CN101325118A - Dry-type transformer with vapor-liquid two-phase cooling circuit - Google Patents

Abstract

The invention discloses a dry-type transformer with a vapor-liquid two-phase heat dissipation circuit, comprising at least one iron core and at least one coil assembly arranged around the iron core, wherein the dry-type transformer has at least one vapor-liquid two-phase heat dissipation circuit, The vapor-liquid two-phase heat dissipation circuit includes an evaporator arranged in the area of the coil assembly, a condenser arranged outside the dry-type transformer, a vapor-phase pipeline connected between the vapor-phase outlet of the evaporator and the vapor-phase inlet of the condenser, and a vapor-phase pipeline connected to the The liquid phase pipeline between the liquid phase outlet of the condenser and the liquid phase inlet of the evaporator, and the vapor-liquid two-phase working fluid circulating in the vapor-liquid two-phase cooling circuit. The invention adopts the method of direct evaporation-condensation inside the loop, and utilizes evaporation to convert part of the heat into kinetic energy of steam and potential energy of liquid to drive or partially drive the loop to realize efficient heat dissipation of the transformer.

Description

Dry-type transformer with vapor-liquid two-phase cooling circuit

technical field

The invention relates to a dry-type heat dissipation transformer structure; more specifically, the invention relates to a dry-type transformer with a vapor-liquid two-phase heat dissipation circuit.

Background technique

Traditional transformers generally use oil-immersed heat dissipation, and the heat generated by the coil is taken out by the natural convection of the oil and dissipated into the air. However, this cooling method is less efficient.

Later, people invented the evaporative cooling transformer, by spraying the surface of the transformer coil (such as the related technology disclosed in Japanese Patent No. 58101407 and No. No. 3887759 and the related technology disclosed in No. 4011535) to dissipate heat.

For the transformer placed underground, a heat dissipation method of "heat pipe" (as disclosed in Japanese Patent No. 7037725) or "loop heat pipe" (as disclosed in Japanese Patent No. 7220936) has been invented. However, in the above inventions, the transformers are all placed in packaging containers, and the transformers are cooled by the evaporation of insulating gas, liquid or liquid; the "loop heat pipe" method also includes multiple heat exchangers, and the heat exchange efficiency is low.

With the development of dry-type transformers and heat dissipation technologies, the above heat dissipation methods for transformers cannot provide high heat dissipation efficiency. Dry-type transformers generally adopt the natural convection cooling method of air. For example, there is a gap of tens of millimeters between the low-voltage coil and the high-voltage coil that generate a lot of heat, so that a sufficient amount of air can pass through to dissipate heat from the low-voltage coil and the high-voltage coil. However, this design is effective for low-power dry-type transformers, but with the increase of power, the volume of the coil increases and the heat generation is large. The general natural convection of air cannot effectively cool the dry-type transformer.

Therefore, it is an urgent problem to provide a dry-type transformer capable of realizing high-efficiency heat dissipation.

Contents of the invention

The purpose of the present invention is to provide a dry-type transformer with a vapor-liquid two-phase heat dissipation circuit capable of realizing high-efficiency heat dissipation.

The technical solution of the present invention is achieved by providing a dry-type transformer with a vapor-liquid two-phase heat dissipation circuit, including at least one iron core and at least one coil assembly arranged around the iron core, wherein the dry-type transformer has at least one The vapor-liquid two-phase heat dissipation circuit, the vapor-liquid two-phase heat dissipation circuit includes an evaporator arranged in the area of the coil assembly, a condenser arranged outside the dry-type transformer, and connected between the vapor phase outlet of the evaporator and the vapor phase inlet of the condenser The vapor phase pipeline, the liquid phase pipeline connected between the liquid phase outlet of the condenser and the liquid phase inlet of the evaporator, and the vapor-liquid two-phase working fluid circulating in the vapor-liquid two-phase cooling circuit.

