CN210772852U - Transcritical carbon dioxide refrigerating device - Google Patents
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- CN210772852U CN210772852U CN201921903379.1U CN201921903379U CN210772852U CN 210772852 U CN210772852 U CN 210772852U CN 201921903379 U CN201921903379 U CN 201921903379U CN 210772852 U CN210772852 U CN 210772852U
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Abstract
The utility model discloses a transcritical carbon dioxide refrigerating plant, including first compressor, first gas cooler, second compressor, second gas cooler, inside regenerator, expander and evaporating pot, wherein: the pressure increasing end of the expander is connected with the first compressor and/or the second compressor, and the expansion end of the expander is connected with the evaporating tank through a pipeline; further comprising: a pressure stabilizing tank arranged between the expansion end of the expansion machine and the evaporating pot, and a liquid storage pot arranged between the evaporating pot and the low-pressure side of the internal heat regenerator. The utility model discloses a transcritical carbon dioxide refrigerating plant utilizes the expander to retrieve and export mechanical energy and drive the compressor and make it accomplish the compression to use two compressors to improve supercritical carbon dioxide's compressibility and use two gas cooler and inside regenerator to cool off carbon dioxide gas, in order to improve carbon dioxide's circulation efficiency.
Description
Technical Field
The utility model relates to a refrigeration technology field especially relates to a transcritical carbon dioxide refrigerating plant.
Background
The existing refrigerant has adverse effect on the environment, mainly expressed in the damage and generation of the ozone layerThe greenhouse effect. The ozone layer destruction and the greenhouse effect are expressed in that the ozone content is continuously reduced and the concentration of greenhouse gases is continuously increased, which can have great influence on the living environment of human beings and even have serious consequences. And CO2As a natural refrigerant, the natural refrigerant is a safe choice in the technical field of refrigeration, due to CO2Are considered to be the most potential long-term substitutes for CFCs, HCFCs and HFCs. Because of natural working medium CO2With the advantages of good environmental protection characteristic, excellent heat transfer characteristic, quite large refrigerating capacity per unit volume and the like, the former international society of refrigeration society, G.Lorentzen, considers carbon dioxide as an irreplaceable refrigerating working medium, and proposes a transcritical cycle theory to point out that the carbon dioxide is expected to play an important role in the fields of automobile air conditioners and heat pumps.
Patent WO2004072567a2 discloses a supercritical pressure control of a vapour compression system, the refrigerant circulating through the vapour compression system comprising a compressor, a gas cooler, an expansion device and an evaporator, preferably carbon dioxide being used as refrigerant. The expansion device is a work recovery device that extracts energy from the expansion process and is connected to a fluid pumping device that cools the refrigerant flowing through the gas cooler. The fluid pumping device pumps fluid through the gas cooler at a flow rate related to the amount of energy extracted from the expansion process, but suffers from the disadvantages of single stage compression expansion, low energy efficiency, and low refrigeration capacity.
Patent CN105371516A discloses a carbon dioxide two-stage combined cooling and heating system, which includes a carbon dioxide subcritical compressor, a carbon dioxide transcritical compressor, a first oil separator, a first condenser, a first expander, a second oil separator, a second condenser, a second expander, a maintenance system, a liquid storage tank, a first gas-liquid separator and a second gas-liquid separator, but it has the defect that more energy is converted into heat and the refrigeration energy efficiency is low.
For another example, CN 106196685A discloses a transcritical carbon dioxide refrigeration system, which adopts an integrated expansion-compressor, a double-cylinder simultaneous compression and a primary expansion for two throttling ways, so as to improve the refrigeration performance of the transcritical carbon dioxide refrigeration system, and adopts an integrated expansion-compressor, wherein the expander is connected with the compressor through a shaft, and the expansion work recovered by the expander can be used as a part of the compression work of the compressor, thereby reducing the power consumption of the compressor. But the defects of single-stage compression, large pressure difference before and after compression, low energy efficiency and small refrigerating capacity also exist.
In summary, it is necessary to develop a refrigeration apparatus that is environmentally friendly and has high refrigeration cycle efficiency, in view of the defects of low refrigeration efficiency and small refrigeration capacity commonly found in WO2004072567a2, CN105371516A and CN 106196685A in the related art.
SUMMERY OF THE UTILITY MODEL
The utility model discloses the technical problem that will solve is: aiming at the defects in the prior art, the transcritical carbon dioxide refrigerating device which is environment-friendly, high in refrigerating cycle efficiency and low in production cost is provided.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
the utility model provides a transcritical carbon dioxide refrigerating plant, including first compressor, first gas cooler, second compressor, second gas cooler, inside regenerator, expander and evaporating pot, wherein:
the low-pressure side of the internal heat regenerator is connected with the first gas cooler through the first compressor by a pipeline and is used for preliminarily compressing the superheated carbon dioxide steam flowing through the low-pressure side of the internal heat regenerator into subcritical carbon dioxide and preliminarily cooling the carbon dioxide steam by the first gas cooler;
the first gas cooler is connected with the high-pressure side of the internal heat regenerator through the second compressor and the second gas cooler in sequence through pipelines, and is used for secondarily compressing the primarily cooled subcritical carbon dioxide into supercritical carbon dioxide and carrying out secondary cooling through the second gas cooler;
the first compressor is connected with the gas cooler through a pipeline, and the high-temperature low-pressure carbon dioxide gas subjected to heat regeneration at the high-pressure side of the internal heat regenerator is compressed and cooled into supercritical carbon dioxide through the compressor and the gas cooler in sequence;
the gas cooler is connected with the expansion machine through the internal heat regenerator through a pipeline, so that the supercritical carbon dioxide is further cooled by the internal heat regenerator and then throttled into low-temperature and low-pressure subcritical carbon dioxide by the expansion machine;
an exhaust port of the expansion machine is connected with the evaporation tank through a pipeline, the critical carbon dioxide in the low-temperature and low-pressure state cools the refrigerant outside the evaporation tank, and the refrigerant is evaporated into the carbon dioxide gas in the high-temperature and low-pressure state; and
the evaporation tank is connected with the first compressor through a pipeline through the low-pressure side of the internal heat regenerator, so that the high-temperature low-pressure carbon dioxide gas absorbs the heat of the high-pressure side of the internal heat regenerator and then is converted into superheated steam to enter the first compressor for cyclic utilization.
Further, in the transcritical carbon dioxide refrigerating device, an output shaft of the expander is connected with the first compressor and/or the second compressor, and the expander recovers the expansion function of the carbon dioxide and outputs mechanical energy to the first compressor and/or the second compressor.
Further, the transcritical carbon dioxide refrigeration apparatus further includes:
a surge tank disposed on a pipe between an exhaust port of the expander and the evaporation tank to balance a pressure and a flow rate of the subcritical carbon dioxide before entering the evaporation tank.
Further preferably, the transcritical carbon dioxide refrigeration apparatus further includes:
and the flowmeter is arranged on a pipeline between the pressure stabilizing tank and the evaporating tank.
Further preferably, in the transcritical carbon dioxide refrigerating device, the expander is connected with the evaporating tank through the pressure stabilizing tank and a flow meter by a pipeline so as to throttle the supercritical carbon dioxide to the low-temperature subcritical state.
Further, the transcritical carbon dioxide refrigeration apparatus further includes:
and the liquid storage tank is arranged on a pipeline between the evaporation tank and the low-pressure side of the internal heat regenerator to separate carbon dioxide liquid and lubricating oil in the high-temperature low-pressure carbon dioxide gas.
Further, in the transcritical carbon dioxide refrigerating device, the first compressor is a centrifugal refrigerating compressor for compressing carbon dioxide into subcritical carbon dioxide.
Further, in the transcritical carbon dioxide refrigeration device, the second compressor is a piston type refrigeration compressor for compressing the subcritical carbon dioxide into the supercritical carbon dioxide.
Further, in the transcritical carbon dioxide refrigerating device, heat radiation fans are arranged above the first gas cooler, the second gas cooler and the evaporating tank.
Further, in the transcritical carbon dioxide refrigerating device, a refrigerant leakage sensor is arranged on a pipeline between the internal heat regenerator and the first compressor.
Further, in the transcritical carbon dioxide refrigerating device, the refrigerant is water, antifreeze, oil or air.
The above technical scheme is adopted in the utility model, compared with the prior art, following technological effect has:
(1) carbon dioxide is adopted as the refrigerant, is harmless to the environment, does not destroy the ozone layer, has the advantages of good chemical stability, non-combustibility, safety, no toxicity, no odor, large latent heat of evaporation, good fluidity and heat transfer performance and the like, has larger cooling amplitude when expanding and absorbing heat, and is an ideal refrigerant;
(2) the expansion machine is used for replacing a throttling valve, mechanical energy is recovered and output by the expansion machine to drive the compressor to complete compression, the double compressors are used for improving the compression performance of the supercritical carbon dioxide, and a double-gas cooler and an internal heat regenerator are used for cooling the carbon dioxide gas so as to improve the circulating energy efficiency of the carbon dioxide;
(3) a pressure stabilizing tank is arranged behind the expansion machine, the expansion machine throttles the cooled supercritical carbon dioxide gas to a low-temperature low-pressure wet saturated steam state, the pressure and the flow rate of the supercritical carbon dioxide gas are stabilized by the pressure stabilizing tank, the carbon dioxide entering the evaporator is ensured to be uniform and stable, and a mass flowmeter is connected between the pressure stabilizing tank and the evaporator, so that the mass and the flow rate of the carbon dioxide entering the evaporator are detected and controlled in real time;
(4) the liquid storage tank is arranged at the outlet of the evaporator to prevent the liquid impact of the compressor and facilitate the oil return of the compressor, the evaporator is prevented from being evaporated to dryness when the expansion machine is adjusted, the internal volume of the system is increased, and the overhigh pressure in the system when the system idles at high ambient temperature is avoided.
Drawings
FIG. 1 is a process flow diagram of a transcritical carbon dioxide refrigeration unit of the present invention;
fig. 2 is a schematic structural diagram of a transcritical carbon dioxide refrigeration device of the present invention;
fig. 3 is a schematic diagram of an electric control system of a transcritical carbon dioxide refrigeration device of the present invention;
FIG. 4 is a T-S diagram of a secondary cycle in a transcritical carbon dioxide chiller according to the present invention;
wherein the reference symbols are:
1-a first compressor, 2-a first gas cooler, 3-a second compressor, 4-a second gas cooler, 5-an internal heat regenerator, 6-an expander, 7-a surge tank, 8-a flow meter, 9-an evaporator, 10-a liquid storage tank, 11-a first pressure sensor, 12-a first temperature sensor, 13-a first radiator fan, 14-a second temperature sensor, 15-a second pressure sensor, 16-a third temperature sensor, 17-a second radiator fan, 18-a first filter, 19-a fourth temperature sensor, 20-a fifth temperature sensor, 21-a first safety valve, 22-a second filter, 23-a third pressure sensor, 24-a sixth temperature sensor, 25-a first stop valve, 26-a third radiator fan, 27-a second stop valve, 28-a seventh temperature sensor, 29-a fourth pressure sensor, 30-a second relief valve, 31-a refrigerant leakage sensor.
Detailed Description
The present invention will be described in detail and specifically with reference to specific embodiments so as to provide a better understanding of the present invention, but the following embodiments do not limit the scope of the present invention.
Example 1
Referring to fig. 1, the embodiment provides a transcritical carbon dioxide refrigeration device, which includes a first compressor 1, a first gas cooler 2, a second compressor 3, a second gas cooler 4, an internal heat regenerator 5, an expander 6, an evaporator 9 and a liquid storage tank 10.
As shown in fig. 1, the low-pressure side of the internal regenerator 5 is connected to the first gas cooler 2 through the first compressor 1 by a pipeline, and is used for preliminarily compressing the superheated carbon dioxide vapor flowing through the low-pressure side of the internal regenerator 5 into subcritical carbon dioxide and performing preliminary temperature reduction through the first gas cooler 2; first gas cooler 2 passes through in proper order through the pipeline second compressor 3, second gas cooler 4 are connected the high pressure side of inside regenerator 5 for the subcritical carbon dioxide secondary compression after tentatively cooling is supercritical carbon dioxide, and passes through second gas cooler 4 carries out the secondary cooling.
As shown in fig. 1, the first compressor 1 is connected to the gas cooler through a pipeline, and the high-temperature low-pressure carbon dioxide gas reheated at the high-pressure side of the internal reheater 5 is compressed and cooled into supercritical carbon dioxide by the compressor and the gas cooler in sequence; the gas cooler is connected with the expansion machine 6 through the internal heat regenerator 5 through a pipeline, so that the supercritical carbon dioxide is further cooled by the internal heat regenerator 5 and then throttled into low-temperature and low-pressure subcritical carbon dioxide by the expansion machine 6.
As shown in fig. 1, an exhaust port of the expander 6 is connected to the evaporator 9 through a pipe, and the refrigerant outside the evaporator 9 is cooled by the low-temperature and low-pressure critical carbon dioxide, and is evaporated into the high-temperature and low-pressure carbon dioxide gas; and the evaporation tank 9 is connected with the first compressor through a pipeline at the low-pressure side of the internal heat regenerator 5, so that the high-temperature low-pressure carbon dioxide gas absorbs the heat at the high-pressure side of the internal heat regenerator 5 and then is converted into superheated steam to enter the first compressor for cyclic utilization.
In the present embodiment, the output shaft of the expander 6 is connected to the first compressor 1 and/or the second compressor 3, so as to mechanically transmit the expansion function of the carbon dioxide collected by the expander 6 to the first compressor 1 and/or the second compressor 3.
In this embodiment, as shown in fig. 1, the transcritical carbon dioxide refrigeration apparatus further includes: a surge tank 7, the surge tank 7 being disposed between an exhaust port of the expander 6 and the evaporation tank 9 to balance the pressure and flow rate of the subcritical carbon dioxide before entering the evaporation tank 9. And a flow meter 8 is provided on a pipe between the surge tank 7 and the evaporator 9, and the flow meter 8 is used for detecting and controlling the flow rate of the refrigerant of the system.
In this embodiment, as shown in fig. 1, the transcritical carbon dioxide refrigeration apparatus further includes: and the liquid storage tank 10 is arranged between the evaporation tank 9 and the low-pressure side of the internal heat regenerator 5, so that the liquid state of carbon dioxide and lubricating oil in the high-temperature low-pressure carbon dioxide gas are separated. The liquid storage tank 10 is arranged at the outlet of the evaporator 9, so that liquid impact of the compressor 1 is prevented, oil return of the compressor 1 is facilitated, the evaporator 9 is prevented from being evaporated to dryness when the expansion machine 6 is adjusted, the internal volume of the system is increased, and overhigh pressure in the system when idling at high ambient temperature is avoided; the low-pressure saturated vapor from the liquid storage tank 10 enters the low-pressure side channel of the internal heat regenerator 5, and becomes superheated vapor after absorbing the heat of the supercritical fluid in the high-pressure side channel, and then enters the compressor 1 for boosting, and the cycle is completed in cycles.
Example 1
Referring to fig. 1, the present embodiment provides a transcritical carbon dioxide refrigeration method based on the refrigeration apparatus described in the above embodiment 1, which includes the following steps:
(1) after the superheated carbon dioxide steam flowing through the low-pressure side of the internal heat regenerator is pressurized by the first compressor 1 for primary compression treatment, the superheated carbon dioxide steam is adoptedThe first gas cooler 2 performs primary cooling treatment; specifically, the low-pressure superheated carbon dioxide vapor is compressed to a subcritical state (temperature T) in the first compressor 11Pressure P1) Then enters the first gas cooler 1 to be cooled by the cooling medium (temperature T)2)；
(2) After the subcritical carbon dioxide which is subjected to primary temperature reduction and cooling in the first gas cooler 1 is pressurized by the second compressor 2 for secondary compression treatment, the second gas cooler 4 is adopted for secondary cooling treatment; CO after leaving the first gas cooler 22The gas is compressed to a supercritical state (temperature T) in the second compressor 33Pressure P2) The inlet gas second body cooler 4 is subsequently cooled by the cooling medium (temperature T)3)；
(3) The high-pressure supercritical carbon dioxide after the secondary temperature reduction and cooling of the second gas cooler 4 is cooled again through the high-pressure side of the internal heat regenerator 5 and is further cooled (temperature T)4) To improve the circulation efficiency of the trans-critical carbon dioxide; cooling, feeding into expander 6, throttling, and reducing pressure (temperature T5, pressure P)3) Is low temperature subcritical carbon dioxide;
(4) the temperature of the expanded gas is reduced, part of the gas is liquefied, wet steam is fed into the evaporator 9 from the pressure stabilizing tank 7 after the pressure and the flow rate are stable, evaporation and vaporization are carried out, the uniformity and the stability of the refrigerant entering the evaporator 9 are improved through the pressure stabilizing tank 7, the refrigerant absorbs heat and is converted into high-temperature low-pressure carbon dioxide gas, and meanwhile, the refrigerant taken out of the evaporator 9 is cooled;
(5) and sending the evaporated high-temperature low-pressure carbon dioxide gas to the low-pressure side of the internal heat regenerator 5, absorbing the heat of the high-pressure side of the internal heat regenerator 5, converting the carbon dioxide gas into superheated carbon dioxide steam, and sending the superheated carbon dioxide steam to the first compressor 1 for boosting and recycling.
In the embodiment, the adopted refrigerant is transcritical carbon dioxide, the carbon dioxide is a refrigerant, the refrigerant is harmless to the environment and does not damage the ozone layer, meanwhile, the carbon dioxide also has the advantages of good chemical stability, non-combustibility, safety, no toxicity, no odor, large evaporation latent heat, good fluidity and heat transfer performance and the like, and has larger cooling amplitude when expanding and absorbing heat, thereby being an ideal refrigerant.
In the present embodiment, as shown in fig. 1, the first compressor 1 compresses carbon dioxide into subcritical carbon dioxide in step (1). In the step (2), the second compressor 2 compresses the subcritical carbon dioxide into supercritical carbon dioxide. In the step (3), the expansion machine 6 throttles the supercritical carbon dioxide to a low-temperature subcritical state, that is, the carbon dioxide is in the low-temperature subcritical state after being throttled by the expansion machine 6, and then enters the evaporator 9 for evaporation and heat absorption.
In this embodiment, the first compressor 1 is a centrifugal refrigeration compressor, the second compressor 2 is a piston refrigeration compressor, a two-stage compressor is used to improve the cycle performance of the transcritical carbon dioxide, the carbon dioxide is compressed to a subcritical state by the first compressor 1, and the carbon dioxide is compressed to a supercritical state by the second compressor 3, so as to improve the cooling efficiency of the transcritical carbon dioxide.
In the present embodiment, the expander 6 recovers the expansion work of the carbon dioxide in the step (3) and outputs mechanical energy to the first compressor 1 and/or the second compressor 3, that is, the power converted by the expander 6 is provided to the low-pressure chamber first compressor 1 or to the second compressor 2, and the shortage is supplemented by the motor. Preferably, as shown in fig. 1, the expander 6 recovers the expansion work of the carbon dioxide and outputs mechanical energy to the first compressor 1, and the expander 6 recovers the expansion work and outputs mechanical energy to drive the compressor 1 to complete compression.
In this embodiment, the refrigerant in step (4) is water, antifreeze, oil or air. Preferably, when the air is selected as the refrigerant, the air conditioning function can be realized, the exchange of indoor air and outdoor air can be realized while heat exchange is carried out, and the air of the working environment is kept fresh.
In this embodiment, as shown in fig. 1, in step (5), the evaporated high-temperature low-pressure carbon dioxide gas firstly enters the liquid storage tank 10, and is separated from a small amount of liquid carbon dioxide and lubricating oil by the liquid storage tank 10 and then is sent to the low-pressure side of the internal heat regenerator 5, so as to ensure that the dry saturated steam enters the suction chamber of the compressor.
Example 3
Referring to FIG. 2, another embodiment for transcritical CO is provided2Refrigeration control device for transcritical CO2The refrigeration control device is based on the refrigeration device described in the above embodiment 1, and is added with temperature sensors 12, 14, 16, 19, 20, 24, 28 and pressure sensors 12, 15, 23, 29; a first filter 18, a second filter 22, a first stop valve 25, a second stop valve 27, a first relief valve 21, a second relief valve 30, a system leak detection device 31, and heat radiation fans 13, 17, 26 provided on the first gas cooler 2 and the second gas cooler 4 and the evaporator 9 are also added to the circulating refrigeration control system.
In the present embodiment, as shown in fig. 2, the temperature sensors 12, 14, 16, 19, 20, 24, 28 and the pressure sensors 12, 15, 23, 29 are used for collecting the temperature and pressure values of each part, and the control system performs judgment to control the operation conditions of each part. The control device is composed of a refrigeration circuit shutoff valve group of the shutoff valves 25 and 27 and the safety valves 21 and 30, wherein the shutoff valves 25 and 27 are used for controlling the on-off state of the circulation system; the safety valves 21 and 30 are used for controlling the pressure safety condition of the circulation system, and when the pressure exceeds a certain value, the safety valves 21 and 30 are automatically opened to ensure the safety of the system.
In this embodiment, as shown in FIG. 2, the method is used for transcritical CO2A refrigerant leakage sensor 31 for detecting a system leakage in the refrigeration control apparatus, which outputs a refrigerant leakage detection signal indicating that the refrigerant leakage is detected, when the refrigerant leakage is detected; the flow of the refrigerant is cut off by a refrigeration circuit cut-off valve group; the radiator fans 13, 17, 26 are used to adjust the flow rate of the air flow over the gas coolers 2, 4 and the evaporator 9 to adjust the magnitude of the cooling rate. The filters 18, 20 are used to keep the refrigerant in the circulation system clean to protect the safe and proper operation of the equipment.
Example 4
Referring to fig. 3, in this embodiment, a control system of the refrigeration control device according to embodiment 3 is provided, where the sensors of pressure, temperature, and the like transmit data detected by each part to the control system in real time, and the control system changes operation parameters of each part, such as a compressor, a fan, an expander, and the like, according to the data of each part to control an operation condition of the refrigeration cycle system.
When the refrigeration system is started, the first stop valve 25 and the second stop valve 27 are opened firstly, and the refrigeration cycle system is in a passage state; the system leak detection device 31 firstly checks whether the refrigerant leaks, and if no leakage is judged, the first compressor 1 and the second compressor 3, and the first gas refrigerator 2 and the second gas refrigerator 4 are started, and at the moment, the power of the first compressor 1 is mainly provided by a motor. Then the expander works to provide power for the first compressor 1, and the refrigeration system starts to operate circularly; when the pressure and temperature of each part gradually enter the designated working pressure and temperature, the blower 26 on the evaporator 9 starts to rotate, the evaporator 9 starts to evaporate and absorb heat, and the whole system enters a normal working cycle state.
Energy efficiency theoretical calculation under this embodiment:
FIG. 4 shows a T-S diagram of a sub-cycle. This example was analyzed using a simplified model, with the following assumptions:
a. the whole system is under the condition of steady state and steady flow;
b. neither compressors nor expanders are ideal; the compressor efficiency follows a compressor efficiency formula;
c. the recovery work of the expander is equal to the compression work of the first compressor, namely the magnitude of the expansion work determines the input power of the auxiliary compressor;
d、CO2the outlet temperature of the gas cooler is related to the efficiency of the heat exchanger and the ambient temperature. In summer, the typical ambient temperature is higher than CO2Critical point temperature of (1), gas cooler outlet temperature is set to Tx(40℃～50℃)；
e. The system design evaporation temperature is TyIn the analysis process, the evaporation temperature is in the range of-35 ℃ to 12 ℃;
f. suppose CO2The superheat degree of the inlet of a system compressor is zero；
g. The operating pressure at the high pressure side is the optimal pressure of 10MPa for the system;
h. suppose the system design capacity is X.
The actual specific enthalpy values of the compressor inlet state points 1 and 3 are set to h1,h3；h1＝f(S1,T1,P1)；h3＝f(S3,T3,P3)；
The actual specific enthalpy values for the compressor outlet state points 2 and 4 are set to h2,h4；h2＝η1*f(S2,T2,P2)；h4＝η2*f(S4,T4,P4)。
η in the formula1，η2Compression efficiencies of the first compressor and the second compressor, respectively;
the actual specific enthalpy values for the expander inlet and outlet condition points 5 and 6 are set as: h is5,h6；h5＝f(S5,T5,P5)；h6＝η*f(S6,T6,P6)；
η in the above formula is the expansion efficiency of the expander;
the power consumption of the first compressor and the second compressor is respectively as follows: w1＝Mp*(h2-h1)，W2＝Mp*(h4-h3)；
In the above formula MpAn expansion mass for compression by a compressor;
the conversion work of the expander is: w3＝Mp*(h5-h6)
The extra power consumption of the compressor is: w ═ W1+W2-W3
The refrigerating capacity is as follows: q ═ Mp*(h6-h1)
The refrigeration coefficient is as follows: EER ═ Q/W
When the power of the first compressor is supplied exclusively by the expander, i.e. W1＝W3；
Therefore EER ═ Q-W2
From h4-h1＝W1+W2When W is1The larger the size, W2The smaller, i.e. the more power the expander converts, the higher the refrigeration coefficient EER.
To sum up, the utility model provides a transcritical carbon dioxide refrigerating plant, it replaces the choke valve with the expander, utilizes the expander to retrieve and export mechanical energy and drive first compressor and make it accomplish the compression to use two compressors to improve supercritical carbon dioxide's compressibility and use two gas cooler and inside regenerator to cool off carbon dioxide gas, can effectively improve carbon dioxide's circulation efficiency. By adopting the transcritical carbon dioxide refrigerating device, the refrigerating coefficient EER can reach more than 3.2, and can reach the first-level and second-level energy efficiency levels of the national standard.
The above detailed description of the embodiments of the present invention is only for exemplary purposes, and the present invention is not limited to the above described embodiments. Any equivalent modifications and substitutions to those skilled in the art are also within the scope of the present invention. Accordingly, variations and modifications in equivalents may be made without departing from the spirit and scope of the invention, which is intended to be covered by the following claims.
Claims (10)
1. A transcritical carbon dioxide refrigeration unit comprising a first compressor, a first gas cooler, a second compressor, a second gas cooler, an internal regenerator, an expander and an evaporator tank, wherein:
the low-pressure side of the internal heat regenerator is connected with the first gas cooler through the first compressor by a pipeline and is used for preliminarily compressing the superheated carbon dioxide steam flowing through the low-pressure side of the internal heat regenerator into subcritical carbon dioxide and preliminarily cooling the carbon dioxide steam by the first gas cooler;
the first gas cooler is connected with the high-pressure side of the internal heat regenerator through the second compressor and the second gas cooler in sequence through pipelines, and is used for secondarily compressing the primarily cooled subcritical carbon dioxide into supercritical carbon dioxide and carrying out secondary cooling through the second gas cooler;
the first compressor is connected with the gas cooler through a pipeline, and the high-temperature low-pressure carbon dioxide gas subjected to heat regeneration by the high-pressure side of the internal heat regenerator is compressed and cooled into supercritical carbon dioxide by the compressor and the gas cooler in sequence;
the gas cooler is connected with the expansion machine through the internal heat regenerator through a pipeline, so that the supercritical carbon dioxide is further cooled by the internal heat regenerator and then throttled into low-temperature and low-pressure subcritical carbon dioxide by the expansion machine;
an exhaust port of the expansion machine is connected with the evaporation tank through a pipeline, the critical carbon dioxide in the low-temperature and low-pressure state cools the refrigerant outside the evaporation tank, and the refrigerant is evaporated into the carbon dioxide gas in the high-temperature and low-pressure state; and
the evaporation tank is connected with the first compressor through a pipeline through the low-pressure side of the internal heat regenerator, so that the high-temperature low-pressure carbon dioxide gas absorbs the heat of the high-pressure side of the internal heat regenerator and then is converted into superheated steam to enter the first compressor for cyclic utilization.
2. The transcritical carbon dioxide refrigeration unit according to claim 1 wherein the output shaft of the expander is connected to the first and/or second compressor, the expander recovering the expansion work of the carbon dioxide and outputting mechanical energy to the first and/or second compressor.
3. The transcritical carbon dioxide refrigeration unit according to claim 1 further comprising:
and a surge tank provided on a pipe between an exhaust port of the expander and the evaporation tank.
4. The transcritical carbon dioxide refrigeration unit according to claim 3 further comprising:
and the flowmeter is arranged on a pipeline between the pressure stabilizing tank and the evaporating tank.
5. The transcritical carbon dioxide refrigeration unit according to claim 3, wherein said expander is connected to said evaporator tank through said surge tank and a flow meter by piping to throttle said supercritical carbon dioxide to low temperature subcritical.
6. The transcritical carbon dioxide refrigeration unit according to claim 1 further comprising:
and the liquid storage tank is arranged on a pipeline between the evaporating pot and the low-pressure side of the internal heat regenerator.
7. The transcritical carbon dioxide refrigeration unit according to claim 1 wherein said first compressor is a centrifugal refrigeration compressor for compressing carbon dioxide to subcritical carbon dioxide.
8. The transcritical carbon dioxide refrigeration unit according to claim 1 wherein said second compressor is a piston type refrigeration compressor for compressing said subcritical carbon dioxide to supercritical carbon dioxide.
9. The transcritical carbon dioxide refrigeration device according to claim 1, wherein heat dissipation fans are disposed above the first gas cooler, the second gas cooler and the evaporator tank.
10. The transcritical carbon dioxide refrigeration unit according to claim 1 wherein a refrigerant leak sensor is installed on the piping between the internal regenerator and the first compressor.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110806035A (en) * | 2019-11-06 | 2020-02-18 | 上海复璐帝流体技术有限公司 | Transcritical carbon dioxide refrigeration method and device thereof |
| CN112275237A (en) * | 2020-09-08 | 2021-01-29 | 中国科学院广州能源研究所 | CO2 hydrate method concentration system and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110806035A (en) * | 2019-11-06 | 2020-02-18 | 上海复璐帝流体技术有限公司 | Transcritical carbon dioxide refrigeration method and device thereof |
| WO2021089000A1 (en) * | 2019-11-06 | 2021-05-14 | 上海复璐帝流体技术有限公司 | Transcritical carbon dioxide refrigeration method and device |
| CN112275237A (en) * | 2020-09-08 | 2021-01-29 | 中国科学院广州能源研究所 | CO2 hydrate method concentration system and method |
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