Patent Description:
As electronic products develop towards higher capacity and better performance, the integration level, functions and power consumption keep increasing accordingly, while the layout becomes more compact. This poses an enormous challenge to the heat dissipation technology. Especially in an air cooling system, a high-power device is likely to suffer shortage of local heat dissipation space. Since a loop thermosyphon device evolved from a traditional thermosyphon tube employs the design of gas-liquid pipeline division, layout of an evaporation zone (an evaporator) and a condensation zone (a condenser) is more flexible and a heat transmission distance is increased. At present, the loop thermosyphon device has been used in some communication network products. It can achieve long-distance heat migration and expand heat dissipation space for large-power devices.

Siphoning is to drive condensate to return to form gas-liquid circulation by gravity. Siphoning devices are suitable for scenes along gravity where an evaporation zone (a heat source) is located below a condensation zone (a heat sink) in a gravity direction. As a lowest gravity level of an entire device, an evaporation surface of an evaporator naturally gathers liquid working media to achieve pool boiling heat transfer. An evaporator according to the preamble of claim <NUM> is disclosed in <CIT>.

<FIG> is a schematic diagram of a loop thermosyphon device of a vertical evaporator in the related art. As shown in <FIG>, a heat source and a heat sink are far apart in a gravity direction, such that the loop thermosyphon device can exert advantages of long-distance heat migration. However, since a heat source device is in a vertical state, it means that the evaporator also needs to be arranged vertically. Thus, an evaporation surface is not completely at a lowest gravity level, which will lead to some problems as follows:
The heat source cannot be completely covered with liquid working media and becomes partially dried, thereby causing device overheating failure. Simply increasing a filling amount of the working media is not conducive to start and balance of circulation.

A boiling surface is only a liquid level section, such that a space for vapor overflow is narrow, and boiling heat transfer efficiency is low.

In the related art, there is no solution has been proposed to solve problems of how to ensure that the heat source is located in an effective heat transfer zone constantly when the evaporator is in a vertical state and how to improve boiling heat transfer efficiency for the loop thermosyphon device.

The embodiments of the invention provide an evaporator, so as to solve problems of how to ensure that a heat source is located in an effective heat transfer zone constantly when an evaporator is in a vertical state and how to improve boiling heat transfer efficiency for a loop thermosyphon device.

The invention is defined by an evaporator according to claim <NUM>. The evaporator is applied to a loop thermosyphon device and includes: a housing <NUM>, a multi-scale structure <NUM>, a gas outlet nozzle <NUM>, a liquid return nozzle <NUM>, and a liquid working medium <NUM>.

The liquid working medium <NUM> is disposed at a bottom of the housing <NUM>. The gas outlet nozzle <NUM> is disposed at a top of the housing <NUM>. The liquid return nozzle <NUM> is disposed at a position except a zone corresponding to a heat source device <NUM>. The multi-scale structure <NUM> is arranged on an inner wall of a heating surface <NUM>. The heating surface <NUM> is a surface of the housing <NUM> making contact with the heat source device <NUM>.

The liquid working medium <NUM> is configured to absorb heat and then evaporate into gas. The heat is output to a condenser via the gas outlet nozzle <NUM>. The liquid working medium15 is condensed and returned to the bottom of the housing <NUM> via the liquid return nozzle <NUM>.

In an embodiment, the gas outlet nozzle <NUM> is disposed in a gravity direction. The gas outlet nozzle <NUM> is disposed at a position except the zone corresponding to the heat source device <NUM>. The position of the gas outlet nozzle <NUM> is set to be greater than or equal to a liquid level in height. The liquid level is a liquid level of the liquid working medium <NUM>.

In an embodiment, the multi-scale structure <NUM> and the inner wall of the heating surface <NUM> are combined through sintering, cover at least the zone corresponding to the heat source device <NUM> and extend to the bottom of the housing <NUM>.

In an embodiment, the multi-scale structure <NUM> includes a core wick <NUM> and a peripheral wick <NUM>. The core wick <NUM> is arranged in the zone corresponding to the heat source device <NUM>. The peripheral wick <NUM> is arranged around the core wick <NUM>.

In an embodiment, the multi-scale structure <NUM> is configured to generate a capillary force.

The liquid working medium <NUM> rises to cover a heat input zone corresponding to the heat source device <NUM> under the action of the capillary force.

In an embodiment, the core wick <NUM> and the peripheral wick <NUM> are both made of porous medium materials. The porous medium material of the core wick <NUM> has a smaller pore size than the porous medium material of the peripheral wick <NUM>.

In an embodiment, the porous medium material includes metal powder or a wire mesh.

According to the invention, the multi-scale structure <NUM> is a microchannel. The microchannel is formed by machining or etching the inner wall of the heating surface <NUM>.

The liquid return nozzle <NUM> at a top of the heating surface <NUM>.

In an embodiment, the microchannel includes a liquid division channel <NUM> and a main channel <NUM>. One end of the liquid division channel <NUM> is connected to the liquid return nozzle <NUM>, and the other end of the liquid division channel is connected to the main channel <NUM>.

The main channel <NUM> covers at least the zone corresponding to the heat source device <NUM> and extends to the bottom of the housing <NUM>.

In an embodiment, the main channel <NUM> includes a core channel <NUM>. The core channel <NUM> is disposed in the zone corresponding to the heat source device <NUM>.

The core channel <NUM> is formed by parallel channels or crossing channels. The core channel <NUM> has a greater channel density than other zones except the core channel <NUM>. or a channel angle of a partial zone of the core channel <NUM> adjusts the liquid flow distribution to form a diversion and liquid absorption channel.

In an embodiment, the liquid working medium <NUM> is configured to be condensed and returned into the housing <NUM> via the liquid return nozzle <NUM>, and then the liquid working medium <NUM> is divided into a plurality of flows of liquid along the liquid division channels <NUM> and flow into the main channel <NUM> under the action of an adsorption force of the core channel <NUM>, so as to cover a heat input zone corresponding to the heat source device <NUM>.

In an embodiment, the main channel <NUM> is configured to generate a capillary force for the liquid working medium <NUM> when a channel width and a channel distance of the main channel <NUM> satisfy preset conditions, so as to assist in replenishing the heat input zone corresponding to the heat source device <NUM> with liquid.

According to the evaporator of the embodiments of the disclosure, the liquid working medium <NUM> is disposed at the bottom of the housing <NUM>, the gas outlet nozzle <NUM> is disposed at a top of the housing <NUM>, the liquid return nozzle <NUM> is disposed at any position except the zone corresponding to the heat source, and the multi-scale structure <NUM> is arranged on the inner wall of the heating surface <NUM>. The heating surface <NUM> is the surface of the housing <NUM> making contact with the heat source device <NUM>. The liquid working medium <NUM> is configured to absorb the heat and then evaporate into gas. The heat is output to the condenser via the gas outlet nozzle <NUM>, and the liquid working medium is condensed and returned to the bottom of the housing <NUM> via the liquid return nozzle <NUM>. In this way, the problems of how to ensure that the heat source is located in the effective heat transfer zone constantly when the evaporator is in the vertical state and how to improve the boiling heat transfer efficiency for the loop thermosyphon device in the related art can be solved. Designing the multi-scale structure on the inner wall of the heating surface can optimize liquid replenishing performance of the evaporator in a vertical state along gravity, and can ensure that the heat input zone corresponding to the heat source is located in the effective heat transfer zone constantly. Further, the boiling heat transfer efficiency in the zone can be strengthened, such that circulating heat transfer capacity can be improved, advantages of long-distance heat migration along gravity of the loop thermosyphon device can be fully exerted, and technical applicability can be enhanced.

In the figures, <NUM>-heat source device, <NUM>-housing, <NUM>-multi-scale structure, <NUM>-gas outlet nozzle, <NUM>-liquid return nozzle; <NUM>-liquid working medium, <NUM>-heating surface, <NUM>-core wick, <NUM>-peripheral wick, <NUM>-liquid division channel, <NUM>-main channel, <NUM>-core channel.

