Ventilation duct with dehumidifying function

Abstract

The present invention provides a novel means capable of supplying dehumidified air into the cabin of a vehicle, such as an automobile. This ventilation duct comprises: a duct body having a flow path through which air flows and an electrical conductor facing the flow path; an air intake port through which air is taken into the duct body; an air discharge port through which air is discharged from the duct body; a corona discharge unit which is disposed inside the flow path and which is for electrically charging water contained in the air by generating a corona discharge; and a water discharge port. The electrical conductor is potentially grounded via a grounding conductive member in electrical continuity with the electrical conductor, and the charged water condenses on the surface of the electrical conductor and is discharged from the water discharge port. This achieves dehumidification of the air to be discharged from the ventilation duct.

Description

Ventilation duct with dehumidification function

[0004]

[0001] The present invention relates to a ventilation duct with a dehumidification function.

[0002] Generally, vehicles such as automobiles are equipped with vehicle air-conditioning devices that adjust the temperature and humidity inside the vehicle cabin. Such a vehicle air-conditioning device is configured to generate conditioned air at a predetermined temperature by dehumidifying and cooling the air blown by a blower fan with an evaporator and heating a part of the cooled air with a heater core.

[0003] In addition, in vehicles such as automobiles, in winter or the rainy season, in order to prevent the window from becoming cloudy due to condensation, the air in the cabin is discharged to the outside, or the dehumidification function of the air conditioner is used to dehumidify the air in the cabin. An air-conditioning device for dehumidification is described, for example, in Japanese Patent Application Laid-Open No. 2013-14234.

[0004] An object of the present invention is to provide a novel means capable of supplying dehumidified air into a cabin of a vehicle such as an automobile.

[0005] One embodiment of the present invention includes a duct body having a flow path through which air flows and an electric conductor facing the flow path, an air inlet for taking in the air into the duct body, an air outlet for discharging the air from the duct body, a corona discharge unit disposed inside the flow path for charging water contained in the air by generating corona discharge, and a water outlet. The electric conductor is electrically grounded through a grounding conductive member electrically connected to the electric conductor, and the charged water condenses on the surface of the electric conductor and is discharged from the water outlet. This is a ventilation duct.

[0006] FIG. 1 is a cross-sectional view showing an example of the configuration of a vehicle air-conditioning duct according to an embodiment of the ventilation duct of the present invention. FIG. 2A is a cross-sectional view taken along line A-A in FIG. 1. FIG. 2B is a cross-sectional view taken along line B-B in FIG. 1. FIG. 3 is a modified example of the cross-sectional shape of the duct body constituting the vehicle air-conditioning duct. FIG. 4 is a graph showing the results of a dehumidification test in the column of Examples described later.

[0007] The embodiments of the present invention will be described below with reference to the attached drawings, but the technical scope of the present invention is not limited to the following forms. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted. Also, the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from the actual ratios. In this specification, "X to Y" indicating a range means "X or more and Y or less". Unless otherwise specified, operations and measurements of physical properties, etc., are performed under conditions of room temperature (20 to 25°C) / relative humidity 40 to 50%.

[0008] <Vehicle Air Conditioning System> Figure 1 is a cross-sectional view showing an example of the configuration of a vehicle air conditioning duct 10 according to one embodiment of the ventilation duct of the present invention.

[0009] In this embodiment, the vehicle air conditioning duct 10 is located upstream of the HVAC system 20 mounted in the vehicle. The HVAC system is a car air conditioning unit that adjusts the temperature, airflow, and outlets of the air to maintain a comfortable temperature inside the cabin of a car, for example. Air conditioning devices such as HVAC systems mounted in automobiles are usually located inside the dashboard.

[0010] In this embodiment, the vehicle air conditioning duct 10 has a duct body 100 having a flow path 110 through which air flows, and a wire mesh 120 (an example of an "electrical conductor") facing the flow path 110. The wire mesh 120 is made of aluminum, and the surface of the wire mesh 120 is treated with a conductive water-repellent coating. The duct body 100 has an insulating duct 130 that covers the wire mesh 120 in the circumferential direction, an upstream insulating duct 140 positioned upstream of the wire mesh 120, and a downstream insulating duct 150 positioned downstream of the wire mesh 120. Furthermore, the vehicle air conditioning duct 10 is equipped with an air intake port 160 at the upstream inlet of the duct body 100 to take in air, and an air outlet port 170 at the downstream outlet of the duct body 100 to discharge air.

[0011] Figure 2A is a cross-sectional view taken along the line A-A in Figure 1. Figure 2B is a cross-sectional view taken along the line B-B in Figure 1. As shown in Figures 2A and 2B, the wire mesh 120 is circumferentially covered by the insulating duct 130 such that a gap 112 exists between the wire mesh 120 and the insulating duct 130. Here, the wire mesh 120 is supported by a support part (not shown) so that the wire mesh 120 is fixed inside the insulating duct 130 even with the gap 112 present.

[0012] The wire mesh 120 has a cylindrical shape with its central axis aligned along the longitudinal direction of the duct body 100, and has openings 122 at regular intervals along this longitudinal direction. In this embodiment, the openings 122 of the wire mesh 120 are located at the top, bottom, left, and right in the cross-sectional view of the duct body 100.

[0013] The vehicle air conditioning duct 10 is further equipped with a corona discharge electrode 200 in the flow path 110 located inside the upstream insulator duct 140. That is, the wire mesh 120 is located downstream of the corona discharge electrode 200. The corona discharge electrode 200 has the function of charging water contained in the air by generating electrons through corona discharge, and normally negatively charging the water. The charged water in this way releases the accumulated charge onto the wire mesh 120 surface and condenses.

[0014] A water outlet 300 for discharging condensed water is provided at the connection point between the insulator duct 130 and the downstream insulator duct 150. In this embodiment, the duct body 100 has a slope toward the bottom so as to connect the upstream insulator duct 140, which is located above the downstream insulator duct 150, with the downstream insulator duct 150. That is, the water outlet 300 is provided at the bottom of the duct body 100. In this specification, "upper" and "lower" refer to positions along the vertical line. Also, "bottom of the duct body" means a part that is located relatively lower than other parts of the duct body.

[0015] The wire mesh 120 is grounded to the body earth by electrically connecting with the vehicle body conductive part 400 via an electrical wire 124 (an example of a "conductive member for grounding") which is electrically connected to the wire mesh 120. Because the wire mesh 120 is grounded to the body earth in this way, water that has been charged by contact with electrons generated by corona discharge is attracted to the wire mesh 120 by Coulomb force. The electrical wire 124 is electrically connected to the top of the wire mesh 210 and is led out to the outside of the duct body 100 so as to penetrate the duct body 100.

[0016] In this embodiment, the wire mesh 120 is made of aluminum, the electrical wiring 124 is made of copper, and the vehicle body conductive part 400 is made of iron. In other words, these components are made of different conductive materials. Furthermore, corrosion-resistant treatment is applied to the conductive parts between the aluminum wire mesh 120 and the copper electrical wiring 124, and between the copper electrical wiring 124 and the iron vehicle body conductive part 400.

