such an embodiment can be the same or similar to that as described above.
The technical effects and benefits of exemplary embodiments include providing a mechanism to create fluid expansion channels in a PCM heat sink to reduce or eliminate harmful effects of thermal expansion.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. While the description of the present invention has been presented for purposes of illustration and description, it is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications, variations, alterations, substitutions, or equivalent arrangement not hereto described will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. Additionally, while various embodiment of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
Claims
1. A phase change material heat sink comprising:
- a sealed enclosure containing a phase change material and including a top, a bottom and sides; and
- a fluid passage element in contact with the sealed enclosure, the fluid passage element including a thermal exchange layer in thermal contact with the top and that directs fluid in a first flow direction and a shunt passage element in thermal contact with at least one of the sides or the bottom and that directs fluid in a second flow direction, wherein the fluid passage element is configured to direct the fluid through the shunt passage element before it is directed to the thermal exchange layer.
2. The phase change material heat sink of claim 1, wherein the sealed enclosure is formed at least partially of metal.
3. The phase change material heat sink of claim 3, wherein the sealed enclosure is formed of braised metal.
4. The phase change material heat sink of claim 1, wherein the phase change material is wax.
5. The phase change material heat sink of claim 1, wherein the shunt passage element includes a first element and a second element, the first element being in contact with a first of the sides and the second element being in contact with a second of the sides.
6. The phase change material heat sink of claim 1, wherein the first flow direction is anti-parallel to the second direction.
7. The phase change material heat sink of claim 1, wherein the shunt passage element is in thermal contact with at least one of the sides and further comprising:
- a heat release element in thermal contact with the bottom or the sides of the sealed enclosure.
8. A phase change material heat sink comprising:
- a sealed enclosure containing a phase change material and including a top, a bottom and sides; and
- a fluid passage element in contact with the sealed enclosure, the fluid passage element including a thermal exchange layer in thermal contact with the top and that directs fluid in a first flow direction and a shunt passage element passing between the top and bottom that directs fluid in a second flow direction, wherein the fluid passage element is configured to direct the fluid through the shunt passage element before it is directed to the thermal exchange layer.
9. The phase change material heat sink of claim 8, wherein the sealed enclosure is formed of a metal.
10. The phase change material heat sink of claim 9, wherein the sealed enclosure is formed of braised metal.
13. The phase change material heat sink of claim 8, wherein the phase change material is wax.
14. The phase change material heat sink of claim 8, wherein the first flow direction is anti-parallel to the second direction.
15. The phase change material heat sink of claim 8, further comprising:
- a heat release element in thermal contact with the bottom of the sealed enclosure.
16. A phase change material heat sink comprising:
- a sealed enclosure containing a phase change material and including outer walls; and
- a fluid passage element in contact with the outer walls, the fluid passage element including a thermal exchange layer in thermal contact with one side of the outer walls that directs fluid in a first flow direction and a shunt passage element in thermal contact with another side of outer walls that directs fluid in a second flow direction, wherein the fluid passage element is configured to direct the fluid through the shunt passage element before it is directed to the thermal exchange layer.
Type: Application
Filed: Jul 8, 2011
Publication Date: Jan 10, 2013
Applicant: HAMILTON SUNDSTRAND CORPORATION (Windsor Locks, CT)
Inventors: Gregory Quinn (Windsor, CT), Jesse Joseph Stieber (Waterbury, CT)
Application Number: 13/178,981