Noise reduction mechanism of horizontal blowout unit heater

Abstract

To provide a mechanism capable of reducing noise such as wind noise in a horizontal blowout (H-shaped) unit heater.SOLUTION: A noise reduction mechanism of a horizontal blowout unit heater is configured such that in a horizontal blowout unit heater in which a bell-mouth suction opening with a circular cross section is provided on an upstream side and a coil serving as a horizontal or vertical heat exchanger is arranged immediately behind, a straightening plate is arranged near both ends of the horizontal or vertical coil, parallel to fins on a pair of coils, to increase an opening area of the bell-mouth suction opening, thereby reducing a vortex generation area formed by the bell-mouth suction opening and an opening part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an abnormal noise reduction mechanism that reduces abnormal noise such as wind noise in a side-blowing type (H-type) unit heater. [Background technology]

[0002] Conventional unit heaters use steam or hot water as a heat source, and the air heated by a coil is blown downward or sideways by a highly efficient pressure propeller fan, making them widely used for heating occupied areas, as well as for heating occupied areas such as factories, warehouses, gymnasiums, and exhibition halls.The main types of unit heaters are downward-blowing and side-blowing, and the one shown in Figure 1 is a side-blowing unit heater. This side-discharge type unit heater has a bell-mouth type suction opening (pressure ventilation fan) 2 on the upstream side, a heating coil 4 on the downstream side, and a damper section 5 at the outlet further downstream.It can be used to heat the entire factory in a large factory, or to heat only certain areas as space heating, or as spot heating to heat only living areas, and is widely used because it is easy to install and install. Although the horizontal discharge type unit heater is easy to use, it has the disadvantage of being prone to generating abnormal noises such as wind noise. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Utility Model Registration No. 3220002 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a mechanism for reducing abnormal noise such as wind noise in a side-blowing type (H-type) unit heater. [Means for solving the problem]

[0005] This is an abnormal noise reduction mechanism for a side-blowout unit heater in which a bell-mouth suction opening with a circular cross section is provided on the upstream side and a coil serving as a heat exchanger is arranged horizontally or vertically immediately behind it, and in which straightening vanes are placed near both ends of the horizontal or vertical coil in parallel to the fins on the pair of coils, thereby enlarging the opening area of ​​the bell-mouth suction opening (pressure ventilation fan) and reducing the size of the vortex generating section formed by the bell-mouth suction opening and the opening, and further a straightening vane reinforcing section is provided in the center of the pair of straightening vanes to connect them. The bell-mouth type suction opening is preferably a pressurized ventilation fan, as shown in Figure 1, which is provided at the opening to send air in. [Effects of the Invention]

[0006] According to the noise reduction mechanism for a side-blowout unit heater of the present invention, by arranging straightening vanes parallel to the fins near both ends of the coil to enlarge the opening area of ​​the bell-mouth suction opening and reduce the size of the vortex generating area formed by the bell-mouth suction opening and the opening, it is possible to reduce noise such as wind noise. Also, by providing a horizontal straightening vane in the center of the pair of vertical straightening vanes and providing a straightening vane reinforcement, it is possible to prevent deformation of the straightening vane when strong wind pressure is applied. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1(a) is a perspective view of the overall appearance of the blowing side of a heat exchanger of an embodiment of a unit heater, which is the premise of the present invention; FIG. 1(b) is a perspective view of the overall appearance of the intake side; [Figure 2] Figure 2 is an explanatory diagram of the air volume of the noise reduction mechanism of a conventional blow-out type unit heater without a straightening plate. Figure 2(a) is an overall perspective view, Figure 2(b) is a partially enlarged view of Figure 2(b), and Figure 2(c) is a partially enlarged view showing the state of the air flow. [Figure 3]FIG. 3 is an explanatory diagram of the air volume of the noise reduction mechanism of the blow-out type unit heater in which the rectifying plate of this embodiment is arranged, FIG. 3(a) is an overall perspective view, FIG. 3(b) is a partially enlarged view thereof, and FIG. 3(c) is a partially enlarged view showing the state of the air flow. [Figure 4] FIG. 4(a) is a perspective view of the opening of a conventional bell-mouth type suction opening, FIG. 4(b) is a cross-sectional view thereof, and FIG. 4(c) is an enlarged view of the circular chain line thereof. [Figure 5] FIG. 5(a) is a perspective view of the opening of the bell-mouth type suction opening of this embodiment, FIG. 5(b) is a cross-sectional view thereof, and FIG. 5(c) is an enlarged view of the dashed circular line thereof. [Figure 6] Case A in Figure 6 shows the 1 / 1 octave band analysis results for a conventional product, Case B shows the 1 / 1 octave band analysis results for a state where the opening was enlarged (widened), Case C shows the 1 / 1 octave band analysis results for a state where a rectifying plate was installed, and Case D shows the 1 / 1 octave band analysis results for a state where both were installed. DETAILED DESCRIPTION OF THE INVENTION

[0008] A preferred embodiment of a side-blowing type unit heater according to the present invention will be described with reference to the drawings. The side-blowing type unit heater shown in Figures 1(a) and (b) uses hot water or steam as a heat source, and air heated by a coil 4 is blown out by a fan 3 through an intake opening 2. In the side-blowing type (H-shaped) unit heater of the present invention, an intake opening is attached to the rear panel 11 of the case 1, but when the intake opening is used, an unpleasant wind noise (high-pitched noise) is generated from the downwind side. The present invention aims to eliminate this annoying wind noise (high-pitched noise), and for this reason, point (1) is that when the coil 4 is arranged horizontally, the straightening plate 6 is arranged vertically (parallel to the fin surface of the coil), but when the coil piping is horizontal (HW type), it is made "H" shaped, and when it is vertical (HS type), it is made "H" shaped. Point (2) was to enlarge the air suction opening area of ​​the suction opening mounting plate (rear case plate) 11, in other words, to match the opening diameter to the diameter of the discharge side of the bell mouth. By using points (1) and (2) together, it was possible to eliminate the abnormal noise.

