Two-phase temperature equalizing device for temperature control of radar seeker

Abstract

The invention relates to a two-phase temperature equalizing device for radar seeker temperature control, belongs to the technical field of radar heat dissipation, and solves the problems of low heat dissipation efficiency and high energy consumption of a heat dissipation mode in the prior art. Comprising a two-phase vapor chamber and a heat sink, the two-phase vapor chamber comprises a cover plate, a capillary structure and a base, the base is provided with a middle cavity for storing liquid water; the capillary structure is arranged in the base, and the capillary structure can absorb water through the capillary effect; the cover plate is fixedly connected with the base and can seal the middle cavity of the base; the cover plate is fixedly connected with a TR assembly of the radar. Capillary layers are machined on the surfaces of the inner walls of the base and the cover plate. Liquid in the two-phase vapor chamber is diffused based on the capillary effect, the evaporation surface is enlarged, and the heat exchange efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of radar heat dissipation, and in particular to a two-phase temperature equalization device for temperature control of a radar seeker. Background Art

[0002] In recent years, the requirements for the integration, light weight, and miniaturization of military equipment have been strict. The high degree of integration has caused the thermal power density of on-board electronic equipment to rise sharply, and the miniaturization and light weight have reduced the heat capacity of the equipment. The thermal control problem of on-board electronic equipment has become increasingly prominent. The heat dissipation performance of electronic chips directly affects the reliability and working performance of electronic devices. High-efficiency temperature control technology has become one of the key technologies restricting the development of weapon equipment.

[0003] The transceiver component (TR) power amplifier chip in the radar seeker is small in volume, high in power density, and low in efficiency. Once the chip temperature reaches the maximum allowable temperature, it will seriously endanger the stability and reliability of its operation, and may even cause burnout. With the continuous improvement of the requirements for improving the performance of the radar seeker, relying solely on the methods of metal heat transfer or phase change material heat storage has the defects of poor thermal conductivity, low heat dissipation efficiency, and insufficient heat storage capacity in a limited space, and cannot cope with the continuous heat release of the TR component.

[0004] Therefore, a new set of temperature control devices is needed to achieve sustainable heat dissipation of the TR component. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a two-phase temperature equalization device for temperature control of a radar seeker to solve the problems of low heat dissipation efficiency and high energy consumption of existing heat dissipation devices.

[0006] The object of the present invention is mainly achieved through the following technical solutions:

[0007] A two-phase temperature equalization device for temperature control of a radar seeker includes: a two-phase temperature equalization plate and a heat sink;

[0008] The two-phase temperature equalization plate includes: a cover plate, a capillary structure, and a base; the base is provided with an intermediate cavity for storing liquid water;

[0009] The capillary structure is arranged inside the base, and the capillary structure can absorb water through capillary action;

[0010] The cover plate and the base are fixedly connected and can seal the intermediate cavity of the base; the cover plate is fixedly connected to the TR component of the radar; the inner wall surfaces of the base and the cover plate are both processed with capillary layers.

[0011] Further, the capillary structure includes a plurality of strip-shaped plates arranged side by side.

[0012] Alternatively, the capillary structure comprises a rectangular plate and a strip plate; the strip plates are symmetrically arranged on both sides of the rectangular plate.

[0013] Furthermore, a plurality of protrusions are provided on both sides of the strip plate.

[0014] Furthermore, the capillary structure is a capillary wick.

[0015] Furthermore, the capillary layer is a capillary pattern processed on the inner wall surface of the two-phase temperature balancing plate.

[0016] Furthermore, the capillary lines are annular grooves arranged in parallel.

[0017] Furthermore, the capillary lines are interconnected grid networks.

[0018] Alternatively, the capillary layer is metal powder or metal wire mesh sintered on the inner wall surface.

[0019] Furthermore, the capillary lines are parallel annular structures; or, the capillary lines are interconnected grid networks.

[0020] Furthermore, the heat sink is a heat sink fixedly mounted on both sides of the two-phase temperature balancing plate. Alternatively, the heat sink is a condenser; and the condenser is connected to the inside of the two-phase temperature balancing plate.

[0021] Furthermore, the condenser is a grid-shaped cooling pipeline.

