JPH0989483A - Plate heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat transfer efficiency by uniformizing fluid flow rate between a plurality of plate flow passages to prevent non-uniform flow distribution. SOLUTION: In a heat exchanger wherein a plurality of plates 1, 2 alternate with each other so as to be tightened so that heat exchange passages 11, 12, between high temperature side fluids and low temperature side fluids, are alternately formed, and passages for both of the fluids are arranged in n parallel rows × m stages, a non-uniform flow preventing plate 17, which has a small diameter part 18, in which an inlet side passage hole is made smaller than that of other plate, is provided intermediate the parallelly arranged passages between the plates of each stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate heat exchanger having a function of preventing uneven distribution of flow paths between plates which are arranged in parallel.

[0002]

2. Description of the Related Art Generally, a plate heat exchanger is a type in which a high temperature side fluid and a low temperature side fluid are caused to flow on both sides of a plate for heat exchange. Therefore, for example, in FIG.
As shown in FIG. 2, the two types of plates 1 and 2 are formed with passage holes 3, 4, 5, and 6 for both fluids and heat transfer surfaces 7 and 8, respectively. At that time, in order to alternately flow both fluids to the heat transfer surfaces on both sides of the plates 1 and 2, gaskets 9 and 10 are attached to hermetically surround the passage holes of each fluid and the heat transfer surface. The flow paths 11 and 12 for two types of fluid are alternately formed.

In the case of FIG. 3A, one fluid enters from the left side and rises in the two parallel flow passages 11a and 11b in the front stage, and then descends in the two parallel flow passages 11c and 11d in the rear stage. And flows out to the right side, the other fluid enters from the right side, rises in the two parallel flow passages 12a and 12b in the front stage, and then descends in the two parallel flow passages 12c and 12d in the rear stage and flows out to the left side. The case is illustrated. That is, (A) of FIG. 3 illustrates a case where the number of parallel flow paths is “2” and the number of stages is “2”, and the plate knitting is performed. This plate knitting is as shown in FIG. 3B. In addition, it is simply shown in FIG.

Generally, in the plate formation of the plate heat exchanger, the number of parallels is set according to the flow rate used, and the number of stages is set according to the temperature condition. FIG. 3C shows n parallels ×
The case of two stages is shown.

The state of fluid flow in the plate heat exchanger having the flow passages arranged in parallel is such that the fluid flowing from the passage hole on the inlet side is blind due to the inertial force of the plate at the end of the parallel flow passages. Part (passage hole closing part: reference numeral 1 in FIG. 3A)
(See 3, 14, 15, and 16), go straight, hit the blind portion, change direction, and flow through the plate heat transfer surface. Therefore, the fluid flows from the heat transfer surfaces of the parallel plate-to-plate flow passages in the depth direction, and the overflow that cannot be flowed only by the depth portion flows to the heat transfer surface of the plate-to-plate flow passage on the inlet side. As a result, as shown in FIG. 3D, the flow rate distribution decreases on the inlet side in the parallel flow direction and increases on the depth side.
So-called drift occurs.

This tendency is caused when the specific gravity of the fluid is large,
This is a low pressure loss type plate and tends to occur when there are many parallel plates.

The region in which this drift occurs is uneven on both sides of the plate heat exchanger for both fluids, as shown in FIG. 3 (E), resulting in a significant decrease in heat transfer efficiency. There's a problem. In (E) of the figure, the shaded portions a and b are the large flow rate portions.

Further, the above-mentioned drift is due to the inertial force of the fluid and is not affected by the flow direction of the fluid in the plate (up → down, down → up), that is, it is not affected by gravity.

Further, the tendency of the drift occurs regardless of the magnitude of the flow rate. That is, when the flow rate is large, the flow velocity in the passage hole of each plate is large, and the inertial force is large, so that a large amount flows to the depth side. Further, when the flow rate is small, the flow velocity and the inertial force in the passage hole of each plate are small, so that the flow rate and the inertial force are alleviated to some extent, but the amount overflowing to the inlet side is small, and a large amount also flows to the depth side.

