Heat exchange unit, heat exchange device, and heat exchange method

Abstract

A heat exchange unit according to the present disclosure comprises: a base part that is electrically connected to a reference potential point; a plurality of heat dissipation members that are supported by the base part; a discharge electrode that is formed from a conductive material; and a voltage application part that generates ions by applying a voltage between a heat dissipation member and the discharge electrode so as to cause a corona discharge.

Description

Heat exchange unit, heat exchange device, and heat exchange method

[0001] The present disclosure relates to a heat exchange unit, a heat exchange device, and a heat exchange method.

[0002] When turbulence occurs in fluids used in fluid machinery, heat exchangers, etc., pressure loss increases, which can be a problem. To address this issue, technologies have been developed to control fluids using ionization, such as plasma actuators.

[0003] For example, Patent Document 1 listed below discloses an automotive air conditioning system that includes a blower mounted on the vehicle, an air outlet that opens into the vehicle cabin, a flow passage that connects the blower and the air outlet and guides air blown from the blower to the air outlet, and a plasma actuator that is positioned in the flow passage and changes the direction of air flow by generating plasma.

[0004] JP 2017-65463 A

[0005] However, when using a plasma actuator as in the automotive air conditioning system described in Patent Document 1 above, there are problems such as the plasma actuator's low fluid acceleration capacity, which makes it difficult to obtain sufficient acceleration, and the plasma actuator's high power consumption.

[0006] In view of the above-mentioned problems, the present disclosure aims to provide a heat exchange unit, a heat exchange device, and a heat exchange method that can appropriately improve heat exchange performance.

[0007] In order to solve the above-mentioned problems and achieve the objectives, the heat exchange unit of the present disclosure comprises a base electrically connected to a reference potential point, a plurality of heat dissipation members supported on the base, a discharge electrode formed of a conductive material, and a voltage application unit that applies a voltage between the heat dissipation members and the discharge electrode to cause a corona discharge and generate ions.

[0008] In order to solve the above-mentioned problems and achieve the objectives, the heat exchange device of the present disclosure comprises the heat exchange unit described above, a fan that applies pressure to air by rotating, a drive unit that drives the fan, a casing having an intake port for allowing air to flow in, and the heat exchange unit located at at least one of the four corners of the casing.

[0009] In order to solve the above-mentioned problems and achieve the objectives, the heat exchange method disclosed herein is a heat exchange method for a heat exchange unit having a base electrically connected to a reference potential point, a plurality of heat dissipation members supported on the base, and a discharge electrode formed of a conductive material, in which a voltage is applied between the heat dissipation members and the discharge electrode to cause a corona discharge and generate ions.

[0010] According to the present disclosure, heat exchange performance can be appropriately improved.

[0011] FIG. 1 is a schematic diagram showing an example of the configuration of a heat exchange unit according to the present disclosure. FIG. 2 is a schematic diagram showing an example of the structure of a heat sink according to the present disclosure. FIG. 3 is a schematic diagram showing the structure of a first embodiment of a heat exchange unit according to the present disclosure. FIG. 4 is a schematic diagram showing the structure of a second embodiment of a heat exchange unit according to the present disclosure. FIG. 5 is a first diagram illustrating the action of ions generated by a discharge electrode according to the present disclosure. FIG. 6 is a second diagram illustrating the action of ions generated by a discharge electrode according to the present disclosure. FIG. 7 is a diagram showing an example of the configuration of a heat exchanger according to the present disclosure. FIG. 8 is a diagram showing the structure of an indoor heat exchanger in the heat exchanger according to the present disclosure. FIG. 9 is a diagram showing enstrophy isosurfaces in the heat exchanger according to the present disclosure.

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present disclosure is not limited to the embodiments described below.

[0013] (Configuration of Heat Exchanger Unit) First, the configuration of a heat exchanger unit according to the present disclosure will be described using Fig. 1. Fig. 1 is a schematic diagram showing an example configuration of a heat exchanger unit according to the present disclosure. As shown in Fig. 1, a heat exchanger unit 100 according to the present disclosure includes a heat sink 102, a voltage application unit 106, and a discharge electrode 104.

[0014] The heat sink 102 includes a base 120 electrically connected to the reference potential point 108 and a plurality of heat dissipation members 122 having one end connected to the base 120. An example of the structure of the heat sink 102 will now be described with reference to FIG. 2. FIG. 2 is a schematic diagram showing an example of the structure of a heat sink according to the present disclosure. As shown in FIG. 2, the heat sink 102 is formed such that a plurality of heat dissipation members 122 are arranged in parallel at equal intervals on one surface of the base 120 and protrude vertically from the one surface of the base 120. The heat sink 102 is electrically connected to the reference potential point 108.

[0015] The heat dissipation member 122 in this embodiment has a flat plate shape as shown in FIG. 2 . However, the shape of the heat dissipation member 122 is not limited to a flat plate shape. The heat dissipation member 122 may be a pin fin shaped like a pin holder, a corrugated fin formed by bending a flat fin into a wave shape, or the like. Furthermore, the distance between a specific heat dissipation member 122 and an adjacent heat dissipation member 122 among the multiple heat dissipation members 122 may be determined after performing a thermal fluid analysis in order to optimize the convective heat transfer of air.

[0016] The heat dissipation member 122 may be made of a metal with high thermal conductivity, such as aluminum, an aluminum alloy, copper, or a copper alloy. Furthermore, the surface of the heat dissipation member 122 may be anodized to improve the emissivity of heat radiation from the surface of the heat dissipation member 122.

[0017] The discharge electrode 104 is provided at a position spaced a predetermined distance from the tip of the heat dissipation member 122. The position at which the discharge electrode 104 is provided will now be described with reference to FIG. 3 . FIG. 3 is a schematic diagram showing the structure of a first embodiment of a heat exchange unit according to the present disclosure. As shown in FIG. 3 , the discharge electrode 104 may be provided at a position spaced a predetermined distance from one end of each of the heat dissipation members 122 connected to the base 120 of the heat sink 102, the other end being spaced a predetermined distance from the other end. Here, the predetermined distance may be set arbitrarily, but may be, for example, 2.5 to 5 cm when the height of the heat dissipation member 122 is 2.5 cm.

[0018] The discharge electrode 104 is made of a conductive material. The discharge electrode 104 may be made of a metal such as aluminum, copper, stainless steel, or tungsten. The discharge electrode 104 is formed in the shape of a wire, and is formed in the shape of a needle with a pointed tip. When a voltage is applied to the discharge electrode 104 by the voltage application unit 106, a corona discharge occurs, generating ions. Note that a corona discharge is a type of discharge, and when the potential difference between the electrodes reaches a corona critical voltage, a dielectric breakdown occurs in the gas between the electrodes, causing electrons to be emitted and a current to flow.

[0019] The reference potential point 108 is a potential that serves as a reference for an electric circuit, and is also called an earth or a ground. The reference potential point 108 may be realized by an earth or a ground. The earth may be a frame ground or a signal ground. The ground may be a frame ground or a signal ground.

[0020] The voltage application unit 106 applies a voltage to the heat dissipation member 122, generating a potential difference between the heat dissipation member 122 and the discharge electrode 104. The voltage application unit 106 applies a DC voltage to the heat dissipation member 122. The voltage application unit 106 generates a DC voltage from, for example, an AC voltage supplied from a power grid. In this case, the voltage application unit 106 may include a rectifier circuit, a transformer, a smoothing capacitor, etc. The voltage application unit 106 may apply a voltage using an independent power source such as a lithium-ion battery, a nickel-cadmium battery, a lead-acid battery, or an alkaline storage battery. The voltage application unit 106 generates a potential difference between the heat dissipation member 122 and the discharge electrode 104, thereby generating a corona discharge between the heat dissipation member 122 and the discharge electrode 104.

[0021] The voltage application unit 106 applies a high DC or AC voltage of, for example, 10 kV to the discharge electrode 104 electrically connected to the voltage application unit 106. Note that the applied voltage of 10 kV is an example, and the voltage applied by the voltage application unit 106 may be in the range of 5 to 20 kV, and may have either negative or positive polarity. Furthermore, the voltage application unit 106 need only be electrically connected to the discharge electrode 104 so as to generate a potential difference that generates a corona discharge between the discharge electrode 104 and the surface of the heat sink 102, and does not have to be physically connected to the heat sink 102. In other words, the heat sink 102 and the voltage application unit 106 may be connected to different reference potential points 108.

[0022] Here, the position where the discharge electrode 104 is provided will be described with reference to FIG. 4 . FIG. 4 is a schematic diagram showing the structure of a second embodiment of a heat exchange unit according to the present disclosure. As shown in FIG. 4 , the discharge electrode 104 may be provided between a heat dissipation member 122a and a heat dissipation member 122b, one end of which is connected to the base 120 of the heat sink 102. Note that the discharge electrode 104 is not limited to being provided between any two heat dissipation members 122 among the plurality of heat dissipation members 122 as shown in FIG. 4 , but may be provided between all adjacent heat dissipation members 122, or may be provided between any number of heat dissipation members 122. Furthermore, the position where the discharge electrode 104 is provided may be 0 to 2.5 cm away from the base 120, for example, when the height of the heat dissipation member 122 is 2.5 cm.

[0023] The discharge electrode 104 further includes an insulating cover C made of an insulator and provided on the side away from the base 120. The insulating cover C may be made of polyethylene, polyvinyl chloride (PVC), fluororubber, silicone rubber, ethylene-propylene rubber, or the like. As shown in Fig. 4, the insulating cover C may be provided over the entire surface of one side of the discharge electrode 104. This allows a corona discharge to be generated in the direction of the base 120, thereby efficiently attracting ions to the heat dissipation member 122 and the surface of the base 120.

[0024] (Operation of Heat Exchange Unit) Next, the operation of the heat exchange unit 100 according to the present disclosure will be described with reference to FIGS. 5 and 6. FIG. 5 is a first diagram illustrating the operation of ions generated by the discharge electrode according to the present disclosure. As shown in FIG. 5, when a voltage is applied between the heat dissipation member 122 and the discharge electrode 104 by the voltage application unit 106, the applied voltage generates a corona discharge, ionizing electrons from nitrogen molecules. As a result, positively charged ions (nitrogen ions) 130 are attracted to the base 120 connected to the reference potential point 208. Note that, as shown in FIG. 5, the air flow velocity 150 is in a state in which a boundary layer is formed in which the velocity near the surface of the base 120 is reduced due to the viscosity of the air.

[0025] The ions 130 then act as shown in FIG. 6 . FIG. 6 is a second diagram illustrating the action of ions generated by the discharge electrode according to the present disclosure. As shown in FIG. 6 , the ions 130 attracted to the base 120 become part of the boundary layer formed near the surface of the base 120, increasing the air flow rate 152 near the base 120. This reduces the thickness of the thermal boundary layer and increases the heat transfer rate due to air convection, thereby improving the heat exchange efficiency of the heat exchange unit 100. While the above embodiment describes the surface of the base 120, a similar phenomenon can also occur on the surface of the heat dissipation member 122, thereby increasing the flow rate.

[0026] In this embodiment, the heat sink 102 of the heat exchange unit 100 has a structure in which one ends of multiple heat dissipation members 122 are supported by the base 120, but this is not limiting. The heat sink 102 may support the multiple heat dissipation members 122 using a heat transfer member that penetrates the multiple heat dissipation members 122, such as a heat transfer tube through which a heat medium flows. Alternatively, the heat dissipation members 122 may not be provided, and the plate-shaped base 120 may serve as the heat dissipation member. In this case, too, the flow rate on the surface of the heat dissipating member can be increased by ions, thereby increasing the heat transfer rate.

[0027] (Configuration of Heat Exchanger) Next, the configuration of the heat exchanger 10 according to the present disclosure will be described with reference to Fig. 7. Fig. 7 is a diagram showing an example configuration of the heat exchanger according to the present disclosure. The heat exchanger 10 according to the present disclosure is configured with an air conditioning indoor unit 11 shown in Fig. 7 as a main element.

