JPH11325787A - Shell and tube heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance heat exchanging efficiency of shell and tube heat exchanger employing nonazeotrope refrigerant. SOLUTION: Since the inside of a shell 2 is sectioned by a refrigerant baffle plate, refrigerant from a refrigerant inlet 6 counter flows through a second tube 11 in first refrigerant channel 12 and a first tube 10 in third refrigerant channel 14. Consequently, flow rate of refrigerant in the shell 2 is increased and heat exchanging performance can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shell and tube type heat exchanger used for a condenser of a refrigeration / air-conditioning apparatus.

[0002]

2. Description of the Related Art Refrigerants containing chlorine atoms such as R22 and R502, which have been used as refrigerants in the fields of refrigeration and air conditioning, are known to destroy the ozone layer in the stratosphere, and their use is regulated. As an alternative to these refrigerants, a refrigerant HFC containing no chlorine atom which is an ozone depleting substance
(Hydrofluorocarbon) 32, HFC125, H
Refrigerants mixed with FC134a, HFC143a and the like are known. Among these mixed refrigerants, R407C, R41
Refrigerants such as 0A and R404A are considered as alternative candidates.

However, these alternative refrigerants have lower thermophysical efficiency than conventional refrigerants and are mixed refrigerants, so that they are used in shell-and-tube type heat exchangers.
In addition to the conventional temperature gradient, the concentration gradient becomes a hindrance factor of the heat exchange performance, resulting in a decrease in performance. For this reason, for example, Japanese Patent Application Laid-Open No. 8-233408 is known as a technique for increasing supercooling and improving performance.

[0004]

In the above prior art, when a non-azeotropic mixed refrigerant is used, supercooling becomes large,
Although the performance can be improved, it is not considered in the temperature gradient and the concentration gradient of the condensation zone, which are the characteristics of the non-azeotropic refrigerant mixture. If a shell and tube heat exchanger is used for the condenser,
Usually, the temperature difference between the inlet and outlet of the cooling medium is about 5 ° C.
When a single refrigerant such as 22 is used, the condensation temperature is 1-2C higher than the outlet cooling medium for complete condensation.

However, a typical non-azeotropic refrigerant, R
At 407C, the temperature changes by about 5 ° C. even during the condensation because the gas composition changes from the start to the end of the condensation. Therefore, in order to end the condensation, it is necessary to set the condensation end temperature higher than the outlet temperature of the cooling medium, and the condensing pressure increases, and when used in a refrigeration cycle, the compressor power increases.

Further, the high-boiling-point refrigerant is easily condensed, the composition of the condensed liquid refrigerant is often high-boiling-point refrigerant, and the gas has a large amount of low-boiling-point refrigerant. Let it.

An object of the present invention is to provide a shell and tube heat exchanger having high heat exchange performance even when a non-azeotropic mixed refrigerant is used.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to provide a shell provided with a refrigerant inlet and a refrigerant outlet, and a plurality of tubes through which a plurality of cooling mediums flow, so that the flow of the cooling medium becomes a plurality of paths. In the shell-and-tube type heat exchanger configured as described above, this can be achieved by using a non-azeotropic mixed refrigerant as the refrigerant and providing a refrigerant partition plate so that the flows of the condensed gas and the cooling medium are opposed to each other.

A further object of the present invention is to provide a shell-and-tube heat exchanger comprising a shell provided with a refrigerant inlet and a refrigerant outlet, and a plurality of tubes through which a cooling medium flows. Using a boiling mixed refrigerant,
This can also be achieved by providing a throttle portion at the refrigerant inlet portion and providing a bypass passage through which the throttle portion communicates with the gas refrigerant near the cooling medium.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to embodiments.

FIG. 1 is a longitudinal sectional view of a shell and tube heat exchanger according to a first embodiment of the present invention, and FIG. 2 is a cross sectional view of the shell and tube heat exchanger according to the first embodiment. is there. FIG. 7 shows the temperature distribution of the refrigerant and the cooling water.