[0010]

Since the occurrence of the uneven flow causes a remarkable decrease in heat transfer efficiency, it is desirable to make the fluid flow rate distribution among a plurality of plate flow paths uniform.

An object of the present invention is to provide a plate heat exchanger capable of making the fluid flow rate distribution among a plurality of plate flow paths uniform and preventing uneven flow to improve heat transfer efficiency.

[0012]

To achieve the above object, according to the present invention, a plurality of plates are laminated and tightened to alternately form heat exchange passages for a high temperature side fluid and a low temperature side fluid between each plate. In addition, in the plate heat exchanger in which the passages of both fluids are knitted in n parallel × m steps, the diameter of the inlet side passage hole is set to be smaller than that of the other plate during the parallel knitting of the passages between the plates in each step. It incorporates a drift prevention plate having a reduced small diameter portion.

With the above structure, the fluid flows through the inlet side passage holes of the parallel flow passages of each stage toward the depth end portion, but the fluid flows straight as it is due to the resistance of the small diameter portion of the non-uniform flow prevention plate installed on the way. It is divided into a thing and a thing which changes a direction there and flows into the flow path between plates on the way. This allows
Prevents a large amount of fluid from drifting to the depth side of the parallel flow path,
It is possible to equalize the fluid flow rate distribution of the flow paths between the plurality of plates.

Further, a plurality of the non-uniform flow prevention plates may be installed in the parallel flow passages of each stage, and the small diameters of the plural non-uniform flow prevention plates may be different from each other. This is suitable for application when the number of parallel connections is large, that is, when the fluid flow rate is large. The small diameter portion may be provided for both the high temperature side fluid and the low temperature side fluid. As a result, it is possible to prevent the occurrence of uneven flow for both fluids.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is a schematic configuration diagram of a plate knitting according to the present invention, and FIG. 1B is a schematic front view of a drift prevention plate. In FIG. 1A, 1 and 2
Shows two types of plates having the same structure as the conventional one, 11 and 12 show flow paths of both fluids, 17 is a non-uniform flow prevention plate, and this non-uniform flow prevention plate 17 is shown in FIG. As described above, the portion corresponding to the inlet side passage hole 3 for one of the fluids is the small diameter portion 18. Other configurations are the same as the conventional one. That is, assuming that the diameters of the one fluid outlet side passage hole 4 and the other fluid inlet / outlet passage holes 5 and 6 are φD, the small diameter portion 18 of the one fluid inlet side passage hole 3 is formed. The diameter is φd (D> d) smaller than φD.

The degree of the magnitude relationship of D> d and the installation position of the drift prevention plate 17 are appropriately set in consideration of the flow rate of the fluid, the coefficient of kinematic viscosity, etc., and the parallel flow paths between the plates. This is to ensure that the flow rate distribution of the fluid in is as uniform as possible.

By installing the non-uniform flow prevention plate 17 having the above-mentioned structure in the middle of the parallel formation of the interplate flow passages of each stage, the fluid directs the inlet side passage hole 3 of the parallel flow passage of each stage toward the depth end. However, due to the resistance of the small-diameter portion 18 of the non-uniform flow prevention plate 17 installed midway, it goes straight as it is, and the inter-plate flow passage 11 on the way changes its direction.
It is divided into what flows into. As a result, it is possible to prevent a large amount of uneven flow of fluid on the depth side of the parallel flow passage 11 and to equalize the fluid flow rate distribution in the plurality of inter-plate flow passages 11.

Although FIG. 1A illustrates the case of 3 parallels × 1 stage, the present invention can be applied to the case of n parallels × m stages, in which case the parallel flow of each stage. The drift prevention plate 17 having the above structure is incorporated in the passage.

A plurality of the drift prevention plates 17 may be incorporated in the parallel flow passages at each stage. In this case, the number of the uneven flow prevention plates 17 to be incorporated, the installation positions, and the installation intervals are appropriately set in consideration of the flow rate of the fluid, the coefficient of kinematic viscosity, and the like. This is to ensure that the distribution is as even as possible.

The small-diameter portion 18 of the drift prevention plate 17
Although it is possible to manufacture a separate part and install it in the passage hole of the conventional plate, it is easier to produce a plate with only the diameter of the passage hole smaller, and an inexpensive plate with no drift A heat exchanger can be provided.

As another embodiment of the present invention, in order to prevent uneven flow of both the high temperature side fluid and the low temperature side fluid, as shown in FIG. As shown in FIG. 2B, the drift prevention plate 17a provided with the small diameter portions 18a and 18b at positions corresponding to the holes is
It can be installed in the middle of each parallel channel. In this case, the small-diameter portions 18a, 18 for the respective fluids
Although b shows the case where they are provided on the same plate, they may be provided on different plates.

According to the present invention, as described above, the drift prevention plate can be used for only one fluid or for both fluids, and the selection is made in consideration of the properties of the fluid to be handled and the operating conditions. It is done by doing.

[0023]

According to the present invention, a large amount of fluid can be prevented from flowing unevenly in the depth direction of the parallel flow paths, and the flow rate distribution of the fluid in the flow paths between the plurality of plates can be equalized, and the heat transfer efficiency can be improved. Can be improved.

Further, a plurality of non-uniform flow prevention plates may be installed in the parallel flow paths of each stage. This is suitable for application when the number of parallel connections is large, that is, when the fluid flow rate is large. The small diameter portion may be provided for both the high temperature side fluid and the low temperature side fluid. As a result, it is possible to prevent the occurrence of uneven flow for both fluids.

Regarding the pressure loss, in the conventional knitting in which the non-uniform flow is not prevented, most of the fluid flows only in a part of the flow passages between the plates, so that the pressure loss becomes large. According to the invention, since the fluid flows evenly through the flow paths between the plates, it is possible to prevent an increase in pressure loss, and the small diameter portion 1
Even if 8a and 18b are provided, the total pressure loss of the present invention is lower than that of the conventional knitting.

[Brief description of drawings]

1A is a schematic configuration diagram of a plate knitting according to the present invention, and FIG. 1B is a schematic front view of a drift prevention plate.

FIG. 2 (A) is a schematic front view of a drift prevention plate showing another embodiment of the present invention, and FIG. 2 (B) is a schematic configuration of a plate organization of parallel flow paths of both fluids when this plate is incorporated. Fig.

3A is an exploded perspective view showing an example of a conventional plate knitting, FIG. 3B is a schematic configuration diagram of the plate knitting in that case, and FIG. 3C is a plate knitting in the case of n parallel × 2 stages. Schematic configuration diagram, (D) is an explanatory diagram of the flow rate distribution state of the fluid in the conventional parallel flow path, (E) is an explanatory diagram of the uneven flow generation region of both fluids.

[Explanation of symbols]

 1, 2 Plates 3, 4, 5, 6 Passage holes 7, 8 Heat transfer surface 9, 10 Gasket 11, 11a-11d, 12, 12a-12d Flow path 17, 17a Drift prevention plate 18, 18a, 18b Small diameter part

Claims (4)

[Claims] 1. A plurality of plates are laminated and tightened to alternately form heat exchange passages for a high temperature side fluid and a low temperature side fluid between the respective plates, and the passages for both fluids are n parallel × m stages. In the plate-type heat exchanger to be knitted into, in the middle of parallel knitting of the interplate flow passages of each stage, a drift prevention plate having a small diameter part in which the diameter of the inlet side passage hole is smaller than other plates is incorporated. Characteristic plate type heat exchanger. 2. The plate heat exchanger according to claim 1, wherein a plurality of non-uniform flow prevention plates are incorporated in the middle of the parallel formation of the flow paths between the respective stage plates. 3. The plate heat exchanger according to claim 1, wherein a plurality of non-uniform flow prevention plates having different small diameter dimensions are incorporated in the middle of the parallel formation of the flow paths between the respective stage plates. 4. The plate type according to claim 1, wherein the drift prevention plate is provided with a small diameter portion for both the high temperature side fluid and the low temperature side fluid. Heat exchanger.