The dry-type transformer two-phase loop heat dissipation method of the present invention is to absorb the heat emitted by the coil by evaporating the liquid (such as water) through the evaporator inside the transformer, and bring the steam to the condenser outside the transformer through loop circulation, and condense it again into liquid, while dissipating heat into the air through the condenser. Different from general evaporative heat dissipation transformers, the evaporation-condensation process of the present invention occurs inside the circuit, so the volume is small and the required cooling medium is also small.

The invention adopts a loop-type two-phase heat dissipation technology, which can not only realize effective cooling of large dry-type transformers, but also reduce the gap between low-voltage coils and high-voltage coils, thereby saving coil wires.

The invention also uses (or partially utilizes) the evaporation of the liquid to convert part of the heat into the kinetic energy of the steam and the potential energy of the liquid to drive (or auxiliary drive) the loop circulation and realize efficient heat dissipation of the transformer.

The driving method of the circuit depends on the technical requirements such as the structure of the transformer and heat dissipation, and the structure and location of the main components of the circuit are also different. The drive mode of the circuit includes pump drive, gravity drive and capillary force drive. Those with small heat dissipation requirements generally adopt evaporation-gravity drive and capillary force drive, which are characterized by no moving mechanical parts and external energy; those with large heat dissipation requirements generally adopt pump drive methods. According to the structure of the evaporator (such as a spiral evaporator), the evaporator can be connected to the circuit through an electrically insulating connector, so that the liquid circulates in the circuit while suppressing or reducing the eddy current loss. The electrically insulating connection can be at the inlet or outlet of the evaporator, or at the same time at the inlet and outlet of the evaporator.

The working fluid of the two-phase circuit can be (but not limited to) water, ammonia, propylene, etc.; the general requirements are non-toxic, non-flammable, non-conductive fluid, and its freezing point should be lower than the lowest temperature of the transformer working environment; It can be a pure substance, or a mixture of two or more different substances, for example, a mixture of water and ammonia with a mass ratio of 9:1.

Optionally, the condenser can be arranged above the dry-type transformer. In this case, it further includes a liquid accumulator disposed between the liquid phase outlet of the condenser and the liquid phase inlet of the evaporator, and the liquid accumulator is also located above the dry-type transformer. At this time, preferably, a one-way valve, a filter, and an electrically insulating connector are provided before the liquid phase inlet of the evaporator; and the one-way valve and the insulating connector can be integrated as a whole. The bottom wall of the reservoir slopes toward the outlet end of the reservoir. Alternatively, when the accumulator is located above the dry-type transformer, the condenser and the accumulator can be combined into a condensate accumulator.

Optionally, it further includes a circulation pump arranged in the liquid phase pipeline. At this time, the condenser and the liquid reservoir can be arranged at any position outside the dry-type transformer, such as above or below the dry-type transformer. At this time, preferably, a one-way valve connected in parallel with the circulation pump is provided before the liquid phase inlet of the evaporator.

Optionally, it further includes a liquid accumulator disposed between the liquid phase outlet of the condenser and the liquid phase inlet of the evaporator, and the liquid accumulator is located below the dry-type transformer. At this time, preferably, at least one capillary liquid absorbing wick is arranged in the liquid reservoir, and the capillary liquid absorbing wick extends upwards at least to the inlet of the evaporator.

Among them, the coil assembly includes a low-voltage coil close to the iron core and a high-voltage coil located on the periphery of the low-voltage coil. There is a gap between the low-voltage coil and the high-voltage coil, and the evaporator can be arranged in the gap, or the evaporator can also be arranged on the low-voltage coil. and/or the interior of the high voltage coil, alternatively, the evaporator can be attached to the outer surface of the low voltage coil.

Specifically, the evaporator includes at least one heat exchange tube and/or heat exchange plate.

Optionally, the evaporator includes eight or more heat exchange tubes, and the eight or more heat exchange tubes are arranged in parallel between the liquid phase inlet and the vapor phase outlet of the evaporator. Preferably, the evaporator includes upper and lower manifold connectors. Here, a manifold connector is a connecting device that connects multiple pipes with a single pipe or a small number of pipes. The upper and lower manifold connectors may further be provided with one-way valves, filters and/or temperature sensors such as armored thermocouples. The vapor phase outlet and the liquid phase inlet of the evaporator are respectively set at the upper manifold connector and the lower manifold connector, and the upper and lower ends of eight or more heat exchange tubes are respectively connected with the upper manifold and the lower manifold connector .

In another way, the evaporator evaporator may include an upper ring pipe and a lower ring pipe, and the upper and lower ends of eight or more heat exchange tubes may communicate with the upper ring pipe and the lower ring pipe respectively.

Optionally, the evaporator includes four or more heat exchange plates, and the four or more heat exchange plates are arranged in parallel between the liquid phase inlet and the vapor phase outlet of the evaporator.

Optionally, the evaporator includes four or more heat exchange plates and four or more heat exchange tubes, and the four or more heat exchange plates and four or more heat exchange tubes are connected between the liquid phase inlet and the four or more heat exchange tubes of the evaporator. The vapor phase outlets are set in parallel.

Optionally, the heat exchange tubes of the evaporator are formed of tubular coil windings of a dry-type transformer.

Optionally, the evaporator includes at least one spiral heat exchange tube surrounding the outer surface of the low-pressure coil.

Optionally, the heat exchange plate and/or the heat exchange tube are arranged inside the low voltage coil.

Preferably, insulated connectors are respectively provided at the connections between the evaporator and the vapor phase pipeline and the liquid phase pipeline, including an insulated connector integrating a one-way valve, a filter and a manifold connector.

Optionally, it includes a plurality of parallel heat exchange tubes, and each heat exchange tube may be in a wave shape or a pulse shape, or similar to a stepped shape.

Optionally, a plurality of heat exchange tubes may be interlaced and stacked.

Optionally, the cross-section of the heat exchange tube evaporator can be round or flat; along the direction of the heat exchange tube, the tube wall can be pressed into a shape matching the shape of the coil to increase the heat exchange area.

In addition, other components such as valves and filters may also be provided in the circuit.

The beneficial effects of the present invention are: 1. The present invention adopts the method of direct evaporation-condensation inside the circuit, and utilizes evaporation to convert part of the heat into kinetic energy of steam and potential energy of liquid, and drives or partially drives the circuit to circulate, so as to realize high-efficiency transformer heat dissipation 2, the evaporation-condensation process of the present invention completely takes place inside the circuit, therefore, the volume of the cooling circuit structure is small, and the required cooling medium is also less; 3, the heat dissipation method of the present invention can also reduce the distance between the low-voltage coil and the high-voltage coil The gap between them reduces the size of the transformer and saves materials.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to these embodiments, and any improvement or substitution on the basic spirit of the present invention still belongs to the scope of protection claimed in the claims of the present invention.

Description of drawings

Fig. 1 is a schematic diagram of a dry-type transformer according to Embodiment 1 of the present invention.

Fig. 2 is a schematic diagram of a dry-type transformer according to Embodiment 2 of the present invention.

Fig. 3 is a schematic diagram of a dry-type transformer according to Embodiment 3 of the present invention.

Fig. 4 is a schematic cross-sectional view of a cage heat pipe evaporator structure of the present invention.

Fig. 5 is a schematic longitudinal sectional view of a cage heat pipe evaporator structure of the present invention.

Fig. 6 is a schematic cross-sectional view of a structure of a plate heat pipe evaporator according to the present invention.

Fig. 7 is a schematic longitudinal sectional view of a structure of a plate heat pipe evaporator according to the present invention.

Fig. 8 is a schematic diagram of a three-phase dry-type transformer of the present invention.

Fig. 9 is a schematic cross-sectional view of a structure of a pulsating heat pipe evaporator according to the present invention.

Fig. 10 is a schematic longitudinal sectional view of a structure of a pulsating heat pipe evaporator according to the present invention.

Fig. 11 is a schematic diagram of a structure of a pulsating stepped heat pipe evaporator according to the present invention.

Fig. 12 is a schematic diagram of the structure of an electrical insulation manifold connector of the present invention, wherein (a) is a longitudinal sectional view of the upper manifold connector; (b) is a longitudinal sectional view of the lower manifold connector; (c) It is a cross-sectional view of the connection end of the manifold connector and the evaporator.