In FIG. 1, 1 is a shell and tube heat exchanger, 2 is a shell, 3 is a first header, and 4 is a second header.
5, a cooling water partition wall for preventing the cooling water at the cooling water inlet 8 of the first header 3 from mixing with the cooling water at the cooling water outlet 9, a coolant inlet 6, a coolant outlet 7, Reference numeral 10 denotes a plurality of first tubes (represented by one in FIG. 1) through which cooling water as a cooling medium flows, 11 denotes a plurality of second tubes (represented by one in FIG. 1), and 12 denotes A first refrigerant flow path through which a non-azeotropic mixed refrigerant flows, 13 is a second refrigerant flow path, 14 is a third refrigerant flow path, 15 is a second refrigerant flow path 1 in the shell 2.
A refrigerant partition plate that is horizontally installed except for the portion 3 and separates the first refrigerant flow channel 12 and the third refrigerant flow channel 14, and 16 is a liquid refrigerant provided at a contact portion of the refrigerant partition plate 15 with the inner wall of the shell 2. Notch for flowing the water downward, 17 is a first partition wall for separating the refrigerant and cooling water in the shell 2, and 18 is a second partition wall The shell and tube heat exchanger configured as described above 1 is a high-temperature gas refrigerant (temperature T1 in FIG. 7), for example, R4
07C is supplied from the refrigerant inlet 6. The supplied gas refrigerant flows through the first refrigerant flow channel 12 in the shell 2 and exchanges heat with the cooling water flowing in the second tube 11 to lower the temperature. Condensation starts at the refrigerant temperature T2, and as the refrigerant flows through the first refrigerant flow path 12, a part of the refrigerant condenses, the liquid refrigerant drops, and the temperature of the gas refrigerant also decreases.
Is cooled by the cooling water flowing through the first tube 10 in the third refrigerant flow path 14 through the refrigerant flow path 13 and the condensation is completed at the temperature T3. The liquid refrigerant condensed in the first refrigerant flow path 12 travels along the inner wall of the shell 2 through the notch 16 provided in the refrigerant partition wall 15 and falls to the lower part of the shell 2.

On the other hand, the liquid refrigerant condensed in the third refrigerant flow path 14 falls directly below the shell 2, mixes with the liquid refrigerant in the first refrigerant flow path 12, and flows outside from the refrigerant outlet 7. On the other hand, the cooling water at the temperature t1 is supplied to the first header 3 from the cooling water inlet 8 and then divided into the first tube 10 to cool the refrigerant flowing through the third refrigerant passage 14, thereby reducing the temperature. While ascending, rejoin at the second header 4,
The coolant is further cooled by the second tube 11 and rises to the temperature t2, merges again at the first header 3, and the cooling water outlet 9
From the outside.

Therefore, in the first embodiment, the refrigerant gas in the shell 2 and the cooling water in the tube flow oppositely,
As shown in FIG. 7, from the temperature T1, which is the superheated gas range, to T2
Except for the part, the change in the difference between the refrigerant temperature and the cooling water temperature can be reduced, and the heat exchange performance can be improved. Further, the liquid refrigerant condensed in the first refrigerant flow path 12 is caused to fall downward from the notch of the refrigerant partition wall 15 so that the condensed liquid does not fall on the first tube 10 so that the outer surface of the first tube 10 Can be reduced, and the heat exchange performance can be further improved. Further, by providing the refrigerant outlet 7 in the vicinity of the cooling water inlet, the temperature of the liquid refrigerant at the refrigerant outlet 7 is also the lowest, and foaming due to mixing with the liquid refrigerant having a higher temperature can be reduced.

A second embodiment of the present invention will be described with reference to FIGS.

FIG. 3 is a horizontal sectional view of a shell-and-tube heat exchanger according to a second embodiment of the present invention, and FIG. 4 is a cross-sectional view of the shell-and-tube heat exchanger according to the second embodiment. is there.

3 and 4, reference numeral 20 denotes a refrigerant partition plate B in which the first tube 10 and the second tube 11 are vertically divided in the shell 2 except for the second refrigerant passage 13. The other parts are configured so that the refrigerant flow path is turned in the horizontal direction by the refrigerant partition plate 20, but perform the same operation.

In the shell-and-tube heat exchanger constructed as described above, the refrigerant flowing through the first refrigerant flow path 12, the second refrigerant flow path 13, and the third refrigerant flow path 14 is a first tube. 10, flows countercurrently to the cooling water flowing in the second tube 11, and performs heat exchange between the refrigerant and the cooling water. Also, the first
The liquid refrigerant condensed in the refrigerant flow path 12 of the first refrigerant flow path,
The refrigerant flows through the lower part of the second refrigerant passage and the lower part of the third refrigerant passage, and flows to the outside from the refrigerant outlet 7.