[0022] Alternatively, the condenser is a cooling pipeline with a simulated crystal structure.

[0023] The technical solution of the present invention can achieve at least one of the following effects:

[0024] 1. The two-phase temperature equalization device for temperature control of radar seeker of the present invention is used for high heat flux density (>100W / cm 2 ) two-phase temperature control of the TR component. Liquid water is stored inside the two-phase temperature plate. The liquid working fluid absorbs heat and evaporates, and can quickly take away the heat generated by the TR component through steam. The capillary structure is an extremely important component of the two-phase temperature plate, which enables the two-phase temperature plate to achieve rapid heat diffusion. The vapor-liquid evaporation of liquid water can absorb a large amount of heat and maintain the temperature of the TR component within a reliable range.

[0025] 2. The two-phase temperature equalizing device for temperature control of a radar seeker of the present invention has a capillary layer processed on the inner wall surface of the cover plate and the base, so that the liquid inside the two-phase temperature equalizing plate is distributed on the inner wall surface of the cover plate and the base through the capillary layer; after the cover plate absorbs the heat of the TR component, the liquid adsorbed by the capillary layer on its inner wall surface can evaporate and absorb heat; and then the heat can be conducted out of the two-phase temperature equalizing plate through the vaporized gas.

[0026] 3. The two-phase temperature equalizing device for the temperature control of the radar seeker according to the present invention realizes the condensation of the vaporized working medium by setting a condenser, and further realizes the recycling of the working medium inside the two-phase temperature equalizing plate; and the reciprocating movement of the working medium between the condenser and the two-phase temperature equalizing plate can occur spontaneously, reducing energy consumption.

[0027] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combined solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can be made obvious from the description, or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the content specifically pointed out in the description and the drawings. Description of the Drawings

[0028] The drawings are only for the purpose of showing specific embodiments, and are not considered as a limitation to the present invention. Throughout the drawings, the same reference signs denote the same components.

[0029] Figure 1 It is a schematic diagram of the heat dissipation principle of the two-phase temperature equalizing device for the temperature control of the radar seeker in Embodiment 1 of the present invention;

[0030] Figure 2 It is an exploded view of the two-phase temperature equalizing plate in Embodiment 1 of the present invention;

[0031] Figure 3 It is one of the schematic diagrams of the capillary structure in Embodiment 1 of the present invention;

[0032] Figure 4 It is the second schematic diagram of the capillary structure in Embodiment 1 of the present invention;

[0033] Figure 5 It is a schematic diagram of the structure of the base in Embodiment 1 of the present invention;

[0034] Figure 6 It is a schematic diagram of the structure of the heat dissipation plate assembly of the radiator in Embodiment 2 of the present invention;

[0035] Figure 7 It is a sectional view effect diagram of the heat dissipation plate assembly in Embodiment 2 of the present invention;

[0036] Figure 8 It is an exploded view of the heat dissipation plate assembly in Embodiment 2 of the present invention;

[0037] Figure 9 It is a half-sectional view effect diagram of the heat dissipation plate in Embodiment 2 of the present invention;

[0038] Figure 10 It is a top view of the heat dissipation plate in Embodiment 2 of the present invention;

[0039] Figure 11Schematic structural diagram of the capillary wick of the radiator in Embodiment 2 of the present invention;

[0040] Figure 12 Schematic structural diagram of the condenser in Embodiment 3 of the present invention;

[0041] Figure 13 Schematic structural diagram of the condenser with a double-layer condensation pipeline in Embodiment 3 of the present invention;

[0042] Figure 14 Schematic diagram of the internal pipeline structure of the condenser with a multi-layer condensation pipeline in Embodiment 3 of the present invention;

[0043] Figure 15 Condenser with a graphene-like crystal-shaped condensation pipeline in Embodiment 3 of the present invention.