Fig. 13 is a schematic diagram of another insulating connector structure adopted in the present invention.

FIG. 14 is a schematic perspective view of a cage heat dissipation structure of the present invention.

Detailed ways

Example 1

Please refer to FIG. 1 , this embodiment adopts an evaporation-gravity-driven dry-type transformer two-phase cooling circuit structure. The dry-type transformer may be a three-phase transformer, including three iron cores, as shown in FIG. 8 . An iron core is now used for illustration. The iron core 30 and the coil assembly surrounding the iron core 30 , and the coil assembly generally includes a low voltage coil 50 and a high voltage coil 70 , and a gap 57 filled with electric insulating filler is provided between the low voltage coil 50 and the high voltage coil 70 .

The two-phase cooling circuit includes an evaporator 100 that is in good thermal contact with the coil assembly inside the dry-type transformer, a condenser 300 outside the transformer, and a liquid reservoir 500, and passes through the fluid pipeline (including the vapor phase pipeline 610 and the liquid phase pipeline 610). Conduit 630) constitutes a circuit. The evaporator 100 can be (but not limited to) a spiral tube 130 arranged close to the outer surface of the low-voltage coil 50, and an electrically insulating connector (not shown) is used at the inlet and outlet to form a liquid circuit, but not an electrical circuit, so as to Reduce eddy current loss. Wherein, the spiral tube 130 is wound with a copper tube or a stainless steel tube outside the low-voltage coil 50 , and the fabricated metal spiral tube will have good thermal contact with the low-voltage coil 50 .

The condenser 300 and the liquid storage 500 can be integrated by design, so that the liquid storage 500 has the functions of condensation and cooling, and at the same time, the liquid level inside the liquid storage 500 does not change much.

When the transformer is working, the heat generated by it causes the liquid in the evaporator 100 to evaporate into steam. Due to the low density of the steam, the steam rises and condenses into liquid in the condenser 300; The pipes between the evaporators 300 are filled with steam or liquid-vapor two-phase mixture, while those between the liquid receiver 500 and the evaporator 100 are filled with liquid, and under the action of gravity, the liquid with high density flows downward, thus forming A two-phase circulation loop. The maximum driving force of the loop depends on the vapor content and the height of the liquid reservoir 500 relative to the evaporator 100; while the flow rate of the loop depends on the evaporation amount (heating value of the transformer). At the inlet of the evaporator 100, an orifice throttling valve (not shown) may be connected as required.

The advantage is that no external drive (energy consumption) is required and no moving parts.

Example 2

Please refer to FIG. 2 , this embodiment adopts a two-phase heat dissipation circuit structure of a dry-type transformer driven by capillary force. Among them, the liquid reservoir 500 is placed at the bottom of the circuit, from the liquid reservoir 500 to the evaporator 100, there is a capillary liquid suction wick 700 in the pipeline, so that the liquid climbs to the evaporator 100 against gravity and evaporates in the evaporator 100 endothermic. After the steam rises to the condenser 300 and recondenses into a liquid, it returns to the liquid storage 500 along the pipeline from the condenser 300 to the liquid storage 500 . By design, the liquid reservoir 500 can further cool the liquid. The driving force of this structure depends on the capillary force of the liquid-absorbing core 700, and the maximum flow rate depends on the driving force and flow resistance of the liquid-absorbing core 700. The evaporator 100 may adopt (but is not limited to) a spiral tube 130 disposed close to the outer surface of the low-voltage coil 50 .

Example 3

Please refer to FIG. 2 , this embodiment adopts a two-phase cooling circuit structure of a dry-type transformer driven by a circulating pump. Among them, the liquid reservoir 500 is placed at the top or bottom of the circuit, which acts as a liquid compensation; when the working pressure on the circuit is required to be higher than one atmospheric pressure, it is at the top of the circuit; and when the working pressure is required to be lower than one atmospheric pressure , which is at the bottom of the loop. The liquid flows to the evaporator 100 under the action of the pump 800, and evaporates and absorbs heat in the evaporator 100 to form a two-phase fluid and continue to flow upward to the condenser 300. After the two-phase fluid condenses into a liquid, it is sucked back to the inlet of the pump 800. form a loop.

Since the circuit is driven by the circulation pump 800, its flow has nothing to do with the evaporation amount, and the heat dissipation capacity of the system depends on the heat dissipation area of the fins on the condenser 300. An electric fan (not shown in the figure) can be further used, and the cooling capacity of the condenser 300 can be significantly increased by means of forced convection (or even spraying). The evaporator 100 can adopt, but is not limited to, a spiral tube 130 arranged close to the outer surface of the low-voltage coil 50, and an electrically insulating connector (not shown) is used at the inlet and outlet to form a liquid circuit, but not an electrical circuit, so as to Reduce eddy current loss.

For the circuit where the liquid reservoir is above the transformer, optionally, a check valve connected in parallel with the circulation pump is installed at the inlet of the evaporator. When the transformer is at or close to no-load (low calorific value), it is not necessary to start the circulation pump. The working mode of Example 1 is used to dissipate heat.

The evaporator 100 of this system is relatively simple, has high stability in system operation, and large heat dissipation.

Example 4

As another scheme of the present invention, other parts are identical with embodiment 1, 2 or 3, and difference is: for the transformer of high power, its low-voltage coil 50 can be made by winding with copper tube; Copper tube itself conducts electricity, The inside of the tube is used as an evaporator 100 .

Example 5

As another solution of the present invention, other parts are the same as those in Embodiment 1, 2 or 3, except that, as shown in FIG. 4 and FIG. 5 , the evaporator 100 is a cage heat pipe evaporator. The evaporator 100 is formed by connecting the upper and lower heat exchange tubes 150 to the upper and lower two non-closed annular tubes 156 (the non-closed annular tubes 156 are for suppressing eddy current loss), and is a parallel fluid channel structure; The upper and lower annular pipes 156 are the outlet and inlet of the evaporator 100, respectively.

Example 6

As another solution of the present invention, other parts are the same as those in Embodiment 1, 2 or 3, except that, as shown in FIG. 6 and FIG. Similar to the cage-type heat pipe evaporator 100, several tubes are replaced with hollow thin plates 160 with an internal structure, which can increase the contact (heat exchange) area and save the space of the evaporator 100.

The upper and lower ends of the "hot plate" are respectively connected to the upper and lower two non-closed annular pipes 166, and the upper and lower annular pipes 166 are the outlet and the inlet of the evaporator 100 respectively.

Since the "hot plate" is thin, it is installed inside the low-voltage coil 50 in this embodiment to enhance the heat dissipation effect.

Meanwhile, in this embodiment, the heat exchange tubes 150 oriented up and down are also used.

Example 7

As another solution of the present invention, other parts are the same as in Embodiment 6, except that the hollow thin plate 160 is installed in the gap 57 between the low-voltage coil 50 and the high-voltage coil 70, (insulating filler is poured into the gap 57) , and cling to the outer surface of the low-voltage coil 50 . Also, the heat exchange tubes 150 oriented up and down may not be provided.

Example 8

As another solution of the present invention, the other parts are the same as in Embodiment 1, 2 or 3, except that the heat exchange tube 150 of the evaporator 100 adopts a pulsating structure as shown in FIG. 9 and FIG. 10 .

Example 9

As another solution of the present invention, the other parts are the same as in Embodiment 1, 2 or 3, except that the heat exchange tube 150 of the evaporator 100 adopts a stepped pulsation structure as shown in FIG. 11 .

