Capillary-assisted evaporator.

p0001The invention relates to an evaporator for heat kapillarunterstützten receiving and transporting a heat transfer medium according to the preamble of Claim first

p0002Capillary evaporators can be used in so-called "Two-Phase Flow" -Wärmetransportkreisläufen. Among heat transport systems are understood to be those taken heat losses in the evaporator element and transported under evaporation of a suitable heat transfer medium as latent heat in the steam to the condenser, then released to a heat sink. Such capillary evaporators allow heat flows from dissipating components receive a high power density and transferred to an evaporating heat carrier. The capillary structure used therein causes the distribution of the liquid medium along the heat-absorbing wall, as well as a pressure potential between the vapor and liquid phase of the heat carrier. Thus, the required circulation of the heat carrier, and thus the supply of the liquid medium to the evaporator (heat source) is made possible. This is especially true for applications in zero gravity (space). Such capillary evaporators are particularly advantageously used as a thermal component in heat transfer systems, when an operation is required with minimum vibration and additional acceleration (no moving parts), and no additional power requirement. The capillary evaporator is to be coupled into the circuit so that the heat carrier medium is supplied as a subcooled liquid flows out and, after evaporation as a saturated vapor. Due to the capillary separation of the two phases, a uniform distribution of liquid as well as a pump the liquid is due to the capillary forces acting in the capillary.

p0003The basic design and operation of a capillary evaporator is known from "Experimental Feasibility Study of Water Filled Capillary Pumped Heat Transfer Loop, NASA TMX 1310, November 1966". The so-called capillary pump described therein consists of two coaxially arranged tubes, and an intermediate capillary of quartz fiber. It surrounds a perforated pipe and is located on a formed with longitudinal grooves and bars with direct interface inner surface of the outer tube to. As a result of capillary forces caused by the pressure difference, the medium flows through the inner perforated tube in the capillary structure, and evaporated under supply of heat (generated by an electric heating wire) at the interface between the capillary and the webs. The resulting vapor flows from here through arranged between the webs longitudinal grooves.

p0004The disadvantage here is that the capillary used higher for future applications required heat transfer capacity is not being achieved and an extreme sensitivity to non-condensable gases or formation of vapor bubbles, which interrupt the transport of liquid exists.

p0005The object of the invention is to provide a kapillarunterstützten evaporator, with the high heat transport services using a special capillary structure and avoiding the gas and vapor lock sensitivity can be achieved. For the use of large temperature differences between the heat-absorbing wall and vaporizing medium good internal thermal conductivity of the assembled components should be ensured with simple manufacture and assembly.

p0006To achieve this object, the characterizing features of claim 1 are provided. Advantageous developments emerge from the dependent claims.

p0007The advantage of the invention is that a high capillary force is achieved by using very fine carbon fibers for the capillary structure obtained which is therefore larger with the measured heights of rise of approximately 10 to 15 cm, than the conventional capillary structures or tissues of metal fibers. The carbon fibers are of usual used as heat transfer liquids at temperatures required readily wettable, chemically and thermally resistant, durable, and flexible and therefore easy to wrap and install. Furthermore, carbon fibers have a relatively low thermal conductivity, so that vapor lock is in the capillary structure largely avoided.

p0008Embodiments are described below and by sketches he explained.

p0009Show it:<ul><li>1 shows a longitudinal and cross section of a capillary evaporator having a provided on the inner surface with V-shaped longitudinal grooves outer tube, a coaxially arranged perforated inner tube and arranged in between carbon fibers as capillary,</li><li>Figure 2 is a longitudinal and cross section of a capillary evaporator arranged with one on the inner surface with circumferential grooves provided outer tube and a coaxial, provided on the outer surface with longitudinal grooves inner tube and arranged in between carbon fibers as a capillary structure,</li><li>Figure 3 shows a plate-shaped capillary evaporators.</li></ul>

p0010a capillary evaporator 1 in the longitudinal (top) and cross section (below) can be seen from FIG. 1 It consists of two coaxially disposed tubes 2, 3, of which the wall 4 of the inner tube 2 with a perforation 5 and the wall 6 of the outer tube 3 on the inner surface with a V-shaped longitudinal groove 7 is provided. Around the inner pipe 2 is to the Perforation 5 is a wound of carbon fibers 8 very fine capillary structure arranged in a ring whose outer surface bears firmly against the longitudinal webs of the outer tube 3rd The required radial contact pressure resulting from the taper of the inner tube 2 and outer tube 3 by axial displacement. The inner tube 2 is closed on the steam outlet side with a plug 9 and the outer pipe 3 is connected to a manifold 10th The supply of a suitable liquid medium as heat transfer medium 11 takes place axially in the inner tube 2 and radially through the perforations 5 of the wall 4 in the arranged thereabove made of carbon fibers 8 be related capillary structure (see arrows). Here, the liquid medium is distributed 11 and evaporated in heat (see arrows) through the wall 6 to form an inverted meniscus at the interface 12 between the liquid and the V-shaped longitudinal webs 7. The supply of the required heat flow, for example, by waste heat dissipating components or arranged around the outer tube 3 electric heating coil (not shown in the figure) carried out. The resulting vapor flows through the partially filled with the liquid medium 11 V-shaped longitudinal ridges 7 to manifold 10 (see arrows).

p00112 shows a further variant of a capillary evaporator 1 in the longitudinal (top) and cross section (below) is visible. Unlike the embodiment of Figure 1 here, the liquid medium 11 is first one located at the inlet (see arrow) and fed by a cover 13 of the inner tube 2 and the outer tube 3 with cover 14 formed free space 15th From here, the medium 11 flows through openings provided in the lid 13 in holes 16 arranged at the outer periphery of the inner tube 2 as a longitudinal groove flow channels 17 (see arrows), which act alternately as steam and liquid channels. The around the inner pipe 2 and acting as a capillary structure arranged carbon fibers 8 suck the liquid medium 11 from the corresponding liquid-filled longitudinal grooves 17 and cause the arranged on the inner circumference of the outer tube 3 circumferential grooves 20, in addition, a uniform distribution. Under supply of a heat flow in the wall 6 of the outer tube 3 (see arrow), the medium 11 is evaporated within the capillary structure from the carbon fibers 8 or at its interface to the circumferential grooves 20 of the itself in this case resulting two radially directed flow is the flow of the liquid medium 11 to the outside and the other of the vaporized medium 11 inwardly into the steam channels 17th The vaporous medium 11 flows through the perforation 18 from periodically arranged in the collecting pipe 19th When using a split outer tube 3 and to generate the necessary contact pressure for a good contact between the carbon fibers 8 and the tube material, as well as simple installation, the two tube halves are 3 means of a screw 21 interconnected (lower figure).

p00123 shows a section through a capillary evaporator 22 in plate form. It consists of two superimposed plates 23, 24, of which the lower plate 23 is traversed by pointing to the inside of channels 25 through which the carbon fibers 8 are set as the capillary in a wide recess 26th The top plate 24 is traversed on the side facing the carbon surface 8 with a number of grooves 27 which open at the rear end of the plate in a connected there collecting duct 28th The liquid medium 11 passes from the channels 25 (see arrows) into the carbon fibers 8, is distributed there and by supplying a heat flow (see vertical arrow) evaporated in the top plate 24 at the interface between the carbon fibers 8 and webs 30th The resulting vapor flows, as explained above, in the collecting duct 28 and from there to the heat sink from. The two plates 23, 24 are secured together by a screw 29th