JP3576938B2 - heat pump - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heat pump that combines an ammonia refrigerant and a carbon dioxide refrigerant, and particularly when a cascade condenser is difficult to install above an evaporator, liquefied carbon dioxide (liquefied carbon dioxide) is generated by a pressure difference of carbon dioxide gas (carbon dioxide gas). Gas), and a heat pump capable of natural circulation.
[0002]
[Prior art]
Conventionally, a natural circulation type heat pump system combining an ammonia refrigerant and a carbon dioxide refrigerant has existed. In such a heat pump system, it may be difficult to install the cascade condenser above the evaporator due to the installation space, the structure of the building, noise, and the like. In this case, the natural circulation cycle, which is a feature of the natural circulation heat pump system, becomes difficult.
[0003]
[Problems to be solved by the invention]
The present invention has been made in view of the above points, and in a natural circulation type heat pump system combining an ammonia refrigerant and a carbon dioxide refrigerant, an installation space, a structure of a building, a problem such as noise, the cascade condenser from the evaporator. It is an object of the present invention to provide a heat pump that enables natural circulation even when it cannot be installed at the top.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 includes a cascade condenser, an ammonia refrigeration system, and a carbon dioxide refrigeration system. in natural circulation type heat pump device configured to row no liquid carbon dioxide heat exchange with the ammonia solution, lifting the liquefied carbon dioxide refrigerant of carbon dioxide refrigeration system by utilizing the pressure difference between the carbon dioxide gas A pumping means for liquefying and circulating is provided, the pumping means is provided with a pressurized tank, the liquefied carbon dioxide from the cascade condenser is accommodated in the pressurized tank, and the liquefied carbon dioxide is converted into ammonia via a heat exchanger. The inside of the pressurized tank is pressurized by heat exchange with ammonia liquid from a refrigeration system and heated, and the liquefied carbon dioxide in the pressurized tank is removed by the diacid. Characterized by the liquid being pumped through the surge tank provided above the direct or evaporator to the evaporator carbon refrigeration system.
[0005]
The invention according to claim 2 is provided with a cascade condenser, an ammonia refrigeration system, and a carbon dioxide refrigeration system. The carbon dioxide gas generated in the carbon dioxide refrigeration system is guided to the cascade condenser, and is interposed between the cascade condenser and the ammonia refrigeration ammonia liquid. Pumping means for pumping and circulating a liquefied carbon dioxide refrigerant in a carbon dioxide refrigeration system using a pressure difference of carbon dioxide gas in a natural circulation heat pump device configured to perform heat exchange with liquefied carbon dioxide The pumping means is provided with a liquefied carbon dioxide from a cascade condenser above the evaporator of the carbon dioxide refrigeration system, and a surge tank which can be supplied to the evaporator under natural flow is installed. The gas is cooled through a heat exchanger and decompressed, or is depressurized by suction with a suction machine, and cascaded into the surge tank using the decompression. Characterized by the liquid being pumped liquefied carbon dioxide from the condenser.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a system configuration example of a natural circulation type heat pump in which an ammonia refrigerant and a carbon dioxide refrigerant are combined according to the present invention. In FIG. 1, 1 is a compressor, 2 is a condenser, 3 is a cascade condenser, 4 is an evaporator, 5-1 and 5-2 are pressurized tanks, 6 is a surge tank, and 7 is a flow control valve. The cascade condenser 3, the evaporator 4, the pressurized tanks 5-1, 5-2, and the surge tank 6 are connected by a carbon dioxide gas refrigerant path 9 to form a carbon dioxide gas system, and the compressor 1, the condenser 2, the cascade condenser 3, and The pressurized tanks 5-1 and 5-2 are connected by an ammonia refrigerant path 10 to form an ammonia refrigerant system.
