JP2018173224A - Heating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric heating device utilizing heat storage and heat radiation, which can improve heat exchange efficiency of a conductor during heat radiation. In the electric heating device, an alternating current having a first frequency is passed through the conductor while the conductor generates heat when energized and heat is stored in the conductor, and heat is radiated from the conductor by heat exchange by blowing air. The control unit controls so that an alternating current having a second frequency, which is higher than the first frequency and has a skin effect, is caused to flow through the conductor. [Selection diagram] Figure 1

Description

  The present invention relates to an electric heating device using heat storage and heat dissipation.

  For example, in Patent Document 1, an electric heat storage hot air heater (heating) that heats and stores heat with a heating heater (conductor) and discharges air blown from a fan using the heat stored in the heat storage body Apparatus).

JP-A-8-022885

  In the heat storage hot air device described in Patent Document 1, the method of heating the conductor is not changed between heat storage and heat dissipation. For this reason, even at the time of heat dissipation, the conductor central part that is not easily heat-exchanged is immediately heated, and the heat exchange efficiency of the conductor at the time of heat dissipation is not improved.

  This invention is made | formed in view of the said subject, and it aims at providing the heating apparatus which can improve the heat exchange efficiency of the conductor at the time of heat radiation.

  In order to solve the above-described problem, an aspect of the present invention is an electric heating device that uses heat storage and heat dissipation, and a conductor that generates heat by energization and a first frequency while the conductor stores heat. A control unit for controlling the AC current to flow through the conductor at a second frequency that is higher than the first frequency and provides a skin effect while the AC current is passed through the conductor and heat is dissipated from the conductor by heat exchange by air blowing; It is characterized by providing.

  In this aspect, the frequency of the alternating current that flows through the conductor (first frequency) is relatively low during heat storage of the conductor, and the frequency of the alternating current that flows through the conductor (second frequency) is relatively low during heat dissipation of the conductor. The skin effect is high (first frequency <second frequency).

  With this configuration, while the heat is stored, the center portion of the conductor can be effectively heated by the low-frequency alternating current. On the other hand, while the heat is radiated, only the surface portion of the conductor is heated by the high frequency alternating current by the skin effect, and the heat can be effectively radiated by the air blowing using a blower such as a fan.

  As described above, according to the heating device of the present invention, the heat exchange efficiency of the conductor during heat radiation can be improved.

The figure which shows schematic structure of the heating apparatus which concerns on one Embodiment of this invention. Diagram explaining the change in the positional relationship between the vehicle and the building entrance Diagram explaining the change in the positional relationship between the vehicle and the building entrance Diagram explaining the change in the positional relationship between the vehicle and the building entrance The figure explaining the heating control which the heating apparatus which concerns on one Embodiment of this invention performs

[Overview]
The present invention is a heating device using a conductor that generates heat when energized. In this heating apparatus, low-frequency alternating current is passed through a conductor to store heat, and high-frequency alternating current is passed through a conductor to radiate heat. By setting this high frequency to a value at which the frequency is higher than the low frequency and a skin effect is obtained, the heat exchange efficiency of the conductor during heat dissipation is improved.

[Configuration of heating system]
FIG. 1 is a diagram illustrating a schematic configuration of a heating device 1 according to an embodiment of the present invention. The heating device 1 of this embodiment illustrated in FIG. 1 includes a conductor 10, a power supply unit 20, a blower unit 30, and a control unit 40.

  The conductor 10 is a heat storage body that has both a heat storage function capable of storing heat therein and a heat radiation function (heat exchange function) capable of exchanging the stored heat with air and releasing the heat. The conductor 10 includes, for example, a heater coil including a main body portion 11 made of a metal that generates heat when energized and a heat dissipating fin portion 12 provided on the outer peripheral wall of the main body portion 11 at a predetermined interval. Can be used.

  The power supply unit 20 is a variable current source capable of flowing an alternating current Iac having an arbitrary frequency through the conductor 10. The power supply unit 20 is connected to the conductor 10 by a cable 21 and has a role of flowing an alternating current Iac having a predetermined frequency f to the conductor 10 based on control by the control unit 40.

  The air blower 30 is a blower mechanism that can send air to the conductor 10 and apply it. A propeller fan device etc. can be used for the ventilation part 30, for example. The blower 30 has a role of efficiently performing heat exchange between the conductor 10 and air by blowing air to the conductor 10 at a predetermined timing based on control by the control unit 40.

  The control unit 40 can control the frequency f of the alternating current Iac that the power supply unit 20 flows through the conductor 10 (selectively switches between a low frequency and a high frequency) according to the opening / closing timing of the quick shutter 4 described later.

  Moreover, the control part 40 can control the ventilation state of the air which directed the conductor 10 by the ventilation part 30 according to the opening / closing timing of the quick shutter 4 mentioned later (it selectively switches between blowing or not blowing).

[Operation of heating system]
Next, with reference further to FIG. 2A, FIG. 2B, FIG. 2C, and FIG. 3, the heating control by the heating apparatus 1 which concerns on one Embodiment of this invention is demonstrated. Hereinafter, the heating control performed by the heating device 1 installed at the doorway of the building 3 through which the vehicle 2 passes will be described as an example.

