JP2003148885A - Refrigerant natural circulation type heating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerant natural circulation type heating system that dissolves the backflow of liquid without lowering heating capacity. SOLUTION: A liquid receiver 10 is arranged in a higher position than a heat exchanger 14 for evaporating a refrigerant to supply refrigerant vapor to indoor units 18a-18c, and refrigerant liquid condensed by the indoor units 18a-18c is stored therein. The refrigerant liquid is supplied from the liquid receiver 10 to the heat exchanger 14 through a decompression device 28. The decompression device 28 is controlled in the opening so that the degree of superheat of the refrigerant is constant by computing the degree of superheat at a refrigerant outlet 15 of the heat exchanger 14 by a computing element 34 on the basis of the detection output of a temperature sensor 30 and a pressure sensor 32. Consequently, the degree of superheat at the refrigerant outlet 15 of the heat exchanger 14 is always controlled to be constant. The backflow of the liquid is thereby prevented, and a lowering of heating capacity is also prevented since there is no need to reduce the refrigerant filling quantity for preventing the backflow of liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a refrigerant natural circulation type heating system for heating a room while naturally circulating a refrigerant.

[0002]

2. Description of the Related Art Conventionally, a refrigerant natural circulation type heating system for heating a building or the like by naturally circulating a refrigerant has been used. FIG. 2 shows an example of such a conventional refrigerant natural circulation type heating system.

In FIG. 2, a liquid receiver 10 for storing a refrigerant and a liquid refrigerant are supplied from the liquid receiver 10 to an underground of a building through an inlet pipe 12 and a refrigerant inlet 13. And a heat exchanger 14 for evaporating the heat. A hot water pipe 16 for receiving hot water as a heat source is also connected to the heat exchanger 14.

Further, a plurality of indoor units 18a, 18b, 18c, etc. are installed at a position higher than the positions of the liquid receiver 10 and the heat exchanger 14, for example, at the ceiling of the first floor. Each of the indoor units 18a, 18b, 18c has a valve 20a, 20b,
The horizontal refrigerant pipe 22 is connected via 20c, and the vertical refrigerant pipe 24 is connected thereto. The refrigerant vertical pipe 24 is connected to the upper portion of the liquid receiver 10. On the other hand, the refrigerant outlet pipe 15 of the heat exchanger 14 is connected to a refrigerant vapor pipe 26, and the other end of the refrigerant vapor pipe 26 is connected to the indoor units 18a, 18b, 18c and the like.

In the heat exchanger 14, the refrigerant liquid is heated by hot water, which is a heat medium, and evaporated to become refrigerant vapor.
The refrigerant vapor is discharged to the refrigerant vapor pipe 26 and supplied to the indoor units 18a, 18b, 18c and the like due to the pressure difference. In the indoor units 18a, 18b, 18c, etc., the supplied refrigerant gas and room air are heat-exchanged, the room air is heated to heat the room, and the refrigerant gas is cooled and condensed and liquefied.

The refrigerant liquefied as described above is supplied to the valve 2
It flows into the above-mentioned refrigerant horizontal pipe 22 via 0a, 20b, and 20c, then reaches the refrigerant vertical pipe 24, and flows into the liquid receiver 10 from the refrigerant vertical pipe 24. Here, the valves 20a to 20c
When the room temperature is lower than the set temperature, it is opened to perform heating, and when the room temperature is higher than the set temperature, it is closed to interrupt the flow of the refrigerant and suspend the heating.

A position head (pressure) is applied to the liquid receiver 10 by the refrigerant liquid in the vertical refrigerant pipe 24, and
The refrigerant liquid therein is supplied to the heat exchanger 14 via the inlet pipe 12 and the refrigerant inlet 13 by this position head. The refrigerant liquid supplied to the heat exchanger 14 evaporates again and repeats circulation, whereby the heating cycle is completed.

As described above, in the conventional heating system, the refrigerant is used as the working medium, and the refrigerant is naturally circulated by the difference in specific gravity between the refrigerant vapor and the refrigerant liquid due to the phase change accompanying the condensation and evaporation and the pressure difference between the components. In addition, a refrigerant natural circulation type heating system that performs air conditioning by transferring heat utilizing the above phase change is also provided.

[0009]

However, in the conventional refrigerant natural circulation type heating system described above, when the height difference between the heat exchanger 14 and the indoor units 18a, 18b, 18c, etc. becomes large, the refrigerant vertical pipe 24 is The refrigerant liquid also increases the position head from the liquid receiver 10 to the heat exchanger 14, and an excessive amount of the refrigerant liquid exceeding its evaporation capacity flows into the heat exchanger 14. As a result, there is a problem that a so-called liquid back state occurs in which the refrigerant liquid that cannot be evaporated is discharged to the refrigerant vapor pipe 26 in the liquid state.

Of the indoor units 18a to 18c, etc., only the indoor unit 18a is in operation and the other indoor units 18b, 18c.
When c etc. are stopped, during the heating system,
The amount of refrigerant corresponding to the amount of heat exchange of the indoor unit 18a in operation is circulating. At this time, the stopped indoor units 18b, 1
In 8c and the like, the valves 20b and 20c and the like are closed, so that the refrigerant in the stopped indoor unit is cooled and condensed by the indoor air and stays there. Here, when all the indoor units are switched to the operation, the indoor unit 1 which has been stopped
Refrigerant liquid accumulated in 8b, 18c, etc.
Then, the amount of the refrigerant in the vertical refrigerant pipe 24 increases, and the position head increases. Therefore, as in the case described above, there is a problem that a liquid back state occurs.

When a liquid back state occurs, the refrigerant vapor pipe 2
The ratio of the refrigerant vapor originally contributing to heating in 6 decreases, and the pressure loss in the refrigerant vapor pipe 26 also increases. As a result, the refrigerant vapor flow rate decreases and the condensation temperature in the indoor units 18a to 18c and the like decreases, and the heating capacity of the heating system decreases.

The liquid back state can be eliminated by reducing the amount of the refrigerant filled in the heating system.
That is, if all the indoor units 18a to 18c and the like are filled with the refrigerant in an amount such that liquid back does not occur even when operating at maximum load, the position head applied to the heat exchanger 14 is lowered and the occurrence of the liquid back state can be suppressed.

However, if the amount of refrigerant charged into the heating system is reduced, for example, when only the indoor unit 18a is operated, the refrigerant stays in the other indoor units 18b, 18c which are not operating,
The position head in the refrigerant vertical pipe 24 becomes too small. Therefore, the refrigerant flow rate to the heat exchanger 14 becomes insufficient,
There was a problem that the heating capacity was reduced.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a refrigerant natural circulation type heating system capable of eliminating liquid back without lowering the heating capacity.

[0015]

In order to achieve the above object, the present invention is a refrigerant natural circulation type heating system for heating a room while naturally circulating the refrigerant, wherein the refrigerant is evaporated to an indoor unit. A heat exchanger for supplying steam, arranged at a position higher than the heat exchanger, and containing the refrigerant liquid from the indoor unit, and a receiver for supplying the refrigerant liquid to the heat exchanger, and from the heat exchanger And a refrigerant supply control means for controlling the amount of refrigerant liquid supplied from the liquid receiver to the heat exchanger according to the degree of superheat of the discharged refrigerant vapor.

According to the above construction, the amount of the refrigerant liquid supplied from the liquid receiver to the heat exchanger is controlled according to the degree of superheat of the refrigerant vapor discharged from the heat exchanger, so that the liquid back phenomenon is suppressed. You can

Further, in the above refrigerant natural circulation type heating system, the liquid receiver has a cylindrical shape and is horizontally placed so that the body portion is substantially horizontal.

According to the above construction, even if the number of operating indoor units fluctuates, the fluctuation of the liquid level of the refrigerant in the receiver can be reduced, so that the operation of the heating system can be stabilized. You can

In the refrigerant natural circulation type heating system, the refrigerant supply control means includes a temperature sensor for measuring the temperature of the refrigerant vapor discharged from the heat exchanger, a pressure sensor for measuring the pressure, and the temperature and It is characterized by including a calculator for calculating the degree of superheat of the refrigerant vapor from the measured value of the pressure, and a pressure reducing device for controlling the flow rate of the refrigerant supplied to the heat exchanger according to the output of the calculator.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a configuration example of a refrigerant natural circulation type heating system according to the present invention. The same elements as those of the conventional example shown in FIG. Omit it. In FIG. 1, the liquid receiver 10 is a heat exchanger 14
It is installed at a higher position, such as in the ceiling on the first floor,
The indoor units 18a to 18c and the like are connected by a horizontal refrigerant pipe 22. The liquid receiver 10 includes indoor units 18a to 18a.
The refrigerant liquid discharged from 18c or the like is stored. The vertical refrigerant pipe 24 is connected to the bottom of the liquid receiver 10. The refrigerant inlet pipe 1 of the heat exchanger 14 is connected to the refrigerant vertical pipe 24.
A pressure reducing device 28 is provided in the vicinity of 3. As the decompression device 28, for example, a linear electronic expansion valve or the like can be used.

Further, in the refrigerant vapor pipe 26, a temperature sensor 30 and a pressure sensor 32 are provided near the refrigerant outlet 15 of the heat exchanger 14. The outputs of the temperature sensor 30 and the pressure sensor 32 are input to a calculator 34 that calculates the degree of superheat of the refrigerant vapor in the refrigerant vapor pipe 26. The decompression device 28 described above is controlled by the output of the calculator 34. These decompression device 28 and temperature sensor 3
0, the pressure sensor 32, and the calculator 34 constitute the refrigerant supply control means according to the present invention.

In the refrigerant natural circulation type heating system according to the present embodiment as described above, the refrigerant liquid is heated in the heat exchanger 14 using the hot water supplied by the hot water pipe 16 as a heat medium, and is evaporated to be the refrigerant vapor. Becomes The refrigerant vapor is supplied from the refrigerant outlet 15 through the refrigerant vapor pipe 26 to the indoor units 18a to 18c and the like due to the pressure difference. Indoor unit 1
In 8a to 18c and the like, the supplied refrigerant vapor is heat-exchanged with air to heat the air to heat the interior of the room and condense and liquefy the refrigerant vapor. Each indoor unit 18a-1
Refrigerant condensed and liquefied in 8c etc. are valves 20a-20.
It flows from c into the liquid receiver 10 through the horizontal refrigerant pipe 22.

In the liquid receiver 10, the supplied refrigerant is separated into gas and liquid, and the liquid single-phase refrigerant flows down the refrigerant vertical pipe 24 and is supplied to the heat exchanger 14. The flow rate of this refrigerant liquid is controlled by the pressure reducing device 28 based on the degree of superheat of the refrigerant vapor calculated by the calculator 34. That is, as described above, the output signals of the temperature sensor 30 and the pressure sensor 32 are input to the calculator 34, and the refrigerant superheat degree at the refrigerant outlet 15 of the heat exchanger 14 is calculated. The calculator 34 controls the opening degree of the decompression device 28 so that the refrigerant superheat degree at the refrigerant outlet 15 becomes the target superheat degree from the difference between the calculated refrigerant superheat degree and the preset target superheat degree. For example, the indoor unit 18
When the heating load on a to 18c increases, the refrigerant vapor pressure in the refrigerant evaporation pipe 26 decreases, but if the refrigerant vapor temperature rises at this time, the degree of superheat of the refrigerant vapor at the refrigerant outlet increases, so the calculator 34 decompresses. The opening degree of the device 28 is controlled to be increased. As a result, the refrigerant vertical pipe 2
4, the refrigerant liquid amount (refrigerant liquid supply amount) supplied to the heat exchanger 14 from the pressure reducing device 28 increases, and the superheat degree of the refrigerant vapor at the refrigerant outlet 15 of the heat exchanger 14 decreases. Conversely, when the degree of superheat of the refrigerant vapor at the refrigerant outlet 15 of the heat exchanger 14 decreases, the calculator 34 reduces the opening degree of the decompression device 28 to reduce the amount of refrigerant liquid supplied to the heat exchanger 14. By lowering it, the steam superheat is increased.

As described above, in the refrigerant natural circulation type heating system according to the present embodiment, the liquid receiver 10 to the heat exchanger 1 are changed according to the degree of superheat of the refrigerant vapor discharged from the heat exchanger 14.
4 is controlled so that the degree of superheat of the refrigerant vapor at the refrigerant outlet 15 of the heat exchanger 14 is constant.

Further, as described above, in this embodiment, the liquid receiver 10 is arranged at a position higher than the heat exchanger 14. Therefore, the refrigerant in the refrigerant vertical pipe 24 can be in a liquid single phase, and the position head required for controlling the heating system can be secured.

Further, the liquid receiver 10 according to the present embodiment.
As shown in FIG. 1, it has a cylindrical shape and is horizontally placed so that the body portion is substantially horizontal. As a result, even when the number of operating indoor units 18a to 18c or the like suddenly increases or decreases, it is possible to suppress fluctuations in the liquid level of the refrigerant in the liquid receiver 10. As a result, the fluctuation of the position head is also suppressed.

With the above-described structure, the amount of the refrigerant liquid supplied from the liquid receiver 10 to the heat exchanger 14 can be stably controlled while the refrigerant superheat degree is constantly calculated by the calculator 34. It is possible to prevent the occurrence of the liquid back phenomenon in which the liquid refrigerant is discharged from the refrigerant outlet 15. For this reason,
The occurrence of the liquid back phenomenon can be suppressed without reducing the amount of the refrigerant liquid filling the heating system, and stable operation can be performed without lowering the heating capacity.

Further, as described above, the indoor units 18a-1
Even if there is a change in the number of operating units such as 8c, the change in the liquid level of the refrigerant in the liquid receiver 10 can be reduced, so that it is also possible to prevent the heating capacity from deteriorating due to insufficient refrigerant flow.

When all of the indoor units 18a to 18c are stopped, if the decompression device 28 is fully closed, the amount of refrigerant accumulated in each of the indoor units 18a to 18c will be heat-exchanged when stopped. Only the amount of the refrigerant existing in the container 14 can be used. Therefore, the amount of refrigerant staying in the indoor units 18a to 18c can be reduced, and the indoor units 18a to 18c can be restarted quickly. Further, in this case, the amount of refrigerant staying in the indoor units 18a to 18c and the like decreases, so that the amount of hot water heating for starting can be reduced.

In the refrigerant natural circulation heating system according to this embodiment, not only a single refrigerant but also a non-azeotropic mixed refrigerant and a pseudo-azeotropic mixed refrigerant can be used.

Further, in the above embodiment, the case where only one decompression device 28 is installed is shown, but when the number of installed indoor units is larger than one evaporator 14,
The refrigerant flow rate required on the indoor unit side is one decompression device 28.
In some cases, the flow rate range that can be controlled by is exceeded. In such a case, it is also suitable to install a plurality of decompression devices 28 in parallel.

[0033]

As described above, according to the present invention,
Since the amount of refrigerant liquid supplied from the liquid receiver to the heat exchanger is controlled according to the degree of superheat of the refrigerant vapor discharged from the heat exchanger, the liquid back phenomenon can be suppressed.

Further, if the liquid receiver is a cylindrical container laid horizontally such that the body is substantially horizontal, even if the number of operating indoor units fluctuates, the refrigerant in the liquid receiver will change. Since the fluctuation of the liquid level can be reduced, the operation of the heating system can be stabilized.

Further, since the liquid receiver can absorb the fluctuation of the circulating amount of the refrigerant, it is not necessary to reduce the amount of the refrigerant filled in the heating system, and the reduction of the heating capacity due to the lack of the refrigerant can be suppressed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a refrigerant natural circulation type heating system according to the present invention.

FIG. 2 is a configuration diagram of a conventional refrigerant natural circulation type heating system.

[Explanation of symbols]

10 receiver, 12 inlet pipe, 13 refrigerant inlet, 14
Heat exchanger, 15 Refrigerant outlet, 16 Hot water piping, 18
a, 18b, 18c Indoor unit, 20a, 20b, 20c
Valve, 22 Refrigerant horizontal tube, 24 Refrigerant vertical tube, 26 Refrigerant vapor tube, 28 Pressure reducing device, 30 Temperature sensor, 32 Pressure sensor, 34 Computing unit.

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[Procedure amendment]

[Submission date] December 17, 2001 (2001.12.
17)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

As described above, the conventional heating system uses the refrigerant as the working medium, and naturally circulates the refrigerant by the density difference between the refrigerant vapor and the refrigerant liquid due to the phase change caused by the condensation and evaporation and the pressure difference between the constituent devices. In addition, a refrigerant natural circulation type heating system that performs air conditioning by transferring heat utilizing the above phase change is also provided.

Continued front page    (72) Inventor Tsuneo Yumikura             2-6-2 Otemachi 2-chome, Chiyoda-ku, Tokyo             Ryoden Building Techno Service Co., Ltd. F term (reference) 3L060 AA05 AA08 CC04 CC16 DD02                       EE09

Claims (3)

[Claims] 1. A refrigerant natural circulation heating system for heating a room while naturally circulating a refrigerant, comprising: a heat exchanger for evaporating a refrigerant to supply a refrigerant vapor to an indoor unit; Arranged at a high position, while accommodating the refrigerant liquid from the indoor unit, and a receiver for supplying the refrigerant liquid to the heat exchanger, depending on the degree of superheat of the refrigerant vapor discharged from the heat exchanger, A refrigerant natural circulation type heating system, comprising: a refrigerant supply control means for controlling a refrigerant liquid supply amount from the liquid receiver to the heat exchanger. 2. The refrigerant natural circulation type heating system according to claim 1, wherein the liquid receiver has a cylindrical shape, and the body is laid horizontally so that the body is substantially horizontal. Type heating system. 3. The refrigerant natural circulation type heating system according to claim 1 or 2, wherein the refrigerant supply control means measures a temperature of a refrigerant vapor discharged from the heat exchanger, and a pressure sensor. A pressure sensor for measuring, a calculator for calculating the degree of superheat of the refrigerant vapor from the measured values of the temperature and pressure, and a pressure reducing device for controlling the flow rate of the refrigerant supplied to the heat exchanger according to the output of the calculator. A refrigerant natural circulation type heating system comprising: