Positive-pressure-withstanding high-power flat evaporator, processing methods thereof and flat loop heat pipe based on evaporator

Abstract

The present disclosure provides a positive-pressure-withstanding high-power flat evaporator, processing methods thereof and a flat loop heat pipe including the evaporator. The evaporator includes a housing, and reinforcing ribs and a capillary wick which are positioned inside the housing, and the arrangement of the reinforcing ribs can ensure that the strength of the whole evaporator is capable of withstanding positive pressure. The capillary wick is composed of four parts, namely, an evaporating wick, a heat insulating wick, a sealing wick and a transfer wick. Through the large permeability of the transfer wick, liquid supply with low flow resistance can be realized, the heat transfer capability of the loop heat pipe is greatly improved, and the problems of long liquid supply path and large flow resistance caused by a large-area evaporator are solved.

Claims

1. A positive-pressure-withstanding high-power flat evaporator, comprising a housing and a capillary wick arranged inside the housing (1), wherein one or more reinforcing ribs (2) are arranged inside the housing (1), and the reinforcing ribs (2) are positioned at the middle section of the housing (1) wherein the two ends of each reinforcing rib (2) in a length direction do not extend out of the housing (1); the capillary wick is of a rectangular structure consistent with an inner cavity structure of the housing (1), and comprises an evaporating wick (3), a heat insulating wick (4) and a transfer wick (6); wherein the evaporating wick (3) is used for providing capillary force, and vapor channels (7) having the same length as the evaporating wick (3) are arranged on the end surface of one side of the evaporating wick (3); wherein an air accumulation chamber is defined by a space formed by a gap between one end of the evaporating wick (3) in a length direction and the inner surface of the housing (1); and the other end of the evaporating wick (3) in the length direction is provided with the heat insulating wick (4) for blocking heat leakage from the evaporator to a reservoir; wherein the transfer wick (6) is arranged on a surface of the evaporating wick (3) opposite to the surface on which the vapor channels (7) are positioned, and the transfer wick (6) is used for realizing low-flow-resistance liquid transfer from the reservoir to the evaporating wick (3); and the end of the transfer wick (6) proximal to the air accumulation chamber side does not penetrate through the evaporating wick (3) and is wrapped by the evaporating wick (3).

2. The positive-pressure-withstanding high-power flat evaporator according to claim 1, further comprising a sealing wick (5) arranged at the end of the heat insulating wick (4) for sealing the heat insulating wick (4).

3. The positive-pressure-withstanding high-power flat evaporator according to claim 1, wherein the transfer wick (6) is a metal sintered felt or a screen.

4. The positive-pressure-withstanding high-power flat evaporator according to claim 1, wherein the transfer wick (6) is formed by powder sintering or pressing.

5. The positive-pressure-withstanding high-power flat evaporator according to claim 3, wherein the end of the transfer wick (6) distal to the air accumulation chamber extends through the entire capillary wick to the reservoir or to a point where the evaporating wick (3) and the heat insulating wick (4) are butted.

6. The positive-pressure-withstanding high-power flat evaporator according to claim 4, wherein the end, away from the air accumulation chamber, of the transfer wick (6) extends to a point where the evaporating wick (3) and the heat insulating wick (4) are butted.

7. The positive-pressure-withstanding high-power flat evaporator according to claim 1, wherein the evaporating wick (3) is formed by sintering or pressing of powder with high thermal conductivity and small particle sizes, and the heat insulating wick (4) is a powder layer with low thermal conductivity and large particle sizes.

