JP4070583B2 - Compression heat pump system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a compression heat pump system including a circulation channel in which a working medium circulates in the order of a compression unit, a heat dissipation unit, an expansion unit, and a heat absorption unit.
[0002]
[Prior art]
A conventional compression heat pump system using an artificial working medium such as chlorofluorocarbon as a working medium circulates the working medium in a circulation flow path and compresses the working medium in a gas phase state by a compressor (compression unit), and then a radiator (heat radiation). In the liquid phase by radiating heat and cooling to a liquid phase, reducing the pressure of the cooled working medium liquid with an expansion valve (expansion part), and evaporating it with a heat absorber (heat absorption part) to take away latent heat of vaporization from the atmosphere. Heat is absorbed from the heat absorber to the radiator side by utilizing heat absorption / radiation when the artificial working medium such as Freon is changed between a gas phase state and a liquid phase state. It is configured to forcibly move.
[0003]
In recent years, from the viewpoint of protecting the ozone layer and preventing global warming, the use of natural working media such as carbon dioxide has attracted attention as working media for compression heat pump systems, not artificial working media such as chlorofluorocarbons. A compression heat pump system using such carbon dioxide as a working medium has been put into practical use.
[0004]
Since the critical point temperature of carbon dioxide as such a natural working medium is lower than the artificial working medium such as chlorofluorocarbon, for example, when the outside air temperature is high such as in summer, the temperature of carbon dioxide in the radiator is the critical point of carbon dioxide. It becomes higher than the temperature, and carbon dioxide may not be in a liquid phase in the radiator.
Therefore, in a compression heat pump system using a natural working medium such as carbon dioxide, the operating pressure of the compressor (working medium discharge pressure) may be set to an extremely high value of about 10 MPa in order to exhibit sufficient performance.
[0005]
On the other hand, when the rotational drive source of the compressor of the compression heat pump system is an external rotational drive source such as an engine installed outside, the compressor is driven by a drive shaft for rotating a compression rotor for compression. It is necessary to configure as an externally driven compressor with the coupling part exposed outside the main body. Between the drive shaft and the main body, the working medium flows out along the drive shaft from the compression rotor side in the main body. A shaft seal portion such as a known mechanical seal is provided to prevent this.
[0006]
[Problems to be solved by the invention]
In a compression heat pump system using an artificial working medium such as chlorofluorocarbon, the operating pressure is relatively low, about 3 MPa, so that the outflow of the working medium can be easily suppressed at the shaft seal portion of the compressor. In a compression heat pump system using a natural working medium, the operating pressure is as high as about 10 MPa, so it is difficult to sufficiently suppress the working medium from flowing out to the outside at the shaft seal portion of the compressor.
[0007]
When the working medium leaks and the pressure of the working medium of the compression heat pump system decreases in this way, the COP in the heat pump system is lowered, and the maximum hot water temperature that can be generated in the radiator may be lowered. . COP indicates a coefficient of performance of the heat pump system, and is expressed as a ratio of the amount of heat radiated by the radiator to that obtained by converting the compressor driving power into the amount of heat.
[0008]
Therefore, in the case of using a natural working medium such as carbon dioxide that needs to be compressed to a very high pressure in view of the above circumstances, the present invention can prevent a reduction in efficiency due to leakage of the working medium. The purpose is to realize a compression heat pump system.
[0009]
[Means for Solving the Problems]
In order to achieve this object, the first characteristic configuration of the compression heat pump system according to the present invention is the operation that circulates through a predetermined portion of the circulation flow path as described in claim 1 of the claims. Replenishing means for replenishing the circulation channel with the working medium so that the pressure of the medium becomes a set pressure set with respect to the predetermined part, and the working medium is carbon dioxide; The drive source of the compression unit is an engine, and the replenishment unit includes carbon dioxide generation unit that separates and generates carbon dioxide to replenish the circulation flow path from exhaust gas of the engine, and is common to the compression unit In the point which is comprised with the compression means which drives with the driving force of a drive source and compresses the carbon dioxide produced | generated by the said carbon dioxide production | generation means .
[0010]
That is, according to the compression heat pump system of the first characteristic configuration, even if the working medium in the circulation flow channel leaks through the seal portion such as the compression portion by the replenishing means, the working medium for the leakage is removed. The recirculation flow path is automatically replenished, and the pressure at a predetermined part of the recirculation flow path is maintained at the set pressure set for that part in order to maintain high efficiency, thereby preventing a decrease in efficiency. can do.
Even when carbon dioxide that needs to be compressed to a high pressure at the compression section and has a high possibility of leakage is used as a working medium, the efficiency can be prevented by replenishing the circulation channel with carbon dioxide by the replenishing means. .
When the driving source of the compression unit is an engine, by providing the carbon dioxide generating means, carbon dioxide is separated from the exhaust gas discharged from the engine and generated, and the generated carbon dioxide is supplied to the circulating flow. The road can be replenished, and there is no need to prepare additional carbon dioxide for replenishment. In addition, when the carbon dioxide generated from the exhaust gas of the engine by the carbon dioxide generating means is replenished to the circulation flow path, by providing the compression means, a part of the driving force of the engine can be obtained without providing a separate driving source. Utilizing this, the generated carbon dioxide can be compressed, and high-pressure carbon dioxide can be replenished to the circulation flow path at a replenishment pressure higher than the set pressure of the circulation flow path.
[0011]
The second characteristic configuration of the compression heat pump system according to the present invention is that, in addition to the first characteristic configuration, the replenishing means is configured as the predetermined portion as described in claim 2 of the claims. The working medium is placed in the low pressure side flow path so that the pressure of the low pressure side flow path from the expansion part to the compression part of the circulation flow path becomes a set pressure set for the low pressure side flow path. It is a means to replenish.
[0012]
That is, according to the compression heat pump system of the second characteristic configuration, the pressure of the relatively low pressure side flow path is detected by a relatively simple and inexpensive pressure detecting means or the like, and the detected low pressure side flow path is detected. The working medium can be easily replenished to the low-pressure channel with a relatively low replenishment pressure so that the pressure becomes a predetermined set pressure. Therefore, the replenishing means can be configured simply and inexpensively.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
As is well known, in the compression heat pump system 100 shown in FIG. 1, the working medium X includes a compressor 2 (compression unit), a radiator 3 (radiation unit), an expansion valve 4 (expansion unit), and a heat absorber 5 (heat absorption unit). The working medium X absorbs heat in the heat absorber 5, and the working medium X radiates heat in the radiator 3.
[0018]
Here, the heat absorption target in the heat absorber 5 is assumed to be the atmosphere, and a gas-liquid heat exchanger is adopted as the heat absorber 5. Moreover, the heating object in the radiator 3 is hot water for hot water supply, and the radiator 3 employs a liquid-liquid heat exchanger.
[0019]
The working medium X is carbon dioxide as a natural working medium.
The state in each device will be described. In the circulation flow path 7 constituted by the pipe material connected from the heat absorber 5 to the compressor 2, the working medium X having a temperature of about 4 ° C. and a pressure of about 4 MPa flows. 2, the working medium X having a temperature of about 80 ° C. and a pressure of about 9.0 to 10 MPa circulates in the circulation flow path 8 composed of a pipe connected to the heat radiator 3. In the circulation flow path 9 constituted by the pipe material connected to the pipe, the working medium X having a temperature of about 4 ° C. and a pressure of about 9.0 to 10 MPa flows and the pipe material connected from the expansion valve 4 to the heat absorber 5. In the circulation flow path 10 constituted by the operating pressure of the compressors 2 and 20 (the discharge pressure of the working medium X) and the expansion valve 4 so that the working medium X having a temperature of about 4 ° C. and a pressure of about 4 MPa flows. Set differential pressure, etc. It has been set.
[0020]
The compressor 2 is configured as a known vane rotary compressor, and a drive shaft 21 of the compressor 2 is rotationally driven via a belt 27 to a drive shaft 26 of an engine 25 as an external rotational drive source.
[0021]
The compression heat pump system 100 is configured so that the pressure of the working medium X flowing through the predetermined portion of the circulation flow paths 7, 8, 9, and 10 becomes a set pressure set for the predetermined portion. A replenishing means 60 for replenishing the predetermined portion with the working medium X is provided. By providing the replenishing means 60, even if the high-pressure working medium X leaks through the shaft seal portion or the like of the drive shaft 21 of the compressor 2, the leaked working medium X is passed through the circulation flow path 7, A predetermined portion of 8, 9, 10 can be automatically replenished, and the pressure of the circulation flow path 7, 8, 9, 10 is maintained at a high pressure to maintain high efficiency, and the working medium X It is possible to prevent a decrease in efficiency due to leakage.
[0022]
Further, the replenishing means 60 is configured so that the pressure of the circulation passage 10 that is a part of the low-pressure side passage extending from the outlet side of the expansion valve 4 to the compressor 2 is set to the set pressure ( For example, it is configured as means for replenishing the circulation channel 10 with the working medium X, which is carbon dioxide, so as to be 4 MPa.
[0023]
Specifically, the replenishing means 60 includes a compression device 45 (compression means) that compresses the working medium X that is carbon dioxide, and a set pressure (for example, about 4 MPa) of the working fluid X compressed by the compression device 45. A reservoir 48 such as a tank that stores at a higher replenishment pressure, a supply channel 49 that guides the working medium X stored in the reservoir 48 to the circulation channel 10, and the circulation channel 10 provided in the supply channel 49. When the pressure on the side becomes less than the set pressure, the flow of the working medium X in the supply flow path 49 is allowed. Conversely, when the pressure on the circulating flow path 10 side becomes higher than the set pressure, the supply flow path 49 and a pressure regulating valve 50 for preventing the working medium X from flowing.
By such a replenishing means 60, the compression device 45, the reservoir 48, and the pressure regulating valve 49 generate and store the working medium X having a relatively low replenishment pressure, and the pressure of the circulation flow path 10 is relatively low. A simple and inexpensive configuration that can be set to the set pressure can be used.
[0024]
The compressor 45 of the replenishing means 60 has a drive shaft 46 that is rotationally driven via a belt 47 to the drive shaft 26 of the engine 25 that drives the compressor 2 on the heat pump side, and is driven by a driving force common to the compressor 2. It is configured.
[0025]
Further, the replenishing means 60 takes in the exhaust gas Y discharged from the engine 25 through the exhaust gas flow path 28, generates carbon dioxide for replenishing the circulation flow path 10 separately from the exhaust gas Y, and supplies the supply flow A carbon dioxide generating means 30 for feeding into the compression device 45 through a passage 43 is provided.
[0026]
The carbon dioxide generating means 30 brought the absorbent Z that can absorb a large amount of carbon dioxide into contact with the exhaust gas Y, and absorbed the carbon dioxide in the exhaust gas Y into the absorbent Z and the carbon dioxide. A regenerator 35 that recovers carbon dioxide by heating the absorbing liquid Z is provided, and is configured to generate carbon dioxide from the exhaust gas Y using a so-called gas absorption method.
[0027]
The carbon dioxide generating means 30 separates and generates carbon dioxide from the exhaust gas Y discharged from the engine 25 in the compression heat pump system 100 including the engine 25 as a drive source, and the generated carbon dioxide. After the carbon is compressed by the compression device 45, the circulation channel 10 can be replenished, and there is no need to separately prepare carbon dioxide for replenishment.
[0028]
As a heat source of the regenerator 35 of the carbon dioxide generating means 30, exhaust heat of the engine 25, that is, exhaust gas discharged from the engine 25, heat of cooling water, or the like can be used.
