JPH0236061Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a dry shell-and-tube evaporator.

(Prior technology) The dry shell-and-tube evaporator was first developed in 1972.
It is already known as it is also described in 90179 publication.

When this evaporator is applied to a refrigeration system equipped with a compressor that enables capacity control, the following steps are taken to improve the return of lubricating oil to the compressor during partial capacity operation. The flow rate of refrigerant flowing through the evaporator is ensured.

That is, to explain with reference to FIG. 2 according to the present invention, the evaporator is provided with a refrigerant inlet space 7, a refrigerant outlet space 9, and a plurality of pipes 10 groups communicating these spaces 7, 9 in the casing 4. In the container A, the refrigerant inlet space 7 and the refrigerant outlet space 9,
Inlet side and outlet side partition plates 11 and 12 are respectively provided to partition these spaces 7 and 9 left and right, respectively, and first and second heat exchange parts A1,
This is because A2 is divided and formed.

Note that 13 and 13 are refrigerant return pipes.

Thus, for example, during partial capacity operation in which only one of the two first and second compressors 20 or 30 is operated, the second heat exchanger corresponding to the compressor 30 on the stopped side The second electromagnetic on-off valve 32 provided on the inflow side of the section A2 is closed, and only the first electromagnetic on-off valve 22 provided on the inflow side of the first heat exchange section A1 is opened. Thus, the refrigerant flow area in the evaporator A is reduced, and the desired refrigerant flow rate is maintained at the outlet of the evaporator A, despite the reduction in the amount of refrigerant circulated due to this partial capacity operation. This was done so that oil could be returned in the same way as when operating at full capacity.

(Problem to be Solved by the Present Invention) However, in this case, during the above-mentioned partial capacity operation, the second heat exchange section A2 on the stop side is also maintained at a low temperature, so that the second electromagnetic on-off valve 32 When refrigerant leaks, the liquid refrigerant leaks from the high-pressure liquid pipe section to the second heat exchange section A2 via the on-off valve 32 and stays in the heat exchange section A2. As a result, when the second heat exchange section A2 on the stopped side is restarted, for example, when returning from partial capacity operation to full capacity operation, a problem arises in which liquid backs up.

Therefore, an object of the present invention is to provide a small hole in the evaporator A that communicates the first heat exchange section A1 and the second heat exchange section A2, and to devise a position where the small hole is formed. The liquid refrigerant leaking into the heat exchanger on the stop side is quickly sucked into the heat exchanger on the operating side while containing lubricating oil, and the liquid refrigerant and lubricant are collected in the heat exchanger on the stop side. The object of the present invention is to improve the performance of oil return, and also to reliably prevent liquid backflow when restarting the heat exchanger on the stopped side.

(Means for Solving the Problems) Therefore, the configuration of the present invention will be explained based on FIGS. 1 and 2. In the casing 4, there are a refrigerant inlet space 7, a refrigerant outlet space 9, and A plurality of groups of pipes 10 are provided to communicate the refrigerant inlet space 7 and the refrigerant outlet space 9, and inlet side and outlet side partition plates 11 and 12 are respectively provided in the refrigerant inlet space 7 and the refrigerant outlet space 9 to partition these spaces 7 and 9 into left and right sides. In the dry shell-and-tube evaporator in which the first and second heat exchange parts A1 and A2 are separately formed in the casing 4, the first heat exchange part A1 is provided at the lower end of the inlet side partition plate 11. A small hole 1 that communicates the refrigerant inlet space 7a of the and the refrigerant inlet space 7b of the second heat exchange section A2.
1a was formed.

The evaporator A according to the present invention shown in FIG.
The present invention is applied to a refrigeration system in which the compressors 20 and 30 are connected in parallel and the compressors 20 and 30 are selectively driven to perform partial capacity operation.

