JPH0258560B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Detailed Industrial Description] The present invention relates to a heat transfer device for heating, cooling, drying, etc., and particularly to a jet heat transfer device with high heat transfer efficiency.

[Prior Art] Jet heat transfer devices are used in heating devices, coolers, dryers, etc., and devices with higher heat transfer coefficients are considered more advantageous.

The heat transfer coefficient improves as the flow rate increases, but spraying a large amount of fluid to improve the heat transfer coefficient results in a loss of heat and power energy.

Thus, the value of the heat transfer coefficient, or heat transfer efficiency, under constant flow rate determines the performance of the heat transfer device.

In general, this jet heat transfer device uses a parallel flow method, in which heat is transferred by flowing the fluid in the same direction as the traveling direction of the object to be heated, and a countercurrent method, in which the fluid flows in the opposite direction, parallel to the surface to be heated. This method has been attracting a lot of attention in recent years because it is advantageous in that it can increase heat transfer efficiency compared to methods that transfer heat through a continuous flow.

[Objective] The present invention aims to further improve heat transfer efficiency than conventional jet heat transfer devices.

[Structure] To explain the main points of the present invention, the conventional device, which was composed of a jet port A, a discharge port B, and a heat transfer target surface C as shown in FIG. 1, was improved, and as shown in FIG. As shown in FIG. 2, a fluid guide plate D having an ejection port A and a discharge port B is provided to face the heat transfer target surface C in a parallel plane, and a fluid baffle plate E is provided from the guide plate D. By providing it so as to protrude toward the heat transfer body surface C side, it is intended to improve the heat transfer coefficient. In addition, in the conventional device as shown in FIG. 1, even if the baffle plate is simply provided as appropriate so as to protrude toward the heat transfer target surface C, the baffle plate and the heat transfer target surface C can be
By reducing the distance between Providing the fluid guide plate D facing the heating body surface C in a plane parallel to the heating body surface C reduces the flow on the side away from the surface of the heat transfer target body, and further increases the heat transfer efficiency.

[Example] Next, the present invention will be described in detail using an example of application to a drying device. Conventionally, when coating ink, adhesive, etc. on paper, metal foil, plastic film, etc., and evaporating and drying, a jet type drying apparatus is usually used to increase the drying speed.

One example is the arch-type and flat-type drying apparatuses shown in Figs. 3 and 4.
A coating liquid 4 such as ink or adhesive is applied between the rolls 2 and 3, and the liquid is run on guide rolls 5 and sent to a drying device 6.

Inside the drying device 6, a duct 8 is provided which has nozzles 7 at regular intervals, for example, every 100 to 400 mm, in the direction in which the strip 1 moves, and the strip 1 is sent through this duct 8 from a blower (not shown). The hot air a is blown out from the nozzle 7 at a constant speed, e.g.
The strip 1 becomes a jet stream with a speed of 50 m/sec.
The water is ejected towards the belt-shaped material 1, and the strip-shaped material 1 is dried.

The air used for drying is exhausted from exhaust ports 9 provided on both sides of the nozzle 7. The opening width of the ejection port of the nozzle 7 is about 1 to 10 mm, and the distance from the tip of the nozzle 7 to the strip 1 is about 10 to 50 mm.

In contrast, in the present invention, as shown in FIG. 5 as an example, by attaching a complementary body 11 provided with a fluid baffle plate 10(E) between the nozzle 7 and the discharge port 9 of the conventional device, a band-shaped A baffle plate is formed that protrudes toward the object 1 side. Of course, the nozzle 7, the discharge port 9, the fluid baffle plate 10, and the fluid guide plate D (12), which is a part of the complementary body 11 facing the strip 1 in a parallel plane, are each separate bodies. may be partially separate, partially integrated, or may be entirely integrated. Although the fluid guide plates D (12) are shown as being on the same plane in the drawings, they do not necessarily need to be on the same plane.

The hot air a ejected from the nozzle 7 has the effect of the baffle plate 10 that reduces the distance between its tip and the strip 1. One effect is that the flow velocity near the membrane is increased, and the other is that the degree of turbulence is reduced. After being promoted and flowing along the strip 1, it is discharged b from the discharge ports 9 provided on both sides of the nozzle 7 or near the nozzle 7. At this time, when the fluid a flowing from the nozzle 7 hits the strip 1 due to the guide roller 5 provided at a position facing the nozzle 7, the pressure applied in the direction perpendicular to the running direction of the strip 1 is Since this is suppressed, the belt-like object 1 can maintain stable running.

