JPS6179986A - Flow-down liquid film evaporating type heat exchanger - Google Patents

Abstract

PURPOSE:To permit to improve heat exchanging efficiency by forming good liquid refrigerant thin film on the surface of heat transfer tubes in each stage by a method wherein openings, provided on liquid refrigerant distributing members in respective stages, are designed so that the diameter of the opening in the lower stage is smaller than the diameter of the same in the higher stage. CONSTITUTION:The diameter D1 of the opening 7a in the liquid refrigerant distributing member 6a of first stage is designed so as to be the optimum diameter for forming uniform liquid refrigerant thin film 11 on the surface of the heat transfer tube 2 in the area I with respect to the supplying amount of the liquid refrigerant. The diameter D2 of the opening 7b in the liquid refrigerant distributing member 6b of the second stage is designed so as to be optimum for forming uniform liquid refrigerant thin film 11 in the area II with respect to the amount of refrigerant in which the amount of the refrigerant, evaporated in the area I, is subtracted from the supplying amount of the same. The diameter D3 of the opening 7c in the third stage is also designed in the same manner and the relations therebetween become D1>D2>D3. According to this method, formation of the thin films in respective stages may be effected well and the heat exchanging efficiency of the heat exchanger may be improved.

Description

[Detailed Description of the Invention] [Technical Field to which the Invention Pertains] The present invention relates to a cooling system comprising a shell, a plurality of heat transfer tubes arranged vertically within the shell, and at least two or more stages of liquid refrigerant distribution members. This invention relates to a liquid film evaporative heat exchanger.

[Prior art and its problems]

Figure 3 shows a conventional falling film evaporative heat exchanger; Figure 4 shows a conventional falling film evaporative heat exchanger;
A diagram for explaining the relationship between the amount of liquid refrigerant and the opening diameter is shown.

A large number of heat transfer chambers (2) installed vertically Km inside the shell (1)
) are fixed at their upper and lower ends by a tube plate (3), and headers (4) and (5) for supplying high temperature fluid W into these heat transfer tubes (2) are installed on the outside of the tube plate (3). It is provided.

Liquid refrigerant distribution member (6a), (6b) + (6C)
The heat exchanger tubes (2
), and there is an opening (
7a), (7b), and (7c) are formed.

A liquid refrigerant supply port (8) and a vapor outlet (9) are provided above the heat exchanger main body, and a liquid refrigerant discharge port (1) is provided below.

The liquid refrigerant supplied from the liquid refrigerant supply port (8) is attached to the first stage liquid refrigerant distribution member (6a), and freely falls from the opening (7a) provided therein to the heat transfer tube. (2) forming a liquid refrigerant thin film (11) on the outer surface and flowing down region I;
At this time, a high-temperature fluid W is flowing inside the heat exchanger tube (2), so that the liquid refrigerant thin film (11) is heated and a part of it evaporates to form steam V, which is passed from the steam outlet (9) to the heat exchanger. leaks to the outside. Further, the unevaporated liquid refrigerant that has not been completely evaporated here flows down through the region 1t and reaches the second stage liquid refrigerant distribution member (6b).

Also in the second-stage liquid refrigerant distribution member (6b), the liquid refrigerant falls freely from the opening (7b), forms a liquid refrigerant thin film (11) on the outer surface of the heat transfer tube (2), and flows down the area (2). However, a part of it evaporates and becomes vapor V, and the remaining unevaporated liquid refrigerant reaches the next third stage liquid refrigerant distribution member (6C).

After flowing through region I, the unevaporated liquid refrigerant is discharged to the outside of the heat exchanger from the liquid refrigerant discharge port (10).

In a conventional heat exchanger with such a configuration, all the openings have the same diameter, so the efficiency of heat exchange was low.The reason for this can be explained as follows. There is an optimum value for the diameter of the opening. If there is too little liquid refrigerant, the liquid refrigerant will flow down from the green opening (7) before reaching the outer surface of the heat exchanger tube (2), as shown in Figure 4 (a). On the other hand, if the amount of liquid refrigerant is too large, the openings (7) will have a nozzle-like effect and the liquid refrigerant will flow radially, as shown in Figure 4(b). As a result, it becomes impossible to form a thin liquid refrigerant film (11) on the outer surface of the heat transfer tube (2). On the other hand, in a heat exchanger having a multi-stage liquid refrigerant distribution member as shown in Fig. 3, the flow rate of liquid decreases as it goes to the lower stage. A phenomenon as shown in Figure 4(a) occurred, resulting in low heat exchange efficiency.

