Impact jet flow array phase change cooling device combined with foam metal
Technical Field
The invention relates to a heat dissipation device, in particular to an impact jet flow array phase change cooling device combined with foam metal.
Background
Phase change cooling devices are in the phase of upgrading due to the heat dissipation requirements of high heat flux density devices. Jet boiling heat exchange proves to have extremely high heat exchange coefficient and is highly concerned by application, but when the heat flow density is extremely high, a heating surface is covered by a gas film layer, and a liquid working medium is difficult to enter the heating surface, so that the further improvement of the critical heat flow density CHF is limited.
Chinese patent No. CN108418545A, published No. 2018.08.17, luo xian et al of the university of southern china, proposed a micro-jet cooling plate device with a porous heat transfer surface, which uses micro-jets to vertically impact the heat transfer surface to achieve cooling by boiling heat transfer, and uses a super-hydrophilic surface, so as to accelerate the separation frequency of boiling bubbles and supplement liquid phase working medium in time. This patent presents two main problems: firstly, boiling bubbles need to be discharged from the side channels, secondly, the super-hydrophilic surface has no benefit on the improvement of CHF, and has limited effect on the supplement of liquid-phase working medium.
The foam metal structure is also applied to heat dissipation systems such as heat pipes, and because the foam metal not only can greatly increase the density of a vaporization core for boiling heat exchange and reduce the degree of superheat of a wall surface, but also can utilize the capillary force of the foam metal structure to strengthen liquid supply to a heated surface, thereby being beneficial to the improvement of the critical heat flux CHF.
Chinese patent No. CN104201160A, publication No. 2014.12.10, chenzhen and juan of university in south east, etc. propose an enhanced boiling heat exchange structure with porous metal foam, in which the pore diameter of the metal foam layer is gradually increased in a direction perpendicular to the flow, so as to effectively reduce the flow resistance of bubbles during boiling.
The invention has the main starting point that the impinging jet boiling is combined with the foam metal, the fractal tree structure is adopted to evenly distribute the liquid working medium, the foam metal capillary core divides the jet heat exchange working chamber into a plurality of chamber units so as to be beneficial to the independence of jet tissues, the liquid working medium is timely supplemented to a heated surface under the action of capillary force, and meanwhile, the vapor phase working medium moves to the upper part of the chamber under the action of buoyancy force, thereby ensuring the good separation of gas phase and liquid phase, being beneficial to greatly improving CHF and avoiding the early occurrence of film boiling.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide an impact jet flow array phase change cooling device combined with foam metal, which enables vapor phase working media after boiling to be smoothly discharged through a mutual combination mode of jet flow boiling heat exchange and a foam metal capillary core, and simultaneously greatly improves the CHF limit of the critical heat flow density.
The technical scheme is as follows: the invention relates to an impact jet flow array phase change cooling device combined with foam metal, which comprises
The heat sink chamber comprises a lower working chamber, an upper steam chamber and a foam metal capillary core, the upper surface of a base plate in the heat sink chamber comprises a capillary core thin layer and a plurality of mutually staggered porous fins, and the working chamber is divided into a plurality of cavity units among the fins;
the flow divider adopts a tree-shaped fractal structure, the inlet of the flow divider is communicated with an inlet pipeline at the top end of the working chamber, and the outlet of the flow divider is arranged above the cavity unit of the working chamber;
the pressure pump is used for providing pressurized liquid working media for the flow divider, the inlet of the pressure pump is connected with the condenser, and the outlet of the pressure pump is communicated with the inlet of the flow divider; one end of the condenser is communicated with the pressure pump, and the other end of the condenser is communicated with the side wall of the working chamber close to the top.
By adopting the technical scheme, after entering the flow divider for flow division, the liquid working medium vertically shoots to the substrate with the thin-layer capillary core on the surface through the flow dividing port under the action of the pressure pump, the liquid working medium with a certain speed can quickly permeate the foam metal capillary core for heat exchange, the liquid working medium is heated and boiled to be converted into the vapor working medium, then the vapor working medium rises to the steam chamber, finally enters the condenser through the left side outlet of the steam chamber, is emitted to the external environment in the condenser in an air cooling mode, and finally the vapor working medium is converted into the liquid for recycling.
Has the advantages that: the invention combines jet impact boiling heat exchange with foam metal, so that steam working medium can be smoothly discharged after boiling, the fractal tree-shaped structure is adopted to uniformly distribute liquid working medium, the foam metal capillary core divides the jet heat exchange working chamber into a plurality of chamber units, the independence of jet organization is facilitated, the liquid working medium is timely supplemented to a heating surface under the action of capillary force, and meanwhile, the vapor working medium moves towards the upper part of the chamber under the action of buoyancy force, so that the good separation of gas phase and liquid phase can be ensured, the CHF can be greatly facilitated to be improved, and the early occurrence of film boiling can be avoided.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention;
FIG. 2 is a perspective view of a working chamber;
FIG. 3 is a schematic structural view of a foam metal wick and fins;
fig. 4 is a schematic view of the structure of the flow divider.
Detailed Description
As shown in fig. 1, the impinging jet array phase-change cooling device combined with the foam metal comprises a heat sink chamber (1), a substrate (2), a working chamber (3), a foam metal capillary core (4), a flow divider (5), a steam chamber (6), a pressure pump (7), a condenser (8), a drying filter (9) and a working medium (10). The heat sink chamber 1, the pressure pump 7, the filter (9) and the drying condenser 8 are sequentially connected through a pipeline and a valve (11) to form a closed system, wherein a liquid outlet of the pressure pump (7) is connected with an inlet of the heat sink chamber 1, and a liquid inlet of the condenser (8) is connected with an outlet of the heat sink chamber 1.
As shown in fig. 1 and 2, the heat sink chamber (1) is made of copper or aluminum alloy, the heat sink chamber (1) is arranged on the substrate (2) with the heat source and is welded with the substrate (2), and before the heat sink chamber (1) is welded, the foam metal capillary core (4) is welded in advance in the area of the substrate (2).
Particularly, the foam metal capillary wick (4) and the base plate (2) are connected by a vacuum brazing method, and the foam metal capillary wick needs to be cleaned to remove an oxide layer on the surface of the foam metal capillary wick before welding.
Referring to fig. 2 and 3, the upper surface of the foam metal capillary wick (4) is provided with a plurality of mutually staggered fins, and a plurality of cavity units are formed between the fins and between the base plates.
The foam metal capillary core (4) is made of foam aluminum or foam copper, the foam metal capillary core (4) is integrally formed by adopting a die pressing method, the porosity of the foam metal capillary core (4) is 0.7-0.9, and the pore density is 200-300 PPI.
Referring to fig. 2 and fig. 4, then installing a current divider (5) in the heat sink chamber (1), where the current divider (5) is disposed above the foam metal capillary wick, and its inlet is communicated with the inlet of the heat sink chamber 1, and its outlet is disposed above the cavity unit; the flow divider 5 is a tree-shaped fractal structure unit to ensure the flow dividing uniformity of the liquid working medium (10).
The working principle is as follows: under the action of the pressure pump 7, the liquid working medium 10 enters the flow divider 5 for flow division, vertically shoots to the foam metal capillary core 4 through the flow divider outlet, the liquid working medium 10 with a certain speed can rapidly permeate the foam metal capillary core 4 for heat exchange, the liquid working medium 10 is heated and boiled to be converted into a vapor working medium 10, rises to the vapor chamber 6 at the upper part of the heat sink chamber 1, finally enters the condenser 6 through the left outlet, is dissipated to the external environment in the condenser 6 in an air cooling mode, and finally the vapor working medium 10 is converted into a liquid state for recirculation.
Working medium 10 is freon or dielectric fluid and other cooling medium, and before working medium 10 is added, the working medium 10 must be strictly cleaned, leak-tested, pressure-maintained, vacuumized and the like before being injected.