CN110762581A - A system for providing stable hot water with heat pipes in cooperation with medium and high temperature phase change heat storage medium - Google Patents

Abstract

The invention relates to a system for providing stable hot water with heat pipes in cooperation with medium and high temperature phase change heat storage medium, which comprises a water supply subsystem for supplying cold water; a circulating heating subsystem for supplying hot water to users; A medium-high temperature phase-change heat storage subsystem for realizing heat storage by changing the sensible heat and latent heat of the heat storage medium; a heat transfer water storage subsystem, which is fluidly connected between the water supply subsystem and the circulating heating subsystem; and a heat pipe radiator A system comprising at least a closed heat pipe and a heat pipe phase change medium contained in the heat pipe, two ends of the heat pipe are respectively placed in the heat transfer water storage subsystem and the medium and high temperature phase change heat storage subsystem to pass the phase change of the heat pipe The medium transfers heat from the medium and high temperature phase change heat storage subsystem to the heat transfer and water storage subsystem, thereby heating the cold water entering the heat transfer and water storage subsystem into hot water. According to the system of the present invention, the medium and high temperature phase change heat storage medium is selected, and the heat dissipation subsystem of the heat pipe is added to ensure the timeliness and stability of the hot water supply.

Description

A system for providing stable hot water with heat pipes in cooperation with medium and high temperature phase change heat storage medium

technical field

The invention relates to hot water supply, and more particularly to a system for providing stable hot water with heat pipes in cooperation with medium and high temperature phase change heat storage medium.

Background technique

With the improvement of people's living standards, low-cost and stable and continuous hot water supply has become an important part of life. In the past five years, the research on providing hot water through phase change materials has successively applied for patents (including solar phase change water heaters such as CN 109084477 A and CN 108800292 A, electric heating phase change water heaters, phase change hot water heating such as CN207162719 U, etc.). The advantages of phase change thermal storage are described in detail in these patent documents, including the use of valley electricity, no-sun night heating, and stable outlet water temperature. However, no matter which structure and material are used in the above reports, the phase change material below the boiling point of water is used as the heat storage medium, the heat storage density is low, and it is difficult to obtain a continuous and efficient hot water supply.

CN201410479367 discloses a solar heat storage type vacuum heat pipe hot water supply technology in which a high temperature phase change heat storage medium is placed in a heat pipe to increase the heat storage density of the heat pipe, but does not involve how to solve the problem that the phase change heat storage temperature is higher than that of water The boiling point caused by the heating temperature and pressure is too high.

In some seasons in the south (the end of October to the end of March of the second year) and most of the seasons in the north (four seasons such as Northwest, Inner Mongolia, Northeast, etc.; in North China, from mid-September to May of the next year), low-cost, continuous and stable Hot water supply. In the utilization of valley electricity and solar energy, due to the low energy storage density, the continuous hot water supply at intervals of more than 8 hours is generally realized by increasing the volume of the low temperature phase change material. High temperature phase change heat storage (use temperature ≥ 100) can comprehensively use its sensible heat and latent heat to store heat. Compared with low temperature heat storage materials, it has the advantage of high heat storage density. High temperature phase change materials are mostly used to heat steam for drying and heating to utilize waste heat. , the steam supply is relatively concentrated, and the temperature fluctuation is small. For intermittent hot water heating and heating with small temperature fluctuations, due to the low heat exchange efficiency, the outlet water temperature is low when a large flow of water passes through, and the water outlet temperature is too high when it is not used for a long time or when the water flow is small. It is difficult to use high-temperature thermal storage materials to store and release application heat, which limits its wide application.

In short, the hot water supply system of the low phase transition point heat storage material has a low heat storage density, a large volume of the heat storage device, and a short heat storage time, so it is difficult to meet the long-term heat supply demand. Most of the high-temperature phase change materials are higher than the boiling point of water or close to the boiling point of water. The pipeline is in contact with water, and there are use problems caused by too high outlet water temperature, and equipment safety and cost problems caused by high temperature and pressure of water.

SUMMARY OF THE INVENTION

In order to solve the problems of insufficient heat storage of low temperature phase change materials, low heat exchange efficiency, high outlet water temperature of high temperature phase change materials, and adverse effects of high temperature, high pressure and corrosion on equipment in the prior art, the present invention aims to provide a A system in which the heat pipe cooperates with the medium and high temperature phase change heat storage medium to provide stable hot water.

The invention provides a system for providing stable hot water with heat pipes in cooperation with medium and high temperature phase change heat storage medium, which comprises a water supply subsystem for supplying a cold water; a circulation heating subsystem for supplying a hot water to users; A medium and high temperature phase change heat storage subsystem for realizing heat storage by utilizing the sensible heat and latent heat of a medium and high temperature phase change heat storage medium; a heat transfer water storage subsystem, which is fluidly connected to the water supply subsystem and the circulating heating subsystem and a heat pipe cooling subsystem, which includes at least one enclosed heat pipe and a heat pipe phase change medium accommodated in the heat pipe, and the two ends of the heat pipe are respectively placed in the heat transfer water storage subsystem and the medium and high temperature phase change storage system. In the heat subsystem, heat is transferred from the medium-high temperature phase change heat storage subsystem to the heat transfer water storage subsystem through the heat pipe phase change medium, thereby heating the cold water entering the heat transfer water storage subsystem into hot water. In particular, by means of the heat pipe, the heat pipe phase change medium rapidly transfers heat from the medium and high temperature phase change heat storage subsystem to the heat transfer water storage subsystem.

Compared with the existing water supply system (where the temperature of the phase change material is less than 100°C), the system according to the present invention selects a medium and high temperature phase change heat storage medium (for example, a phase change heat storage material with a phase change temperature higher than 100°C), A heat pipe cooling subsystem is added to ensure the timeliness (that is, the rapid supply of hot water) and stability of hot water supply.

Preferably, the heat transfer water storage subsystem includes a water storage tank and a pipe arranged in the water storage tank, cold water from the water supply subsystem enters the pipe and is heated in the pipe to supply the circulation to the circulation The thermal subsystem provides hot water.

Preferably, the heat transfer and water storage subsystem further includes a vent valve for emptying the heat transfer and water storage subsystem. In particular, the vent valve is used to drain the heat transfer water storage subsystem when the hot water is not used for a long period of time.

Preferably, the circulating heating subsystem includes a drain valve for both draining and supplying hot water. A small amount of water remaining in the heat transfer and water storage subsystem can be evacuated through the ventilation valve and the drain valve to prevent the pressure and corrosion of the pipeline due to the high temperature of the outlet water during heating and the high temperature gasification of the water that has not been used for a long time.

Preferably, the circulating heating subsystem further comprises at least one heat exchanger or heat exchange unit for heating when applied to the heating field.

Preferably, the medium and high temperature phase change heat storage subsystem includes a casing and a heating source, and the medium and high temperature phase change heat storage medium is accommodated in the casing and heated by the heating source. Preferably, the heating source is electric heating, air energy heating, solar heating or the like. Preferably, the casing is a corrosion-resistant casing.

Preferably, the phase transition temperature of the medium and high temperature phase change heat storage medium is ≥100°C or the maximum use temperature is ≥100°C. Preferably, the phase transition temperature of the medium and high temperature phase change heat storage medium is higher than 100°C. Preferably, the phase transition temperature of the medium and high temperature phase change heat storage medium is higher than 150°C. More preferably, the phase change temperature of the medium and high temperature phase change heat storage medium is between 150-400°C. Most preferably, the phase change temperature of the medium and high temperature phase change heat storage medium is between 200-350°C. In a preferred embodiment, the phase transition temperature of the medium and high temperature phase change heat storage medium is 308°C.

Preferably, the medium and high temperature phase change heat storage medium comprises a medium and high temperature phase change material. More preferably, the medium and high temperature phase change material is an inorganic phase change material such as NaNO ₃ , NaNO ₃ -KNO ₃ , NaNO ₃ -KNO ₃ -NaNO ₂ , or a high phase change point organic phase change heat storage material. It should be understood that the medium and high temperature phase change heat storage medium may be molten salt, metal, polymer, and the like. According to different phase transition temperatures, the device is equipped with a controller for heating temperature and heating time. When the set temperature or time is reached, the heating will automatically stop and enter the heat preservation. In order to improve the heat exchange efficiency of the phase change heat storage material of the device, high thermal conductivity porous foam, powder, etc. can also be added.

Preferably, the medium and high temperature phase change heat storage medium further includes a high thermal conductivity material for enhancing heat transfer. More preferably, the high thermal conductivity material is graphite powder. In a preferred embodiment, the high thermal conductivity material is 5wt% graphite powder.

Preferably, the heat pipe phase change medium is a heat pipe low temperature phase change material, such as water, acetone, ethanol and other low boiling point media.

Preferably, the phase transition temperature of the low temperature phase change material of the heat pipe is lower than 100°C. More preferably, the phase transition temperature of the low temperature phase change material of the heat pipe is between 70-90°C. In a preferred embodiment, the phase transition temperature of the low-temperature phase change material of the heat pipe is 80° C., and the degree of vacuum is controlled to control the phase transition temperature of the medium in the heat pipe.

Preferably, a thermal insulation device is provided between the heat transfer and water storage subsystem and the medium and high temperature phase change heat storage subsystem.

The invention realizes heat storage by utilizing the sensible heat and latent heat of the medium and high temperature phase change heat storage medium through the medium and high temperature phase change heat storage subsystem, and improves the heat storage density and stability of the heating system; The uniformity of the internal temperature of the high temperature phase change heat storage medium material can prevent the local overheating of the medium and high temperature phase change heat storage medium, and can ensure efficient and stable heat supply, and prevent the sudden rise and fall of the outlet water temperature. In a word, the system for providing stable hot water with heat pipes in cooperation with medium and high temperature phase change heat storage medium according to the present invention can effectively solve the problems of high outlet water temperature, large variation of water temperature, poor stability of outlet water flow rate and high water pressure in existing hot water supply systems. Moreover, the system for providing stable hot water with the heat pipe in cooperation with the medium and high temperature phase change heat storage medium according to the present invention can reduce the volume of the heat storage device, improve the thermal energy utilization efficiency, save thermal energy and reduce costs. Further, the system for providing stable hot water with heat pipes in cooperation with medium and high temperature phase-change heat storage medium according to the present invention can provide low-cost hot water with stable temperature and controllable water flow and flow rate, and meet users' demands for high-quality hot water.

Description of drawings

FIG. 1 is a schematic structural diagram of a system for providing stable hot water by a heat pipe in conjunction with a medium and high temperature phase change heat storage medium according to a preferred embodiment of the present invention.

Detailed ways

Below in conjunction with the accompanying drawings, preferred embodiments of the present invention are given and described in detail.

As shown in FIG. 1 , according to a preferred embodiment of the present invention, a system for providing stable hot water with a heat pipe in conjunction with a medium and high temperature phase-change heat storage medium includes a water supply subsystem 1 , a heat transfer and water storage subsystem 2 , and a circulating heating subsystem 3 , medium and high temperature phase change heat storage subsystem 4 and heat pipe cooling subsystem 5, wherein the water supply subsystem 1 is used to supply cold water 11, the circulating heating subsystem 3 is used to provide hot water 31 to users, and the medium and high temperature phase change heat storage subsystem The subsystem 4 utilizes the sensible heat and latent heat of the medium and high temperature phase change heat storage medium to achieve heat storage, the heat transfer and water storage subsystem 2 is fluidly connected between the water supply subsystem 1 and the circulating heating subsystem 3, and the heat pipe cooling subsystem 5 It is connected between the heat transfer water storage subsystem 2 and the medium and high temperature phase change heat storage subsystem 4 to transfer heat from the medium and high temperature phase change heat storage subsystem 4 to the heat transfer water storage subsystem 2, so that the heat transfer water will enter the heat transfer water storage subsystem 2. The cold water 11 of the subsystem 2 is heated to the hot water 31 .

Wherein, according to the change of the outside temperature, the water intake amount and water flow speed of the cold water 11 of the water supply subsystem 1 can be adjusted through the valve 12 as required. The water supply subsystem 1 is urban tap water or purified water, and the valve 12 can be controlled to adjust the water output according to needs, and the flow rate is 0-3 m ³ /h.

