RU2473035C1 - Heat loop pipe - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: heat loop pipe includes evaporator consisting of several cylindrical housings located near each other and having common compensation cavity divided into two parts. Capillary porous head pieces arranged inside each cylinder are sealed on their end faces so that two parts of compensation cavity can freely rotate through feed channels with each other, and at the same time so that they cannot have any connection to steam discharge channels. In order to supply heat to cylindrical housings, the latter can be built in a common contact flange from conductive material. When using heat loop pipe for heat exchange with fluid media, cylinders can be equipped with ribs (for example longitudinal) from conductive material, or external surface of the cylinders themselves is used to perform heat exchange with fluid medium; at that, cylinders can be installed in rows in a staggered order.

EFFECT: enlarging the surface of heat removal zone of evaporator of heat loop pipe; reducing the temperature gradient in contact zone of evaporator with cooled item.

4 cl, 8 dwg

Description

The invention relates to the field of heat engineering, in particular to contour heat pipes, and can be used in various thermal control systems, including spacecraft, for efficient removal of heat fluxes from solid heat-generating surfaces, as well as from liquid and gaseous media.

Known loop heat pipe (CTT) with an evaporator containing a housing with a capillary-porous nozzle placed inside, impregnated with a coolant, and a compensation cavity located on the inlet side of the liquid coolant evaporator (patent US 2009314472 (A1), publ. 12.24.2009, cl . F28D 15/04), (AS USSR No. 449213, class F28D 15/00, published 05.11.1974).

The KTT evaporator simultaneously performs four functions: a steam generator, a capillary pump, a hydraulic shutter and a thermal shutter. The presence of a compensation cavity allows the CTT to work reliably at its various positions, as well as when the relative volume of the liquid phase of the charged coolant changes, which occurs due to a change in the operating temperature.

Along with a number of advantages that contour heat pipes possess (for example, the transfer of large heat loads and reliable operation in conditions of counteraction of gravitational forces to capillary forces), there are various kinds of restrictions on their use that arise when organizing heat supply to the evaporator. Optimization of the size and configuration of the evaporator, as a rule, comes into logical conflict with the optimization of the thermal interface with the cooled object.

Due to the technological features associated with the manufacture of a capillary-porous nozzle and its placement inside the evaporator body, the most widespread are loop heat pipes having a cylindrical evaporator. Cylindrical evaporators better withstand the internal pressure of a charged biphasic coolant, while it is easier to provide high quality contact between the housing and the capillary-porous nozzle, and it is also easier to achieve an acceptable seal to ensure the operation of the capillary valve.

To connect to flat surfaces, cylindrical evaporators are equipped with transition elements - contact flanges made of heat-conducting material, which provide efficient heat transfer from a flat surface to a cylindrical one. However, when working with high thermal loads or when removing heat from large surfaces, it is necessary to increase the heat transfer zone, mainly by increasing the length of the cylinders of the evaporators. The increase in the diameter of the evaporator has technological limitations, and, in addition, with a one-sided heat supply, increasing the diameter is irrational due to the increase in the radial unevenness of the heat supply. Practice, however, also showed a low reliability of excessively long cylindrical evaporators, the long supply channels of which can be blocked by steam bubbles with subsequent drainage of the evaporator.

In (W.Bienert, D.Wolf, M.Nikitkin etc., The Proof-of-Feasibility of Multiple Evaporator LHPs, ESA-SP-400, 6th EU Syposium on SECS, NL, 1997), one of the methods increasing the surface and changing the configuration of the heat supply zone by creating a loop heat pipe (CTT) with several evaporators, each of which has its own compensation cavity. Despite the fact that this solution is in principle operational, it was not widely used, since the stability of a CTT containing several evaporators has a number of significant limitations on refueling, distribution of heat load, relative location of CTT elements, etc.

Considering the shortcomings of the analogs described above, in most cases, if it is necessary to increase the heat supply zone of the evaporator of the contour heat pipe, specialists decide to install several parallel CTTs, each of which is equipped with one evaporator, as is done, for example, to cool the battery in operation (K .Goncharov, V.Buz, etc. Development of loop heat pipes for thermal control system of nickel-hydrogen batteries of "Yamal" satellite, 13th IHPC, Shanghai, China, 2004) or for heat removal from a liquid medium of a single-phase circuit with a mechanical pump in work (D.Tulin, E.Kotlyarov, G.Se rov and I. Tulin, The 4000W hybrid single- and two-phase thermal control system for payload and equipment of geostationary communication satellite (AIAA # 772668, ICES-40, Barcelona, 2010).