[0017] Next, the operation of the vehicle air conditioning duct 10 will be explained. When the vehicle air conditioning duct 10 is in operation, outside air is first taken in from the air intake port 160 into the flow path 110. The taken-in air usually contains water in the form of liquid (water droplets) or gaseous (water vapor). Here, when electrons are generated by corona discharge at the corona discharge electrode 200, the water in the air comes into contact with these electrons and becomes charged (usually negatively). Meanwhile, the wire mesh 120 installed inside the duct body 100 (insulator duct 130) is electrically connected to the vehicle body conductive part 400 and is grounded to the body earth. Therefore, the charged water is attracted to the wire mesh 120 by Coulomb force, adheres to its surface and condenses. In this way, the water in the air taken into the flow path of the duct body 100 is recovered. The air from which the water has been recovered is discharged from the air outlet 170 and flows into the HVAC system 20 located further downstream. The amount of water vapor contained in the air flowing into the HVAC system 20 is reduced by passing through the vehicle air conditioning duct 10. Therefore, dehumidification of the air within the HVAC system is achieved. Conventionally, dehumidification in HVAC systems was mainly carried out by the evaporator. In contrast, by using the vehicle air conditioning duct according to this embodiment, it becomes possible to eliminate the evaporator in the HVAC system. As a result, it can effectively contribute to miniaturization and weight reduction of the vehicle. Furthermore, since it is possible to dehumidify without excessively cooling the cooler as in the conventional method and without placing an excessive load on the onboard air conditioner, there is an advantage in reducing power consumption and further improving fuel efficiency and / or electricity efficiency. In addition, while conventional dehumidification using a cooler only condenses water in the air by randomly coming into contact with the cooler, this embodiment can condense more water by attracting it to the wire mesh (electrical conductor) using Coulomb force. Therefore, it also has the advantage of superior dehumidification efficiency.

[0018] It should be noted that a technique for collecting water by charging water in the air using corona discharge, moving it to a grounded cylindrical wire by Coulomb force, and condensing it is publicly known (MJ Zeng, ZG Qu, JF Zhang, Separation and Purification Technology 305 (2023) 122465). However, this document does not consider applying this technology to the dehumidification of air inside the cabin of vehicles such as automobiles.

[0019] In this embodiment, a wire mesh made of aluminum is used as the electrical conductor. However, it is not limited to wire mesh; any electrical conductor can be used. In particular, it is preferable that the electrical conductor has a mesh-like structure, such as wire mesh. This configuration allows for the construction of an electrical conductor using inexpensive and lightweight materials, and also has the advantage that condensed water can be efficiently discharged downwards through the openings in the mesh. Furthermore, the constituent material of the electrical conductor is not limited to aluminum, and other electrical conductors can be used as appropriate. However, it is preferable that the constituent material of the electrical conductor be one or more selected from the group consisting of aluminum or its alloys, copper or its alloys, stainless steel, and conductive resin. By using these materials, oxidation due to contact with condensed water is less likely to occur, and the durability of the electrical conductor can be improved.

[0020] In this embodiment, the duct body further includes an insulating duct that circumferentially covers a wire mesh (electrical conductor). This has the advantage of reducing the pressure loss of the air flowing through the duct body and preventing accidents such as electric shock by insulating the outer surface of the duct body. However, the installation of the insulating duct is optional.

[0021] In this embodiment, a gap exists between the wire mesh (electrical conductor) and the insulating duct. This reduces the pressure loss of the air flowing through the duct body and has the advantage of improving the condensation efficiency of water by increasing the contact area with the air. However, it is not always necessary to provide a gap.

[0022] In this embodiment, the wire mesh (electrical conductor) has a cylindrical shape with its central axis aligned along the longitudinal direction of the duct body. This reduces pressure loss of the air flowing through the duct body and simplifies the handling of the ventilation duct according to this embodiment when it is installed. The cross-sectional shape of the cylinder is not particularly limited and may be circular as shown in Figure 2A, or it may be a polygon such as a square or rectangle, or an ellipse. Furthermore, the shape of the electrical conductor does not have to be cylindrical.

[0023] In this embodiment, as shown in Figures 2A and 2B, the wire mesh (electrical conductor) has openings along the longitudinal direction of the duct body. This increases the surface area of ​​the electrical conductor that comes into contact with the air flowing through the duct body, improving the water condensation efficiency. In addition, since the condensed water is discharged through the openings, there is also the advantage of improved dehumidification efficiency.

[0024] Furthermore, the openings are provided on the top, bottom, left, and right sides of the wire mesh (electrical conductor). By providing openings at least at the bottom of the electrical conductor, condensed water moves downwards due to gravity and is discharged through the openings, thus improving dehumidification efficiency. However, it is also possible for these openings to be provided only in parts other than the bottom of the electrical conductor.