In this refrigeration system, the first compressor 2
The first and second electromagnetic on-off valves 22 and 32 provided on the inflow side of the evaporator A are opened and closed corresponding to each operation of the evaporator A and the second compressor 30.
The second heat exchange parts A1 and A2 can be selectively activated.

(Function) When applied to the refrigeration system shown in FIG. 2, for example, the second compressor 30 is stopped, only the first compressor 20 is operated, and the second electromagnetic on-off valve 32 is closed. To explain the case where only the first electromagnetic on-off valve 22 is opened and partial capacity operation is performed in which only the first heat exchange section A1 is operated, when the first compressor 20 is driven, the first heat exchange section A is operated.
A low-pressure liquid refrigerant whose pressure has been reduced by a temperature-sensitive expansion valve 21 flows into the pipe 10 , and this liquid refrigerant flows through the pipe 10 at a sufficiently high flow rate while evaporating, and flows through the refrigerant discharge space 9 into the evaporator. Flows outside A.

On the other hand, when liquid refrigerant containing lubricating oil leaks into the refrigerant inlet space 7b of the second heat exchange section A2 via the second electromagnetic on-off valve 32, this liquid refrigerant
The first refrigerant is sucked into the refrigerant inlet space 7a of the first heat exchanger A1 through the small hole 11a without remaining in the heat exchanger A2, while containing lubricating oil, and passes through the first electromagnetic on-off valve 22. The refrigerant flowing into the inlet space 7a flows through the pipe 10 and the refrigerant outlet space 9a at a high flow rate, and is returned to the first compressor 20.

In this way, since the liquid refrigerant does not remain in the second heat exchange section A2, no liquid back up occurs when the heat exchange section A2 is restarted, and moreover, no liquid refrigerant leaks into the second heat exchange section A2. Since the liquid refrigerant containing the lubricating oil is sucked into the first heat exchange section A1 as it is, there is no possibility that the lubricant oil will remain in the second heat exchange section A2.

(Example) What is shown in FIG. 2 is a refrigeration system to which an evaporator A according to an example of the present invention is applied.

The refrigeration system includes two first and second compressors 2.
0 and 30 in parallel, and a full capacity operation in which the first compressor 20 and the second compressor 30 are operated simultaneously;
Partial capacity operation in which only the first or second compressor 20 or 30 is operated can be performed.

The evaporator A will be described in detail with reference to FIGS. 1 and 2. A cylindrical body 1 having a brine inlet 1a and a brine outlet 1b is provided, and one side opening of the cylindrical body 1 is connected to a pair of cylindrical bodies. It is closed with a bowl-shaped first lid body 2 having a refrigerant inlet 2a, 2b, and the other side opening of the cylinder 1 is closed with a second bowl-shaped lid body 2 having a pair of refrigerant outlet ports 3a, 3b. The casing 4 is closed with a lid 3 to form a hermetically sealed casing 4, and a pair of tube plates 5 and 6 are provided at both ends of the cylindrical body 1 in the casing 4 to partition the inside of the casing 4 into three parts. A refrigerant inlet space 7, a heat exchange space 8, and a refrigerant outlet space 9 are formed within the casing 4.

Both ends of a large number of pipes 10 passing through the heat exchange space 8 and communicating between the refrigerant inlet space 7 and the refrigerant outlet space 9 are fixed to each of the tube plates 5 and 6. .

Further, an inlet side partition plate 11 is provided to partition the refrigerant inlet space 7 into left and right sides, dividing the space 7 into a first refrigerant inlet space 7a and a second refrigerant inlet space 7b, and also divides the refrigerant outlet space 9 into left and right sides. An outlet-side partition plate 12 is provided to divide the space 9 into a first refrigerant outlet space 9a and a second refrigerant outlet space 9b, thus creating a first refrigerant inlet space 7 in the evaporator A.
a, the first refrigerant outlet space 9a and these spaces 7a,
a first heat exchange section A1 consisting of a group of 10 pipes communicating with each other; and a second heat exchange section A1 consisting of a group of 10 pipes communicating the second refrigerant inlet space 7b, a second refrigerant outlet space 9b, and these spaces 7b, 9b. It forms a two-system heat exchange section with exchange section A2.

Further, as shown in FIGS. 2 and 3, each of the refrigerant outlet spaces 9a and 9b is provided with a normal refrigerant return pipe 13 that communicates with the refrigerant outlet ports 3a and 3b, respectively. Note that 13a is an oil return hole.

In the dry shell-and-tube evaporator A configured as described above, the first
A small hole 11a that communicates with the second refrigerant inlet spaces 7a and 7b is opened.

Hereinafter, the refrigeration system using the dry shell-and-tube evaporator A will be explained based on FIG. 2.

A first temperature-sensitive expansion valve 21 and a first electromagnetic on-off valve 22 are provided on the inflow side of the first heat exchange section A1 in the evaporator A.
are connected in sequence, and the first compressor 20 is connected to the outflow side to form a first heat exchange circuit.

Similarly, a second temperature-sensitive expansion valve 31 and a second electromagnetic on-off valve 32 are sequentially connected to the inflow side of the second heat exchange section A2, and the second compressor 30 is connected to the outflow side of the second heat exchange section A2.
are connected to form a second heat exchange circuit.

Further, these first and second heat exchange circuits are connected in parallel, and a condenser B and a receiver C are connected in series to this parallel circuit to form a refrigerant circuit.

In addition, 23 and 33 are suction check valves provided on the inflow side of each of the compressors 20 and 30, 24 and 34 are discharge check valves provided on the outflow side of the same compressors 20 and 30, and 25,
Reference numeral 35 denotes a temperature-sensitive cylinder of the expansion valves 21, 31 attached to each suction pipe 26, 36.

Next, the evaporator A accompanying the operation of the refrigeration system
Explain the effect of

Partial capacity operation in which only the first compressor 20 is operated will be explained. In this case, the first electromagnetic on-off valve 22 is opened and the second electromagnetic on-off valve 32 is closed.

Thus, when only the first compressor 20 is operated, the high-pressure gas refrigerant discharged from the compressor 2 is condensed in the condenser B to become a liquid refrigerant, and then passes through the liquid receiver C to the first The temperature-sensitive expansion valve 21 is reached.

The liquid refrigerant whose pressure has been reduced to a low pressure by the first temperature-sensitive expansion valve 21 flows into the first refrigerant inlet space 7a, and further into the pipe 10 communicating with the space 7a.
At this constant flow rate, the brine flowing into the heat exchange space 8 heats and evaporates, turning into a low-pressure gas refrigerant and flowing out into the first refrigerant outlet space 9a.

The refrigerant is then discharged to the suction pipe 26 via the refrigerant return pipe 13 and sucked into the first compressor 20 again.

During this partial capacity operation, high-pressure liquid refrigerant acts on the inlet side of the second electromagnetic on-off valve 32 on the stop side, so a large pressure difference occurs between the inlet and the outlet of the electromagnetic on-off valve 32. Therefore, during operation, refrigerant leaks from the electromagnetic on-off valve 32, and liquid refrigerant containing lubricating oil leaks into the second refrigerant inlet space 7b of the second heat exchange section A2 while it is stopped. There are cases where

However, even if the liquid refrigerant leaks into the second refrigerant inlet space 7b, since the small hole 11a is opened at the lower end of the suction side partition plate 11,
The leaked liquid refrigerant enters the second refrigerant inlet space 7b.
The liquid refrigerant is drawn into the first refrigerant inflow space 7a while containing lubricating oil without remaining in the heat exchanger, and flows into the first heat exchanger A1 via the first electromagnetic on-off valve 22. A1 is circulated at high speed and returned to the first compressor 20.

Thus, during this partial capacity operation, the liquid refrigerant does not remain in the second heat exchange section A2 on the stopped side, so no liquid back up occurs when the second compressor 30 is restarted. Furthermore, the liquid refrigerant leaking into the second refrigerant inlet space 7b is immediately sucked into the first refrigerant inlet space 7a, flows through the pipe 10, and reaches the second refrigerant outflow space 9b. Since there is almost no lubricating oil left behind in the second heat exchange section A2, the oil can be returned satisfactorily.

To explain this point in comparison with a comparative example in which the small holes 11a are provided not in the suction side partition plate 11 but in the outlet side partition plate 12, in the case of this comparative example, the second refrigerant inlet The liquid refrigerant that has leaked into the space 7b flows through the pipe 10, is heated to brine in this process, evaporates, flows out into the second refrigerant outlet space 9b, and then flows through the small hole into the first refrigerant. The refrigerant is sucked into the refrigerant outlet space 9a, but in this case, since the amount of refrigerant flowing into the second heat exchange section A2 is small, the flow rate of the refrigerant on the exit side of the heat exchange section A2 is small. Sufficient oil return cannot be expected.

Although a detailed explanation will be omitted, even during partial capacity operation in which the first electromagnetic on-off valve 22 is closed and the second electromagnetic on-off valve 32 is opened to drive only the second compressor 30, the oil return Of course, the same effect can be obtained, in that it is possible to prevent the liquid refrigerant from stagnation in the second heat exchange section A1 while efficiently performing the above operations.

Further, during full capacity operation, both the first and second electromagnetic on-off valves 22 and 32 are opened, and the first and second compressors 20 and 30 are operated simultaneously, so that the first and second Heat exchange part A1, A
The two are made to work together.

Further, in the embodiment, the evaporator A of the present invention can be operated at partial capacity by connecting two compressors 20 and 30 in parallel and selectively driving these compressors 20 and 30. Although the present invention has been applied to a refrigeration system as described above, it is of course applicable to a refrigeration system equipped with a single compressor equipped with a capacity controller.

(Effect of the invention) As described above, the present invention provides a refrigerant inlet space of the first heat exchange section and a second
Since the small hole is formed to communicate with the refrigerant inlet space of the heat exchange section, when the evaporator of the present invention is used in a refrigeration system that enables partial capacity operation, a large amount of water is generated in the heat exchange section on the stop side. This makes it possible to prevent liquid from accumulating, thereby reliably preventing liquid back up when the heat exchanger on the stopped side is restarted.

Moreover, since the liquid refrigerant that has flowed into the refrigerant inlet space of the heat exchange section on the stop side is directly sucked into the refrigerant inlet space of the heat exchange section on the operation side through the small holes, The lubricating oil does not remain in the heat exchange section, and the oil return effect can be improved.

[Brief explanation of the drawing]

FIG. 1 is a drawing showing the main parts of an embodiment of the present invention, and is an enlarged sectional view taken along the line - in FIG. 2, FIG. FIG. 2 is an enlarged cross-sectional view taken along the - line in FIG. 1 of the same embodiment. 4...Casing, 7...Refrigerant inlet space, 9...
... Refrigerant outlet space, 10 ... Pipe, 11 ... Inlet side partition plate, 11a ... Small hole, 12 ... Outlet side partition plate, A1 ... First heat exchange section, A2 ... Second heat exchange section.

Claims (1)

[Scope of utility model registration request] In the casing 4, a refrigerant inlet space 7, a refrigerant outlet space 9, and a plurality of groups of pipes 10 connecting these spaces 7 and 9 are provided. , 9 into left and right sides, an inlet side and an outlet side partition plate 11,
In the dry shell and tube type evaporator in which the first and second heat exchange parts A1 and A2 are separately formed in the casing 4,
A refrigerant inlet space 7a on the first heat exchange section A1 side and a second heat exchange section A are provided at the lower end of the inlet side partition plate 11.
A small hole 11a that communicates with the refrigerant inlet space 7b on the second side.
A dry shell and tube type evaporator characterized by forming.