8. A positive-pressure-withstanding high-power flat loop heat pipe, comprising an evaporator, a condenser, a reservoir, a vapor line and a liquid line, wherein the evaporator is the positive-pressure-withstanding high-power flat evaporator according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic structural diagram of a loop heat pipe in the prior art;

(2) FIG. 2 is a sectional view of an evaporator in the prior art;

(3) FIG. 3 is a main sectional view of an evaporator of the present disclosure;

(4) FIG. 4 is a left sectional view of an evaporator of the present disclosure;

(5) FIG. 5 is a structural schematic diagram of high-permeability metal sintered felt or screen with an integrated special-shaped structure;

(6) FIG. 6 is a top sectional view of an evaporator when a transfer wick is made of metal sintered felt or screen with an integrated special-shaped structure;

(7) FIG. 7 is a top sectional view of an evaporator when a transfer wick is formed by sintering or pressing of powder with large particle sizes;

(8) FIGS. 8A-8F show the manufacturing process of a flat loop heat pipe evaporator when a transfer wick is made of metal sintered felt or screen; and

(9) FIGS. 9A-9F show the manufacturing process of a flat loop heat pipe evaporator when a transfer wick is formed by sintering or pressing of powder.

(10) Wherein: 1—housing, 2—reinforcing rib, 3—evaporating wick, 4—heat insulating wick, 5—sealing wick, 6—transfer wick, 7—vapor channel.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(11) The present disclosure will be described in detail below with reference to the accompanying drawings and specific embodiments.

Embodiment 1

(12) This embodiment provides a positive-pressure-withstanding high-power flat loop heat pipe evaporator, which adopts a composite capillary wick structure to improve heat transfer capability, solves the problem of pressure withstanding ability when an evaporator uses a positive-pressure working fluid, and has higher heat transfer capability without increased thickness.

(13) The structure of the evaporator is shown in FIG. 3, comprising a housing 1 and a capillary wick arranged inside the housing 1.

(14) The structure of the housing 1 takes into account the requirements for both positive pressure withstanding ability and uniform liquid supply, and the housing 1 is of a rectangular structure with two ends open and the inside provided with reinforcing ribs 2. Specifically, two reinforcing ribs 2 are arranged in the housing 1 in parallel along a height direction, and the width of the reinforcing ribs 2 is consistent with the width of the housing 1. The reinforcing ribs 2 are located at the middle section of the evaporator, that is, the length of the reinforcing ribs 2 is smaller than the length of the housing 1 of the evaporator, the two ends of each reinforcing rib 2 do not extend out of the housing 1, and the regions, with no reinforcing rib 2 arranged, at the two inner ends of the housing 1 are through spaces. When the capillary wick fills the housing 1, the capillary wick in the through spaces can carry out self-regulation of flow to realize uniform liquid supply, the reinforcing ribs 2 at the middle section ensure that the strength of the whole evaporator meets the requirement for withstanding positive pressure, and the thickness and spacing of the reinforcing ribs 2 should be determined through mechanical analysis according to the pressure in the working temperature region of a working fluid and based on the physical properties of the material.

(15) The capillary wick is of a rectangular structure consistent with an inner cavity structure of the housing 1 as a whole, and is composed of four parts, namely, an evaporating wick 3, a heat insulating wick 4, a sealing wick 5 and a transfer wick 6. In a length direction of the capillary wick, the evaporating wick 3, the heat insulating wick 4 and the sealing wick 5 are arranged in sequence. The evaporating wick 3 is formed by sintering or pressing of powder with high thermal conductivity (such as copper and nickel) and small particle sizes, and powder with small particle sizes can provide small capillary pore diameters, thus providing large capillary force. The end surface, connected with a vapor line, of the evaporating wick 3 is taken as a left end surface, and the end surface opposite to the left end surface is taken as a right end surface (a reservoir is arranged on the right side of the evaporator); and grooves formed in the front end surface of the evaporating wick 3 are vapor channels 7, and two ends of the vapor channels 7 extend to the left end surface and the right end surface of the evaporating wick 3 respectively. When in use, a wall surface, opposite to the vapor channels 7, of the evaporator is attached to a heating device for absorbing the heat of the device. A space between the left end surface of the evaporating wick 3 and the housing 1 is an air accumulation chamber.

(16) The transfer wick 6 is attached to the rear end surface of the evaporating wick 3 (i.e., the end surface opposite to the surface where the vapor channels 7 are located) to realize low-flow-resistance liquid transfer from the reservoir to the evaporating wick 3. Since the width of the reinforcing ribs 2 is consistent with the width of the housing 1, the reinforcing ribs 2 extend to the transfer wick 6 in a width direction. The transfer wick 6 can be directly made of high-permeability metal sintered felt or screen with an integrated special-shaped structure and directly inserted into the housing, as shown in FIG. 5 (grooves therein are used for accommodating the reinforcing ribs 2), or the transfer wick can be formed by sintering or pressing of powder with low thermal conductivity and large particle sizes. The end of the transfer wick 6 proximal to the air accumulation chamber does not penetrate through the evaporating wick 3 but is wrapped by the evaporating wick 3, thereby ensuring that the evaporating wick 3 is capable of providing circulating capillary driving force. When the metal sintered felt or screen with an integrated special-shaped structure is used, the other end of the transfer wick 6 can directly penetrate through the whole structure of the capillary wick to extend to the reservoir, as shown in FIG. 6, or can only extend to the heat insulating wick 4; and when sintering or pressing of powder with large particle sizes is conducted, the transfer wick 6 only extends to the heat insulating wick 4, as shown in FIG. 7.

(17) The function of the heat insulating wick 4 is to block or reduce heat leakage from the evaporator to the reservoir, while not increasing the flow resistance of liquid from the reservoir to the evaporator. The heat insulating wick 4 should be a powder layer with low thermal conductivity and large particle sizes, such as stainless steel, titanium and titanium alloy or polytetrafluoroethylene powder. The heat insulating wick 4 may be in a loose state, or may be sintered or pressed.

(18) The function of the sealing wick 5 is to seal the loose powder of the heat insulating wick 4 between the transfer wick 6 and the sealing wick 5, and if the heat insulating wick 4 has strength after being formed, the sealing wick 5 is not needed anymore. When the heat insulating wick 4 is in a loose state, the sealing wick 5 is required. If the metal sintered felt or screen is used as the transfer wick 6, the particle size of the powder used for the sealing wick 5 is not limited as long as a sealing effect can be achieved after sintering or pressing. If the transfer wick 6 is formed by powder sintering or pressing, the sealing wick 5 should be made of a material with large particle sizes to improve permeability and reduce the flow resistance of liquid supplied from the reservoir to the evaporator.

Embodiment 2

(19) This embodiment provides a processing method of a positive-pressure-withstanding high-power flat loop heat pipe evaporator, and a transfer wick 6 in the evaporator uses metal sintered felt or screen.

(20) Raw materials include a housing, a screen or sintered felt, powder required for a heat insulating wick, powder required for an evaporating wick, powder required for a sealing wick, a limiting tool and vapor channel tools.

(21) (1) The vapor channel tools (metal wires) are vertically placed on a boss located on the upper surface of the limiting tool, and then the housing (integrated with reinforcing ribs) is installed on the boss located on the upper surface of the limiting tool (after evaporator processing is completed, the space inside the housing occupied by the boss is an air accumulation chamber) such that the vapor channel tools are all positioned in the housing, and the vapor channel tools are attached to the end surface of one side of the housing, as shown in FIG. 8A.

(22) (2) The housing is filled with the powder for the evaporating wick, so as to form a front end of the evaporating wick, as shown in FIG. 8B, wherein the powder filling thickness is 5 mm, and the pressure is 90-120 MPa.

(23) (3) The screen or sintered felt is cut into a size matched with the size of the inner wall of the housing, then inserted into the housing, and attached to a side opposite to the vapor channel tools to serve as a transfer wick, as shown in FIG. 8C.

(24) (4) The powder required for the evaporating wick is continued to be filled into the housing until the powder is flush with the tops of the vapor channel tools, so as to form a rear end of the evaporating wick, as shown in FIG. 8D; and the front end of the evaporating wick and the rear end of the evaporating wick together form the evaporating wick.