[0044] Reference numerals:

[0045] 1 - Two-phase isothermal plate; 2 - Heat sink; 3 - TR component; 4 - Condenser;

[0046] 101 - Cover plate; 102 - Capillary structure; 103 - Base; 1021 - Rectangular plate; 1022 - Strip-shaped plate; 1023 - Protrusion; 104 - Heat dissipation plate; 105 - Transverse strip-shaped groove; 106 - Longitudinal strip-shaped groove; 107 - Circular groove; 108 - Cylindrical hole; 109 - Capillary wick; 109a - Transverse core strip; 109b - Longitudinal core strip; 109c - Circular core; 109d - Cylindrical core;

[0047] 401 - Transverse pipeline; 402 - Longitudinal pipeline; 403 - Spherical connecting pipe; 404 - Shunt pipe; 405 - Intake pipe; 406 - Outlet pipe; 407 - Connecting pipe. Detailed implementation manners

[0048] The following specifically describes the preferred embodiments of the present invention with reference to the accompanying drawings. The accompanying drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principle of the present invention, rather than to limit the scope of the present invention.

[0049] Embodiment 1

[0050] A specific embodiment of the present invention discloses a two-phase isothermal device for temperature control of a radar seeker, such as Figure 1 , Figure 2 , Figure 5As shown in the figure, it includes: a two-phase heat pipe 1 and a heat sink 2; the two-phase heat pipe 1 includes: a cover plate 101, a capillary structure 102, and a base 103; the base 103 is provided with an intermediate cavity for storing liquid water; the capillary structure 102 is arranged inside the base 103, and the capillary structure 102 can absorb water through capillary action; the cover plate 101 and the base 103 are fixedly connected and can seal the intermediate cavity of the base 103; the cover plate 101 is fixedly connected to the TR component 3 of the radar; capillary layers are processed on the inner wall surfaces of the base 103 and the cover plate 101.

[0051] The two-phase heat pipe of the present invention is in direct contact with the TR component electronic device, and by relying on the evaporation and boiling of the working fluid inside the two-phase heat pipe to absorb a large amount of heat, the electronic device is cooled.

[0052] In a specific embodiment of the present invention, the TR component is fastened to both sides of the two-phase heat pipe by screws, and a thermal interface material is coated on the contact surface to reduce the contact thermal resistance.

[0053] In a specific embodiment of the present invention, the thermal interface material can be selected from thermal grease, thermal gel, thermal pad, etc.

[0054] Furthermore, a liquid filling tube is arranged on the side of the two-phase heat pipe, which serves to evacuate and fill the working fluid in the two-phase heat pipe. The cover plate 101 and the base 103 are welded to achieve sealing, ensuring that there is no gas-liquid leakage in the two-phase heat pipe 1.

[0055] In the present invention, the materials of the cover plate 101 and the base 103 include but are not limited to metal materials such as stainless steel, aluminum alloy, magnesium alloy, copper, etc. The cover plate 101 and the base 103 are welded together by welding, and the welding methods thereof include but are not limited to molecular diffusion welding, laser welding, brazing, etc.

[0056] Specifically, to improve the boiling heat transfer efficiency, capillary layers with a thickness of 10 - 100 μm are also processed on the inner surfaces of the base 103 and the cover plate 101.

[0057] In the present invention, the form of the capillary structure 102 includes but is not limited to being formed by high-temperature resistant materials with water absorption effects, metal powders, sintered metal meshes, or a combination of sintered capillary structures and capillary tubes.

[0058] Exemplarily, a capillary plate with high porosity is formed by sintering metal powders on the surface of a metal plate, and then the capillary plate is used to fabricate the capillary structure 102 of the present invention by bonding or welding.

[0059] Or, the metal material is made into a structural shape as shown in Figure 3 、 Figure 4 shown, and then metal powders are sintered on its surface to form the capillary structure 102.

[0060] As Figure 2 shown, the capillary structure 102 includes a plurality of strip plates 1022 arranged side by side.

[0061] As Figure 3 shown, the capillary structure 102 includes a rectangular plate 1021 and strip plates 1022; the strip plates 1022 are symmetrically arranged on both sides of the rectangular plate 1021.

[0062] As Figure 4 shown, a plurality of protrusions 1023 are provided on both sides of the strip plate 1022.

[0063] Furthermore, the capillary layer is a capillary texture processed on the inner wall surface of the two-phase thermosyphon 1; preferably, the width of the capillary texture is 10 - 100 μm.

[0064] In a specific embodiment of the present invention, the capillary texture is a plurality of annular grooves arranged side by side;

[0065] Specifically, the capillary texture is a grid network that is interconnected.

[0066] Specifically, the capillary layer is metal powder or a metal wire mesh sintered on the inner wall surface.

[0067] Furthermore, the heat sink 2 is a heat sink fixedly installed on both sides of the two-phase thermosyphon 1. Alternatively, the heat sink 2 is a condenser 4. The vaporized steam flows to the heat dissipation plate and is liquefied upon cooling, or the vaporized steam enters the condenser 4 for condensation and liquefaction and then returns to the two-phase thermosyphon.

[0068] During implementation, heat is conducted to the base 103 or the cover plate 101 of the two-phase thermosyphon 1 through the thermal interface material, and then the heat is transferred to the internal working fluid through the capillary structure 102. The working fluid is heated and evaporated, boils after reaching the saturation temperature, and absorbs a large amount of heat.

[0069] The vaporized working fluid (water) exchanges heat and condenses through the two heat sinks 2 in contact with the two-phase thermosyphon 1, and finally becomes a liquid working fluid and returns to the heated surface of the two-phase thermosyphon 1 by capillary force, realizing repeated heat dissipation.

[0070] Alternatively, the vaporized working fluid (water) is condensed through the condenser 4 connected to the two-phase thermosyphon 1, and the liquefied liquid working fluid can return to the two-phase thermosyphon 1, thereby enabling the recycling of the working fluid and continuous heat dissipation of the radar heating module.

[0071] Embodiment 2

[0072] A specific embodiment of the present invention is an improvement based on Embodiment 1: providing a two-phase heat pipe 1 with multiple layers of heat dissipation plates 104; the multiple layers of heat dissipation plates 104 are arranged inside the two-phase heat pipe 1 and are smaller than the size of the internal cavity of the two-phase heat pipe 1. The multiple layers of heat dissipation plates 104 are immersed in the liquid working medium inside the two-phase heat pipe 1.

[0073] As Figure 6 , Figure 7 , Figure 8 shown, slotted networks are provided on both the upper and lower surfaces of the heat dissipation plate 104.

[0074] Preferably, the heat dissipation plate 104 is made of a metal material with a high thermal conductivity.

[0075] Furthermore, the thickness of the heat dissipation plate 104 is less than 5 mm.

[0076] Specifically, the structural shapes and sizes of the multiple layers of heat dissipation plates 104 are the same, and the multiple layers of heat dissipation plates 104 are stacked vertically.

[0077] Specifically, as Figure 9 , Figure 10 shown, the slotted network on the surface of the heat dissipation plate 104 includes: a plurality of mutually parallel horizontal strip-shaped grooves 105, a plurality of mutually parallel vertical strip-shaped grooves 106, and a plurality of circular grooves 107; the horizontal strip-shaped grooves 105 and the vertical strip-shaped grooves 106 are perpendicular to each other; the circular grooves 107 are opened at the intersection positions of the horizontal strip-shaped grooves 105 and the vertical strip-shaped grooves 106.

[0078] Furthermore, slotted networks are provided on both the upper and lower surfaces of the heat dissipation plate 104, and cylindrical holes 108 penetrating the heat dissipation plate 104 are opened between two relatively upper and lower circular grooves 107; as Figure 9 shown.

[0079] Furthermore, capillary wicks 109 are filled in the slotted networks and the cylindrical holes 108 on both sides of the heat dissipation plate 104; the capillary wicks 109 in multiple heat dissipation plates 104 are connected to each other.

[0080] As Figure 11 shown, the capillary wick 109 includes: a horizontal core strip 109a, a vertical core strip 109b, a circular core 109c, and a cylindrical core 109d. And, the horizontal core strip 109a, the vertical core strip 109b, the circular core 109c, and the cylindrical core 109d are connected into an integral structure, so that the liquid working medium can diffuse into the whole of the capillary wick 109.

[0081] Among them, the horizontal core strip 109a is arranged in the horizontal strip-shaped groove 105, the vertical core strip 109b is arranged in the vertical strip-shaped groove 106, the circular core 109c is arranged in the circular groove 107, and the cylindrical core 109d is arranged in the cylindrical hole 108.

