Air curtain device

Abstract

[Object of the Invention] An object of the present invention is to develop an air curtain device generating parallel air flow based on the knowledge in that parallel air flow generated at the outlet of a turbulent flow runup zone does not include vortex flows and has strong air current interruption performance. [Disclosure of the Invention] An air curtain device comprises a first ventilation box comprising a discharge elbow provided with guide vanes, a honeycomb, an industrial use ventilating fan, a suction elbow provided with guide vanes, and a pre-filter, wherein the aforesaid elements are sequentially accommodated in a rectangular box whose one side surface is open and an outlet port of the discharge elbow provided with guide vanes and the pre-filter are disposed on the open side surface of the rectangular box, and a second ventilation box of the same structure as the first ventilation box, wherein the first ventilation box is put on an entrance floor with the discharge elbow provided with guide vanes above, and the second ventilation box is put on the entrance floor with the discharge elbow provided with guide vanes below, so that the first ventilation box and the second ventilation box oppose each other at their open side surfaces in a mutually upside-down manner and the first ventilation box and the second ventilation box are distanced from each other by a breadth Xg of the entrance, and wherein an entrance ceiling is provided to a breadth equal to the distance between the ventilation boxes so as to connect a top of the first ventilation box with a top of the second ventilation box, thereby forming an air curtain device entrance, wherein relation between the breadth Xg of the entrance of the air curtain device and a breadth D of the outlet ports of the discharge elbows provided with guide vanes is set at Xg5D.

Claims

1. An air curtain device comprising a first ventilation box comprising a discharge elbow provided with guide vanes, a honeycomb, an industrial use ventilating fan, a suction elbow provided with guide vanes, and a pre-filter, wherein the aforesaid elements are sequentially accommodated in a rectangular box whose one side surface is open and an outlet port of the discharge elbow provided with guide vanes and the pre-filter are disposed on the open side surface of the rectangular box, and a second ventilation box of the same structure as the first ventilation box, wherein the first ventilation box is put on an entrance floor with the discharge elbow provided with guide vanes above, and the second ventilation box is put on the entrance floor with the discharge elbow provided with guide vanes below, so that the first ventilation box and the second ventilation box oppose each other at their open side surfaces in a mutually upside-down manner and the first ventilation box and the second ventilation box are distanced from each other by a breadth Xg of the entrance, and wherein an entrance ceiling is provided to a breadth equal to the distance between the ventilation boxes so as to connect a top of the first ventilation box with a top of the second ventilation box, thereby forming an air curtain device entrance, wherein relation between the breadth Xg of the entrance of the air curtain device and a breadth D of the outlet ports of the discharge elbows provided with guide vanes is set at Xg5D, and wherein the discharge elbow provided with guide vanes comprises an elbow of rectangular cross section and expansion ratio f of 1<f5, and one or more guide vanes disposed in the elbow, while the guide vane or the guide vanes are made of a curved plate and a pair of flat plates connected to the curved plate, with one of them being located in front of the curved plate and the other being located to the rear of the curved plate, wherein m number of sub-channels similar to one another are formed in the elbow based on the following formulas, whereafter the inner sidewall of the elbow is deformed into a curved plate coaxial with the curved plate of the adjacent guide vane to deform n=1 sub-channel into a coaxial bend channel provided with a uniform breadth equal to the inlet breadth b.sub.1 of the sub-channel,
p=h/{[f/(fr)].sup.m1}(1)
a.sub.n=pr[f/(fr)].sup.n(2)
b.sub.n=a.sub.n/f(3)
f=W.sub.0/h(4)
W=W.sub.0(a.sub.1b.sub.1)(5) p: overhang length at the outlet of the elbow h: inlet breadth of the elbow W.sub.0: baseline outlet breadth of the elbow W: outlet breadth of the elbow f: expansion ratio of the elbow (f=W.sub.0/h, 1<f5) r: aspect ratio of the sub-channels (r<f) m: number of sub-channels (m2) a.sub.n: outlet breadth of n-th sub-channel (a.sub.0 indicates the radius of curvature of the inner sidewall and a.sub.m indicates the radius of curvature of the outer sidewall) b.sub.n: inlet breadth of n-th sub-channel and wherein the suction elbow provided with guide vanes comprises an elbow of rectangular cross section and contraction ratio f of 1<f5, and one or more guide vanes made of a curved plate and flat plates connected to the curved plate disposed so as to make the shapes of the sub-channels defined thereby similar to each other based on the following formulas,
P=h/{[f/(fr)].sup.m1}(6)
a.sub.n=Pr[f/(fr)].sup.n(7)
b.sub.n=a.sub.n/f(8) P: overhang length at the inlet of the elbow h: outlet breadth of the elbow W: inlet breadth of the elbow f: contraction ratio of the elbow (f=W/h, 1<f5) r: aspect ratio of the sub-channels (r<f) m: number of sub-channels (m2) a.sub.n: inlet breadth of n-th sub-channel (a.sub.0 indicates the radius of curvature of the inner sidewall and a.sub.m indicates the radius of curvature of the outer sidewall) b.sub.n: outlet breadth of n-th sub-channel wherein a higher level non-axisymmetric outlet port and a lower level non-axisymmetric outlet port oppose each other axisymmetrically with respect to a center horizontal plane, a higher level non-axisymmetric jet core screen and a lower level non-axisymmetric jet core screen simultaneously becomes irrotational parallel flows so as to form an upper level parallel flow air curtain and a lower level parallel flow air curtain, whereby the higher level and the lower level oppositely directed air flows form an axisymmetric internally circulating parallel flow air curtain as a whole.

2. An air curtain device of claim 1, wherein an inlet air flow speed of the discharge elbow is reduced to an outlet air flow speed of the discharge elbow at an initial operation stage so as to recover dynamic pressure, thereby keeping an outlet pressure of the industrial use ventilating fan negative at initial operation stage so as to make an operation air flow rate of the higher level parallel flow air curtain and an operation air flow rate of the lower level parallel flow air curtain at initial operation stage equal to free air flow rate of the industrial use ventilating fan.

3. An air curtain device of claim 1, wherein an ion-pole is disposed at each of the outlet port of the discharge elbow of the first ventilation box and the outlet port of the discharge elbow of the second ventilation box, wherein each ion-pole extends over the whole length of the outlet port, and wherein the ion-poles generate ions, so as to ionize the higher level parallel flow air curtain and the lower level parallel flow air curtain, thereby forming an ionized parallel flow air curtain as a whole.

4. An air curtain device of claim 2, wherein an ion-pole is disposed at each of the outlet port of the discharge elbow of the first ventilation box and the outlet port of the discharge elbow of the second ventilation box, wherein each ion-pole extends over the whole length of the outlet port, and wherein the ion-poles generate ions, so as to ionize the higher level parallel flow air curtain and the lower level parallel flow air curtain, thereby forming an ionized parallel flow air curtain as a whole.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a set of views each showing a free jet of turbulent flow.

(3) FIG. 2 is a view explaining a runup zone.

(4) FIG. 3 is a view showing a slot type outlet nozzle.

(5) FIG. 4 is a set of views each showing speed distribution of parallel air flow in a duct. (a) shows contour lines of equal speed flows of thoroughly developed turbulent parallel flow in a duct of rectangular cross section after passing through a runup zone. (b) shows speed distribution of thoroughly developed turbulent parallel flow after passing through a runup zone.

(6) FIG. 5 is a set of views each showing a parallel air flow core. (a) shows a parallel air flow core formed near an outlet port formed at an end of a runup zone of a three dimensional axisymmetric rectangular section duct. (b) shows a parallel air flow core screen formed near an outlet port formed at an end of a runup zone of a three dimensional axisymmetric rectangular section duct when only the ceiling and the floor of the duct are extended from the outlet port.

(7) FIG. 6 is a set of structural views of a parallel flow air curtain device. (a) shows a front view, (b) shows a view in the direction of arrows A-A in (a), and (c) shows a view in the direction of arrows B-B in (a).

(8) FIG. 7 is a detailed view of a discharge elbow 2a.

(9) FIG. 8 is a view showing air flow speed distribution in a duct connected to the discharge elbow.

(10) FIG. 9 is a photo showing an air jet of the discharge elbow.

(11) FIG. 10 is a set of structural views of a suction elbow. (a) shows detailed structure and (b) shows suction flow speed distribution.

(12) FIG. 11 is a detailed view of a suction elbow 5a.

(13) FIG. 12 is a set of views showing a free shear vortex street 11. (a) shows relation among a higher level axially asymmetric flow air screen 20a, a lower level axially asymmetric flow air screen 20b, and the free shear vortex street 11. (b) shows the free shear vortex street 11.