[0009] These two points will be explained in detail below. Regarding the rectifier plate at point (1) FIG. 2 shows a conventional side-blowing unit heater in which a bell-mouth suction opening 2 with a circular cross section is provided on the upstream side, and a coil 4 serving as a heat exchanger is placed horizontally (or vertically) immediately behind it. Figure 3 shows a straightening plate according to an embodiment of the present invention, in which a pair of straightening plates 6 are provided near both ends of the horizontal (or vertical) coil, parallel to the fins 41 of the horizontal coil 4, and a straightening plate reinforcement portion 61 is provided in the center of the pair of straightening plates to connect the two straightening plates. Comparing the conventional example shown in FIG. 2(c) with the present example shown in FIG. 3(c), the strength of the air flow in the conventional example is uneven, which is thought to be one of the causes of the abnormal noise. The results of the abnormal noise measurement at this time are shown in the table in Figure 6. The 1 / 1 octave band analysis result when no rectifying plate was installed and no other measures were taken is Case A, but the result when the rectifying plate was installed is Case C, where the noise was reduced by -5.3 dB at the audible frequency of 4 kHz, but the abnormal noise remained. When the coil 4 is installed horizontally, the fins 41 are vertical, but when the coil 4 is vertically oriented, the fins 41 are horizontal, so the pair of straightening plates 6 are horizontal and the central straightening reinforcement plate is vertical. In other words, when the coil piping is vertical (HS type), the coil fin surface is horizontal, so the H-shaped straightening plate is also arranged horizontally. The octave band analysis in the table in Figure 6 is a long-standing method of noise analysis, and although there are other methods such as "1 / 1 octave band analysis" and "1 / 3 octave band analysis," we have adopted "1 / 1 octave band analysis" here. In addition, we can usually sense eardrum vibrations as sound from as low as 20Hz to as high as 15kHz or 20kHz (this may vary from person to person), and this frequency range is called the audible range. However, sounds that people find unpleasant are in the middle range of the audible range, and it is said that the frequency range of 2kHz to 4kHz is the most unpleasant abnormal sound. In the table in Figure 6, 4 kHz stands out more than 2 kHz in cases A and B. In case C, it is almost the same, and in case D, the level is clearly lower than the adjacent 2 kHz. It is when you hear the 4 kHz sound in cases A and B that you perceive it as an abnormal noise, and in case C, it is only when you can detect the abnormal noise, but it is not perceived as an abnormal noise when the level drops gently from 2 kHz to 4 kHz to 8 kHz, as in case D.

[0010] (2) Suppression of vortex flow As mentioned above, even if a straightening plate is provided, abnormal noises such as wind noise remain. Therefore, it is thought that the source of the abnormal noise is a vortex generated in the space that exists in the retention space 71 (dotted circle in Figure 4(c)) that exists in the opening 7 of the bell-mouth type suction opening 4 in Figure 4. Therefore, by enlarging the opening 7 and making the retention space 71 into an extremely small retention space 72 (dotted circle in Figure 5(c)), the space in which vortices can occur is eliminated as much as possible, and the generated vortex is also extremely small. The air volume of the unit heater (HW-95-2 / 50Hz) in the table in Figure 6 is 4795 m 3 / h. As a result, the results of the 1-octave band analysis in Table 1 of Figure 6 were Case B, which was a reduction of -0.9 dB at the audible frequency of 4 kHz compared to Case A, but the abnormal noise remained.

[0011] Functions and Effects of the Examples of the Present Invention As described above, by eliminating the rectifying plate 6 and the retention space 71, it was possible to reduce abnormal noise, etc. However, since harsh abnormal noise still remained, 1 / 1 octave band analysis was attempted in an embodiment in which both the rectifying plate 6 and the retention space 71 were eliminated. As a result, case D in the table in Figure 6 was the result of the 1 / 1 octave band analysis, which showed a reduction of -6.8 dB at the audible frequency of 4 kHz compared to case A, and a reduction of -1.5 dB at 4 kHz compared to case D, eliminating the abnormal noise in the audible range (2 kHz to 4 kHz). [Explanation of symbols]

[0012] 1··Case, 11··Back plate, 2. Bell-mouth type suction opening 3··Fan, 4. Coil (heat exchanger), 41. Fin 5. Damper section, 6. Rectifier plate, 61, Rectifier plate reinforcement part, 7...opening, 71...retention space, 72...minimum retention space

Claims

1. A horizontal blow-out type unit heater has a bell-mouth type suction opening with a circular cross section on the upstream side, and a coil serving as a heat exchanger arranged horizontally or vertically immediately after the opening. a current plate is disposed near both ends of the horizontal or vertical coil in parallel with the fins provided on the pair of coils; The opening area of ​​the bell-mouth type suction opening is enlarged, and the vortex generating portion formed by the bell-mouth type suction opening and the opening is reduced in size. A noise reduction mechanism for a side-blowing unit heater.

2. 2. The noise reduction mechanism for a side-blowout unit heater according to claim 1, wherein a reinforcing portion for the pair of straightening plates is provided at the center of the pair of straightening plates to connect the two straightening plates.

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