[0082] In a specific embodiment of the present invention, the capillary wick 109 is made of capillary material.

[0083] In a specific embodiment of the present invention, the capillary wick 109 can be formed by sintering metal powder on the surface of a metal structure; alternatively, the capillary wick 109 can be formed by machining grooves on the surface.

[0084] Furthermore, the topmost heat dissipation plate 104 is in direct contact with the cover plate 101, facilitating rapid heat transfer.

[0085] In the present invention, the capillary wick 109 and the heat dissipation plate 104 are nested, which on the one hand is conducive to rapid heat transfer, and on the other hand is conducive to the rapid evaporation of the liquid working medium, thereby improving the heat dissipation efficiency.

[0086] In this embodiment, the capillary wick 109 includes multiple layers of capillary networks, and the multiple layers of capillary networks are connected by an intermediate cylindrical core 109d; thus, the capillary wick 109 can guide the liquid working medium to the gap between the topmost heat dissipation plate 104 and the multiple layers of heat dissipation plates 104 through capillary force.

[0087] In this embodiment, when the two-phase heat pipe 1 absorbs the heat generated by the TR component and heats up, the heat is transferred to the multiple layers of capillary networks of the capillary wick 109 through the heat dissipation plate 104, and the liquid working medium in the multiple layers of capillary networks simultaneously undergoes evaporation and heat absorption, thereby rapidly absorbing heat and realizing rapid cooling of the TR component.

[0088] In this embodiment, by providing a capillary wick 109 with multiple layers of capillary structures, when the liquid working medium inside the two-phase heat pipe 1 decreases, the liquid working medium can infiltrate the capillary wick 109 under the action of capillary force, so that it still maintains a good heat dissipation effect.

[0089] In this embodiment, through the mutually nested capillary wick 109 and heat dissipation plate 104, rapid heat conduction can be achieved through the heat dissipation plate 104 made of metal material, and at the same time, heat exchange between the heat energy in the metal material heat dissipation plate 104 and the liquid working medium can be realized through the capillary wick 109 nested in multiple layers in the heat dissipation plate 104, promoting the rapid evaporation of the working medium.

[0090] Embodiment 3

[0091] In a specific embodiment of the present invention, on the basis of Embodiment 1, a condenser 4 for the heat pipe device in Embodiment 1 is provided; as Figure 12 、 Figure 13 shown.

[0092] In this embodiment, the condenser 4 includes: a transverse pipeline 401, a longitudinal pipeline 402, and a spherical connecting pipe 403; asFigure 12 As shown, multiple horizontal pipelines 401 are sequentially connected through multiple spherical connecting pipes 403, and multiple vertical pipelines 402 are sequentially connected through multiple spherical connecting pipes 403. The intersection position of the horizontal pipeline 401 and the vertical pipeline 402 shares a spherical connecting pipe 403. The horizontal pipeline 401 and the vertical pipeline 402 form a grid-shaped pipeline network and are internally interconnected.

[0093] In a specific implementation manner of this embodiment, as Figure 14 shown, the condenser 4 is provided with multiple layers of pipeline networks, and adjacent two layers of pipeline networks are connected through a shunt pipe 404.

[0094] In another implementation manner of this embodiment, the pipeline network of the condenser 4 is a crystal-like structure; specifically, as Figure 15 shown, the pipeline network of the condenser 4 is composed of multiple pipeline units spliced together. One pipeline unit is a regular pentagon pipeline composed of five connecting pipes 407 and five spherical connecting pipes 403; adjacent two pipeline units share the connecting pipe 407 and the spherical connecting pipe 403 to form a multi-branch pipeline network.

[0095] Furthermore, the multi-branch pipeline networks of the condenser 4 are arranged in a stacked manner and are connected through a shunt pipe 404 to form a condensation pipeline network with a graphite crystal-like structure (not shown in the figure).

[0096] The crystal-like structure pipeline network condenser 4 of this embodiment can perform multiple shunts and diffusions on the steam, improving the efficiency of its heat dissipation.

[0097] Preferably, the spherical connecting pipe 403 is made of soft metal material; for example: aluminum alloy; by using the deformable characteristics of the soft metal, the size parameters and structural shape of the condenser 4 can be moderately adjusted, and then it can be adapted to the condition limitations of different installation spaces.

[0098] Furthermore, the pipeline network condenser 4 of this embodiment can adjust the positions and angles of each branch pipe according to the shape state of the equipment cabin or the aircraft skin panel, and then it can be fitted with the equipment cabin or the aircraft skin, which is convenient for fixing, reduces the occupied space and can facilitate the rapid transfer of heat to the external environment.

[0099] Furthermore, an air inlet pipe 405 is provided at the highest end of the condenser 4, and a water outlet pipe 406 is provided at the lowest end. Both the air inlet pipe 405 and the water outlet pipe 406 are simultaneously connected to the internal cavity of the two-phase isothermal plate 1.

[0100] Preferably, the condenser 4 stores a spare liquid working medium; when the liquid working medium in the two-phase isothermal plate 1 evaporates, the liquid working medium in the condenser 4 can directly be replenished into the two-phase isothermal plate 1 through the water outlet pipe 406 for evaporation and heat absorption.

[0101] Preferably, the volume of the liquid working medium in the condenser 4 is not less than one-tenth of the total volume of its internal space.

[0102] In this embodiment, the high-temperature steam generated after the evaporation or boiling of the liquid working medium in the two-phase isothermal plate 1 enters the pipeline network of the condenser 4 and exchanges heat with the condenser. After the heat exchange, the temperature of the high-temperature steam decreases and condenses to the liquid state, and then it can flow back to the lowest end, and then can flow back into the two-phase isothermal plate 1 through the water outlet pipe 406.

[0103] During implementation, the air pressure generated by the evaporation of the working medium can also push the liquid working medium in the condenser 4 into the two-phase isothermal plate, thereby realizing rapid liquid replenishment and ensuring the full replenishment of the liquid working medium in the wick.

[0104] As described above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A two-phase temperature equalization device for temperature control of a radar seeker, characterized in that include: Two-phase temperature balancing plate (1) and heat sink (2); The two-phase temperature-averaging plate (1) comprises: a cover plate (101), a capillary structure (102) and a base (103); the base (103) is provided with an intermediate cavity for storing liquid water; The capillary structure (102) is arranged inside the base (103), and the capillary structure (102) can absorb water through the capillary effect; The cover plate (101) and the base (103) are fixedly connected and are capable of sealing the middle cavity of the base (103); the cover plate (101) is fixedly connected to the TR component (3) of the radar; and the inner wall surfaces of the base (103) and the cover plate (101) are both processed with a capillary layer.

2. The two-phase temperature equalization device for temperature control of a radar seeker according to claim 1, wherein, The capillary structure (102) includes a plurality of strip plates (1022) arranged in parallel.

3. The two-phase temperature equalizing device for temperature control of a radar seeker according to claim 1, characterized in that, The capillary structure (102) comprises a rectangular plate (1021) and a strip plate (1022); the strip plates (1022) are symmetrically arranged on both sides of the rectangular plate (1021).

4. The two-phase temperature equalization device for temperature control of a radar seeker according to claim 2 or 3, characterized in that, A plurality of protrusions (1023) are provided on both sides of the strip plate (1022).

5. The two-phase temperature equalization device for temperature control of a radar seeker according to any one of claims 1 to 3, characterized in that, The capillary layer is a capillary pattern machined on the inner wall surface of the two-phase temperature balancing plate (1).

6. The two-phase temperature equalization device for temperature control of a radar seeker according to claim 5, characterized in that, The capillary lines are annular grooves arranged in parallel.

7. The two-phase temperature equalizing device for temperature control of a radar seeker according to claim 5, characterized in that, The capillary lines are interconnected grid networks.

8. The two-phase temperature equalization device for temperature control of a radar seeker according to any one of claims 1-3, characterized in that, The capillary layer is metal powder or metal wire mesh sintered on the inner wall surface.

9. The two-phase temperature equalization device for temperature control of a radar seeker according to claim 8, characterized in that, The heat sink (2) is a heat sink fixedly mounted on both sides of the two-phase temperature balancing plate (1).

10. The two-phase temperature equalization device for temperature control of a radar seeker according to claim 8, characterized in that, The heat sink (2) is a condenser (4).

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