Patent Application
20070284090
The present invention is herein illustrated with specific embodiments so that one skilled in the pertinent art can easily understand other advantages and effects of the present invention from the disclosure of the invention. It should be noted that, in the following embodiments, a loop type heat dissipating apparatus with a sprayer is applicable to heat transfer between a heat source (for example, a CPU, laser diode, LED array, and multi-chip module (MCM)) and a heat sink (for example, a cooling fin, a cooler, and a fan). The aforesaid kinds of heat sources and heat sinks are not herein described in detail, as they are known devices and known skills. Considering the way of driving, the sprayer is a capacitive device or alternatively a piezoelectric device; the choice is known and thereby is not herein described in detail.
Referring to
Referring to
The sprayer 115 comprises a diaphragm 1151 and a driving unit 1153. The driving unit 1153 which abuts on the diaphragm 1151 comprises a plurality of orifices 1157. The diaphragm 1151 is a metal film while the orifices 1157 are tiny round holes having an average diameter of 30 micron. The driving unit 1153 is a piezoelectric device for piezo-actuation, for example, a circular piezoceramic device.
In contact with the heat sink, the condenser 13 comprises a third chamber 131 and a wick structure 133. The third chamber 131 communicates with the second chamber 113. The wick structure 133 is disposed on one side of the third chamber 131 and communicates with the first chamber 111. In this embodiment, the wick structure 133 is disposed at the bottom of the third chamber 131 while a wick structure 135 is disposed at the point of connection between the first channel 17 and the wick structure 133. Owing to the wick structure 135, the working fluid 15 is confined to the first chamber 111, the first channel 17, the wick structure 135 and the wick structure 133. The working fluid 15 flows back to the first chamber 111 under a capillary action of the wick structure 135 and completes the cycle of heat transfer.
In this embodiment, the wick structure 133 includes, but is not limited to, a porous structure formed by sintered metal powder. Alternatively, the wick structure 133 can be a plurality of grooves, a metal mesh, or a rough surface structure inside the condenser 13. In other words, the wick structure 133 can be whatever is capable of confining the working fluid 15 to a surface of the condenser 13 and conveying liquid by a capillary action.
The condenser 13 comprises a surface which is mostly smooth except one disposed with the wick structure 133 and the wick structure 135. As shown in
The working fluid 15 fills the wick structure 133 all the way to the first chamber 111 so as to be atomized and sprayed to the second chamber 113 by the sprayer 115, evaporated by the heat source, conveyed to the third chamber 131, condensed, liquefied, and adheres to the wick structure 133. The liquid phase of the working fluid 15 flows back to the first chamber 111 under a pumping force actuated by the sprayer 115 and completes the cycle of heat transfer. In this embodiment, the working fluid 15 is, for example, pure water, methanol, acetone, ammonia, or any appropriate fluid which evaporates readily and has a high latent heat of evaporation.
The first channel 17 connects the first chamber 111 and the wick structure 135. The second channel 19 connects the second chamber 113 and the third chamber 131. The first channel 17 and the second channel 19 are parallel. In this embodiment, the first channel 17 is a liquid line while the second channel 19 is a vapor line. The second channel 19 has a larger caliber than the first channel 17. The wick structure 135 is disposed at a point of connection between the first channel 17 and the condenser 13 and is configured to guide the working fluid 15. The first channel 17 is one of a capillary and a smooth pipe. The second channel 19 is a smooth pipe.
It should be noted that, in this embodiment, the first channel 17 and the second channel 19 are disposed between the evaporator 11 and the condenser 13 such that their layouts are spatially flexible but are not limited to those of this embodiment. For instance, the first channel 17 and the second channel 19 can be disposed as a whole between the evaporator 11 and the condenser 13. In other words, persons ordinarily skilled in the art may modify the layout of a connection between the evaporator 11 and the condenser 13 when necessary, so as to provide the cycle of heat dissipation for the working fluid 15.
It should also be noted that, as shown in the drawings, the evaporator 11 and the condenser 13 has a one-to-one quantitative relationship which merely illustrates the structure of the loop type heat dissipating apparatus of the present invention in a schematic manner. In fact, the structures shown in the drawings are not drawn according to a practical case in terms of quantity, shape and size. In practice, the quantitative relationship between the evaporator 11 and the condenser 13 is one selected from the group consisting of a one-to-one relationship, a one-to-many relationship, a many-to-one relationship, and a many-to-many relationship.
When the sprayer 115 is idle and still, the capillary action generated toward the working fluid 15 by the plurality of orifices 1157 is exactly offset by the weight of the working fluid 15 above the diaphragm 1151. As soon as the diaphragm 1151 starts to vibrate under a voltage, the sprayer 115 disposed right above the heat source turns the liquid phase of the working fluid 15 into microdroplets and conveys microdroplets to the heat source. In so doing, the heat generated by the heat source causes the droplets sprayed over the heat source to undergo phase change, and thus the heat is removed from the heat source because of the latent heat of evaporation, and the goal of spray cooling is achieved.
Afterward, the working fluid 15 is evaporated to gas, and then the gas phase of the working fluid 15 flows toward the condenser 13 via the second channel 19. Then, inside the condenser 13, the gas phase of the working fluid 15 condenses to liquid and adheres to the wick structure 133. Inasmuch as the wick structure 133 is disposed at the bottom of the condenser 13 and the wick structure 135 at a point of connection between the condenser 13 and the first channel 17, the liquid phase of the working fluid 15 in the condenser 13 flows back to the evaporator 11 and completes the cycle of heat transfer under the capillary action of the wick structure 133 and the wick structure 135 as well as the pumping force actuated by vibration of the sprayer 115.
Accordingly, in this embodiment, performance of a heat dissipating apparatus is enhanced by spray cooling, and flow resistance is reduced by a structure for the separation of liquid and gas flow, thus increasing heat transfer and enhancing heat dissipation efficiency.
This embodiment markedly differs from the first embodiment in that the first channel and the second channel are parallel in the first embodiment but crossed in the second embodiment.
As shown in
Unlike the prior art, this embodiment involves using a sprayer to dissipate the heat of a heat source by spray cooling, so as to increase the efficiency of heat dissipation and prevent the liquid phase of a working fluid from accumulating at the bottom of an evaporator. And further, thermal resistance decreases greatly, not only because there is no wick structure at the bottom of the evaporator, but also because the evaporator is panel-shaped and thereby comes into contact with the heat source through a large contact surface. Last but not least, the panel-shaped evaporator absorbs a huge amount of heat through phase change and thereby eliminates a heat spot of the heat source.
With a sprayer being driven by piezoelectric or capacitive means, the diaphragm vibrates and actuates a pumping force. The pumping force, coupled with the wick structures, allows the working fluid to complete the cycle of heat transfer without an external pump and brings advantages like compactness and low power consumption. Installing the sprayer inside the evaporator decreases the size of the loop type heat dissipating apparatus greatly and thereby is conducive to product miniaturization.
The foregoing specific embodiments are only illustrative of the features and functions of the present invention but are not intended to restrict the scope of the present invention. It is apparent to those skilled in the art that all equivalent modifications and variations made in the foregoing embodiments according to the spirit and principle in the disclosure of the present invention should fall within the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 095120789 | Jun 2006 | TW | national |
