JP2002349979A - Co2 gas compressing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high precision control by reducing the pressure applied to an automatic expansion valve, and to provide a CO2 gas compressing system which enables reduction of price of a system device. SOLUTION: The system device comprises a refrigerant circulation circuit B that CO2 gas as a refrigerant successively circulates through a compressor 1, a gas cooler 2, expansion means 3a and 3, and an evaporator 4, the expansion means 3a and 3 consisting of a capillary tube 3a as a fixed restriction means, whose channel opening is fixed and the automatic expansion valve 3 as a variable restriction means whose channel opening is variable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon dioxide gas compression system, and more particularly, to a system for controlling a high-precision valve by reducing the pressure applied to an automatic expansion valve, and at the same time, reducing the price of system equipment. The present invention relates to a carbon dioxide gas compression system which can be manufactured at a low cost.

[0002]

2. Description of the Related Art Conventionally, as a gas compression system using carbon dioxide gas (CO ₂ ) as a refrigerant, a carbon dioxide gas as a refrigerant is supplied to a compressor 1, a gas cooler 2, an automatic expansion valve 3 as shown in FIG. And a refrigerant circulation circuit that sequentially circulates between the evaporators 4 has been put to practical use.

In this case, a high pressure of about 10 MPa of carbon dioxide gas as a refrigerant compressed by the compressor 1 is directly applied to the automatic expansion valve 3.

[0004]

As described above, in the conventional carbon dioxide gas compression system using carbon dioxide gas as a refrigerant, the pressure of the carbon dioxide gas as a refrigerant compressed by the compressor 1 is as high as about 10 MPa. Since the pressure is directly applied to the automatic expansion valve 3, the automatic expansion valve 3 needs to have a large capacity and a specification capable of sufficiently withstanding a high pressure, resulting in a problem that the price is expensive. Further, an automatic expansion valve having a large capacity has a problem that it is not only expensive in price but also difficult to perform highly accurate control.

[0005] In a conventional carbon dioxide gas compression system using carbon dioxide gas as a refrigerant, the temperature of hot water and the like are affected by the outside air temperature.
That is, when the outside air temperature is high, the discharge temperature is as shown in FIG.
(C), a high temperature can be maintained, but when the outside air temperature is low, the temperature of the refrigerant decreases as shown in (b) of FIG. There was a problem that high-temperature hot water supply was difficult.

The present invention has been made in consideration of the above-described problems of the conventional carbon dioxide gas compression system, and has been made capable of performing high-precision control by reducing the pressure applied to an automatic expansion valve, and at the same time, system equipment. It is a first object of the present invention to provide a carbon dioxide gas compression system capable of reducing the price of a carbon dioxide gas.

Another object of the present invention is to provide a carbon dioxide gas compression system capable of supplying a high-temperature hot water while maintaining the temperature of the refrigerant at a high temperature even in winter or the like when the outside air temperature is low. Aim.

[0008]

Means for Solving the Problems In order to achieve the first object, a carbon dioxide gas compression system of the first invention is provided.
Carbon dioxide gas compression system as a refrigerant Carbon dioxide gas, a compressor, a gas cooler, expansion means and a carbon dioxide gas compression system comprising a refrigerant circulation circuit that sequentially circulates between the evaporator, the expansion means, the flow path It is characterized by comprising fixed throttle means having a constant opening degree and variable throttle means having a variable opening degree of the flow path.

In this case, a capillary tube can be used as the fixed throttle means of the expansion means, and an automatic expansion valve such as a thermal expansion valve or an electronic control expansion valve can be used as the variable throttle means.

In this carbon dioxide gas compression system, the expansion means is constituted by fixed throttle means having a fixed flow path opening degree and variable throttle means having a variable flow path opening degree. It is possible to reduce the pressure applied to the variable throttle means having a variable opening degree of the path, specifically, the pressure applied to the automatic expansion valve, and it is possible to perform highly accurate control. Further, the pressure resistance required for the variable aperture means is reduced and the capacity may be small, so that the price of the system equipment can be reduced.

Further, in order to achieve the second object, the carbon dioxide gas compression system according to the second aspect of the present invention comprises:
In the carbon dioxide gas compression system of the present invention, a heating auxiliary circuit in which a heat exchanger for performing heat exchange with the fixed throttle means via a control valve is disposed between an evaporator and a compressor in a refrigerant circuit. Is formed.

In the carbon dioxide gas compression system, for example, in winter, when the outside air temperature is low, heat exchange between the fixed throttle means via a control valve disposed between the evaporator and the compressor in the refrigerant circuit. The temperature of the refrigerant can be kept high by circulating the refrigerant in the auxiliary heating circuit provided with the heat exchanger for performing the above-mentioned process, whereby high-temperature hot water can be supplied.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a carbon dioxide gas compression system according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a carbon dioxide gas compression system according to the present invention. This carbon dioxide gas compression system includes a refrigerant circulation circuit B in which carbon dioxide gas as a refrigerant circulates sequentially between a compressor 1, a gas cooler 2, expansion means 3a, 3 and an evaporator 4. 3a and 3 are automatically expanded such as a capillary tube 3a as a fixed throttle means having a fixed opening degree of a flow path and a temperature-type expansion valve or an electronically controlled expansion valve as a variable throttle means having a variable opening degree of a flow path. The valve 3 is constituted.

Further, in this carbon dioxide gas compression system, heat is transferred between the evaporator 4 of the refrigerant circuit B and the compressor 1 via the control valve 5 and the capillary tube 3a as a fixed throttle means. A heating auxiliary circuit A in which a heat exchanger 6 for replacement is provided is formed.

The gas cooler 2 has a water circulation circuit C through which water a for performing heat exchange with the refrigerant circulation circuit B flows.
To be installed.

In this carbon dioxide gas compression system, as described above, the expansion means 3a and 3 are connected to the capillary tube 3a as a fixed throttle means having a fixed opening degree of the flow path, and the opening degree of the flow path is fixed. Automatic expansion valve 3 such as a temperature-type expansion valve or an electronically-controlled expansion valve as a variable variable throttle means.
The pressure applied to the automatic expansion valve 3 such as a thermal expansion valve or an electronically controlled expansion valve is controlled by the capillary tube 3a from a high pressure close to 10 MPa to a lower pressure, particularly limited. However, the pressure can be reduced to, for example, about 4 to 5 MPa, and the automatic expansion valve 3 can perform highly accurate control up to a target pressure.

In addition, the pressure resistance required for the automatic expansion valve 3 such as a thermal expansion valve or an electronically controlled expansion valve can be reduced, and the capacity of the automatic expansion valve 3 itself can be small. As compared with the case where a large capacity valve capable of withstanding a high pressure of 10 MPa is used for the expansion valve 3,
The price of system equipment can be reduced.

Further, by forming the heating auxiliary circuit A and controlling the control valve 5 disposed in the refrigerant circuit B, a part or all of the refrigerant circulating in the refrigerant circuit B is supplied to the evaporator 4. After exiting, detour to the heating auxiliary circuit A side,
By causing the heat exchanger 6 of the heating auxiliary circuit A to perform heat exchange with the capillary tube 3a as the fixed throttle means, as shown in FIG. 3 (b) to FIG. After the superheat degree is increased, the refrigerant is returned to the refrigerant circuit B and supplied to the compressor 1.

By circulating the refrigerant through the auxiliary heating circuit A even in winter when the outside air temperature is low,
The temperature of the refrigerant can be maintained at a high temperature, so that in the gas cooler 2, heat exchange between the refrigerant flowing through the refrigerant circulation circuit B, which has been heated and increased in pressure by the compressor 1, and the water a flowing through the water circulation circuit C. And hot water supply can be performed.

The switching control of the control valve 5 can employ various methods such as a method of detecting the outside air temperature. In the case of the present embodiment, the degree of superheat of the gas discharged from the compressor 1 is determined. A detection method is used, so that the compressor 1 can be prevented from being overheated.

As described above, the carbon dioxide gas compression system of the present invention has been described based on the embodiment. However, the present invention is not limited to the configuration described in the above-described embodiment, and is not departed from the gist of the present invention. The configuration can be appropriately changed.

[0023]

According to the carbon dioxide gas compression system of the first aspect of the present invention, the expansion means is composed of fixed throttle means having a constant flow path opening and variable throttle means having a variable flow path opening. Therefore, it is possible to reduce the pressure applied to the variable expansion means having a variable opening degree of the flow path, specifically, the pressure applied to the automatic expansion valve, to perform highly accurate control, The compression system can operate smoothly. In addition, since the pressure resistance required for the variable throttle means is reduced and the capacity may be small, the price of system equipment can be reduced and a highly practical carbon dioxide gas compression system can be provided.

Further, according to the carbon dioxide gas compression system of the second invention, heat is exchanged with the fixed throttle means via the control valve disposed between the evaporator and the compressor in the refrigerant circuit. By circulating the refrigerant through the auxiliary heating circuit in which the heat exchanger is provided, the temperature of the refrigerant can be maintained at a high temperature, so that high-temperature hot water can be supplied even in winter when the outside air temperature is low.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a carbon dioxide gas compression system of the present invention.

FIG. 2 is an explanatory diagram showing a conventional carbon dioxide gas compression system.

FIG. 3 is an operation cycle diagram showing a comparison between the present invention and a conventional one in a carbon dioxide gas compression system, wherein (a) is a winter operation cycle diagram according to the present invention, and (b) is a conventional winter operation cycle diagram. (C) is an operation cycle diagram of the present invention and the conventional operation other than the winter season.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Gas cooler 3a Capillary tube (fixed restricting means) 3 Automatic expansion valve (variable restricting means) 4 Evaporator 5 Control valve 6 Heat exchanger a Cooling water A Heating auxiliary circuit B Refrigerant circulation circuit C Water circulation circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Kuramoto 4-5-11 Higashiota, Ibaraki City, Osaka Prefecture Inside Hitachi Air Conditioning Systems Ibaraki Plant (72) Inventor Koji Shimazaki 4-5-11 Higashiota, Ibaraki City, Osaka Prefecture Shares (72) Inventor Kenji Tojo 4-5-11 Higashiota, Ibaraki City, Osaka Prefecture Hitachi Air Conditioning System Ibaraki Plant

Claims (3)

[Claims] In a carbon dioxide gas compression system comprising a refrigerant circulation circuit in which carbon dioxide gas as a refrigerant sequentially circulates between a compressor, a gas cooler, expansion means, and an evaporator, the expansion means includes A carbon dioxide gas compression system comprising fixed throttle means having a fixed opening and variable throttle means having a variable opening of a flow path. 2. The dioxide according to claim 1, wherein a capillary tube is used as a fixed throttle means of said expansion means, and an automatic expansion valve such as a thermal expansion valve or an electronically controlled expansion valve is used as a variable throttle means. Carbon gas compression system. 3. A heating auxiliary circuit is provided between the evaporator and the compressor of the refrigerant circuit, and a heat exchanger for performing heat exchange with the fixed throttle means via a control valve. The carbon dioxide gas compression system according to claim 1 or 2, wherein: