SU1502921A2 - Evaporator - Google Patents

Abstract

The invention relates to heat engineering and can be used to cool the coolant in thermal control systems of objects, mainly under conditions of variable gravity and orientation. The purpose of the invention is to increase the capacity of the evaporator under conditions of a heat load varying in time. This goal is achieved by making longitudinal grooves 12 on the outer surface of the heat exchange tubes 9. In addition, from the side of the annular channels 11 in the initial part of the tube 9, they are successively covered with a layer of porous lyophilic coating 16 and a mesh 17 pressed to the surface of the tubes 9 and corrugated mesh spacers 18 with longitudinal along the refrigerant corrugations. 4 il.

Description

one

(61) 1273699

(21) 4352802 / 23-06

(22) 08.12,87

(46) 08.23.89. Bup. No. 31

(71) Novopolotsk Polytechnic Institute named after Leninsky Komsomol of Belarus

(72) V.A.Mayorov, V.M.Poliev, L.L. Vasiliev and A.L. Magdes N.

(53) 621.57 (088.8)

(56) USSR Author's Certificate 1273699, cl. F 25 B 39/02, 1986.

(54) EVAPORATOR

(57) The invention relates to heat engineering and can be used to cool the coolant in the systems of thermal control of objects, mainly under conditions of variable gravity and orientation. The purpose of the invention is to increase the capacity of the evaporator under conditions of a heat load varying in time. This goal is achieved by making longitudinal grooves 12 on the outer surface of the heat exchange tubes 9. In addition, from the side of the annular channels 11 in the initial part of the tube 9, they are successively covered with a layer of porous lyophilic coating 16 and a mesh 17 pressed to the surface of the tubes 9 and corrugated mesh spacers 18 with longitudinal along the refrigerant corrugations. 4 il.

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The invention relates to heat engineering, can be used to cool the coolant in thermal control systems of objects, mainly in the conditions of variable gravity and orientation, and is an improvement of the known device according to Aut. St. 1273699.

The aim of the invention is to improve the performance of the evaporator under conditions of varying heat load over time.

Figure 1 shows schematically an evaporator with a detached front wall, a general view; figure 2 - section aa in figure 1; on fig.Z - section bb in fig. 2-, in FIG. “A — section B — B in FIG. 2.

The evaporator includes a housing 1, collectors for inlet 2 and outlet 3 for hot heat carrier, distribution manifold 4 for the refrigerant and collector 5 for outlet naiJa. Inside the housing 1, there is a heat exchanger nozzle 6, separated from the collector 4 by supplying the refrigerant with a solid wall 7, and from the vapor collector 5 by a partition 8. The heat exchanging nozzle contains flat heat exchanging tubes 9 for the flow of the cooled heat carrier, inside which are corrugated plates 10 with longitudinal along the heat carrier corrugations. On the side of the annular channels 11, in the initial section (along the refrigerant) on the surface of the tubes 9, longitudinal (along the refrigerant) grooves 12 are made. In the heat exchange tubes 9, the initial ends 13 exit through the wall 7 into the collector 4, and the end ends 14 are bent inside the annular channels 11. On the side of the annular channels 11, in the initial section of tube 9, they are successively covered with a layer of porous lyophilic wick 15, a thin porous lyophobic coating 16 and a mesh 17 pressed to the surface of the tubes 9 with corrugated elastic sintered multilayer 18 mesh with longitudinal corrugations along the refrigerant. In the final part of the tube 9, they are covered with a layer of porous freeze wick 19, whose thickness is equal to the sum of the thicknesses of layers 15-17, and also pressed by spacers 18. In the zone of the border of the initial and final sections, where the longitudinal grooves 12 end, the porous lyophilic fi

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Tils 15 and 19 are impregnated with a sealing compound 20. At the exit of the annular channels 11, permeable partitions 21 curved into the channels against the vapor-droplet flow are installed, covered in front with a layer 22 of porous lyophobic material. The arrows indicate the direction of flow of the refrigerant and the coolant cooled.

The evaporator operates as follows.

The hot coolant is supplied to the collector 2, passes inside the flat tubes 9, releases heat through the wall of the evaporating inside the wicks 15 and 19 to the refrigerant and cooled out through the discharge manifold 3. The liquid refrigerant from the distribution manifold 4 under the action of a constant supply pressure through the grooves 12 at the protruding ends 13 of the heat exchange tubes 9 passes through the wall 7 and then from the grooves 12 the wick 15 is distributed through the layer at the initial part of the heat exchange tubes 9. Inside the wick 15 the refrigerant absorbs the heat transferred from the hot heat medium heat and simmer. The steam flow with microdroplets from the wick layer 15 fits a layer of a thin porous lyophobic material, which separates a liquid droplet from a droplet flow of a microdroplet, the diameter of which is larger than the pore size of the fine porous lyophobic material. The layer also keeps excess liquid refrigerant from pouring out of the wick 15 in modes with reduced thermal loads. A stream of vapor with microdroplets of liquid, the diameter of which is smaller than the size of the porous material, passes through the layer of a fine-porous lyophobic coating. The sealing compound 20 prevents the coolant from being supplied from the grooves 12 and the wick layer 15 to the wick layer 19. The steam and droplet mixture moves along the annular channels 11. Here the droplets are partially caught by the porous lyophilic material of the spacers 18 and transported as a liquid along the spacers 18 to the end section of the channels 11, where the liquid coolant is absorbed from the material of the spacers 18 into the wick layer 19 at their contact points. At the exit of the annular channels 11 is the separation of the vapor-droplet flow. The steam passes through the layer 22 of porous lyophobic material and supports

its permeable partition 21 into the flat collector 5. The liquid microdroplets are retained by the layer 22 of porous lyophobic material, gradually increased due to their fusion and are carried away by the flow of steam through the layer 22 to the wick layer 19. Here they are absorbed by the wick 19 and transported as a liquid inside the wick 19 along the heating surface of the tubes 9 back towards the vapor-droplet flow in the annular channels. Inside the wick 19, the refrigerant evaporates.

The relative length of the final portion of the heat exchange tubes is approximately equal to the mass fraction of the liquid droplets in the vapor-droplet flow flowing in the initial portion through a layer of lyophobic porous coating. The most suitable material for wick 15 is a mesh structure consisting of two copper grids adjacent to the surface of the tubes 9 of the smallest cell size (10 or 40 microns) and two external grids with a cell of 100-130 microns. All these grids are pressed and burned to a heat exchange tube 9, on which the grooves 12 are pre-cut.

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the end can be brought together with the end 13 of the tube 9 into the collector 4. The porosity of the lyophobic layer can be made, for example, of film porous fluoroplastic or polyethylene with a thickness of 0.10-0.20 mm of the minimum possible pore size (5-15 μm) .

Such an embodiment of the evaporator makes it possible to increase productivity by increasing by a factor of 2-3 the permissible heat load per unit of heat exchange surface at a time of 1 h.

Claims (1)

Invention Formula 20 Evaporator according to auth. St. No. 1273699, characterized in that, in order to increase productivity under conditions of varying heat load over time, in the initial part of the heat exchange tubes longitudinal grooves are made on their outer surface, and layers are placed over the porous freeze wick 2Q porous lyophobic material and pressure mesh. t l-i / J G. Fie.7 B b f. . . „, D .. p.,. .., .n, 1 ...,. - - -: j- - -, 0) 1AA get coolant f 5-3 0) (lzhdaemy sh heat carrier 18