JPS60102712A - Evaporative cooling type gas insulating electrical apparatus - Google Patents

Abstract

PURPOSE:To make boundary surfaces in a plurality of cooling ducts higher than that in a tank, and to extend the area of heat dissipation by communicating the lower end sections of the cooling ducts, which are erected and upper end sections thereof are closed, with the tank. CONSTITUTION:A cooler 21 consisting of cooling ducts 22 and a tank 2 are communicated through a lower header 4b and a lower communicating pipe 12, and the upper sections of the cooler are closed. When a temperature rises and vapor pressure increases, boundary surface 13 upwardly moves, but the cooler 21 side is higher than the tank 2 side regarding the positions of height of boundary surfaces when the horizontal sectional areas of the tank 2 and the cooler 21 are equal in the vertical direction because a gas temperature in the tank 2 is higher than that in the cooler 21 and the volume shrinkage rate of a gas 9 on the cooler 21 side is larger than that on the tank 2 side.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to evaporatively cooled gas insulated electrical equipment, particularly.

This invention relates to a cooler that aims to improve cooling efficiency and reduce the size and weight of the cooler.

[Prior art]

Conventionally, in electrical equipment such as transformers, there has been a so-called evaporative cooling method that uses a refrigerant with a phase change as an efficient means of dissipating internal heat generation.
As shown in the figure.

In the figure, an electrical device 1 that generates heat is housed in a tank λ, and the cooler 3 and the tank are communicated via upper and lower headers Qa and lb. In addition, the tank is filled with a certain ratio of non-condensable gas 9 (hereinafter referred to as gas) and a refrigerant that undergoes a gas-liquid phase change when heat is exchanged. The liquid is discharged into the tank tank through the pipe 7 by the liquid pump 6, and is sprayed onto the electric equipment 1 that generates heat. A part of the liquid phase refrigerant S sprayed on the electrical equipment L absorbs heat from the electrical equipment L and at the same time vaporizes to become refrigerant vapor g, but if the specific gravity of this refrigerant vapor g is greater than the specific gravity of gas 9. In this case, the refrigerant vapor g sinks downward and stagnates, and also enters the cooling duct IO through the lower communication pipe /U and the lower header tIb. Therefore.

In this cooling duct IO, the refrigerant vapor is liquefied at the same time as heat is released, and heat is radiated according to the heat radiating capacity of the cooler using the refrigerant as a heat transporter. In such a cooling system, the refrigerant vapor t stagnates downward due to the difference in specific gravity, and the gas 9
is chased upward, so the inside of the tank and the cooler 3
An interface /3 between the refrigerant vapor zone and the gasta occurs within the chamber.

However, since refrigerant vapor is constantly generated from electrical equipment that generates heat, there is actually a clear boundary within the tank.
However, the boundary surface imaginary based on the volume ratio of each refrigerant vapor gas depending on the pressure will be referred to as the boundary surface 13 here. This boundary surface /3 has the configuration shown in FIG.
When communicating through the two lower communication pipes, the cooler 3 side and the inside of the tank are always at the same height HO, and the portion above the boundary surface 13 has a low heat transport capacity. Since the cooling duct 10 of the cooler 3 is filled with a low gasta, the cooling duct 10 of the cooler 3 contributes to effective heat dissipation only up to the height Ho of the interface 13. Therefore, even if a large cooler is installed, there is a drawback that the utilization rate of the cooling area is very low.3 Note that the symbol // is a blower for heat radiation.

[Summary of the invention]

The present invention aims to eliminate the drawbacks of the conventional device described above, improve the utilization rate of the cooling area, and thereby obtain a small evaporative cooling type gas insulated electrical device with a large heat dissipation capacity. .

The cooler includes a plurality of cooling ducts that stand upright and have their upper ends closed, and a lower header that communicates the cooling ducts at the lower ends of the cooling ducts, and connects the cooler and the tank with the lower header. This evaporative cooling type makes it possible to make the cooler smaller and improve its heat dissipation capacity by making the boundary surface inside the cooling duct higher than that inside the tank and expanding the heat dissipation area. Gas insulated electrical equipment is provided.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on figures showing embodiments thereof.

In FIG. 2, a cooler 21 consisting of a cooling duct and a tank are in communication only through a lower header +b and a lower communicating pipe /j, and the upper part of the refrigerant is closed. Note that other than these points, this device is the same as the conventional device.

In such a configuration, the operation when a combination of refrigerant and gas in which the specific gravity of the refrigerant vapor that has undergone evaporation change is larger than the specific gravity of the gas is sealed will be described below.

FIG. 3 shows a cold state in which the electrical equipment 1 does not generate heat in the present invention. At this time, since the vapor pressure of the refrigerant is low, most of the space inside the tank is filled with gas 9 (4'), and the internal pressure of the tank λ at this time is assumed to be P.

Next, FIG. 9 shows an initial transient state in which the electrical equipment takes on a load and shifts to a heat generating state. At this time, a part of the liquid phase refrigerant j that is dropped comes into contact with the heat generating part and vaporizes, but due to its large specific gravity, these refrigerant vapors sink to the bottom of the tank and stagnate, causing the gas 9 above to stagnate. An interface 13 is formed between the two. At this time, if the gas pressure is Pλ, the steam pressure is also equal to P and 2, and both are pressed against the boundary surface 13 with the same pressure and are balanced. The pressure P,2 is also the saturated vapor pressure of this refrigerant determined by the vapor temperature TVJ at this time.

As the heat generation continues, the amount of evaporation of the liquid phase refrigerant S increases, and the vapor temperature also rises from TvJ to TVj.The vapor pressure also rises to P3, driving the gas further upward, and the boundary surface 13 is lowered. It reaches just before the top of the communication pipe. The state at this time is shown in Figure S. In this state, the gas is still communicated between the tank and the cooler 21 through the lower communication pipe 2, so the height of the boundary surface 13 is the same inside the tank and on the cooler 2 side. At this time, 90 volumes of gas above the boundary surface /3 are VT on the tank side,
? , the cooling f%,2 is set to Vc3 on the side. Also, the average temperature of tank 2 and cooler, 2/inside σ) gas t.]
・Set it as 3.

Furthermore, as the VC temperature rises and the vapor pressure increases to become Pu, the interface / , ? moves further upwards beyond the upper end of the lower communicating tube, and the state at this time is shown in FIG. Let the volume of gas q above the boundary surface /3 in FIG. 6 be VTg on the tank 2 side and Vcq on the cooler 21 side. Also, let Pg be the gas temperature in the tank, g IkTiI, the cooler, 2/in θ).

Cooler, 2/ Because the gas tank inside is far from the heat source and is cooled cumulatively from the outside,
z ・ ・ ・(1) There are 3C. x62, In the state shown in Figure 6, the interface with refrigerant vapor g / , ? exists separately in the tank and in the cooler unit, and the respective volumes 'VTf' and V
cz is determined by the formula below.

(7) Therefore.

becomes. Therefore, from equations (1), (4'), and (r).

vTiI/■T3-Vc*/Vc3--Value B). This equation (A) means that the volumetric contraction rate of the gas on the cooler side is larger than on the tank side. Therefore, if the horizontal cut Ifji products of the tanker and cooler si are uniform in the vertical direction, the height position of the boundary surface is as shown in FIG. 6 according to equation (A).

If the cooler U side is Ht and the cooler 2 side is Hs, then the old
It becomes H.

For comparison, a state diagram of a conventional device is shown in Figure 2 (Ir). In this case too, '? >Tt relationship holds, but
Since the gas in the cooler 3 and the tank are communicated through the upper communication pipe /4' from the upper header 4ta, the height of the interface /3 is the same height HO on the tanker side and the cooler 3 side. , H7>Ho>H,2-...(7).

According to the invention, therefore, a larger volume within the cooler 21 can be filled with refrigerant vapor, and the cooling duct, 2.2
Since the heat dissipation area of the equipment can be effectively utilized and the heat dissipation area of the equipment can be made small, it is possible to make the cooler λ/ smaller and lighter.

Next, another embodiment of the present invention is shown in FIG. In contrast to FIG. 2 showing the above-described embodiment of the present invention, FIG. 3 shows an arrangement in which an upper header 33 that does not communicate with the tanker is installed above the three cooling ducts of the cooler 3/.

In this case, a part of the gas 9 is pushed into the upper header 33, so that the refrigerant vapor t reaches further above the cooling ducts 3.
The cooling area can be used more effectively.

FIG. 9 shows a state corresponding to FIG. S in this configuration, and the internal pressure at this time is P? , the average temperature of the gas is Tq,
The volume of gas above the boundary surface 13 is VT on the tank side?
, VC on the cooler side? shall be. Also.

The state corresponding to FIG. 6 is shown in FIG. 1O, and the internal pressure at this time is Pto, and the gas temperature inside the tank is T/θ.

If the gas temperature in the cooler 31 is T//, the gas volume on the tanker side is VTlo, and the gas volume on the cooler 31 side is clo, then the following holds true.

Here, VC? is equal to the sum of the total volume VD of the three cooling ducts and the total volume VUH of the upper header 33.

Let Vct = VD 10VUH...-(g).

Furthermore, assuming that the gas 90 portion acts as a heat insulator,
Since T9 and T// are almost equal and can be approximated as (TvzTlz), equation (ri) can be expressed as the following (qj equation).

Plθ■CIO:P9vCq ・ ・ ・ (q) Here Pro-p.

■If old()□□VD -e I(lθ) q holds, then (fl, (q), (t
From the formula o), VczO=VTJH111(it) holds true.

Therefore, if the vapor pressure in a predetermined operating state is Plo,
(tO) so that the formula holds true, the upper header volume VUH
If you set l-, in this operating state, all the gas will be pushed into the upper header 33 according to the formula Ot), and all the three cooling ducts will be filled with refrigerant vapor, so the cooler 31 will have less heat. All of the heat dissipation area can be used for effective cooling. Incidentally, if the operating state in which the steam pressures P and θ are set as the maximum load condition, this electric device can be operated at substantially constant steam pressure and steam temperature under all operating load conditions. In other words, when the load is small, the vapor pressure is low, so the cooling duct is only partially filled with refrigerant vapor, and as a result, the effective heat dissipation area is small (Figure ii), so the temperature rises and the pressure also decreases. This increases the effective cooling area by raising the boundary surface 13 inside the cooling duct 3. When the load is large, the vapor pressure is large, so the boundary surface /3 is located above the cooling duct 32 and is effective. As the heat dissipation area increases (Fig. 7.2), the steam temperature and steam pressure decrease, which acts to lower the boundary surface 13 and reduce the effective cooling area. Also, the steam pressure is almost constant,
Stable operation is possible where the temperature and interface height settle down and converge.

In addition, as explained above, there is a difference in the height of the boundary surface between the tank side and the cooler side at the point where the boundary surface reaches the upper end of the lower communication pipe, so the position of the lower communication pipe should be adjusted as much as possible. By placing it on the side of the tank near the bottom of the tank, it can be effective at lower steam pressure and lower steam temperature.

〔Effect of the invention〕

In the present invention, as described above, a plurality of cooling ducts with closed upper ends are provided upright, and a ladder is provided at the lower end communicating with the tank only at the lower end, so that refrigerant vapor and gas can be exchanged. The boundary surface is higher on the cooler side than on the tank side, expanding the heat dissipation surface, resulting in an evaporatively cooled gas insulated electrical device that improves cooling efficiency and allows the cooler to be made smaller. have.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view of a conventional evaporative cooling type gas-fed electric device, Fig. 1 is a schematic cross-sectional view of an embodiment of the present invention, and Fig. 3 is a refrigerant vapor when the electric device shown in Fig. 1 is in a cooling state. Fig. 9 is an explanatory diagram of the state of the electric equipment in Fig. 1 at the initial stage of heat generation; The figure is an explanatory diagram of the state when the electric equipment in Fig. 2 generates a large amount of heat, Fig. 7 is an explanatory diagram of the state of the conventional device in the same state as Fig. 6, and Fig. 7 is a schematic cross-section of another embodiment of the present invention. 9 is an explanatory diagram of the state in the case corresponding to FIG. 5 of the apparatus in FIG. 3, FIG. 10 is an explanatory diagram of the state in the case corresponding to FIG. 6, and FIG. FIG. 12 is an explanatory diagram of the state when the load is small, and FIG. 12 is an explanatory diagram of the state of FIG. 3 when the load is large. l...electrical equipment, co...tank, 3...cooler, 'IB
1,3.3...Top header, Dab...Bottom header,
S...Liquid phase refrigerant, 6...Liquid pump, 7...Piping, g...
・Refrigerant vapor, 9.・Non-condensable gas (gas), /θ, j,
2. ．． ? λ・・Cooling duct, //・・Blower, /, 2・
・Lower communicating pipe, /3...boundary surface, lda...upper communicating pipe. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Teruatsu So Ga Michi 9 figures, 1 song, 11 figures, 12 figures procedural amendment ``Spontaneous'' Showa year, month, day, 59.5. 10 Commissioner of the Japan Patent Office 1, Indication of the case Showa SG Patent Application No.: 109tO-2, Name of the invention Evaporative cooling type gas insulated electrical device 3, Name of the person making the amendment (601) Representative of Mitsubishi Electric Corporation Part Hitoshi Yama Department 4, Agent Address: 6, 4th Floor, Marunouchi Building, 2-4-1 Marunouchi, Chiyoda-ku, Tokyo The statement of contents of the amendment is revised as follows.

Claims (1)

[Scope of Claims] (1) Consisting of an electrical device, a tank for housing the electrical device, and a cooler for radiating heat generated from the electrical device to the outside, the tank contains non-condensable gas and gas liquid. In an evaporative cooling type gas insulated electrical device filled with a refrigerant that undergoes a phase change, the cooler includes a plurality of cooling ducts that stand upright and have their upper ends closed, and a lower end of the cooling ducts. An evaporative cooling type gas insulated electrical device, characterized in that it is provided with a lower header that communicates with a cooling duct, and that the cooler and the tank are communicated to the lower part only by a ladder. (:l) The evaporative cooling type gas insulated electrical device according to claim 7, wherein a plurality of cooling ducts whose upper ends are closed are communicated by a closed upper header. (3) Cooling The evaporative cooling type gas insulated electrical device according to claim 1 or 2, wherein the communication between the container and the tank through the lower header is at the side of the tank near the bottom of the tank.