Example 10

As another solution of the present invention, other parts are the same as in Embodiment 5, the difference is that, as shown in FIG. Cage type heat dissipation structure. The manifold connector can be integrated with (but not limited to) the armored thermocouple 1000, and its structure is shown in Figure 12(a)-(c), wherein, Figure 12 (a) is a longitudinal section view of upper manifold connector 960, which includes armored thermocouple 1000, electrical insulation material 950, manifold channel 1010, and gas outlet channel 1020; (b) is the lower manifold connector 970 Longitudinal sectional view, which includes armored thermocouple 1000, electrical insulating material 950, one-way valve 990, filter 995, manifold channel 1010, and liquid inlet channel 1025; (c) is the transverse direction of the manifold connector and the evaporator connection end Sectional view.

In addition, further different from Embodiment 5, the coil of this embodiment may be cylindrical.

Example 11

As another solution of the present invention, the other parts are the same as in Embodiment 1, except that the liquid is connected to the evaporator by using an insulated connector as shown in Figure 13, and the insulated connector can be connected to the armored thermocouple 1000, the electrically insulating one-way valve 990 and the filter 995 are combined into a whole.

Claims (10)

1. A dry-type transformer with a vapor-liquid two-phase cooling circuit, comprising at least one iron core and at least one coil assembly arranged around the iron core, characterized in that the dry-type transformer has at least one vapor-liquid two-phase A phase heat dissipation circuit, the vapor-liquid two-phase heat dissipation circuit includes an evaporator arranged in the area of the coil assembly, a condenser arranged outside the dry-type transformer, a vapor phase outlet connected to the evaporator and the condenser The vapor phase pipeline between the vapor phase inlet of the condenser, the liquid phase pipeline connected between the liquid phase outlet of the condenser and the liquid phase inlet of the evaporator, and circulation in the vapor-liquid two-phase cooling circuit Flowing gas-liquid two-phase working fluid. 2. The dry-type transformer according to claim 1, characterized in that the condenser is arranged above the dry-type transformer, and further comprises a liquid phase outlet arranged between the condenser and the evaporator. A liquid reservoir between the liquid phase inlets, the liquid reservoir is located above the dry-type transformer. 3. The dry-type transformer with vapor-liquid two-phase heat dissipation circuit according to claim 2, further comprising a circulation pump arranged in the liquid phase pipeline. 4. The dry-type transformer according to claim 1, further comprising a liquid reservoir arranged between the liquid phase outlet of the condenser and the liquid phase inlet of the evaporator, the liquid storage The reservoir is located below the dry-type transformer, and at least one capillary liquid-absorbing core is arranged in the liquid reservoir, and the capillary liquid-absorbing core extends upwards at least to the inlet of the evaporator. 5. The dry-type transformer according to any one of claims 1-4, wherein the evaporator includes at least one heat exchange tube and/or heat exchange plate, and the coil assembly includes a low-voltage coil and a high-voltage coil, so A gap filled with electrical insulating filler is provided between the low-voltage coil and the high-voltage coil, and the heat exchange plate and/or heat exchange tube are arranged in the gap or inside the low-voltage coil and/or high-voltage coil . 6. The dry-type transformer according to claim 5, wherein the evaporator includes eight or more heat exchange tubes, or the evaporator includes four or more heat exchange plates, or the evaporator The device includes four or more heat exchange plates and four or more heat exchange tubes; wherein, the heat exchange tubes and/or the heat exchange plates are located between the liquid phase inlet and the vapor phase outlet of the evaporator set in parallel. 7. The dry-type transformer according to claim 6, wherein the evaporator further comprises an electrically insulated upper manifold connector and a lower manifold connector, the vapor phase outlet and the liquid phase inlet of the evaporator respectively arranged on the upper manifold connector and the lower manifold connector, the upper and lower ends of the heat exchange tubes and/or the heat exchange plates are respectively connected to the upper manifold connector and the lower manifold connector connected. 8. The dry-type transformer according to any one of claims 1-4, wherein the evaporator comprises at least one spiral heat exchange tube surrounding the low-voltage coil. 9. The dry-type transformer according to any one of claims 1-4, characterized in that, the heat exchange tube of the evaporator is composed of tubular coil windings of the dry-type transformer. 10. The dry-type transformer according to claim 7, characterized in that, the upper manifold connector and the lower manifold connector are further provided with check valves, filters and/or temperature sensors such as armored thermocouples .

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