[0029]
Further, it opens when the pressure on the storage unit 48 side becomes higher than the replenishment pressure so that the pressure of carbon dioxide stored in the storage unit 48 becomes a replenishment pressure higher than the set pressure of the circulation channel 10. A pressure regulating valve 53 that releases the carbon dioxide from the reservoir 48 through the flow path 52 to the outside may be provided. Further, the carbon dioxide released through the flow path 52 can be used for other purposes such as production of solid carbon dioxide as a coolant and cultivation of agricultural products.
[0030]
[Another embodiment]
In the above embodiment, the carbon dioxide generating means 30 is configured to generate carbon dioxide from the exhaust gas Y by the gas absorption method. Separately, the carbon dioxide generating means 30 is replaced with other methods such as an adsorption method and a membrane separation method. Thus, carbon dioxide may be generated from the exhaust gas Y.
[0031]
In the above embodiment, in order to set the pressure of the circulation flow path 10 to the set pressure, the pressure adjustment valve 50 is opened and closed by pressure fluctuation on the circulation flow path 10 side, and the pressure on the circulation flow path 10 side is set to the set pressure. Although used, instead of the pressure regulating valve 50, a control valve that can be opened and closed by a control signal from a control device or the like is provided in the supply flow path 49, and based on the detection result of the pressure sensor that detects the pressure in the circulation flow path 10. The control valve provided in the supply flow path 49 may be feedback controlled to set the pressure of the circulation flow path 10 to the set pressure.
[0032]
In the above embodiment, the replenishing means 60 is configured to replenish the working medium X to the relatively low-pressure circulation flow path 10, but separately, the working medium X is also supplied to the low-pressure circulation flow path 7 and other circulation flows. The replenishing means 60 may be configured to supply to the paths 8 and 9. Further, the replenishing means 60 is configured so that the circulation channels 7, 8, 9 other than the circulation channel 10 are set to the set pressure (for example, the circulation channel 7) with respect to the circulation channels 7, 8, 9. Is about 4 MPa, and about 9 MPa for the circulation channels 8 and 9), the working medium X may be replenished to the circulation channel 10 and the other circulation channels 7, 8, 9. I do not care.
[Brief description of the drawings]
FIG. 1 is a diagram showing the configuration of a compression heat pump.
2: Compressor (compression unit)
3: Radiator (heat radiation part)
4: Expansion valve (expansion part)
5: Heat absorber (heat absorption part)
7, 8, 9, 10: Circulation passage 25: Engine 28: Exhaust gas passage 30: Carbon dioxide generating means 31: Absorber 35: Regenerator 45: Compression device (compression means)
46: drive shaft 47: belt 48: reservoir 49: supply flow path 50: pressure regulating valve 60: replenishing means 100: compression heat pump system X: working medium Y: exhaust gas Z: absorption liquid

Claims (2)

The working medium is a compression heat pump system provided with a circulation flow path that circulates in the order of the compression part, the heat dissipation part, the expansion part, and the heat absorption part,
Replenishing means for replenishing the circulation channel with the working medium so that the pressure of the working medium flowing through the predetermined region of the circulation channel becomes a set pressure set for the predetermined region; Prepared ,
The working medium is carbon dioxide, and the driving source of the compression unit is an engine.
The replenishing means includes carbon dioxide generating means for generating carbon dioxide to be replenished to the circulation flow path by separating it from exhaust gas of the engine, and is driven by a driving force of a driving source common to the compression unit, A compression heat pump system configured to include a compression unit that compresses carbon dioxide generated by a carbon dioxide generation unit .   The replenishing means is configured so that the pressure of the low-pressure side flow channel from the expansion portion to the compression portion of the circulation flow channel as the predetermined portion becomes a set pressure set for the low-pressure side flow channel. The compression heat pump system according to claim 1, which is means for replenishing the low-pressure channel with the working medium.

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