[0025] In this embodiment, the grounding conductive member, which is electrically connected to the wire mesh (electrical conductor), is led out so as to penetrate the duct body. This increases the degree of freedom in arranging the grounding conductive member and has the advantage of avoiding the consumption of unnecessary conductive members for grounding. However, in some cases, the grounding conductive member may be led out from the end of the duct body, for example, so as not to penetrate the electrical conductor. Also, in this embodiment, the grounding conductive member (electrical wiring) is electrically connected to the upper part of the electrical conductor (wire mesh). By electrically connecting the grounding conductive member to the upper part of the electrical conductor in this way, the conductive portion between the grounding conductive member and the electrical conductor is less likely to come into contact with condensed water in the electrical conductor, thereby preventing electrolytic corrosion of the conductive portion.

[0026] In this embodiment, the duct body has a lowest point that is located relatively lower than other parts, and has a slope toward this lowest point. The water outlet is located at this lowest point. This has the advantage of improving dehumidification efficiency as condensed water moves toward the lowest point due to gravity and is discharged from the water outlet. However, the water outlet may be located at a point other than the lowest point. Also, the duct body does not necessarily have a slope.

[0027] In this embodiment, the ventilation duct is configured such that the entire wire mesh (electrical conductor) is located downstream of the corona discharge electrode. As a result, water contained in the air flowing through the duct body becomes charged by corona discharge before reaching the wire mesh (electrical conductor). Consequently, the frequency of water condensation on the wire mesh (electrical conductor) increases, which has the advantage of improving dehumidification efficiency. However, the entire wire mesh (electrical conductor) does not necessarily have to be located downstream of the corona discharge electrode; for example, the corona discharge electrode may be provided at the location where the electrical conductor exists. With such a configuration, a metallic conductor is present near the water charged by corona discharge, which has the advantage of increasing the frequency of water condensation on the wire mesh (electrical conductor) and improving dehumidification efficiency.

[0028] In this embodiment, the duct body further includes an upstream insulator duct and a downstream insulator duct, which are positioned upstream and downstream of the wire mesh (electrical conductor). This allows for the separation of parts of the duct body that condense water from parts that do not, increasing the design flexibility of the drainage system. Furthermore, by providing the connection point to the outside when installing the ventilation duct in the upstream or downstream insulator duct, leakage current can be prevented. However, the installation of such upstream or downstream insulator ducts is optional.

[0029] In this embodiment, the surface of the wire mesh (electrical conductor) is treated with a conductive water-repellent coating. This prevents galvanic corrosion of the electrical conductor while accelerating the removal of condensed water. However, such a water-repellent coating is not essential.

[0030] The electrical conductor (wire mesh) is grounded to the body earth by electrically connecting with the vehicle body conductive part 400 via a grounding conductive member (electrical wiring) that is electrically connected to the electrical conductor (wire mesh). By grounding the electrical conductor with this configuration, water charged by contact with electrons can be reliably attracted to the electrical conductor. Here, "vehicle body conductive part" refers to the part of the vehicle body made of a conductive material. This vehicle body conductive part constitutes the outer edge of the vehicle, the boundary between the engine room and the cabin (passenger compartment), etc. The vehicle body conductive part does not necessarily have to be constructed as a single unit; if it is divided into multiple parts, it is sufficient that it has a structure that has a low impedance to the extent that it can be considered to be short-circuited with each other.

[0031] In this embodiment, the electrical conductor (wire mesh) and the grounding conductive member (electrical wiring) are composed of different conductive materials, and the grounding conductive member (electrical wiring) and the conductive part of the vehicle body are composed of different conductive materials. Each conductive part is treated with corrosion protection. There are no particular restrictions on the specific conductive materials that constitute the electrical conductor, the grounding conductive member, and the conductive part of the vehicle body, but those skilled in the art can make appropriate selections while considering conductivity, contribution to weight reduction, and common technical knowledge. When the materials of both components constituting the conductive part (the conductive part between the electrical conductor and the grounding conductive member, or the conductive part between the grounding conductive member and the conductive part of the vehicle body) are different from each other, it is preferable that the conductive part is treated with corrosion protection. This can effectively prevent electrolytic corrosion of the conductive part. Regarding specific forms of such corrosion protection treatment, conventionally known knowledge can be appropriately referred to, but examples include a method of applying a corrosion protectant (sealant) to the conductive part, or a method of constructing the conductive part using a waterproof connector.

[0032] On the other hand, it is also a preferred embodiment that the constituent materials of both components constituting the conductive portion (the conductive portion between the electrical conductor and the grounding conductive member, or the conductive portion between the grounding conductive member and the vehicle body conductive portion) are identical to each other. With such a configuration, the potential difference between the two constituent materials becomes almost zero, and the occurrence of electrolytic corrosion can be effectively prevented.

[0033] In this embodiment, the vehicle air conditioning duct (ventilation duct) is positioned upstream of the HVAC system installed in the vehicle. This allows the vehicle air conditioning duct of this embodiment to supply dehumidified air into the cabin of a vehicle such as an automobile. Furthermore, using the ventilation duct according to this embodiment as a vehicle air conditioning duct eliminates the need to install a heat exchanger for dehumidification, which has the advantage of increasing the free space in the vehicle. In addition, since dehumidified air can be supplied to the vehicle's HVAC system, the humidity inside the HVAC system is reduced, which can also suppress the growth of bacteria. Moreover, in winter, since it is not necessary to lower the air temperature for the purpose of dehumidification, heating efficiency can also be improved.

[0034] There are no particular restrictions on the specific configuration of the corona discharge section that generates corona discharge, and conventionally known knowledge may be referenced as appropriate. Corona discharge is a discharge phenomenon that occurs when a high voltage is applied between electrodes. This phenomenon can be efficiently induced depending on the shape and arrangement of the electrodes, and any of the following types of electrodes may be used: needle electrodes, wire electrodes, plate electrodes, mesh electrodes, etc. As for the materials used to construct the electrodes, durable metals that are resistant to oxidation and corrosion, such as stainless steel or tungsten, may be used. Furthermore, there are no particular restrictions on the high-voltage generator that generates the high voltage, and conventionally known knowledge may be referenced as appropriate. As an example, the magnitude of the voltage applied to the electrodes by the high-voltage generator is in the range of several hundred volts to several kV.

[0035] Although one embodiment of a ventilation duct has been described above, the present invention is not limited to the configuration described in the above-described embodiment, and can be modified as appropriate based on the claims.

[0036] For example, the cross-sectional shape of the duct body may be such that there is no gap between the electrical conductor and the insulating duct, as shown in Figure 3, or the opening may be provided only below or only above the electrical conductor.

[0037] Furthermore, the lowest part of the duct body may be located at the air outlet. This has the advantage of improving drainage performance, as condensed water is pushed towards the bottom by the air circulating through the duct body. On the other hand, the lowest part of the duct body may be located at the air intake. This improves drainage performance as the condensed water moves to the lowest point located on the air intake side, and also effectively prevents damage to equipment installed outside the air outlet by preventing the condensed water from being discharged from the air outlet.

[0038] Furthermore, the following items are also included in the scope of the present invention: Item 1: A ventilation duct comprising: a duct body having a flow path through which air flows and an electrical conductor facing the flow path; an air intake port for taking the air into the duct body; an air outlet for discharging the air from the duct body; a corona discharge unit disposed inside the flow path for charging water contained in the air by generating corona discharge; and a water outlet, wherein the electrical conductor is electrically grounded via a grounding conductive member that is electrically conductive with the electrical conductor, and the charged water condenses on the surface of the electrical conductor and is discharged from the water outlet; Item 2: The ventilation duct according to Item 1, wherein the duct body further comprises an insulating duct that circumferentially covers the electrical conductor; Item 3: The ventilation duct according to Item 2, wherein a gap exists between the electrical conductor and the insulating duct; Item 4: The ventilation duct according to Item 2 or 3, wherein the electrical conductor has a mesh-like structure; Item 5: A ventilation duct according to any one of items 1 to 4, wherein the electrical conductor has a cylindrical shape with its central axis aligned along the longitudinal direction of the duct body; Item 6: A ventilation duct according to item 5, wherein the electrical conductor has an opening along the longitudinal direction; Item 7: A ventilation duct according to item 6, wherein the opening is located at the lower part of the electrical conductor; Item 8: A ventilation duct according to any one of items 1 to 7, wherein the grounding conductive member penetrates the duct body; Item 9: A ventilation duct according to any one of items 1 to 8, wherein the duct body has a lowest point that is located relatively lower than other parts of the duct body; Item 10: A ventilation duct according to item 9, wherein the duct body has a slope toward the lowest point; Item 11: A ventilation duct according to item 10, wherein the lowest point is located at the air outlet; Item 12: A ventilation duct according to item 10, wherein the lowest point is located at the air intake; Item 13: A ventilation duct according to any one of items 9 to 12, wherein the water outlet is located at the lowest part; Item 14: A ventilation duct according to any one of items 1 to 13, wherein at least a portion of the electrical conductor is located downstream of the corona discharge electrode; Item 15: A ventilation duct according to item 14, wherein the corona discharge electrode is located where the electrical conductor is present;16: The ventilation duct according to any one of claims 1 to 15, wherein the duct body further comprises an upstream insulating duct and a downstream insulating duct, which are arranged upstream and downstream of the electrical conductor; 17: The ventilation duct according to any one of claims 1 to 16, wherein the constituent material of the electrical conductor is one or more selected from the group consisting of aluminum or an alloy thereof, copper or an alloy thereof, stainless steel and conductive resin; 18: The ventilation duct according to any one of claims 1 to 17, wherein the surface of the electrical conductor is treated with a conductive water-repellent coating; 19: The ventilation duct according to any one of claims 1 to 18, for use in an air conditioning duct mounted on a vehicle; 20: The ventilation duct according to claim 19, wherein the grounding conductive member is grounded to body earth by electrically conducting with the conductive part of the vehicle body; 21: The ventilation duct according to claim 19, for use in an upstream location of an HVAC system mounted on the vehicle.

[0039] The embodiments of the present invention will be described in more detail below using experimental examples (dehumidification tests), but the technical scope of the present invention is not limited by the experimental examples below.

[0040] First, an insulating duct (15 cm long, 5 cm in diameter) made of plastic (square cross-section) was prepared, and a cylindrical electrical conductor (14 cm long) made of aluminum expanded metal (square cross-section) was placed inside it, with a small gap between it and the ventilation duct, so that the inner surfaces of both ends of the insulating duct were exposed for a length of 0.5 cm each, thereby creating the duct body.

[0041] Next, the duct body fabricated above was fixed with a 30° inclination with respect to the horizontal plane such that the air inlet was at the bottommost part. Thereafter, one end of a copper wire was connected to the end on the air outlet side of the electrical conductor, and the other end of the copper wire was grounded. Then, one end of a corona discharge electrode composed of a single straight stainless wire was inserted from the air inlet side along the center of the circle constituting the cross-section of the duct body and fixed such that the tip was at a position 10 cm from the air inlet. Also, the other end of the stainless wire was connected to a high-voltage generator (manufactured by Spellman, SL30N10). In this way, a ventilation duct was fabricated.

[0042] Subsequently, a voltage of -8.7 kV was applied to the corona discharge electrode using the high-voltage generator to generate corona discharge. In this state, steam generated using a humidifier (ultrasonic humidifier, humidifying spray amount 90 mL / hr) was made to flow in from the air inlet of the above duct body and sprayed for 1 minute, 2 minutes, or 3 minutes, and the amount of water dehumidified by the above ventilation duct was measured respectively. In the experimental examples where spraying was performed for 2 minutes or more, a state where the dehumidified water dripped from the bottommost part of the duct body was observed. Therefore, regarding the amount of dehumidified water, it was measured by weighing the total amount of the mass change of the tray that received the water dripping from the bottommost part of the ventilation duct from the start to the end of spraying and the mass change due to water adhering to the duct body. In addition, a similar experiment was conducted without generating corona discharge as a comparative experimental example. The results are shown in Table 1 and Figure 4 below.