[0028] As shown in Figure 7, the air conditioning indoor unit 11 is composed of the following main elements: a casing 17, a drive unit 18 which is a motor arranged inside the casing 17, a fan 19 which is rotated by the drive unit 18, an intake port 20 through which indoor air flows in, an intake port 21 which directs the air from the intake port 20 to the fan 19, a heat exchanger 22 which heats or cools the air, and an outlet port 23 which discharges the air into the room.

[0029] A heat exchanger 22 is provided in a substantially rectangular shape around the fan 19. Fig. 8 is a diagram showing the structure of the heat exchanger in the heat exchange device according to the present disclosure. As shown in Fig. 8, the heat exchanger 22 is composed of flat plate portions 22A having a substantially planar shape and corner portions 22B with a small radius of curvature that connect adjacent flat plate portions 22A.

[0030] In this embodiment, the corner portion 22B of the heat exchanger 22 may be realized by the above-described heat exchange unit 100. In other words, it can be said that the heat exchange unit 100 is disposed in at least one of the four corners of the casing 17.

[0031] Here, because the fan 19 is circular and the casing 17 is rectangular, regions where the flow velocity is slow are formed in the circumferential direction of the fan 19. As a result, the flow velocity distribution becomes non-uniform inside the casing 17. In this regard, the results of a computational fluid dynamics (CFD) analysis of the air inside the casing 17 of the air conditioning indoor unit 11 are shown in Fig. 9. Fig. 9 is a diagram showing an image of the results of the computational fluid dynamics analysis of the heat exchanger according to the present disclosure.

[0032] As shown in the analysis result image in Figure 9, in areas 210 at the four corners of the casing, the air flow stagnates, creating areas where the air flow velocity is slow. At the electrical equipment panel installation position 212, a drift 214 occurs, indicating that there is a deviation in the air flow velocity in the area where the heat exchanger 22 inside the air conditioning indoor unit 11 is located. Therefore, by providing the above-mentioned heat exchange unit 100 in a location in the casing 17 where the air flow velocity is slow, the air conditioning indoor unit 11 can increase the air flow velocity and improve heat transfer efficiency.

[0033] (Configuration and Function) The heat exchange unit 100 according to the present disclosure comprises a base 120 electrically connected to a reference potential point 108, a plurality of heat dissipation members 122 supported by the base 120, a discharge electrode 104 formed of a conductive material, and a voltage application section 106 that applies a voltage between the heat dissipation member 122 and the discharge electrode 104 to cause a corona discharge and generate ions.

[0034] This configuration allows ions generated by corona discharge to be attracted to the heat dissipation member 122 and the base 120, thereby increasing the flow velocity of the boundary layer near the heat dissipation member 122 and the base 120. This improves the heat transfer efficiency of the heat exchange unit 100. This makes it possible to provide a heat exchange unit 100 that can appropriately improve heat exchange performance.

[0035] In the heat exchange unit 100 according to the present disclosure, the discharge electrode 104 is provided at a position spaced a predetermined distance from the heat dissipation member.

[0036] According to this configuration, even with a small number of discharge electrodes 104, the potential difference between the discharge electrodes 104 and the base 120 generates corona discharge, and the resulting ions are attracted to the surface of the heat dissipation member 122 and the surface of the base 120, thereby increasing the flow velocity of the boundary layer formed on these surfaces, thereby improving heat transfer efficiency. Therefore, it is possible to provide a heat exchange unit 100 that can appropriately improve heat exchange performance.

[0037] In the heat exchange unit 100 according to the present disclosure, the heat dissipation member is plate-shaped. With this configuration, the flow rate on the surface of the heat dissipation member can be further increased.

[0038] The heat exchange unit 100 according to the present disclosure includes a plurality of heat dissipation members, and the heat dissipation members are arranged in parallel with adjacent heat dissipation members. This configuration can further increase the heat dissipation efficiency.

[0039] In the heat exchange unit 100 according to the present disclosure, the discharge electrode 104 is provided between at least two adjacent heat dissipation members 122 among the plurality of heat dissipation members.

[0040] With this configuration, the potential difference between the discharge electrode 104 and the base 120 generates a corona discharge, and the ions generated can be accurately attracted to the surface of the heat dissipation member 122 and the surface of the base 120. This increases the flow rate of the boundary layer formed on these surfaces, thereby improving heat transfer efficiency. Therefore, it is possible to provide a heat exchange unit 100 that can appropriately improve heat exchange performance.

[0041] The heat exchange unit 100 according to the present disclosure further includes an insulating cover C formed of an insulating material and provided on the side of the discharge electrode 104 in the direction away from the base 120 .

[0042] With this configuration, ions are not generated by corona discharge in a direction away from the base 120 of the discharge electrode 104, and therefore ions can be more accurately attracted to the surface of the heat dissipation member 122 and the surface of the base 120. Therefore, it is possible to provide a heat exchange unit 100 that can appropriately improve heat exchange performance.

[0043] The heat exchange device 10 according to the present disclosure comprises the heat exchange unit described above, a fan 19 that applies pressure to air by rotating along a rotation axis, a drive unit 18 that drives the fan 19, a casing 17 having an intake port for allowing air to flow in, and a heat exchange unit 100 arranged at at least one of the four corners of the casing 17.

[0044] According to this configuration, the flow velocity at the four corners of the casing 17, where the flow velocity is normally reduced, can be increased by the ions, thereby improving the heat exchange performance of the heat exchange device 10. Therefore, it is possible to provide a heat exchange device 10 that can appropriately improve the heat exchange performance.

[0045] The heat exchange method according to the present disclosure is a heat exchange method for a heat exchange unit 100 having a base 120 electrically connected to a reference potential point, a plurality of heat dissipation members 122 supported by the base 120, and a discharge electrode 104 formed of a conductive material, in which a voltage is applied between the heat dissipation member 122 and the discharge electrode 104 to cause a corona discharge and generate ions.

[0046] This configuration allows ions generated by corona discharge to be attracted to the heat dissipation member 122 and the base 120, thereby increasing the flow velocity of the boundary layer near the heat dissipation member 122 and the base 120. This improves the heat transfer efficiency of the heat exchange unit 100, thereby improving the heat exchange performance appropriately.

[0047] Although the embodiments of the present disclosure have been described above, the embodiments are not limited to the contents of these embodiments. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiments.

[0048] REFERENCE SIGNS LIST 10 Heat exchange device 11 Air conditioning indoor unit 17 Casing 18 Drive unit 19 Fan 20, 21 Intake port 22 Heat exchanger 23 Outlet 100 Heat exchange unit 102 Heat sink 104 Discharge electrode 106 Voltage application unit 108 Reference potential point 120 Base 122 Heat dissipation member

Claims

1. A heat exchange unit comprising: a base electrically connected to a reference potential point; a plurality of heat dissipation members supported on the base; a discharge electrode formed from a conductive material; and a voltage application unit that applies a voltage between the heat dissipation members and the discharge electrode to cause a corona discharge and generate ions.

2. The heat exchange unit according to claim 1, wherein the discharge electrode is provided at a position spaced a predetermined distance from the heat dissipation member.

3. The heat exchange unit according to claim 1, wherein the heat dissipation member is plate-shaped.

4. The heat exchange unit according to claim 3, comprising a plurality of the heat dissipation members, the heat dissipation members being arranged in parallel with adjacent heat dissipation members.

5. The heat exchange unit according to claim 4, wherein the discharge electrode is provided between at least two adjacent heat dissipation members among the plurality of heat dissipation members.

6. The heat exchange unit according to claim 1, further comprising an insulating cover made of an insulator and provided on a side of the discharge electrode in a direction away from the base.

7. A heat exchange device comprising: a heat exchange unit according to any one of claims 1 to 6; a fan that sends air towards the heat exchange unit; a drive unit that drives the fan; a casing having an intake port for allowing air to flow in; and the heat exchange unit arranged in at least one of the four corners of the casing.

8. A heat exchange method for a heat exchange unit having a base electrically connected to a reference potential point, a plurality of heat dissipation members supported by the base, and a discharge electrode formed of a conductive material, comprising applying a voltage between the heat dissipation members and the discharge electrode to cause a corona discharge and generate ions.

Images