However, the presence of several parallel, autonomous, simultaneously operating CTTs may be accompanied by a significant uneven distribution of the heat flux and the temperature gradient between the evaporators. In addition, in proportion to the number of CTT, the means of regulation, monitoring and control should be increased, which is a significant drawback of this solution in its practical implementation.

The contour heat pipe according to the patent of the Russian Federation No. 2079081 (publ. 05/10/1997) is closest to the proposed invention.

The present invention is aimed at obtaining a technical result, which consists in increasing the surface area of the heat supply zone of the KTT evaporator, while ensuring its predetermined proportions, as well as in reducing the temperature gradient in the zone of contact of the evaporator with the cooled object. When disclosing the essence of the invention and describing an example of its implementation, other types of achieved result will be named, with which the above technical result has a causal relationship.

The proposed contour heat pipe, as well as the closest CTT, contains a condenser connected by a steam and condensate conduit and at least one evaporator equipped with a capillary-porous nozzle with steam and supply channels, a compensation cavity in communication with the condensate conduit, and an auxiliary capillary structure, located inside the supply channels and the compensation cavity and connecting the supply channels to the compensation cavity.

To achieve the specified technical result in the proposed device, in contrast to the specified closest known to it, the evaporator of the contour heat pipe is made in the form of several adjacent cylindrical bodies with capillary-porous nozzles installed inside them with through feed channels, while the compensation cavity is divided into two parts communicating with each other through the supply channels and located at opposite ends of the capillary-porous nozzles, and steam drainage channels Displayed pairs from each capillary-porous nozzle to the common steam line.

In addition, cylindrical bodies are integrated into a common contact flange of heat-conducting material.

In addition, the cylindrical bodies are externally provided with ribs of heat-conducting material.

In addition, the cylindrical bodies are arranged in rows in a checkerboard pattern.

The proposed design solutions make it possible to create a CTT with an evaporator, in which at almost any point in the connected volume formed by two parts of the compensation cavity and all supply channels, the coolant is present in a saturated state, which ensures uniform temperature and pressure, as well as the same temperature level of operation of the evaporator parts. Moreover, by varying the number of cylinders and the distance between them, it is possible to optimize or provide a given configuration of the heat transfer zone from the cooled object to the evaporator.

The removal of vapor bubbles from the supply channels can occur in two directions, and the liquid for feeding the capillary-porous nozzle can also come from two sides, which significantly increases the reliability of the evaporator.

Dividing the compensation cavity into two parts expands the possibilities of using an evaporator consisting of several cylinders, in particular, restrictions on the orientation of the evaporator in the field of mass forces can be minimized or removed.

The regulation of the temperature level of the evaporator and the control of the CTT can be ensured by well-known common methods: using a regulator-heater, pressure regulator, thermoelectric micro-refrigerator (TEMX). At the same time, the number of applied means of regulation, monitoring, and control, namely, sensors, valves, heaters, TEMX, etc., corresponds to their quantity used for CTT having one evaporator. That is, the evaporator in the proposed KTT is not a combination of several evaporators in a single unit, but is structurally and functionally one evaporator, consisting of several sections (parts) that ensure joint operation in a single mode.

To supply heat to the cylindrical bodies, the latter can be built into a common contact flange of heat-conducting material, which will ensure heat transfer from the flat surface of the heat pipe to all cylinders.

The proposed contour heat pipe can be used for heat exchange with fluids, for example, for cooling the flow of gas or liquid. In this case, for the development of the surface of the external heat transfer, the cylinders are equipped with (for example, transverse) ribs of heat-conducting material, or the external surface of the cylinders themselves is used for heat exchange with the fluid, and the cylinders can be staggered in rows in the same way as in shell-and-tube heat exchangers.

In the description of the specific implementation of the proposed device, the physical effects that determine the achievement of the technical result inherent in the invention will be discussed in more detail.

The invention is illustrated by drawings, which show:

- figure 1 is a General view of a contour heat pipe with an evaporator made of several cylindrical bodies built into a common contact flange, the section of the evaporator in DD;

- figure 2 is a sectional view of the KTT evaporator according to AA in figure 1;

- figure 3 is a sectional view of the CTT evaporator according to BB in figure 1;

- figure 4 is a sectional view of the KTT evaporator according to BB in figure 1;

- figure 5 is a section of one cylinder of the evaporator according to G-D in figure 4;

- Fig.6 is a General view of the evaporator of a contour heat pipe (for cooling the fluid flow), made of several cylindrical bodies equipped with fins from the heat-conducting material from the outside;

- Fig.7 is a General view of the evaporator of a contour heat pipe (for condensing an external steam stream) made of several cylindrical bodies arranged in rows in a checkerboard pattern;

- on Fig - section of the evaporator according to EE in Fig.7.

The proposed contour heat pipe, shown in figure 1, contains an evaporator consisting of several cylindrical bodies (1) located next to each other. The capillary-porous nozzles (2) available inside each cylinder are sealed from the ends so that two parts of the compensation cavity (3) freely communicate with each other through the supply channels (4), and at the same time do not have a connection to the vapor channels (5) . The auxiliary capillary structure (6) provides a capillary connection of all the supply channels with both parts of the compensation cavity (3). The steam generated by each porous nozzle enters the common steam line through steam exhaust channels (7). The steam line is connected to the inlet to the condenser (8), and the condenser outlet is connected to the compensation cavity by means of the condensate line (9) to ensure the return of the liquid coolant to the evaporator.

To supply heat to the cylindrical bodies, the latter can be built into a common contact flange (10) of heat-conducting material, which provides heat transfer from a flat surface of the heat supply to each cylinder of the evaporator.

Figure 6 shows an application of CTT for cooling a liquid or gas medium. For this, the cylinders of the evaporators are equipped with ribs (11), in this example transverse. The fins can be made of various heat-conducting materials (aluminum, steel, copper, non-metals) depending on the task. The principle of selecting the number of fins, their pitch and thickness is fully consistent with the engineering methods for selecting the design of recuperative heat exchangers.

Figure 7 also shows an example of the use of CTT for cooling fluids or for condensing steam, however, there are no fins, and the surface of the external heat transfer is formed from the outer surface of the cylinders themselves. This solution is advisable to apply in cases where the density of the heat flux entering the cylinders is high enough, and the required hydraulic resistance to the flow (moving cooled medium) must be minimized.

Contour heat pipe works as follows. The liquid coming from the condensate line (9) of the loop heat pipe into the compensation cavity (3) feeds each capillary-porous nozzle (2) of the evaporator using an auxiliary capillary structure (6). Steam bubbles formed due to the operation of the evaporator periodically exit the supply channels (4), without interfering with the feeding of capillary-porous nozzles (2) with a liquid coolant. The steam generated in the contact zone of the capillary-porous nozzles (2) with the inner walls of the cylindrical bodies (1) of the evaporator is discharged through the steam channels (5) into a common steam line (7), as shown in Fig. 1-Fig. 4.

Further, the contour heat pipe works, like any other CTT, in a closed evaporation-condensation cycle. The vapor from the evaporator moves to the condenser, condenses and, in a regenerative way (through a sealed wall), transfers heat to the environment or to another object of the temperature control system. KTT capacitor is a flow type capacitor, i.e. steam enters from the inlet side, and the condensed coolant enters the outlet in the form of liquid. The liquid coolant through the condensate line from the condenser is delivered back to the evaporator. The circulation occurs due to the pressure difference arising on the capillary-porous nozzles during the operation of the CTT evaporator.

The use of the invention will significantly expand the possibilities of using contour heat pipes for cooling heat-stressed platforms with various equipment, including equipment that generates heat with high density, as well as for creating heat exchangers based on the KTT evaporator, designed for efficient cooling of gas and liquid flows in various industries, including transport equipment, the work of which is accompanied by a change in the orientation of the object and the creation of various overloads narrow, as well as space technology, the systems of which must be operational in the absence of gravity.

Claims (4)

1. A contour heat pipe containing a condenser and an evaporator connected by a steam and condensate conduit, equipped with a capillary-porous nozzle with steam and supply channels, a compensation cavity in communication with the condensate pipe, and an auxiliary capillary structure located inside the supply channels and the compensation cavity and connecting the supply channels with a compensation cavity, characterized in that the evaporator of the contour heat pipe is made in the form of several adjacent cylindrical bodies with capillary-porous nozzles installed inside them with through feed channels, while the compensation cavity is divided into two parts communicating with each other through the feed channels and located at opposite ends of the capillary-porous nozzles, and vapor drainage channels remove steam from each capillary-porous nozzle into the common steam line. 2. The contour heat pipe according to claim 1, characterized in that the cylindrical body is built into a common contact flange of heat-conducting material. 3. The contour heat pipe according to claim 1, characterized in that the cylindrical bodies are provided on the outside with fins made of heat-conducting material. 4. The contour heat pipe according to claim 1, characterized in that the cylindrical bodies are arranged in rows in a checkerboard pattern.

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