Therefore, in the second embodiment, as in the first embodiment, the heat exchange performance can be improved by flowing the refrigerant and the cooling water countercurrently. Further, since the liquid refrigerant that has exchanged heat with the cooling water in the first refrigerant flow path 12 and the third refrigerant flow path 14 and condensed falls directly to the lower part of the shell 2, it is not necessary to form a notch in the refrigerant partition plate 15. And the structure can be simplified.

In the first embodiment and the second embodiment, the case where the flow of the cooling water is two passes is described. However, the same effect can be obtained by installing the refrigerant partition plate horizontally and vertically even in the case of two or more passes. Is obtained.

A third embodiment of the present invention will be described with reference to FIGS.

FIG. 5 is a longitudinal sectional view of a shell and tube heat exchanger according to a third embodiment of the present invention, and FIG. 6 is a transverse sectional view of a shell and tube heat exchanger according to the third embodiment. is there.

5 and 6, reference numeral 30 denotes a bypass for returning the gas refrigerant near the cooling water inlet to the refrigerant inlet 6, and reference numeral 31 denotes a throttle provided in the refrigerant inlet 6.

With the above configuration, the first refrigerant flow path 12, the second refrigerant flow path 13, and the third refrigerant flow path 1
The coolant flowing through the tube 4 flows countercurrently to the cooling water flowing through the first tube 10 and the second tube 11, and performs the same operation as in the first embodiment in which the heat exchange between the coolant and the cooling water is performed. Furthermore, since the refrigerant speed increases at the throttle portion 31 of the refrigerant inlet portion 6 and the static pressure decreases, the uncondensed gas refrigerant near the cooling water inlet passes through the bypass 30 and returns to the refrigerant inlet portion 6 again.
Supplied to

Therefore, in the third embodiment, in addition to the first embodiment, the flow rate of the refrigerant flowing in the shell 2 can be increased, and the concentration of the refrigerant that hinders heat exchange when a non-azeotropic mixed refrigerant is used. The gradient can be reduced, and the heat exchange performance can be further improved.

[0026]

According to the present invention, a shell provided with a refrigerant inlet and a refrigerant outlet, and a plurality of tubes through which a plurality of cooling mediums flow are provided in the shell, so that the flow of the cooling medium becomes a plurality of passes. In the shell-and-tube type heat exchanger, the refrigerant gradient plate is provided so that the flow of the condensed gas and the cooling medium are opposed to each other, so that the temperature gradient at the time of condensation can be effectively used even when a non-azeotropic mixed refrigerant is used. And a shell-and-tube heat exchanger with improved heat exchange performance can be provided.

In a shell and tube type heat exchanger comprising a shell provided with a refrigerant inlet and a refrigerant outlet and a plurality of tubes through which the cooling medium flows, a throttle is provided at the refrigerant inlet. Along with the provision, by providing a bypass path through which the gas refrigerant near the cooling medium communicates with the throttle portion, the refrigerant speed in the shell can be improved, and even when a non-azeotropic mixed refrigerant is used, the heat exchange performance is improved. A shell and tube heat exchanger can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a shell and tube heat exchanger according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the shell-and-tube heat exchanger according to the first embodiment.

FIG. 3 is a horizontal sectional view of a shell and tube heat exchanger according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a shell-and-tube heat exchanger according to a second embodiment.

FIG. 5 is a longitudinal sectional view of a shell and tube heat exchanger according to a third embodiment of the present invention.

FIG. 6 is a cross-sectional view of a shell and tube heat exchanger according to a third embodiment.

FIG. 7 is a heat exchange performance characteristic diagram showing a change in a difference between a refrigerant temperature and a cooling water temperature.

[Explanation of symbols]

1. Shell and tube heat exchanger, 2. Shell, 6
... refrigerant inlet, 7 ... refrigerant outlet, 10 ... first tube, 11 ... second tube, 12 ... first refrigerant flow path, 1
3 ... second refrigerant flow path, 14 ... third refrigerant flow path, 15 ... refrigerant partition plate, 16 ... notch, 20 ... refrigerant partition plate B, 30
... throttle, 31 ... bypass path.

Claims (1)

[Claims] A shell-and-tube type heat pump comprising: a shell provided with a refrigerant inlet and a refrigerant outlet; and a plurality of tubes through which a plurality of cooling mediums flow, wherein the flow of the cooling medium is made into a plurality of paths. A shell-and-tube heat exchanger, wherein a non-azeotropic mixed refrigerant is used as a refrigerant, and a refrigerant partition plate is provided so that flows of a condensed gas and a cooling medium are opposed to each other.