CN1725947A - Flat capillary evaporator with cooling fins for CPL - Google Patents

Abstract

The invention discloses a planar capillary evaporator with cooling fins for CPL, comprising a base, an upper cover and a capillary core, the base and the upper cover are fixed and sealed; the upper cover is divided into a liquid collection chamber by a partition 1. Steam collecting cavity, the liquid collecting cavity is composed of vertical and horizontal grooves, and arranged crosswise, there is a backflow liquid inlet on the liquid collecting cavity, a steam outlet on the steam collecting cavity, and a cooling fin is arranged on the outer surface of the upper cover; The base is provided with a steam channel and a steam channel, the steam channel is composed of longitudinal channels, and the steam channel communicates with the steam channel and the steam collecting cavity; the capillary core is placed between the liquid collecting cavity and the steam channel. The evaporator improves the heat transfer efficiency of the system, improves and enhances the operating performance of the system, and has a more compact structure; uses its own external area to dissipate heat to the surrounding environment, thereby reducing the load on the capillary structure of the evaporator and making the heat transfer of the evaporator The heat capacity has been greatly improved. The invention can be applied to the heat dissipation of portable or desktop computers, electronic instruments, equipment and the like.

Description

Flat capillary evaporator with cooling fins for CPL

technical field

The invention relates to a planar capillary wick evaporator for CPL.

Background technique

Due to the development of technology, the power of electronic devices is increasing, the degree of integration is getting higher and higher, and the heat generated per unit volume is also increasing. At the same time, the effective heat dissipation area is correspondingly reduced, so the heat dissipation problem is more serious. protrude. The capillary pumping two-phase fluid loop (CPL) developed based on heat pipe technology has the advantages of large heat transfer capacity, high temperature control accuracy, low energy consumption and good isothermal performance, and has become an ideal system for cooling electronic devices. CPL mainly includes: evaporator, condenser, liquid receiver, vapor-liquid pipeline and other auxiliary devices. CPL mainly relies on the phase change of the working fluid in the evaporator to absorb heat and the phase change in the condenser to release heat to achieve heat transfer. The evaporator is the part that bears the heat load of the system. In the capillary structure of the evaporator, the liquid working medium is heated and vaporized. After the heat is transported from the heat source to the condenser, the vapor phase working medium condenses and transfers heat to the outside. The capillary core of the evaporator The generated capillary suction makes the condensed liquid in the condenser return to the evaporator through the liquid pipe to complete the system cycle. In the CPL, the evaporator is one of the most critical components. It is not only the heat suction part, but also the source of the driving force required for the circulation of the working medium in the entire system. Its performance directly affects whether the CPL can be started. and the realization of the whole work.

CPL usually uses a tube evaporator. The disadvantages of the tube evaporator are: ①In order to use the tube evaporator for heat dissipation, a cold plate must be attached to contact the cold plate with the load surface to achieve the purpose of heat dissipation. This method increases The heat transfer resistance is reduced, and the heat transfer efficiency of the system is reduced; ② After the liquid enters the central channel of the evaporator, it flows into the capillary core in the radial direction and evaporates, and the generated steam flows into the channel of the tube wall, and then flows into the steam pipe through the end of the channel. When the heat load of the system changes sharply, a large amount of working fluid is vaporized. If the tube evaporator cannot replenish the evaporation in the capillary in time due to the small amount of liquid storage, it will cause insufficient liquid supply to the system. The evaporator is burnt out, resulting in system failure; ③Due to the limitation of the structure of the tube evaporator, the capillary core structure can only be sintered with powder materials, which requires special equipment to make, so the production cost is high; ④The CPL evaporator is only As the heat-absorbing element of the system, the heat dissipation is completed by the condenser, so under high power conditions, both the evaporator and the condenser must bear a large load.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art, to provide a flat capillary wick evaporator with cooling fins for CPL, the evaporator has good working performance, simple structure and convenient manufacture. It can improve the heat transfer efficiency of the system, improve and enhance the operating performance of the system.

In order to achieve the above object, the technical solution adopted in the present invention is: a flat capillary wick evaporator with cooling fins for CPL, comprising a base, a loam cake, and a capillary wick, the base and loam cake are fixed and sealed; The plate divides the upper cover into a liquid collection chamber and a steam collection chamber. The liquid collection chamber is composed of horizontal channels and longitudinal channels, and is arranged crosswise. There is a return liquid inlet on the liquid collection chamber, and a steam collection chamber on the steam collection chamber. Outlet, heat dissipation fins are arranged on the outer surface of the upper cover; there are steam channels and steam channels on the base, the steam channels are composed of longitudinal channels, and the steam channels communicate with the steam channels and the steam collection chamber; the capillary core is placed in the liquid collection chamber. between the cavity and the steam channel.

Compared with the prior art, the present invention has the following significant advantages:

(1) The present invention is a planar evaporator, which can better contact the surface to be cooled, reduces the contact thermal resistance, improves the heat transfer efficiency of the system, and has a more compact structure and is more convenient to use.

(2) Due to the reverse structure, on the one hand, the return liquid inlet is located on the upper surface of the evaporator, the heat load acts on the lower surface of the evaporator, and the condensed liquid flows back on the upper surface of the evaporator. In the gravity field, gravity also acts as Part of the driving force of the liquid backflow is increased, which increases the driving force of the system and is more conducive to the circulation of the working fluid in the system; The saturation temperature reduces the superheat of the steam-generating wall, and the liquid working medium in the evaporator is easier to vaporize, which will reduce the startup and thermal inertia of the system, thereby improving the startup and operating performance of the system.

(3) If there is liquid entrained at the outlet of the steam channel, the liquid can be collected in this chamber, and the steam collecting chamber can function as a vapor-liquid separator to prevent vapor and liquid entrainment and make the system run stably.

(4) The liquid collection chamber composed of vertical and horizontal channels can make the liquid working medium evenly distributed in it, reduce the flow resistance, and a certain amount of liquid can be accumulated in the channel, which acts as a liquid compensation chamber. When the system heat load When a change occurs, the liquid working medium in the channel can be quickly supplied to the capillary core to meet the working quality required by the load, which improves the variable working condition characteristics of the system, makes the system reach another equilibrium point at a faster speed, and reduces the system approach. Balance the time to avoid the system from lack of fluid or burnout.

(5) A heat sink is arranged on the outer surface of the upper cover, which doubles or multiplies the outer surface area of the evaporator, so that the evaporator can not only use the internal liquid working fluid vaporization phase change heat transfer, but also use the outer surface The heat dissipation of the surrounding environment, under the same capillary structure, correspondingly improves the heat transfer capacity of the system, and the structure of the system is more compact, which can improve the heat dissipation capacity of the system in a limited space.

(6) The capillary core can be made by pressing multi-layer wire mesh, so the production is simple, no special equipment is needed, and the development cost of the system is reduced.

Description of drawings

Fig. 1 is a schematic structural view of an embodiment of the present invention.

Fig. 2 is a sectional view along A-A of Fig. 1 .

Fig. 3 is a right side view of Fig. 1 .

Fig. 4 is a schematic structural view of the upper cover in Fig. 1 .

Fig. 5 is a bottom view of the upper cover in Fig. 1 .

Fig. 6 is a schematic structural view of the base in Fig. 1 .

Fig. 7 is a top view of the base in Fig. 1 .

Drawing description: 1-top cover, 2-radiating fins, 3-reflux liquid inlet, 4-collecting chamber, 5-fins of liquid collecting chamber, 6-baffle, 7-steam collecting chamber, 8-steam outlet, 9-base, 10-steam channel, 11-steam channel, 12-capillary core, 13-steam channel rib.

Detailed ways

As shown in FIGS. 1 to 7 , the present invention includes a base 9 , an upper cover 1 and a capillary core 12 . The connection between the upper cover 1 and the base 9 can be welded, or flange bolts can be used. The sealing method is O-ring seal. The flange bolt connection can be used to easily replace the capillary core according to the needs of the work. 12. The development cost of the system is reduced. The capillary core 12 can be pressed from multi-layer wire mesh or sintered from powder metallurgy materials. In order to improve the heat dissipation efficiency of the evaporator, the wall material of the evaporator adopts metal materials with high thermal conductivity, such as copper, aluminum and other materials; the capillary core 12 adopts stainless steel wire mesh or non-metal high polymer wire mesh with relatively small thermal conductivity. Laminated.

The separator 6 divides the upper cover 1 into a liquid collecting chamber 4 and a steam collecting chamber 7, and the liquid collecting chamber 4 is composed of seven transverse grooves and seven longitudinal transverse grooves, which are arranged crosswise. There is a return liquid inlet 3 on the top of the liquid collection chamber 4, a steam outlet 8 is provided on the side of the steam collection chamber 7, and a heat dissipation fin 2 is arranged on the outer surface of the upper cover 1, and its shape is rectangular or triangular, etc. Other shapes to increase the heat dissipation area of the evaporator. The liquid collection chamber 4 may have one or more transverse grooves, and multiple longitudinal transverse grooves. The transverse grooves and the longitudinal grooves may or may not be perpendicular to each other. The cross-sectional shape of the transverse channel and the longitudinal channel is rectangular, and may also be V-shaped, trapezoidal or other shapes.

The base 9 is provided with a steam channel 11 and a steam channel 10, the steam channel 11 is composed of seven longitudinal channels, and the steam channel 10 communicates with the steam channel 11 and the steam collecting chamber 7. The steam channel 11 has a plurality of vertical and horizontal grooves, and its cross-sectional shape is rectangular, and can also be V-shaped, trapezoidal and other shapes.

The capillary wick 12 is placed between the liquid collection chamber 4 and the steam channel 11 , and is in direct contact with the fins 5 of the liquid collection chamber and the fins 13 of the steam channel.

When working, the heating surface of the lower surface of the evaporator is directly in contact with the load surface, and absorbs heat in the form of heat conduction. There are many parallel steam channel fins 13 on the base 9, which are in direct contact with the capillary core 12, which is filled with liquid working medium. When the heating surface absorbs heat, it is transferred to the evaporator through two paths: part of the heat is quickly transferred to the liquid working medium in the capillary wick 12 through the steam channel fins 13; the other part is transferred to the heat dissipation on the upper surface of the evaporator through the wall surface. slice 2. The liquid working medium in the capillary wick 12 that is in direct contact with the steam channel fins 13 is rapidly heated to the saturation temperature and vaporized, and the steam formed after vaporization flows to the steam collecting chamber 7 along the steam channel 11 and through the steam channel 10, Then enter the steam pipe through the steam outlet 8 and flow to the condenser. If liquid droplets are entrained, they can be deposited in the steam collecting chamber 7 .

After the steam is cooled by releasing heat in the condenser, the steam condenses into a liquid, and under the action of the capillary suction force generated by the vapor-liquid phase change of the capillary core of the evaporator, it enters along the liquid pipeline through the liquid return inlet 3 of the evaporator. In the liquid collecting chamber 4, the liquid working medium is under the action of the fluid distributor formed by the vertical and horizontal channels of the liquid collecting chamber 4, and the return liquid is evenly distributed to the capillary core 12, and flows to the vapor-liquid phase change interface for the next cycle of the system .

Claims (2)

1. flange-cooled plane type capillary core evaporator that is used for CPL is characterized in that:

Comprise base (9), loam cake (1), capillary wick (12), base (9) fixes and seals with loam cake (1);

Dividing plate (6) is divided into liquid collecting cavity (4), steam collecting cavity (7) with loam cake (1), liquid collecting cavity (4) is made of and arranged crosswise lateral channel and longitudinal channels, on liquid collecting cavity (4), have withdrawing fluid inlet (3), on steam collecting cavity (7), have steam (vapor) outlet (8), fin (2) is set at the outer surface of loam cake (1);

Have steam conduit (11), steam channel (10) on base (9), steam conduit (11) is made of longitudinal channels, and steam channel (10) is communicated with steam conduit (11) and steam collecting cavity (7);

Capillary wick (12) places between liquid collecting cavity (4) and the steam conduit (11).

2. want the flange-cooled plane type capillary core evaporator of the 1 described CPL of being used for according to right, it is characterized in that: capillary wick (12) is formed by the multi-layer silk screen compacting.

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