[0008]
In the heat pump having the above configuration, the liquefied carbon dioxide gas liquefied by the cascade condenser 3 alternately flows into the plurality of pressurized tanks 5-1 and 5-2 provided below through the outlet valves SV1 and SV2. Then, the internal pressure of the pressurized tanks 5-1 and 5-2 is increased to a specified pressure by a method described later. The liquefied carbon dioxide gas pressurized in the pressurized tanks 5-1 and 5-2 to a pressure higher than the liquid head differential pressure with the upper surge tank 6 flows into the surge tank 6 by opening the outlet valves SV3 and SV4. By performing the above operation alternately in the plurality of pressurized tanks 5-1 and 5-2, the carbon dioxide gas is continuously supplied to the surge tank 6, and a specified amount of liquefied carbon dioxide gas is always supplied to the surge tank 6. Can be secured.
[0009]
The liquefied carbon dioxide gas accumulated in the surge tank 6 descends due to the thermosiphon phenomenon, passes through the flow control valve 7 and enters the evaporator 4 for performing the intended cooling, where it absorbs heat, evaporates and becomes gas again. Return to the cascade capacitor 3. The ammonia liquid used for heating the liquefied carbon dioxide gas in the pressurized tanks 5-1 and 5-2 is supercooled, flows through the flow control valve 8 to the cascade condenser 3, and is used for cooling the carbon dioxide gas. Due to the supercooling of the ammonia liquid, the refrigeration capacity of the ammonia system is increased, so that the liquefied carbon dioxide gas can be pumped without lowering the cooling of the entire system.
[0010]
The liquid supply to the pressurized tanks 5-1 and 5-2 will be described using the pressurized tank 5-1 as an example. When the level of the liquefied carbon dioxide gas in the pressurized tank 5-1 decreases, the level sensor LS detects a decrease in the liquid level. The outlet valve SV3 is closed and the outlet valve SV1 is opened in response to the level sensor LS detection signal indicating a drop in the liquid level. At the same time, the pressure equalizing valve SV7 opens, and the liquefied carbon dioxide gas naturally flows down from the cascade condenser 3. When the liquefied carbon dioxide gas reaches a specified amount, the level sensor LS detects it, closes the outlet valve SV1, closes the equalizing valve SV7, and completes the liquid supply. The liquid supply to the pressurized tank 5-2 is performed in the same manner.
[0011]
The pressurization in the pressurized tanks 5-1 and 5-2 will be described using the pressurized tank 5-1 as an example. After the completion of the carbon dioxide gas supply, the ammonia supply valve SV5 is opened, and the ammonia liquid is supplied to the heat exchanger 5-1a provided in the pressurized tank 5-1. The ammonia liquid entering the heat exchanger 5-1a exchanges heat with liquefied carbon dioxide gas. At this time, since the temperature of the ammonia liquid is higher, the liquefied carbon dioxide gas is heated and pressurizes the inside of the pressurization tank 5-1. Conversely, the ammonia liquid is cooled and supplied to the cascade condenser 3 as a supercooled liquid. When the pressure in the pressurized tank 5-1 reaches the specified pressure, the ammonia supply valve SV5 is closed. When the pressure in the pressurized tank 5-1 becomes equal to or higher than a certain pressure, the relief valve RV is opened to keep the pressure within the certain pressure. The pressurization of the pressurized tank 5-2 is performed in the same manner.
[0012]
The liquid supply to the surge tank 6 will be described by taking the pressurized tank 5-1 as an example. When the liquefied carbon dioxide gas in the pressurized tank 5-2 drops below the specified amount, the outlet valve SV4 of the pressurized tank 5-2 is closed, and the outlet valve SV3 of the pressurized tank 5-1 is opened. Since the pressure in the pressurized tank 5-1 is higher than the pressure in the surge tank 6 by the liquid head difference or more, the liquefied carbon dioxide gas flows into the surge tank 6 due to the pressure difference. If the pressure in the pressurized tank 5-1 drops below the specified pressure during liquid supply, the ammonia supply valve SV5 is opened and closed to maintain the specified pressure. An equalizing pipe 11 is provided for both recovering the flash gas of carbon dioxide gas generated during the supply to the surge tank 6 and equalizing the pressure with the cascade condenser 3. The liquid supply from the pressurized tank 5-2 to the surge tank 6 is performed in the same manner.
[0013]
Next, liquid supply to the evaporator 4 will be described. The liquefied carbon dioxide gas accumulated in the surge tank 6 descends due to the thermosiphon phenomenon, enters the evaporator 4 for performing the intended cooling through the flow control valve 7, where it absorbs heat and evaporates to become a gas, and again becomes a cascade condenser. Go back to 3.
[0014]
In the ammonia system, the ammonia gas evaporated in the cascade condenser 3 is compressed in the compressor 1, and the compressed ammonia gas is condensed in the condenser 2 to become an ammonia liquid, and passes through the expansion valve 12 to the cascade condenser 3 again. Return to the refrigeration cycle.
[0015]
FIG. 2 is a diagram showing an example of a system configuration of a natural circulation type heat pump using a combination of an ammonia refrigerant and a carbon dioxide refrigerant according to the present invention. In FIG. 2, portions denoted by the same reference numerals as those in FIG. 1 indicate the same or corresponding portions, and thus description thereof will be omitted. In FIG. 2, 13 is a receiver tank, 14 is a subcooler, and 15-1 and 15-2 are surge tanks, respectively.
[0016]
When the carbon dioxide gas is cooled by the heat exchangers 15-1a and 15-2a provided in the upper surge tanks 15-1 and 15-2, the pressure in the surge tanks 15-1 and 15-2 is increased to a specified pressure. The pressure is reduced to The cooling by the heat exchangers 15-1a and 15-2a is provided by the residual heat of the ammonia refrigerator or another small capacity refrigerator. The pressure in the surge tanks 15-1 and 15-2 is reduced to the liquid head difference or more from the pressure in the lower receiver tank 13 and the inlet valves SV9 and SV10 of the surge tanks 15-1 and 15-2 are opened. The liquefied carbon dioxide gas in the receiver tank 13 flows into the surge tanks 15-1 and 15-2.
[0017]
The liquefied carbon dioxide gas accumulated in the surge tanks 15-1 and 15-2 descends due to the thermosiphon phenomenon, enters the evaporator 4 for performing intended cooling through the outlet valves SV11 and SV12, and the flow control valve 7, where heat is absorbed. -It evaporates and turns into gas, and returns to the cascade condenser 3 again. Further, a supercooler 14 is provided in the receiver tank 13 or the liquid pipe at the outlet of the receiver tank 13 to prevent the generation of the flash gas of the liquefied carbon dioxide gas which is pumped by subcooling the liquefied carbon dioxide gas. Cooling by the supercooler 14 is provided by the residual heat of the ammonia refrigerator or another small capacity refrigerator.
[0018]
By alternately performing the cooling and depressurizing operations of the two surge tanks 15-1 and 15-2, the liquefied carbon dioxide gas is continuously supplied to the surge tanks 15-1 and 15-2. A specified amount of liquefied carbon dioxide gas can always be ensured in 1, 15-2. Further, the cooling by the heat exchangers 15-1a and 15-2a in the surge tanks 15-1 and 15-2 and the cooling of the liquefied carbon dioxide gas by the supercooler 14 are performed by the residual heat of the ammonia refrigerator or other relatively small capacity. Since it is covered by a refrigerator or the like, a power load required for pumping is small, but a carbon dioxide gas circulation system is established.
[0019]
FIG. 3 is a diagram showing an example of a system configuration of a natural circulation type heat pump using a combination of an ammonia refrigerant and a carbon dioxide refrigerant according to the present invention, in which a pressure difference is applied by suction decompression by a suction machine (pump, fan, compressor, etc.). This is a pumping system. In FIG. 3, portions denoted by the same reference numerals as those in FIGS. 1 and 2 indicate the same or corresponding portions, and thus description thereof will be omitted. In FIG. 3, reference numeral 16 denotes a suction machine (pump, fan, compressor, etc.).
[0020]
A suction device 16 is connected to the upper surge tanks 15-1 and 15-2 via outlet valves SV14 and SV13, respectively, and the carbon dioxide gas in the surge tanks 15-1 and 15-2 is sucked, whereby the surge is discharged. The pressure inside the tanks 15-1 and 15-2 is reduced to a specified pressure. The pressure in the surge tanks 15-1 and 15-2 is reduced to the liquid head difference or more from the pressure in the lower receiver tank 13 and the inlet valves SV9 and SV10 of the surge tanks 15-1 and 15-2 are opened. The liquefied carbon dioxide gas in the receiver tank 13 flows into the surge tanks 15-1 and 15-2.
[0021]
The carbon dioxide gas sucked and discharged by the suction device 16 is condensed and liquefied by the cascade condenser 3 together with the carbon dioxide gas absorbed and evaporated by the evaporator 4. Further, a supercooler 14 is provided in the receiver tank 13 or the liquid pipe at the outlet of the receiver tank 13 to prevent the generation of the flash gas of the liquefied carbon dioxide gas which is pumped by subcooling the liquefied carbon dioxide gas.
[0022]
As described above, the suction tanks 16 are connected to the surge tanks 15-1 and 15-2, respectively, and the suction operation of the suction tanks 16 is alternately performed by the two surge tanks 15-1 and 15-2, so that the liquefaction is performed. The carbon dioxide gas is continuously supplied to the surge tanks 15-1 and 15-2, and a specified amount of liquefied carbon dioxide gas can always be secured in the surge tanks 15-1 and 15-2.
[0023]
FIG. 4 is a diagram showing an example of a system configuration of a natural circulation type heat pump combining an ammonia refrigerant and a carbon dioxide refrigerant according to the present invention. This heat pump system is a system in which a natural circulation heat pump system can be used as a cycle by combining an ammonia refrigerant and a carbon dioxide refrigerant even when it is difficult to install an upper surge tank. That is, the pressure corresponding to the head generated between the upper surge tank and the evaporator is covered by the pressure generated in the pressurized tank to establish the carbon dioxide gas circulation system. In FIG. 4, portions denoted by the same reference numerals as those in FIGS. 1, 2, and 3 indicate the same or corresponding portions, and thus description thereof will be omitted.
[0024]
The method of pressurizing the pressurized tanks 5-1 and 5-2 is the same as that shown in FIG. The liquefied carbon dioxide gas pressurized to the specified pressure in the pressurized tank 5-1 or the pressurized tank 5-2 is opened by opening the outlet valve SV3 or SV4 of the pressurized tank 5-1 or the pressurized 5-2. The evaporator 4 enters the evaporator 4 for performing desired cooling through the flow control valve 7, where it absorbs heat and evaporates to become a gas and returns to the cascade condenser 3 again. The liquefied carbon dioxide gas can be continuously supplied to the evaporator 4 by alternately performing the above operation in the pressurized tanks 5-1 and 5-2 provided with a plurality (two in the figure). The heating of the pressurized tanks 5-1 and 5-2 uses an ammonia solution, and the ammonia solution is supercooled and flows to the cascade condenser 3, and is used for cooling the carbon dioxide gas as in the case of FIG. .
[0025]
【The invention's effect】
As described above, according to the invention described in each claim, the following excellent effects can be obtained.
[0026]
According to the first aspect of the present invention, the liquid pumping means is provided with a pressurized tank, the pressurized tank contains liquefied carbon dioxide from a cascade condenser, and the liquefied carbon dioxide is converted into ammonia via a heat exchanger. The heat is exchanged with the ammonia liquid from the refrigeration system to heat and pressurize the pressurized tank, and the liquefied carbon dioxide in the pressurized tank is directly or directly supplied to the evaporator of the carbon dioxide refrigeration system. and then, is liquid being pumped through the surge tank provided above, by using the subcooling heat like ammonia condensate ammonia refrigeration system can generate an pressure difference of carbon dioxide gas, the entire system It is possible to pump liquefied carbon dioxide in the carbon dioxide refrigeration system without lowering the cooling efficiency of the cascade, and the cascade condenser cannot be installed above the evaporator due to problems such as installation space, building structure, noise, etc. Also in the case, it is possible to provide a heat pump that can be natural circulation.
[0028]
According to the second aspect of the present invention, the pumping means accommodates liquefied carbon dioxide from the cascade condenser above the evaporator of the carbon dioxide refrigeration system, and a surge tank capable of supplying the evaporator under natural flow is installed. Then, the carbon dioxide gas in the surge tank is cooled and depressurized through a heat exchanger, or decompressed by suction with a suction machine, and liquefied carbon dioxide is pumped from a cascade condenser into the surge tank using the depressurization. Because the liquid is configured to be cooled, the residual heat of an ammonia refrigerator or other relatively small-capacity refrigerator or the like is used for cooling the carbon dioxide in the surge tank, or a relatively small volume is used for sucking the carbon dioxide. by utilizing the suction device, the carbon dioxide refrigeration system of the liquefied carbon dioxide can be liquid being pumped and Do Ri of installation space, the structure of the building, the cascade condenser to above the evaporator in such noise problems Even if you can not location, it is possible to provide a heat pump that can be natural circulation.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a system configuration of a natural circulation heat pump combining an ammonia refrigerant and a carbon dioxide refrigerant according to the present invention.
FIG. 2 is a diagram showing an example of a system configuration of a natural circulation heat pump combining an ammonia refrigerant and a carbon dioxide refrigerant according to the present invention.
FIG. 3 is a diagram showing a system configuration example of a natural circulation type heat pump combining an ammonia refrigerant and a carbon dioxide refrigerant according to the present invention.
FIG. 4 is a diagram showing an example of a system configuration of a natural circulation type heat pump combining an ammonia refrigerant and a carbon dioxide refrigerant according to the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 compressor 2 condenser 3 cascade condenser 4 evaporator 5-1 pressurized tank 5-2 pressurized tank 6 surge tank 7 flow control valve 8 flow control valve 9 carbon dioxide gas refrigerant path 10 ammonia refrigerant path 11 equalizing pipe 12 expansion valve 13 Receiver tank 14 Subcooler 15-1 Surge tank 15-2 Surge tank 16 Suction machine SV1 Outlet valve SV2 Outlet valve SV3 Outlet valve SV4 Outlet valve SV5 Ammonia supply valve SV6 Ammonia supply valve SV7 Equalization valve SV8 Equalization valve SV9 Inlet valve SV10 Inlet valve RV Relief valve LS Level sensor

Claims (2)

Cascade condenser, ammonia refrigeration system, comprising a carbon dioxide refrigeration system, the carbon dioxide gas generated in the carbon dioxide refrigeration system leads to the cascade condenser, deeds liquefied carbon dioxide heat exchange with the ammonia solution of the ammonia refrigeration system In a natural circulation heat pump device configured to
A pumping means is provided for pumping and circulating a liquefied carbon dioxide refrigerant of a carbon dioxide refrigeration system using a pressure difference of carbon dioxide gas ,
The liquid pumping means includes a pressurized tank, the pressurized tank contains liquefied carbon dioxide from the cascade condenser, and the liquefied carbon dioxide is exchanged with an ammonia liquid from the ammonia refrigeration system via a heat exchanger. A heat tank is provided to heat and pressurize the inside of the pressurized tank and pressurize the liquefied carbon dioxide in the pressurized tank directly or above the evaporator of the carbon dioxide refrigeration system. A heat pump characterized in that the liquid is pumped through a heat pump. A cascade condenser, an ammonia refrigeration system, a carbon dioxide refrigeration system is provided. In a natural circulation heat pump device configured to
A pumping means is provided for pumping and circulating a liquefied carbon dioxide refrigerant of a carbon dioxide refrigeration system using a pressure difference of carbon dioxide gas,
The pumping means accommodates the liquefied carbon dioxide from the cascade condenser above the evaporator of the carbon dioxide refrigeration system, and installs a surge tank capable of supplying the evaporator under natural flow. The gas is cooled and depressurized through a heat exchanger or depressurized by suction with a suction device, and liquefied carbon dioxide is pumped from the cascade condenser into the surge tank using the depressurization. Heat pump.

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