The heat transfer and water storage subsystem 2 includes a water storage tank 21 and a pipeline 22 arranged in the water storage tank 21. The cold water 11 from the water supply subsystem 1 enters the pipeline 22 and is heated in the pipeline 22 to be supplied to the circulating supply. The thermal subsystem 3 provides hot water 31 . The heat transfer water storage subsystem 2 also includes a thermal insulation material wrapped outside the water storage tank 21 to avoid heat loss. In this embodiment, the thermal insulation material adopts common aluminum silicate thermal insulation cotton. It should be understood that different thermal insulation materials can be replaced according to thermal insulation requirements and material costs. The heat transfer and water storage subsystem 2 also includes a vent valve 23 that cooperates with a drain valve (hot water tap) 32 of the circulating heating subsystem 3 (described in detail below) to drain the heat transfer and water storage subsystem 2 . In this embodiment, when the pressure of the heat transfer and water storage subsystem 2 is greater than a set value (for example, 1.8 atm), the vent valve 23 is automatically opened to release the pressure.

The circulating heating subsystem 3 includes a drain valve 32 for discharging the hot water 31 . The hot water temperature for domestic use is pre-mixed with normal temperature tap water according to the demand of the outlet water temperature, and used through the hot water faucet 32 . In addition, the water in the heat transfer and water storage subsystem 2 can be emptied through the ventilation valve 23 and the drain valve 32, namely, the hot water 31 can be emptied to ensure the safety of the heat transfer and water storage subsystem 2 when the hot water is not used for a long time. This also prevents the cold water 11 from being heated to an excessively high temperature in the outlet pipe 21 . The circulating heating subsystem 3 also includes two heat exchangers or heat exchange units 33 for heating. Circulating heating subsystem 3 is suitable for household heating needs, including two modes, convective heat transfer mode and forced convection mode. The difference is that the convective heat transfer mode uses different temperatures and different water densities to build pipelines to form a loop; forced convection mode uses water pumps. As a power source drive to form a loop. In this embodiment, the heat exchanger 33 is a heat exchange pipe, and a water pump 34 is used for forced convection heat exchange. It should be understood that the heat exchanger 33 can be selected from natural convection heat exchange or multiple heat exchange coils, etc., according to the cost and the actual heat supply, so as to realize heat supply with different structures. Of course, the heat exchanger 33 can increase or replace its heat exchange pipes according to the heating area or the number of heating units. The water pump 34 drives heat supply, and the water volume can be adjusted according to the power of the water pump 34 to adjust the temperature accordingly. The circulating heating subsystem 3 also includes a valve 35. The valve 35 can be exchanged according to needs to match the water pump 34, and the water flow can be adjusted by adjusting the valve 35. In addition, the heat exchanger 33 may be provided with a temperature display instrument to display the indoor temperature. According to the set indoor temperature requirements, the system automatically adjusts the power of the water pump 34 and the valve 35 to realize temperature adjustment, and controls the outlet water temperature in the range of 20 to 60 °C.

The medium and high temperature phase change heat storage subsystem 4 includes a casing 41 and a heating source 42 . The casing 41 accommodates a medium and high temperature phase change heat storage medium 411 , which is heated by the heating source 42 . In this embodiment, the heating source 42 uses valley electricity to heat the medium and high temperature phase change heat storage medium 411 . It should be understood that the heating source 42 can also be heated in the form of solar heating, industrial waste heat heating, etc. according to local conditions.

In this embodiment, the medium and high temperature phase change heat storage medium 411 includes a medium and high temperature phase change material NaNO ₃ , the phase change temperature of which is about 308°C. In practical applications, the user can adjust the type and amount of the medium and high temperature phase change heat storage medium 411 according to cost, heat storage density, heating area, and heating unit. Considering that the medium and high temperature phase change materials generally have low thermal conductivity, the medium and high temperature phase change heat storage medium 411 can be added with a high thermal conductivity material as a heat transfer enhancement material according to actual needs to improve the medium and high temperature phase change heat storage subsystem. 4 heat transfer capacity, so as to quickly transfer heat to the heat pipe cooling subsystem 5. In this embodiment, the enhanced heat transfer material is 5% graphite powder, which can increase the thermal conductivity of NaNO ₃ by 90%. It should be understood that, according to corrosion and heat transfer requirements, the medium and high temperature phase change heat storage medium 411 can be selected from various forms such as metal, high thermal conductivity carbon, powder, foam, etc., or a composite structure thereof. Moreover, the user can adjust the type and amount of medium and high temperature phase change heat storage medium 411 to obtain a suitable heat storage density, and optimize the system by calculating according to the thermophysical parameters of water and heating and heating temperatures.

In this embodiment, the casing 41 is a stainless steel casing. Moreover, the medium and high temperature phase change heat storage subsystem 4 also includes a thermal insulation material wrapped outside the casing 41 to avoid heat loss. In this embodiment, the thermal insulation material adopts aluminum silicate fiber. It should be understood that different thermal insulation materials can be replaced according to thermal insulation requirements and material costs.

The heat pipe cooling subsystem 5 includes a closed heat pipe 51 and a heat pipe phase change medium 511 accommodated in the heat pipe 51 . The top end of the heat pipe is placed in the water storage tank 21 of the heat transfer and water storage subsystem 2 in contact with the pipe 22 and is connected and fixed (for example, by welding), and the bottom end of the heat pipe is placed in the shell 41 of the medium and high temperature phase change heat storage subsystem 4 It is connected and fixed with the casing 41 (for example, by welding), so that the heat transfer between the heat transfer water storage subsystem 2 and the medium and high temperature phase change heat storage subsystem 4 is realized through the heat pipe phase change medium 511 . Specifically, the top end of the heat pipe 51 is in contact with the pipe 22 to realize heat transfer between the heat pipe phase change medium 511 and the cold water 11, and the bottom end of the heat pipe 51 is surrounded by the medium and high temperature phase change heat storage medium 411 to realize the medium and high temperature phase change storage medium 411. Heat exchange between the heat medium 411 and the heat pipe phase change medium 511 .

In this embodiment, the heat pipe phase change medium 511 is water, and the vaporization temperature under vacuum is about 80°C. Specifically, when the temperature in the heat pipe 51 is higher than the phase change temperature of the heat pipe phase change medium 511 (water), the water vaporizes, brings the heat to the cold water 11 and then condenses, and is deposited on the bottom of the heat pipe 51 by gravity to reciprocate heating , to achieve uniform and efficient heat transfer. In this way, by transferring heat through the heat pipe 51, the heat exchange area can be controlled to prevent the cold water 11 from being heated to an excessively high temperature. In a word, the heat pipe cooling subsystem 5 can not only ensure the uniformity of the internal temperature of the medium and high temperature phase change heat storage medium 411, prevent the heat pipe phase change medium 511 from overheating and gasification, but also ensure efficient and stable heat supply, and prevent the cold water 11 from being heated to a sudden The high and low temperature means preventing the temperature of the outlet water from the heat transfer and water storage subsystem 2 from rising and falling sharply.

In this embodiment, the heat pipe 51 is a stainless steel pipe. It should be understood that the heat pipe 51 can also be selected according to the heating temperature and the heating density. In addition, users can use heat pipes of different specifications, such as columnar or U-shaped structures, according to the needs of convenient installation. Heat pipe phase change media with different gasification temperatures correspond to different heat pipe types, which can be selected according to the phase change temperature, hot water outlet temperature and water outlet volume of the medium and high temperature phase change heat storage medium 411 . For example, the phase change temperature of the medium and high temperature phase change heat storage medium 411 is 100°C, the use temperature is 200°C, and the outlet water temperature is 40°C, and the water at 80°C is vaporized by controlling the vacuum degree as the heat pipe phase change medium 511 .

In this embodiment, a thermal insulation device is provided between the heat transfer and water storage subsystem 2 and the medium and high temperature phase change heat storage subsystem 4, for example, heat insulation cotton is used to isolate heat transfer, thereby preventing the heat transfer and water storage subsystem 2 temperature is too high.

In the following, the valley electricity is used as the heat source, and the system for providing stable hot water by the heat pipe in conjunction with the medium and high temperature phase change heat storage medium of the present invention will be further described from the aspects of hot water supply for washing and hot water heating through specific applications. easier to understand and grasp.