Embodiments of the disclosure will be described in detail below with reference to the accompanying drawings in conjunction with the embodiments.

It should be noted that the terms such as "first" and "second" in the description and claims of the disclosure and in the above drawings are used to distinguish between similar objects and not necessarily to describe a particular order or sequential order.

An embodiment of the disclosure provides an evaporator. <FIG> is a schematic diagram of the evaporator according to the embodiment. As shown in <FIG>, the evaporator includes: a housing <NUM>, a multi-scale structure <NUM>, a gas outlet nozzle <NUM>, a liquid return nozzle <NUM>, and a liquid working medium <NUM>.

The liquid working medium <NUM> is configured to absorb heat and then evaporate into gas. The heat is output to a condenser via the gas outlet nozzle <NUM>. The liquid working medium is condensed and returned to the bottom of the housing <NUM> via the liquid return nozzle <NUM>.

In An embodiment, the gas outlet nozzle <NUM> is disposed in a gravity direction. The gas outlet nozzle <NUM> is disposed at a position except the zone corresponding to the heat source device <NUM>. The position of the gas outlet nozzle <NUM> is set to be greater than or equal to a liquid level in height. The liquid level is a liquid level of the liquid working medium <NUM>.

In another embodiment, the multi-scale structure <NUM> and the inner wall of the heating surface <NUM> are combined through sintering, cover at least the zone corresponding to the heat source device <NUM> and extend to the bottom of the housing <NUM>.

According to the evaporator in the embodiment, designing the multi-scale structure on the inner wall of the heating surface can optimize liquid replenishing performance of the evaporator in a vertical state along gravity, and can ensure that a heat input zone corresponding to the heat source is located in an effective heat transfer zone constantly. Further, boiling heat transfer efficiency in the zone can be strengthened, such that circulating heat transfer capacity can be improved, advantages of long-distance heat migration along gravity of the loop thermosyphon device can be fully exerted, and technical applicability can be enhanced. The problems of how to ensure that the heat source is located in the effective heat transfer zone constantly when the evaporator is in a vertical state and how to improve the boiling heat transfer efficiency for a loop thermosyphon device in the related art can be solved.

<FIG> is a first schematic diagram of an evaporator according to an embodiment. As shown in <FIG>, the multi-scale structure <NUM> includes a core wick <NUM> and a peripheral wick <NUM>. The core wick <NUM> is arranged in the zone corresponding to the heat source device <NUM>, and the peripheral wick <NUM> is arranged around the core wick <NUM>.

In an embodiment, the multi-scale structure <NUM> is configured to generate a capillary force. The liquid working medium <NUM> rises to cover a heat input zone corresponding to the heat source device <NUM> under the action of the capillary force.

<FIG> is a second schematic diagram of an evaporator according to an embodiment. As shown in <FIG>, the core wick <NUM> and the peripheral wick <NUM> are both made of porous medium materials. The porous medium material of the core wick <NUM> has a smaller pore size than the porous medium material of the peripheral wick <NUM>. The porous medium material includes metal powder or a wire mesh. That is, the multi-scale structure may be made of a porous medium material. The porous medium material includes metal powder, a wire mesh, etc. The multi-scale structure and the inner wall of the heating surface are combined through sintering, cover at least the zone corresponding to the heat source and extend to a bottom of the evaporator.

Regardless of whether or not the zone is designed differently, the zone corresponding to the heat source is made of the porous medium material having a smaller pore size than other zones, such that a greater capillary force is generated, and the core wick <NUM> is formed. The liquid working medium condensed and returned by gravity is accumulated at the bottom of the evaporator. Generally, the gas outlet nozzle <NUM> is disposed at a top of the evaporator and located at a position not lower than a liquid level in a gravity direction except the zone corresponding to the heat source. The liquid return nozzle <NUM> may be disposed at any position except the zone corresponding to the heat source. The liquid working medium <NUM> at the bottom of the evaporator may rise to cover the entire heat input zone corresponding to the heat source under the action of the capillary force generated by a wick on the inner wall of the vertical heating surface, absorb the heat, then evaporate into gas, and take the heat out to the condenser via the gas outlet nozzle <NUM>.