  2A, 2 </ b> B, and 2 </ b> C are diagrams illustrating changes in the positional relationship between the vehicle 2 and the quick shutter 4 at the entrance / exit of the building 3. FIG. 3 is a diagram illustrating the relationship between the content of the heating control executed by the heating device 1 according to the present embodiment and the amount of stored heat. Note that timings A, B, and C in FIG. 3 correspond to positions a, b, and c in FIGS. 2A, 2B, and 2C, respectively.

  The conductor 10 is not energized until the vehicle 2 traveling toward the building 3 reaches the position a. Therefore, the conductor 10 does not generate heat and is not stored inside (period until timing A in FIG. 3).

  When the vehicle 2 reaches the position a, energization of the conductor 10 is started, and an alternating current Iac having a predetermined low frequency f_low is passed through the conductor 10 (position a in FIG. 2A, timing A in FIG. 3). Thereby, the heat storage to the conductor 10 is started. The fact that the vehicle 2 has reached the position a can be easily determined using, for example, a sensor.

  Here, based on the following equation [1] for obtaining the skin depth δ, which is well known for the skin effect, the low frequency f_low of the alternating current Iac can be set in advance to the frequency value at which the current also flows inside the conductor 10. In this case, the inside of the conductor 10 can also generate heat. When set in this way, the conductor 10 can be sufficiently stored in the interior while the low frequency f_low of the alternating current Iac is passed through the conductor 10 (period A to B in FIG. 3).

δ = 5.03 * √ (ρ / μf) [1]
ρ: Electrical resistivity of the conductor
μ: Absolute permeability of conductor
f: Current frequency

  When the vehicle 2 reaches the entrance / exit position b of the building 3 and the quick shutter 4 is opened, the frequency of the alternating current Iac flowing through the conductor 10 is changed from a low frequency f_low to a predetermined high frequency f_high (f_high> f_low). (Position b in FIG. 2B, timing B in FIG. 3). Further, the air blowing to the conductor 10 is started. Thereby, heat exchange between the heat-storing conductor 10 and air, that is, heat dissipation from the conductor 10 is started. The air heated by this heat exchange is used, for example, as an air curtain for heat insulation inside the building 3 or for heating a passenger of the vehicle 2. The fact that the vehicle 2 has reached the position b can be easily determined using, for example, a sensor.

  Here, based on the above equation [1], if the high frequency f_high of the alternating current Iac is set in advance to a frequency value at which a skin effect can be obtained in which current flows only on the surface of the conductor 10 and does not flow inside, Only the surface of the conductor 10 can generate heat. When set in this way, heat can be generated effectively only on the surface of the conductor 10 while the heat stored in the conductor 10 is released by blowing by the blowing unit 30, so that heat exchange can be effectively performed. Yes (period of timing B to C in FIG. 3).

  Then, when the vehicle 2 travels and reaches the position c where the quick shutter 4 is closed, energization and air blowing to the conductor 10 are terminated (position c in FIG. 2C, timing C in FIG. 3). The fact that the vehicle 2 has reached the position c can be easily determined using, for example, a sensor.

  In addition, the opportunity which complete | finishes electricity supply and ventilation to the conductor 10 is not restricted only to the vehicle 2 having reached the predetermined position c. For example, the energization and the air flow to the conductor 10 may be automatically terminated after a lapse of a predetermined time after the quick shutter 4 is opened.

[Operations and effects in this embodiment]
According to the heating device 1 according to the above-described embodiment of the present invention, while the conductor 10 is stored using the conductor 10 that generates heat by energization, the AC current Iac having a low frequency f_low is passed through the conductor 10. While the conductor 10 is radiating heat, an alternating current Iac having a high frequency f_high is passed through the conductor 10. The high frequency f_high is set to a value that is higher than the low frequency f_low and that provides a skin effect.

  With this configuration and control, while the heat is stored, the center portion of the conductor 10 can be effectively heated by the alternating current Iac having the low frequency f_low, and the conductor 10 can be sufficiently stored. On the other hand, during the heat dissipation, only the surface portion of the conductor 10 is heated by the alternating current Iac of the high frequency f_high due to the skin effect, and the heat exchange of the conductor 10 is effectively performed by the air blowing using the air blower 30 or the like. The conductor 10 can be dissipated.

  As described above, since the heating device 1 according to the present embodiment varies the frequency of the alternating current Iac according to the situation, the heat exchange efficiency of the conductor 10 during heat dissipation can be improved. Furthermore, the heat storage efficiency of the conductor 10 during heat storage can be improved.

  The heating device of the present invention can be used for an air curtain device or the like provided at the entrance of a building, and is useful when it is desired to improve the heat exchange efficiency of the conductor during heat radiation.

DESCRIPTION OF SYMBOLS 1 Heating apparatus 2 Vehicle 3 Building 4 Quick shutter 10 Conductor 11 Main body part 12 Fin part 20 Power supply part 21 Cable 30 Blower part 40 Control part

Claims (1)

An electric heating device using heat storage and heat dissipation,
A conductor that generates heat when energized;
While the heat is stored in the conductor, an alternating current of a first frequency is passed through the conductor, and while the heat is radiated from the conductor by heat exchange by blowing, the skin effect is higher than the first frequency. A control unit for controlling an alternating current of a second frequency to flow through the conductor;
A heating device.