(14) FIG. 13 is a view showing air flow speed distribution of the parallel flow air curtain device.

(15) FIG. 14 is a structural view of a ventilation box 100a.

(16) FIG. 15 is a set of detailed structural views of an inlet port of a discharge elbow. (a) shows a side view, (b) shows a front view of a honeycomb 3a and (c) shows a top view of a reduction flow duct 12.

(17) FIG. 16 is a set of structural views of an ionized parallel flow air curtain device 300. (a) shows a front view and (b) shows a view in the direction of arrows A-A in (a).

(18) FIG. 17 is a structural view of a conventional blower-type destaticizing device.

(19) FIG. 18 shows a chart comparing destaticizing time between a conventional destaticizing device and the ionized parallel flow air curtain device.

(20) FIG. 19 is a structural view of an ionized parallel flow air curtain device 300 of 80 cm entrance breadth.

(21) FIG. 20 is a structural view of an ionized parallel flow air curtain device 300 of 160 cm entrance breadth.

(22) FIG. 21 is a view showing performance of the parallel flow air curtain device in accordance with the present invention installed in an entrance of a class 1 ventilated room (indoor pressure0)

(23) FIG. 22 is a view showing performance of the parallel flow air curtain device in accordance with the present invention installed in an entrance of a class 2 ventilated room (indoor pressure>0)

(24) FIG. 23 is a view showing performance of the parallel flow air curtain device in accordance with the present invention installed in an entrance of a class 3 ventilated room (indoor pressure<0)

(25) FIG. 24 is a view showing energy saving performance of the parallel flow air curtain device in accordance with the present invention installed in an entrance of a cold storage warehouse.

(26) FIG. 25 is a view showing air cleaning performance of the parallel flow air curtain device in accordance with the present invention installed in an entrance of a clean booth.

(27) FIG. 26 is a view showing air cleaning performance of the parallel flow air curtain device in accordance with the present invention installed in an entrance of an injection molding factory.

(28) FIG. 27 is a view showing the parallel flow air curtain device in accordance with the present invention installed in an automobile painting booth.

(29) FIG. 28 is a view showing the ionized parallel flow air curtain device in accordance with the present invention used for continuous destaticizing of automobile bumpers.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(30) Results of performance tests of the air curtain device of the present invention will be described.

(31) FIG. 24 shows results of energy saving performance measurement of the parallel flow air curtain device 200 installed in a vegetable cold storage warehouse. The warehouse doorway is opened at 8.00 am, cold vegetables are carried out, normal temperature vegetables are brought in, and the warehouse doorway is closed at 1.00 pm. Inside temperature is set at 40 C. when the doorway is closed and set at 20 C. when the doorway is open. The aforesaid operation cycle is repeated every day. In FIG. 24, curve (1) shows time-dependent change of power consumption when the doorway is open and the parallel flow air curtain device 200 is not used, and curve (2) shows time-dependent change of power consumption when the doorway is open and the parallel flow air curtain device 200 is used. It can be seen from the curve (1) that a large amount of cold air flows out and outdoor air flows in after the doorway is opened at 8.00 am so that power consumption rapidly increases after 10.00 am and becomes constant after 12.00 noon. It can be seen from the curve (2) that outflow of a large amount of cold air is prevented after the doorway is opened at 8.00 am so that rapid increase of power consumption after 10.00 am is prevented though the air curtain is often broken by workers passing through, and power consumption gradually increases due to freezing of the normal temperature vegetables. After the doorway is closed at 1.00 pm, it is estimated that during the operation between then and 8.00 am the freezing vegetables proceeds and power consumption gradually decreases toward the minimum value at the time of doorway opening at 8.00 am.

(32) Energy saving effect of the air curtain is verified by comparing energy consumption of (1) with energy consumption of (2) during the open period of the doorway. Calculation is carried out as follows.

(33) 1. Energy consumption W during the five hours the doorway is open between 8.00 am to 1.00 pm is calculated based on the energy consumption curves of FIG. 24.

(34) 2. Energy consumption of the curve (1)

(35) W1=289 Kwh

(36) 3. Energy consumption of the curve (2)

(37) W2=210 Kwh

(38) 4. Amount of energy saving during the period the doorway is open

(39) W=W2W1=210 Kwh289 Kwh=79 Kwh

(40) 5. Energy saving ratio during the period the doorway is open

(41) y=W/W1=79 Kwh/289 Kwh=0.27=27%

(42) It can be seen from the aforesaid calculation that the present air curtain device achieves a high energy saving effect of 27% though the air curtain is often broken by workers passing through.

(43) FIG. 25 shows results of an air cleaning performance measurement of the ionized parallel flow air curtain device 300 shown in FIG. 19 installed in a doorway of a clean booth. The clean booth corresponds to the class 2 ventilated room. Cleanliness of clean air supplied to the clean booth is class 10 and cleanliness of environmental air around the clean booth is class 100,000 corresponding to cleanliness of standard outdoor air. Cleanliness of indoor air of the booth in normal operating condition is class 10,000, i.e., 5 m density (number of fine particles of diameter equal to or greater than 5 m) is 80 particles/ft.sup.3. When the ionized parallel flow air curtain device 300 is installed in the doorway of the booth, 5 m density decreases to 11 particles/ft.sup.3 (corresponding to class 4,000). The aforesaid result indicates that installation of the air curtain device 300 and supply of clean air can easily achieve a work room wherein 5 m density is class 4,000.

(44) FIG. 26 shows results of measurement of cleanliness of indoor air when the ionized parallel flow air curtain device 300 of FIG. 19 is installed in a doorway of an injection molding factory of 300 m.sup.2 site area. The injection molding factory corresponds to the class 3 ventilated room of FIG. 23.

(45) An injection molding factory needs large cooling power because many operations are accompanied by heat generation. When an ionized parallel flow air curtain device in accordance with the present invention is installed in an entrance of the factory, outflow of cold air through the entrance is prevented so that air conditioning power is saved, and air temperature distribution in the factory becomes uniform so that accuracy of temperature control of injection molding machines improves and productivity of the factory increases. Humid air is prevented from flowing into the factory on a rainy day so that rusting of fine and precise metal molds is prevented and the cost of metal mold maintenance decreases.

(46) In an injection molding factory, resin dust is usually generated during cooling solidification of molten resin. As can be seen from FIG. 26, 5 m density of indoor air of the factory was reduced to class 50,000 level by the adherent electrostatically charged dust destaticizing performance and dust removal performance of the ionized parallel flow air curtain device 300 of 800 mm entrance breadth shown in FIG. 19 installed in the entrance of the factory. In the factory, dust of 5 to 10 m diameter is suspended in the air all the time during operation. The dust settles after operation is stopped and comes to rest on various equipment, materials, etc. However, after the installation of the ionized parallel flow air curtain device 300, deposit of dust decreased, and the quality of resin products improved. Reduction of floating dust in the factory made the indoor air clear and come to look like blue sky caused by Rayleigh scattering.

(47) As can be seen from the above description, installation of the ionized parallel flow air curtain device 300 in the injection molding factory resulted in (1) energy saving due to air conditioning power saving, (2) quality enhancement of products by decreasing dust suspended in the indoor air, (3) enhancement of productivity by uniformizing air temperature in the factory and (4) decrease of maintenance cost of the metal molds by inhibition of humid air intrusion on a rainy day and prevention of rusting of fine and precise metal molds.

(48) FIG. 27 shows the parallel flow air curtain devices installed in an automobile painting booth. In the painting booth, slow speed air flows downward from outlet openings formed in a ceiling 41 toward suction openings formed in a floor 42 so as to capture and remove paint mists generated during painting work. The downward air flow is a mixed air flow including vortex flows. Therefore, redeposition of paint mists on the works occurs and paint seeds are generated on the painted surface. Reduction of paint seeds removal work is the largest problem in painting work. FIG. 27 shows an effective measure for overcoming this problem. In FIG. 27, each of the cars W1 arranged in series is sandwiched from the front and the back between a pair of air curtain devices of the present invention. Each of the air curtain devices forms the circulation air flows 39 and 40 shown in FIG. 23 in the space surrounding the car W1 so as to entrain the paint mists, thereby capturing the paint mists with the pre-filters 6a and 6b. Installation of the air curtain devices between the cars W1 makes it possible to shorten the distance between adjacent cars W1 so as to minimize the length of the painting booth.

(49) FIG. 28 shows the ionized parallel flow air curtain device used for continuous destaticizing of automobile bumpers made of polymer material. Works W2 were put on moving carriages 46 and passed through the ionized parallel flow air curtain device 300 so as to be destaticized. Good results were obtained.