<FIG> is a third schematic diagram of an evaporator according to an embodiment. As shown in <FIG>, the multi-scale structure <NUM> is a microchannel. The microchannel is formed by machining or etching the inner wall of the heating surface <NUM>. The liquid return nozzle <NUM> is disposed at a top of the heating surface <NUM>. Further, the microchannel includes a liquid division channel <NUM> and a main channel <NUM>. One end of the liquid division channel <NUM> is connected to the liquid return nozzle <NUM>, and the other end of the liquid division channel is connected to the main channel <NUM>. The main channel <NUM> covers at least the zone corresponding to the heat source device <NUM> and extends to the bottom of the housing <NUM>.

The multi-scale structure is a microchannel <NUM>, and is formed by machining or etching the inner wall of the heating surface. In this case, the liquid return nozzle <NUM> on the top of the heating surface. The microchannel includes the liquid division channel <NUM> and the main channel <NUM>. One end of the liquid division channel is connected to the liquid return nozzle, and the other end of the liquid division channel is connected to the main channel. The main channel covers at least the zone corresponding to the heat source and extends to the bottom of the evaporator.

<FIG> is a fourth schematic diagram of an evaporator according to an embodiment. As shown in <FIG>, the main channel <NUM> includes a core channel <NUM>. The core channel <NUM> is disposed in the zone corresponding to the heat source device <NUM>. The core channel <NUM> is formed by parallel channels or crossing channels. The core channel <NUM> has a greater channel density than other zones except the core channel <NUM>. A channel angle of a partial zone of the core channel <NUM> adjusts the liquid flow distribution to form a diversion and liquid absorption channel.

In an embodiment, the liquid working medium <NUM> is configured to be condensed and returned into the housing <NUM> via the liquid return nozzle <NUM>, and then be divided into a plurality of flows of liquid along the liquid division channels <NUM> and flow into the main channel <NUM> under the action of an adsorption force of the core channel <NUM>, so as to cover a heat input zone corresponding to the heat source device <NUM>.

<FIG> is a fifth schematic diagram of an evaporator according to an embodiment. As shown in <FIG>, the zone corresponding to the heat source uses denser parallel channels or crossing channels than other zones to form the core channel <NUM>. The channel angle of the partial zone adjusts the liquid flow distribution to form the diversion and liquid absorption channel.

Claim 1:
An evaporator, applied to a loop thermosyphon device, comprising: a housing (<NUM>), a multi-scale structure (<NUM>), a gas outlet nozzle (<NUM>), a liquid return nozzle (<NUM>), and a liquid working medium (<NUM>), wherein
the liquid working medium (<NUM>)is disposed at a bottom of the housing (<NUM>), the gas outlet nozzle (<NUM>) is disposed at a top of the housing (<NUM>), the liquid return nozzle (<NUM>) is disposed at a position except a zone corresponding to a heat source device (<NUM>), and the multi-scale structure (<NUM>) is arranged on an inner wall of a heating surface (<NUM>), wherein the heating surface (<NUM>) is a surface of the housing (<NUM>) making contact with the heat source device (<NUM>), and
the liquid working medium (<NUM>) is configured to absorb heat and then evaporate into gas, wherein the heat is output to a condenser via the gas outlet nozzle (<NUM>), and the liquid working medium (<NUM>) is condensed and returned to the bottom of the housing (<NUM>) via the liquid return nozzle (<NUM>);
characterised in that
the multi-scale structure (<NUM>) is a microchannel, wherein the microchannel is formed by machining or etching the inner wall of the heating surface (<NUM>); and in that the liquid return nozzle (<NUM>) is disposed at a top of the heating surface (<NUM>).