(25) (5) The housing is filled with the powder required for the heat insulating wick above the evaporating wick to a thickness of 2-5 mm, so as to form the heat insulating wick, as shown in FIG. 8E.

(26) (6) The housing is filled with the powder required for the sealing wick above the heat insulating wick to a thickness of 3 mm, and under a pressure of 90-120 MPa, the sealing wick is formed, as shown in FIG. 8F.

(27) (7) If the powder needs to be sintered, a product formed above is entirely put into a high-temperature furnace, so as to be sintered based on a sintering temperature of the powder; and if the powder is to be directly pressed, sintering is not required, and the next step is carried out.

(28) (8) demolding is carried out to obtain the evaporator.

Embodiment 3

(29) This embodiment provides a processing method of a positive-pressure-withstanding high-power flat loop heat pipe evaporator, and a transfer wick 6 in the evaporator is formed by powder sintering or pressing.

(30) Raw materials include a housing, powder required for the transfer wick, powder required for a heat insulating wick, powder required for an evaporating wick, a limiting tool, a space occupying tool and vapor channel tools.

(31) (1) The limiting tool is assembled with the vapor channel tools (that is, the vapor channel tools are vertically placed on a boss located on the upper surface of the limiting tool), and then the housing is installed on the boss located on the upper surface of the limiting tool such that the vapor channel tools are all positioned in the housing, and the vapor channel tools are attached to the end surface of one side of the housing, as shown in FIG. 9A.

(32) (2) The housing is filled with the powder required for the evaporating wick to a thickness of 5 mm, and under a pressure of 90-120 MPa a front end of the evaporating wick is formed, as shown in FIG. 9B.

(33) (3) The space occupying tool is inserted into the housing and attached to a side opposite to the vapor channel tools in the housing, as shown in FIG. 9B, wherein the space occupying tool is used for occupying the space for the transfer wick in advance, and the size of the space occupying tool is the same as the size of the transfer wick.

(34) (4) The powder required for the evaporating wick is continued to be filled into the housing until the powder is flush with the tops of the vapor channel tools, so as to form a rear end of the evaporating wick, as shown in FIG. 9C; and the front end of the evaporating wick and the rear end of the evaporating wick together form the evaporating wick.

(35) (5) If the powder required for the evaporating wick needs to be sintered, sintering of the evaporating wick is carried out in this state, the sintering process is conducted according to a sintering process of the actually used powder, and if sintering is not required, the next step is carried out.

(36) (6) The space occupying tool is removed, the powder required for the transfer wick is put in the original position of the space occupying tool, and the filling height is consistent with the height of the evaporating wick formed in step (4), so as to form the transfer wick, as shown in FIG. 9D.

(37) (7) The housing is filled with the powder required for the heat insulating wick above the evaporating wick to a thickness of 2-5 mm, so as to form the heat insulating wick, as shown in FIG. 9E.

(38) (8) The housing is filled with powder required for a sealing wick above the heat insulating wick to a thickness of 2-5 mm, and under a pressure of 90-120 MPa the sealing wick is formed, as shown in FIG. 9F.

(39) (9) If the powder required for the sealing wick needs to be sintered, powder sintering is carried out in this state, the sintering process is conducted according to a sintering process of the powder required for the sealing wick, and if sintering is not required, the next step is carried out.

(40) (10) Demolding is carried out to obtain the evaporator.

Embodiment 4

(41) This embodiment provides a positive-pressure-withstanding high-power flat loop heat pipe, comprising an evaporator, a condenser, a reservoir, a vapor line and a liquid line. The evaporator is the evaporator in Embodiment 1, which is manufactured according to the method in Embodiment 2 or 3.

(42) In summary, the above description is only the preferred embodiments of the present disclosure and is not intended to limit the protection scope of the present disclosure. Any modification, equivalent replacement and improvement made within the spirit and principle of the present disclosure shall fall within the protection scope of the present disclosure.