The medium and high temperature phase change heat storage subsystem 4 adopts the Hitec salt ternary nitrate/nitrite mixture, and the composition is NaNO ₃ -KNO ₃ -NaNO ₂ (7%-53%-40%, mass fraction), and its melting point (phase change temperature) is 142 ℃, and the heat storage temperature is not higher than 400 ℃. According to the heating area and the hot water supply amount, the amount of the medium and high temperature phase change heat storage medium 411 in the device is adjusted. Taking Shanghai as the representative, the valley electricity time period is from 22:00 pm to 6:00 the next day. This time period can be used as the valley electricity heating time, and the heating source 42 (power supply) of the medium and high temperature phase change heat storage subsystem 4 is turned on for heating. , open the valve 35 of the circulating heating subsystem 3, turn on the water pump 34, and stop heating when the temperature or time reaches the set value. In this example, the temperature is set to be heated to 380°C, the heating is stopped, and the latent heat and sensible heat of the medium and high temperature phase change heat storage medium 411 are used to complete the heating and hot water supply required during the day. The heat pipe 51 of the heat pipe cooling subsystem 5 is made of stainless steel, and water is selected as the heat transfer material for the heat pipe phase change medium 511 contained therein, and the gasification temperature under vacuum is ~80°C. When the temperature is higher than the phase transition temperature, the water vaporizes, and the heat is brought to the cold water 11 and condensed, and deposited to the bottom of the heat pipe by gravity, and reciprocating heating to achieve uniform and efficient heat transfer. If 24-hour heating is required, open the valve 12 of the water supply subsystem 1, fill in a sufficient amount of cold water 11, adjust the water flow within the range of 0.05-3m ³ /h according to the temperature, and mix with different amounts of normal temperature tap water before the water is discharged , to ensure that the water temperature is controlled at 30 ~ 60 ℃. If the pressure inside the device is greater than 1.8atm, the vent valve will automatically open to release the pressure. According to the indoor temperature demand, the system automatically adjusts the power of the valve 35 and the water pump 34 . When hot water for washing is needed, turn on the hot water tap 32 to get hot water. When heating and hot water are not needed, close the water pump 34, valve 35 and valve 12, open the venting valve 23 and the drain valve (hot water tap) 32, and empty the hot water 13 in the heat transfer and water storage subsystem 2 to protect the circulatory system.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Various changes can be made to the above-mentioned embodiments of the present invention. That is, all simple and equivalent changes and modifications made according to the claims and descriptions of the present invention fall into the protection scope of the claims of the present invention. What is not described in detail in the present invention is conventional technical content.

Claims (10)

1. A system for providing stable hot water by cooperation of a heat pipe and a medium-high temperature phase change heat storage medium, the system comprising:

a water supply subsystem for supplying cold water;

a hydronic heating subsystem for providing a hot water to a user;

a medium-high temperature phase change heat storage subsystem for storing heat by utilizing sensible heat and latent heat of a medium-high temperature phase change heat storage medium;

a heat transfer water storage subsystem in fluid communication between the water supply subsystem and the cyclical heat supply subsystem; and

and the two ends of the heat pipe are respectively arranged in the heat transfer and water storage subsystem and the medium-high temperature phase change heat storage subsystem so as to transfer heat from the medium-high temperature phase change heat storage subsystem to the heat transfer and water storage subsystem through the heat pipe phase change medium, so that cold water entering the heat transfer and water storage subsystem is heated into hot water.

2. The system of claim 1, wherein the heat and water storage subsystem includes a water storage tank and a conduit disposed in the water storage tank, cold water from the water supply subsystem entering the conduit and being heated in the conduit to provide heated water to the circulation heating subsystem.

3. The system of claim 1, wherein the heat and water storage subsystem further comprises a vent valve for venting the heat and water storage subsystem.

4. The system of claim 1, wherein the hydronic heating subsystem includes a drain valve for both draining and supplying hot water.

5. The system of claim 1, wherein the hydronic heating subsystem, when applied in the heating field, further comprises at least one heat exchanger or heat exchange unit for heating.

6. The system of claim 1, wherein the medium-high temperature phase-change thermal storage subsystem comprises a housing and a heating source, the medium-high temperature phase-change thermal storage medium being received in the housing and heated by the heating source.

7. The system of claim 1, wherein the phase change temperature of the medium-high temperature phase change thermal storage medium is greater than 100 ℃.

8. The system of claim 1, wherein the medium-high temperature phase change thermal storage medium comprises a medium-high temperature phase change material.

9. The system of claim 1, wherein the heat pipe phase change medium is a low boiling point medium.

10. The system of claim 1, wherein a thermal insulation device is arranged between the heat transfer water storage subsystem and the medium-high temperature phase change heat storage subsystem.

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