[0043]

[0044] From the above results, it can be seen that according to the configuration of the ventilation duct according to one aspect of the present invention, dehumidification can be realized very efficiently by utilizing corona discharge. On the other hand, in the comparative experimental example where corona discharge was not performed, dehumidification was not confirmed.

[0045] 10 Vehicle air conditioning duct (ventilation duct), 20 HVAC system, 100 Duct body, 110 Flow path, 120 Wire mesh (electrical conductor), 122 Opening, 124 Electrical wiring (conductive material for grounding), 130 Insulator duct, 140 Upstream insulator duct, 150 Downstream insulator duct, 160 Air intake, 170 Air exhaust, 200 Corona discharge electrode (corona discharge section), 300 Water outlet, 400 Conductive section of vehicle body.

Claims

1. A ventilation duct comprising: a duct body having a flow path through which air flows and an electrical conductor facing the flow path; an air intake port for taking the air into the duct body; an air outlet for discharging the air from the duct body; a corona discharge unit disposed inside the flow path for generating corona discharge to charge water contained in the air; and a water outlet, wherein the electrical conductor is electrically grounded via a grounding conductive member that is electrically conductive with the electrical conductor, and the charged water condenses on the surface of the electrical conductor and is discharged from the water outlet.

2. The ventilation duct according to claim 1, wherein the duct body further comprises an insulating duct that covers the electrical conductor in the circumferential direction.

3. The ventilation duct according to claim 2, wherein a gap exists between the electrical conductor and the insulating duct.

4. The ventilation duct according to claim 2 or 3, wherein the electrical conductor has a mesh-like structure.

5. The ventilation duct according to claim 1 or 2, wherein the electrical conductor has a cylindrical shape with its central axis aligned along the longitudinal direction of the duct body.

6. The ventilation duct according to claim 5, wherein the electrical conductor has an opening along the longitudinal direction.

7. The ventilation duct according to claim 6, wherein the opening is provided at the lower part of the electrical conductor.

8. The ventilation duct according to claim 1 or 2, wherein the grounding conductive member penetrates the duct body.

9. The ventilation duct according to claim 1 or 2, wherein the duct body has a lowest part that is located relatively lower than other parts of the duct body.

10. The ventilation duct according to claim 9, wherein the duct body has a slope toward the lowest part.

11. The ventilation duct according to claim 10, wherein the lowest part is located at the air outlet.

12. The ventilation duct according to claim 10, wherein the lowest part is located at the air intake.

13. The ventilation duct according to claim 10, wherein the water outlet is located at the lowest part.

14. The ventilation duct according to claim 1 or 2, wherein at least a portion of the electrical conductor is located downstream of the corona discharge section.

15. The ventilation duct according to claim 14, wherein the corona discharge section is provided at a location where the electrical conductor is present.

16. The ventilation duct according to claim 1 or 2, wherein the duct body further comprises an upstream insulating duct and a downstream insulating duct, which are arranged upstream and downstream of the electrical conductor.

17. The ventilation duct according to claim 1 or 2, wherein the constituent material of the electrical conductor is one or more selected from the group consisting of aluminum or an alloy thereof, copper or an alloy thereof, stainless steel, and conductive resin.

18. The ventilation duct according to claim 1 or 2, wherein the surface of the electrical conductor is treated with a conductive water-repellent coating.

19. A ventilation duct according to claim 1 or 2, for use in an air conditioning duct installed in a vehicle.

20. The ventilation duct according to claim 19, wherein the grounding conductive member is grounded to the body earth by electrically connecting with the conductive part of the vehicle body.

21. The ventilation duct according to claim 19, for use in an upstream location of an HVAC system mounted on the vehicle.

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