This high-speed flow with large turbulence promotes the destruction of the film between the hot air a and the strip 1 between the nozzle and the discharge port, improving the heat transfer coefficient, that is, further improving the drying ability. Note that the baffle plate 10 is provided on the surface of the fluid guide plate D as appropriate, either straight or inclined.

[Effects of the Invention] Since the present invention has the above-described configuration, first, a fluid baffle plate, which is a plate-shaped obstacle, is provided for the fluid flow path between the jet port and the discharge port. This can bring about the following two effects.

One is by constricting the flow path with a plate-like obstacle (baffle plate), which forces the wasteful fluid that previously flows outside of the area near the membrane between the fluid and the surface of the heat-transfer object to be forced into the area near the membrane. By increasing the flow velocity near the membrane, the destruction of the membrane can be promoted, and as a result, the heat transfer coefficient can be increased.

Another method is to disturb the fluid with a plate-like obstacle in the part where the flow used to be almost parallel to the surface of the heat transfer target, which promotes the destruction of the film between the fluid and the heat transfer target surface, and heats up the flow. Transmission rate can be increased.

Furthermore, since the present invention has a fluid guide plate that faces the surface of the heat transfer target in a plane parallel to the surface of the heat transfer target, the flow on the side away from the heat transfer target is reduced, which is combined with the action of the fluid baffle plate. The heat transfer efficiency can be further increased. Furthermore, by arranging the guide rollers opposite the jet ports, the heat transfer object can run in a stable state without increasing the tension applied to the heat transfer object that runs linearly on each guide roller. Since the effects of the above-mentioned plate-shaped obstruction and fluid guide plate are not reduced, the heat transfer efficiency can be further improved.

Next, the effects of the present invention will be explained in more detail using specific examples and comparative examples.

Specific Example When the drying apparatus of the present invention shown in Fig. 5 was measured under the following conditions: distance between nozzle and strip 24 mm, nozzle opening width 3 mm, nozzle pitch 200 mm, hot air blowing speed 43 m/sec, and number of baffle plates 2. The average heat transfer coefficient between the hot air and the strip was 209 [Kcal/hr・m ²・℃].

In addition, in order to locally grasp the degree of improvement in the heat transfer coefficient, the local heat transfer coefficient was determined, and it was as shown in FIG. 6.

Comparative Example In the conventional drying equipment shown in Figure 4, measurements were taken under the following conditions: distance between the nozzle and the strip: 24 mm, nozzle opening width: 3 mm, and hot air blowing speed: 43 m/sec. The average heat transfer coefficient was 148 [Kcal/hr・m ²・℃], and the local heat transfer coefficient at that time was as shown in Figure 6.

As described above, according to the present invention, the average heat transfer coefficient was surprisingly improved by 41% compared to the conventional nozzle system, which is generally considered to have a high heat transfer coefficient.

Furthermore, when looking at the local heat transfer coefficient, a particularly remarkable improvement in the heat transfer coefficient was observed in the vicinity of the baffle plate, and this also indicates the effect of the baffle plate.

[Brief explanation of the drawing]

Fig. 1 is a schematic illustration of a conventional drying device, Fig. 2 is a schematic illustration of a device of the present invention, Fig. 3 is a perspective view showing an example of a conventional drying device, and Fig. 4 is a diagram showing the vicinity of the nozzle of the conventional drying device. A cross-sectional view showing an example; FIG. 5 is a cross-sectional view showing an example of the vicinity of the nozzle of the drying device according to the present invention;
FIG. 6 is a diagram showing an example of the heat transfer coefficient distribution of the conventional drying apparatus and the drying apparatus according to the present invention. A...Blowout port, B...Discharge port, C...Heat transfer target surface, D...Fluid guide plate, a...Hot air, b...Exhaust air, 1...Band shaped object (drying material), 2... ... Coating plate cylinder, 3... Coating impression cylinder, 4... Coating liquid, 5... Guide roll, 6... Drying device, 7... Nozzle, 8
... Duct, 9 ... Discharge port, 10 ... Baffle plate, 1
1... Complementary body, 12... Fluid guide plate.

Claims (1)

[Claims] 1 A fluid ejection port and a discharge port, a guide roller provided at a position opposite to the ejection port, and a fluid ejection port and the It consists of a fluid guide plate provided between the discharge ports, and a fluid baffle plate that projects from the fluid guide plate near the surface of the heat transfer target, and between the tip of the fluid baffle plate and the heat transfer target surface. 1. A jet heat transfer device characterized by making the flow of fluid small, constricting the flow of fluid to increase the flow velocity, and turbulent the flow.