[Purpose of the invention]

In view of the above-mentioned points, an object of the present invention is to provide a falling film evaporative heat exchanger that forms a good thin film at each stage and has high heat exchange efficiency.

[Summary of the invention]

The present invention is a falling liquid film evaporative heat exchanger that performs heat transfer by evaporating a thin film of liquid refrigerant, which is arranged vertically to a shell and is composed of a plurality of heat transfer tubes and at least two or more stages of liquid refrigerant distribution members. This is a falling film evaporative heat exchanger characterized in that the diameter of the opening provided in the liquid refrigerant distribution member is made smaller toward the lower stage according to the amount of liquid refrigerant at each stage.

〔Effect of the invention〕

According to the present invention, since the opening diameter of each stage is made smaller in advance according to the amount of liquid refrigerant in each stage as the lower stage goes, thin film formation in each stage is performed well, resulting in heat exchange efficiency. A high falling film evaporative heat exchanger can be provided.

[Embodiments of the invention]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an embodiment of the present invention, and FIG. 2 is an enlarged view of the main part of FIG. 1, and the same components as in FIG. 3 are given the same numbers.

The difference between the present invention and conventional heat exchangers is that the opening (7a)
, (7b), (7C) o diameter D1. D2. D3
The opening diameter K is set to be optimal depending on the amount of liquid refrigerant at each stage of the crimping, that is, the lower the stage, the smaller the opening diameter is.

To explain more specifically, the diameter of the opening (7a) in the first stage liquid refrigerant distribution member (6a) is within the range ■ with respect to the amount of liquid refrigerant supplied from the liquid refrigerant supply port (8). The diameter of the opening (7b) in the second stage liquid refrigerant distribution member (6b) is set to be the optimum diameter to form a uniform liquid refrigerant thin film (11), and the diameter of the opening (7b) in the second stage liquid refrigerant distribution member (6b) is determined based on the amount of liquid-free refrigerant that is supplied. Area ■ for the amount of liquid refrigerant minus the amount of liquid refrigerant evaporated in I
Set to the optimum diameter to form a uniform liquid refrigerant thin film (11), and also in the third stage, the opening (7C)
The diameter is the optimum diameter that forms a uniform liquid refrigerant thin film (11) in region I for the amount of liquid refrigerant that is obtained by subtracting the amount of liquid refrigerant evaporated in regions I and region ■ from the amount of liquid refrigerant supplied. Set it as follows. That is, the diameter is set smaller toward the lower stage.

In the heat exchanger according to the present invention, the opening diameter of each stage is set in advance to be the optimum diameter according to the amount of liquid refrigerant at each stage, so that thin film formation at each stage is performed well. As a result, a falling film evaporative heat exchanger with high heat exchange efficiency can be provided.

Note that the embodiment shown in Figure @1 shows a structure in which unevaporated liquid refrigerant is extracted to the outside of the heat exchanger. As a pool boiling section, the entire amount of unevaporated liquid refrigerant may be evaporated here.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a falling film evaporative heat exchanger according to the present invention, FIG. 2 is an enlarged view of the main part of FIG. 1, and FIG. 3 is a conventional falling film evaporative heat exchanger. FIG. 4 is a sectional view showing the heat exchanger, and is a sectional view illustrating the relationship between the amount of liquid refrigerant and the opening diameter. 1... Shell, 2... Heat exchanger tube, 6+ 6a+ 6b
+ 6 c...liquid refrigerant distribution member, 7, 7a,
7b, 7c...opening, 8...liquid refrigerant supply port,
9... Steam outlet, 11... Liquid refrigerant thin film. Representative Patent Attorney Kensuke Norichika (and 1 other person) Figure l w Figure 2 Figure 3 f” W

Claims (1)

[Claims] It has a shell, a large number of heat transfer tubes arranged vertically in the shell, and a liquid refrigerant distribution member of at least two stages, and the liquid refrigerant is freely allowed to flow through the gap between the opening provided in the liquid refrigerant distribution member and the heat transfer tubes. drop to form a thin film of liquid refrigerant on the outer surface of the heat transfer tube,
In a falling liquid refrigerant evaporative heat exchanger configured to exchange heat with the fluid flowing in the heat transfer tubes by evaporation of this thin film of liquid refrigerant, the diameter of the opening provided in the liquid refrigerant distribution member of each stage is made smaller as the lower the stage. A falling film evaporative heat exchanger characterized by: