阅读说明：本技术 一种基于双蒸发温度的加氢预冷系统及其控制方法 (Hydrogenation precooling system based on double evaporation temperatures and control method thereof ) 是由 顾玲俐 尹立坤 蔺新星 吴一梅 陈建业 邵双全 于 2021-07-31 设计创作，主要内容包括：本发明公开一种基于双蒸发温度的加氢预冷系统及其控制方法,系统包括高压氢气管线,高压氢气管线输出端与预冷系统输入端连接,预冷系统包括制冷主机,所述制冷主机通过管线分别与第一换热器和第二换热器连接,第一换热器和第二换热器分别布设于高压氢气管线输送前侧和输送后侧；本发明将部分预冷负荷利用较高温度制冷剂进行吸收,剩余预冷负荷用低压蒸发温度制冷剂吸收,在保证氢气预冷设定温度情况下,提高了制冷系统整体蒸发温度及COP,从而降低能耗,并采用制冷剂直接储能和满液蒸发换热,大大提高了换热系数和预冷速度。(The invention discloses a double-evaporation-temperature-based hydrogenation precooling system and a control method thereof, wherein the system comprises a high-pressure hydrogen pipeline, the output end of the high-pressure hydrogen pipeline is connected with the input end of the precooling system, the precooling system comprises a refrigeration host, the refrigeration host is respectively connected with a first heat exchanger and a second heat exchanger through pipelines, and the first heat exchanger and the second heat exchanger are respectively arranged on the conveying front side and the conveying rear side of the high-pressure hydrogen pipeline; the invention absorbs part of the precooling load by using the refrigerant with higher temperature, and absorbs the rest of the precooling load by using the refrigerant with low-pressure evaporation temperature, under the condition of ensuring the preset temperature of hydrogen precooling, the overall evaporation temperature and COP of the refrigerating system are improved, thereby reducing the energy consumption, and the direct energy storage and the full-liquid evaporation heat exchange of the refrigerant are adopted, thereby greatly improving the heat exchange coefficient and the precooling speed.)

1. The utility model provides a hydrogenation precooling system based on two evaporating temperature, includes high-pressure hydrogen pipeline (1), and high-pressure hydrogen pipeline (1) output is connected with precooling system (2) input, its characterized in that: the precooling system (2) comprises a refrigeration main machine (2.1), the refrigeration main machine (2.1) is respectively connected with a first heat exchanger (2.2) and a second heat exchanger (2.3) through pipelines, and the first heat exchanger (2.2) and the second heat exchanger (2.3) are respectively arranged on the conveying front side and the conveying rear side of the high-pressure hydrogen pipeline (1).

2. The dual vaporization temperature-based hydrogenation precooling system according to claim 1, wherein: one output end of the refrigeration main machine (2.1) is connected with the input end of the first heat exchanger (2.2) through a first output pipeline (2.4), and the output end of the first heat exchanger (2.2) is connected with a reflux end of the refrigeration main machine (2.1) through a first reflux pipeline (2.5); the other output end of the refrigeration main machine (2.1) is connected with the input end of the second heat exchanger (2.2) through a second output pipeline (2.6), and the output end of the second heat exchanger (2.2) is connected with the other return end of the refrigeration main machine (2.1) through a second return pipeline (2.7).

3. The dual vaporization temperature-based hydrogenation precooling system according to claim 2, wherein: the refrigeration host (2.1) comprises a first liquid storage device (2.1.1) and a second liquid storage device (2.1.2), the output end of the first liquid storage device (2.1.1) is connected with the input end of a first heat exchanger (2.2) through a first output pipeline (2.4), and the output end of the first heat exchanger (2.2) is connected with the return end of the first liquid storage device (2.1.1) through a first return pipeline (2.5); the output end of the second liquid storage device (2.1.2) is connected with the input end of the second heat exchanger (2.2) through a second output pipeline (2.6), and the output end of the second heat exchanger (2.2) is connected with the return end of the second liquid storage device (2.1.2) through a second return pipeline (2.7).

4. The dual vaporization temperature-based hydrogenation pre-cooling system of claim 3, wherein: first reservoir (2.1.1), second reservoir (2.1.2), first compressor (2.1.3), second compressor (2.1.4) and condenser (2.1.5) are located in proper order on circulating line (2.1.3), wherein first reservoir (2.1.1) play liquid end and second reservoir (2.1.2) feed liquor end pass through the pipeline connection, second reservoir (2.1.2) give vent to anger the end and pass through the pipeline connection with first compressor (2.1.3) input, condenser (2.1.5) output and first reservoir (2.1.1) feed liquor end pass through the pipeline connection, condenser (2.1.5) input and second compressor (2.1.4) output pass through the pipeline connection, first compressor (2.1.3) output passes through the pipeline connection with second compressor (2.1.4) input.

5. The dual vaporization temperature-based hydrogenation precooling system according to claim 4, wherein: the air outlet end of the first liquid storage device (2.1.1) is connected with the input end of the second compressor (2.1.4) through a connecting pipe (2.1.6); and a flow regulating valve (9) is arranged on the high-pressure hydrogen pipeline (1).

6. The dual vaporization temperature-based hydrogenation precooling system according to claim 4, wherein: still be equipped with first expansion valve (2.1.7) on the pipeline between condenser (2.1.5) and first reservoir (2.1.1), still be equipped with second expansion valve (2.1.8) on the pipeline between first reservoir (2.1.1) and second reservoir (2.1.2).

7. The dual vaporization temperature-based hydrogenation precooling system according to claim 1, wherein: a first temperature sensor (3) is arranged on the outer wall of the first heat exchanger (2.2) close to the hydrogen inlet of the high-pressure hydrogen pipeline (1) and used for detecting the wall temperature TW1 of the first heat exchanger (2.2); a second temperature sensor (4) is arranged on the outer wall of the second heat exchanger (2.3) close to the hydrogen inlet of the high-pressure hydrogen pipeline (1) and used for detecting the wall temperature TW2 of the second heat exchanger (2.3); a third temperature sensor (5) is arranged at a hydrogen outlet of the high-pressure hydrogen pipeline (1) in the area of the first heat exchanger (2.2) and is used for detecting the outlet hydrogen temperature TH1 of the first heat exchanger (2.2); and a fourth temperature sensor (6) is arranged at the hydrogen outlet of the high-pressure hydrogen pipeline (1) in the area of the second heat exchanger (2.3) and used for detecting the outlet hydrogen temperature TH2 of the second heat exchanger (2.3).

8. The dual vaporization temperature-based hydrogenation precooling system according to claim 1, wherein: be equipped with first liquid pump (2.8) on first output pipeline (2.4), be equipped with second liquid pump (2.9) on second output pipeline (2.6), first liquid pump (2.8) entrance is equipped with fifth temperature sensor (7) for detect the refrigerant temperature TR1 of first liquid pump (2.8) entrance, second liquid pump (2.9) entrance is equipped with sixth temperature sensor (8), is used for detecting the refrigerant temperature TR2 of second liquid pump (2.9) entrance.

9. A method for controlling a dual-evaporating-temperature-based hydrogenation precooling system according to any one of claims 1 to 8, wherein the method comprises the following steps: it comprises the following steps:

step 1): when a vehicle arrives, the first liquid pump (2.8) and the second liquid pump (2.9) are driven to the maximum rotating speed, the refrigeration host machine (2.1) is started, the first heat exchanger (2.2) and the second heat exchanger (2.3) are cooled in advance, and the wall surface temperature TW1 and the wall surface temperature TW2 of the first heat exchanger are detected; setting the intermediate set temperature to be TS1, the precooling set temperature to be TS2, and the intermediate set temperature TS1> the precooling set temperature TS 2;

step 2): for the first liquid pump (2.8), if TW1> TS1, the maximum rotational speed is maintained; if the TW1 is not more than TS1, reducing the rotating speed to the lowest, and then detecting whether the TW2 reaches TS 2; for the second liquid pump (2.9), if TW2> TS2, the maximum rotational speed is maintained; if TW2 is not more than TS2, judging whether hydrogenation is started, and if not, reducing the second liquid pump (2.9) to the lowest rotating speed;

step 3): in the hydrogen precooling stage, the method for controlling the temperature of the hydrogen at the outlet of the heat exchanger comprises the following steps: if filling is started, detecting the outlet hydrogen temperature TH1 of the first heat exchanger (2.2), detecting the outlet hydrogen temperature TH2 of the second heat exchanger (2.3), and adjusting the rotating speed of the first liquid pump (2.8) according to the difference between the outlet hydrogen temperature TH1 of the first heat exchanger (2.2) and the intermediate set temperature TS1 so that the outlet hydrogen temperature TH1 of the first heat exchanger (2.2) meets the condition: dT1 is less than or equal to (TH 1-TS 1) is less than or equal to dT 2;

and adjusting the rotation speed of the second liquid pump (2.9) to enable the outlet hydrogen temperature TH2 of the second heat exchanger (2.3) to meet the condition: dT3 is not more than (TH 2-TS 2) and not more than dT4, and TH2 is not less than-40 ℃;

step 4): controlling the evaporation temperature of the refrigeration main machine: after the refrigeration host is started, detecting the inlet refrigerant temperature TR1 of the first liquid pump (2.8) and the inlet refrigerant temperature TR2 of the second liquid pump (2.9); adjusting the opening degree of the first expansion valve (2.1.7) and the rotating speed of the second compressor (2.1.4) to ensure that (TR 1-TEV 1) is less than or equal to dT 5; adjusting the opening degree of the second expansion valve (2.1.8) and the rotation speed of the first compressor (2.1.3) to ensure that dT6 is not less than (TR 2-TEV 2) not less than dT 7; wherein the intermediate evaporation temperature TEV1= TS1- Δ T1; the low-pressure evaporation temperature TEV2= TS 2-delta T2, and delta T1 and delta T2 are between 5 and 10 ℃.

10. The method for controlling a dual evaporating temperature based hydrogenation precooling system according to claim 9, wherein: dT1 is-3 to-1 ℃, dT2 is 1 to 2 ℃, dT3 is-3 to 0 ℃, dT4-dT3 is more than or equal to 2 ℃ and less than or equal to 7 ℃, dT5 is 0 to 3 ℃, dT6 is-5 to 0 ℃, and dT7 is 1 to 3 ℃.

Technical Field

The invention relates to the technical field of hydrogenation of a hydrogenation station, in particular to a hydrogenation precooling system based on double evaporation temperatures and a control method thereof.

Background

In order to promote the popularization of the fuel cell vehicle, the construction of related technical facilities such as a hydrogen refueling station is also an important part of the popularization of the hydrogen fuel. The prior technical proposal has a plurality of proposals, one of which is to store the hydrogen in the long pipe of the pipe trailer in a high-pressure storage tank of a hydrogenation station after the hydrogen is pressurized by a compressor. During hydrogenation, hydrogen stored in a high-pressure storage tank of a hydrogenation station passes through a flow regulating valve and then is hydrogenated to a gas cylinder of the fuel cell vehicle through a hydrogenation machine.

For on-vehicle cylinders, there is a clear regulation that the temperature of the gas in the composite cylinder for vehicles cannot exceed 85 ℃. Unlike most gases, hydrogen has a negative Joule Thomson effect in the hydrogenation working space, the temperature of the gas is obviously increased after adiabatic throttling, and the temperature rise after a pressure reducing valve is sometimes as high as 40 ℃. In addition, fill the notes in-process at the gas cylinder, because reasons such as the compression heat effect, hydrogen temperature sharply rises in the gas cylinder, is difficult to the short time and discharges through natural heat dissipation, endangers the gas cylinder safety, influences the hydrogen quality after the hydrogenation to influence the continuation of the journey mileage of car.

SAE J2601-2016 light vehicle hydrogen filling scheme published by SAE of the American society of automotive Engineers recommends that a precooling link is required to be added in a hydrogenation process, and hydrogen temperature is reduced, so that different temperature grades T40, T30, T20 and the like of a hydrogenation station are specified. The hydrogenation station of T40 requires that the hydrogen temperature at the outlet of the hydrogenation station be maintained between-33 ℃ and-40 ℃ during hydrogenation. That is, the hydrogen precooling step needs to reduce the hydrogen from a higher temperature (assuming that the ambient temperature is 35 ℃) to a lower temperature, and the temperature span is very large.

In addition, because there is a discontinuous mode of hydrogenation, the temperature of the refrigerating unit can be gradually increased to the ambient temperature during the hydrogenation interval. The SAE J2601 protocol also requires that the pre-cooling temperature range must be reached within 30s after the hydrogenation is started, for example, the hydrogenation station of T40 will reach a hydrogen temperature of between-33 ℃ and-40 ℃ within 30 s. The refrigeration unit itself has a start-up procedure, which takes up time. And cooling the heat exchanger temperature from ambient temperature (say 20 c) to-40 c is generally difficult to accomplish in a short period of time. During the hydrogenation, the pre-cooling load fluctuates in a very large range, and for the refrigeration system, the lower the evaporation temperature, the lower the COP of the refrigeration system, and the higher the energy consumption. A conventional hydrogen precooling system generally adopts a single-evaporation-temperature refrigeration host machine to carry out direct precooling or indirect precooling.

For a single evaporation temperature precooling system, heat released when the temperature of hydrogen is reduced from normal temperature to a precooling set temperature (generally minus 40 ℃) in the hydrogenation period is completely absorbed by a refrigerant with low-pressure evaporation temperature (evaporation temperature is at least minus 45 ℃), the COP of the refrigeration system is low, and further the energy consumption is large. As for the indirect precooling system with single evaporation temperature, as the secondary refrigerant is adopted, the heat exchange is carried out twice, the evaporation temperature of the precooling system is lower (T40, the evaporation temperature is at least 50 ℃ below zero), and the energy consumption is higher.

Disclosure of Invention

The invention aims to overcome the defects and provides a double-evaporation-temperature-based hydrogenation precooling system and a control method thereof.

In order to solve the technical problems, the invention adopts the technical scheme that: the utility model provides a hydrogenation precooling system based on two evaporating temperatures, includes the high-pressure hydrogen pipeline, and high-pressure hydrogen pipeline output is connected with precooling system input, and precooling system includes the refrigeration host computer, the refrigeration host computer passes through the pipeline and is connected with first heat exchanger and second heat exchanger respectively, and first heat exchanger and second heat exchanger are laid respectively in high-pressure hydrogen pipeline and are carried the front side and carry the rear side.

Preferably, an output end of the refrigeration main machine is connected with an input end of the first heat exchanger through a first output pipeline, and an output end of the first heat exchanger is connected with a return end of the refrigeration main machine through a first return pipeline; the other output end of the refrigeration main machine is connected with the input end of the second heat exchanger through a second output pipeline, and the output end of the second heat exchanger is connected with the other reflux end of the refrigeration main machine through a second reflux pipeline.

Preferably, the refrigeration host comprises a first reservoir and a second reservoir, an output end of the first reservoir is connected with an input end of a first heat exchanger through a first output pipeline, and an output end of the first heat exchanger is connected with a return end of the first reservoir through a first return pipeline; the output end of the second liquid storage device is connected with the input end of the second heat exchanger through a second output pipeline, and the output end of the second heat exchanger is connected with the return end of the second liquid storage device through a second return pipeline.

Preferably, the first liquid storage device, the second liquid storage device, the first compressor, the second compressor and the condenser are sequentially arranged on the circulating pipeline, wherein the liquid outlet end of the first liquid storage device is connected with the liquid inlet end of the second liquid storage device through a pipeline, the gas outlet end of the second liquid storage device is connected with the input end of the first compressor through a pipeline, the output end of the condenser is connected with the liquid inlet end of the first liquid storage device through a pipeline, the input end of the condenser is connected with the output end of the second compressor through a pipeline, and the output end of the first compressor is connected with the input end of the second compressor through a pipeline.

Preferably, the air outlet end of the first liquid storage device is connected with the input end of the second compressor through a connecting pipe; and a flow regulating valve is arranged on the high-pressure hydrogen pipeline.

Preferably, a first expansion valve is further disposed on a pipeline between the condenser and the first reservoir, and a second expansion valve is further disposed on a pipeline between the first reservoir and the second reservoir.

Preferably, a first temperature sensor is arranged on the outer wall of the first heat exchanger close to the hydrogen inlet of the high-pressure hydrogen pipeline and used for detecting the wall temperature TW1 of the first heat exchanger; a second temperature sensor is arranged on the outer wall of the second heat exchanger close to the hydrogen inlet of the high-pressure hydrogen pipeline and used for detecting the wall temperature TW2 of the second heat exchanger; a third temperature sensor is arranged at the hydrogen outlet of the high-pressure hydrogen pipeline in the area where the first heat exchanger is positioned and is used for detecting the hydrogen temperature TH1 at the outlet of the first heat exchanger; and a fourth temperature sensor is arranged at the hydrogen outlet of the high-pressure hydrogen pipeline in the area of the second heat exchanger and used for detecting the hydrogen temperature TH2 at the outlet of the second heat exchanger.

Preferably, a first liquid pump is arranged on the first output pipeline, a second liquid pump is arranged on the second output pipeline, a fifth temperature sensor is arranged at the inlet of the first liquid pump and used for detecting the refrigerant temperature TR1 at the inlet of the first liquid pump, and a sixth temperature sensor is arranged at the inlet of the second liquid pump and used for detecting the refrigerant temperature TR2 at the inlet of the second liquid pump.

In addition, the invention also discloses a control method of the double-evaporation-temperature-based hydrogenation precooling system, which comprises the following steps:

step 1): when a vehicle arrives, the first liquid pump and the second liquid pump are driven to the maximum rotating speed, the refrigeration host is started, the first heat exchanger and the second heat exchanger are cooled in advance, and the wall temperature TW1 of the first heat exchanger and the wall temperature TW2 of the second heat exchanger are detected; setting the intermediate set temperature to be TS1, the precooling set temperature to be TS2, and the intermediate set temperature TS1> the precooling set temperature TS 2;

step 2): for the first liquid pump, if TW1> TS1, then the maximum rotational speed is maintained; if the TW1 is not more than TS1, reducing the rotating speed to the lowest, and then detecting whether the TW2 reaches TS 2; for the second liquid pump, if TW2> TS2, the maximum rotational speed is maintained; if TW2 is not more than TS2, judging whether hydrogenation is started, and if not, reducing the second liquid pump to the lowest rotating speed;

step 3): in the hydrogen precooling stage, the method for controlling the temperature of the hydrogen at the outlet of the heat exchanger comprises the following steps: if filling is started, detecting the outlet hydrogen temperature TH1 of the first heat exchanger, detecting the outlet hydrogen temperature TH2 of the second heat exchanger, and adjusting the rotating speed of the first liquid pump according to the difference between the outlet hydrogen temperature TH1 of the first heat exchanger and the intermediate set temperature TS1 to ensure that the outlet hydrogen temperature TH1 of the first heat exchanger meets the condition: dT1 is less than or equal to (TH 1-TS 1) is less than or equal to dT 2;

and adjusting the rotating speed of the second liquid pump to enable the outlet hydrogen temperature TH2 of the second heat exchanger to meet the condition: dT3 is not more than (TH 2-TS 2) and not more than dT4, and TH2 is not less than-40 ℃;

step 4): controlling the evaporation temperature of the refrigeration main machine: after the refrigeration host is started, detecting the inlet refrigerant temperature TR1 of the first liquid pump and the inlet refrigerant temperature TR2 of the second liquid pump; adjusting the opening degree of the first expansion valve and the rotation speed of the second compressor to ensure that (TR 1-TEV 1) is less than or equal to dT 5; adjusting the opening degree of the second expansion valve and the rotating speed of the first compressor to ensure that dT6 is not less than (TR 2-TEV 2) not less than dT 7; wherein the intermediate evaporation temperature TEV1= TS1- Δ T1; the low-pressure evaporation temperature TEV2= TS 2-delta T2, and delta T1 and delta T2 are between 5 and 10 ℃.

Preferably, the dT1 is-3 to-1 ℃, the dT2 is 1 to 2 ℃, the dT3 is-3 to 0 ℃, the dT4-dT3 is more than or equal to 2 ℃ and less than or equal to 7 ℃, the dT5 is 0 to 3 ℃, the dT6 is-5 to 0 ℃, and the dT7 is 1 to 3 ℃.

The invention has the beneficial effects that:

1. the invention absorbs part of the precooling load by using the refrigerant with higher temperature, and absorbs the rest of the precooling load by using the refrigerant with low-pressure evaporation temperature, under the condition of ensuring the preset temperature of hydrogen precooling, the overall evaporation temperature and COP of the refrigerating system are improved, thereby reducing the energy consumption, and the direct energy storage and the full-liquid evaporation heat exchange of the refrigerant are adopted, thereby greatly improving the heat exchange coefficient and the precooling speed.

2. Compared with a single-evaporation precooling system, the arrangement of the double-evaporation-temperature heat exchanger is equivalent to the splitting of a large heat exchanger into two smaller heat exchangers with different evaporation temperatures, the cost of the heat exchanger cannot be greatly improved, but the overall evaporation temperature of the precooling system can be increased, so that the COP of the precooling system is increased, and the energy consumption is reduced; in addition, compared with the indirect energy storage and heat exchange of the secondary refrigerant, the direct energy storage and heat exchange of the refrigerant are adopted, so that the evaporation temperature of the precooling system can be further increased, the heat exchange coefficient and the cooling speed in the heat exchanger can be increased, and the overall performance of the hydrogenation system can be improved.

Drawings

Fig. 1 is a schematic structural diagram of a hydrogenation precooling system based on double evaporation temperatures.

Detailed Description

The invention is described in further detail below with reference to the figures and specific embodiments.

As shown in fig. 1, a hydrogenation precooling system based on double evaporation temperatures includes a high-pressure hydrogen pipeline 1, an output end of the high-pressure hydrogen pipeline 1 is connected with an input end of a precooling system 2, the precooling system 2 includes a refrigeration host 2.1, the refrigeration host 2.1 is respectively connected with a first heat exchanger 2.2 and a second heat exchanger 2.3 through pipelines, and the first heat exchanger 2.2 and the second heat exchanger 2.3 are respectively arranged on a conveying front side and a conveying rear side of the high-pressure hydrogen pipeline 1.

Preferably, an output end of the refrigeration main unit 2.1 is connected with an input end of the first heat exchanger 2.2 through a first output pipeline 2.4, and an output end of the first heat exchanger 2.2 is connected with a return end of the refrigeration main unit 2.1 through a first return pipeline 2.5; the other output end of the refrigeration main machine 2.1 is connected with the input end of the second heat exchanger 2.2 through a second output pipeline 2.6, and the output end of the second heat exchanger 2.2 is connected with the other reflux end of the refrigeration main machine 2.1 through a second reflux pipeline 2.7.

Preferably, the refrigeration main unit 2.1 comprises a first liquid accumulator 2.1.1 and a second liquid accumulator 2.1.2, an output end of the first liquid accumulator 2.1.1 is connected with an input end of a first heat exchanger 2.2 through a first output pipeline 2.4, and an output end of the first heat exchanger 2.2 is connected with a return end of the first liquid accumulator 2.1.1 through a first return pipeline 2.5; the output end of the second liquid storage device 2.1.2 is connected with the input end of the second heat exchanger 2.2 through a second output pipeline 2.6, and the output end of the second heat exchanger 2.2 is connected with the return end of the second liquid storage device 2.1.2 through a second return pipeline 2.7.

Preferably, first reservoir 2.1.1, second reservoir 2.1.2, first compressor 2.1.3, second compressor 2.1.4 and condenser 2.1.5 locate in proper order on circulation pipeline 2.1.3, wherein first reservoir 2.1.1 goes out the liquid end and passes through the pipe connection with second reservoir 2.1.2 inlet end, second reservoir 2.1.2 is given vent to anger the end and passes through the pipe connection with first compressor 2.1.3 input, condenser 2.1.5 output and first reservoir 2.1.1 inlet end pass through the pipe connection, condenser 2.1.5 input and second compressor 2.1.4 output pass through the pipe connection, first compressor 2.1.3 output and second compressor 2.1.4 input pass through the pipe connection.

Preferably, the air outlet end of the first liquid storage device 2.1.1 is connected with the input end of the second compressor 2.1.4 through a connecting pipe 2.1.6; and a flow regulating valve 9 is arranged on the high-pressure hydrogen pipeline 1.

Preferably, a first expansion valve 2.1.7 is further disposed on a pipeline between the condenser 2.1.5 and the first liquid reservoir 2.1.1, and a second expansion valve 2.1.8 is further disposed on a pipeline between the first liquid reservoir 2.1.1 and the second liquid reservoir 2.1.2.

Preferably, a first temperature sensor 3 is arranged on the outer wall of the first heat exchanger 2.2 close to the hydrogen inlet of the high-pressure hydrogen pipeline 1, and is used for detecting the wall temperature TW1 of the first heat exchanger 2.2; a second temperature sensor 4 is arranged on the outer wall of the second heat exchanger 2.3 close to the hydrogen inlet of the high-pressure hydrogen pipeline 1 and used for detecting the wall surface temperature TW2 of the second heat exchanger 2.3; a third temperature sensor 5 is arranged at the hydrogen outlet of the high-pressure hydrogen pipeline 1 in the area of the first heat exchanger 2.2 and is used for detecting the outlet hydrogen temperature TH1 of the first heat exchanger 2.2; a fourth temperature sensor 6 is arranged at the hydrogen outlet of the high-pressure hydrogen pipeline 1 in the area of the second heat exchanger 2.3 and is used for detecting the outlet hydrogen temperature TH2 of the second heat exchanger 2.3.

Preferably, the first output pipeline 2.4 is provided with a first liquid pump 2.8, the second output pipeline 2.6 is provided with a second liquid pump 2.9, a fifth temperature sensor 7 is arranged at an inlet of the first liquid pump 2.8 and used for detecting a refrigerant temperature TR1 at the inlet of the first liquid pump 2.8, and a sixth temperature sensor 8 is arranged at an inlet of the second liquid pump 2.9 and used for detecting a refrigerant temperature TR2 at the inlet of the second liquid pump 2.9.

In this embodiment, the first reservoir and the second reservoir have refrigerant liquid stored therein, and the outside is wrapped with a heat insulating layer, thereby avoiding absorbing heat from the air and increasing the refrigeration load. The first liquid pump and the second liquid pump are adjustable in rotating speed and are respectively used for controlling whether the outlet hydrogen temperature of the first heat exchanger and the outlet hydrogen temperature of the second heat exchanger reach preset values. The first compressor and the second compressor are adjustable in rotation speed and can be two compressors or two compression cavities of a single compressor. The first heat exchanger and the second heat exchanger are wrapped by heat insulation layers, so that heat absorption from air is avoided, and the refrigeration load is increased. The first heat exchanger and the second heat exchanger adopt a refrigerant direct cooling mode to cool the hydrogen. The refrigerant outlet maintains a two-phase state with a dryness of 0.6-0.95.

In the technical scheme, the hydrogen from the high-pressure hydrogen pipeline is subjected to isenthalpic throttling through the flow regulating valve and then heated, then the temperature is reduced to the intermediate set temperature TS1 through the first heat exchanger in the precooling system, and then the temperature is reduced to the precooling set temperature TS2 through the second heat exchanger. Then enters a hydrogenation machine through a hydrogen outlet for filling.

In a refrigerant flow path, a refrigeration main machine adopts a two-stage compression system, two-stage liquid storage and full liquid evaporation heat exchange are carried out, in the refrigeration main machine, high-pressure refrigerant at the outlet of a condenser is changed into a gas-liquid two-phase state (corresponding to the intermediate evaporation temperature TEV1) with intermediate pressure through primary throttling of a first expansion valve, and gas-liquid separation is carried out in a first liquid storage device; a part of liquid in the first liquid storage device is conveyed through a first output pipeline, is pumped into a first heat exchanger by a first liquid pump, performs primary heat exchange with high-temperature hydrogen, and returns to the first liquid storage device through a first return pipeline; the other part of the liquid in the first liquid storage device enters a second expansion valve for secondary throttling to be changed into a low-pressure gas-liquid two-phase state (corresponding to a low-pressure evaporation temperature TEV2) and stored in the second liquid storage device; the liquid part in the second liquid storage device is conveyed through a second output pipeline, is pumped into a second heat exchanger by a second liquid pump, performs secondary heat exchange with high-temperature hydrogen, and returns to the second liquid storage device through a second return pipeline; the gas part is compressed into intermediate pressure steam by the first compressor, then mixed with the gas part from the connecting pipe of the first liquid storage device and enters the second compressor, and the gas part is compressed to high pressure and then enters the condenser to complete the refrigeration cycle.

In addition, the invention also discloses a control method of the double-evaporation-temperature-based hydrogenation precooling system, which comprises the following steps:

step 1): when a vehicle arrives, the first liquid pump 2.8 and the second liquid pump 2.9 are started to the maximum rotating speed, the refrigeration main machine 2.1 is started, the first heat exchanger 2.2 and the second heat exchanger 2.3 are cooled in advance, and the wall temperature TW1 of the first heat exchanger and the wall temperature TW2 of the second heat exchanger are detected; setting the intermediate set temperature to be TS1, the precooling set temperature to be TS2, and the intermediate set temperature TS1> the precooling set temperature TS 2; in this embodiment, the pre-cooling set temperature TS2 is determined by the fueling station reference protocol according to the station grade, and the range of the T20 hydrogen station is (-26 to-17.5 ℃); for the T30 hydrogen station, the range is (-33 to-26 ℃); for the T40 hydrogen station, the range is (-40 to-33 ℃); the intermediate set temperature TS1> the pre-cooling set temperature TS2, TS1 depends on the environmental temperature, the first inlet temperature of the first heat exchanger, the pre-cooling set temperature TS2, the COP of the pre-cooling system, and other factors, and needs to be considered comprehensively.

Step 2): for the first liquid pump 2.8, if TW1> TS1, the maximum rotational speed is maintained; if the TW1 is not more than TS1, reducing the rotating speed to the lowest, and then detecting whether the TW2 reaches TS 2; for the second fluid pump 2.9, if TW2> TS2, the maximum rotational speed is maintained; if TW2 is not more than TS2, judging whether hydrogenation is started, and if not, reducing the second liquid pump 2.9 to the lowest rotating speed;

step 3): in the hydrogen precooling stage, the method for controlling the temperature of the hydrogen at the outlet of the heat exchanger comprises the following steps: if filling is started, the outlet hydrogen temperature TH1 of the first heat exchanger 2.2 is detected, the outlet hydrogen temperature TH2 of the second heat exchanger 2.3 is detected, the rotating speed of the first liquid pump 2.8 is adjusted according to the difference between the outlet hydrogen temperature TH1 of the first heat exchanger 2.2 and the intermediate set temperature TS1, and the outlet hydrogen temperature TH1 of the first heat exchanger 2.2 meets the condition: dT1 is less than or equal to (TH 1-TS 1) is less than or equal to dT 2;

and adjusting the rotating speed of the second liquid pump 2.9 to ensure that the outlet hydrogen temperature TH2 of the second heat exchanger 2.3 meets the condition: dT3 is not more than (TH 2-TS 2) and not more than dT4, and TH2 is not less than-40 ℃;

step 4): controlling the evaporation temperature of the refrigeration main machine: after the refrigeration host is started, detecting the inlet refrigerant temperature TR1 of the first liquid pump 2.8 and the inlet refrigerant temperature TR2 of the second liquid pump 2.9; adjusting the opening degree of the first expansion valve 2.1.7 and the rotation speed of the second compressor 2.1.4 to ensure that (TR 1-TEV 1) is less than or equal to dT 5; adjusting the opening degree of the second expansion valve 2.1.8 and the rotation speed of the first compressor 2.1.3 to ensure that dT6 is not less than (TR 2-TEV 2) not less than dT 7; wherein the intermediate evaporation temperature TEV1= TS1- Δ T1; the low-pressure evaporation temperature TEV2= TS 2-delta T2, and delta T1 and delta T2 are between 5 and 10 ℃.

Preferably, the dT1 is-3 to-1 ℃, the dT2 is 1 to 2 ℃, the dT3 is-3 to 0 ℃, the dT4-dT3 is more than or equal to 2 ℃ and less than or equal to 7 ℃, the dT5 is 0 to 3 ℃, the dT6 is-5 to 0 ℃, and the dT7 is 1 to 3 ℃.

In this example, the data were analyzed by comparative tests: for example, single-stage precooling uses a heat exchanger to cool the hydrogen to-40 ℃; during double-stage precooling, two heat exchangers are adopted, the high-temperature heat exchanger HX1 firstly cools the hydrogen to the intermediate temperature Tm, and the second heat exchanger cools the hydrogen to-40 ℃; the number of stages of the heat exchanger does not influence the mass flow rate, the inlet temperature and the outlet temperature of the hydrogen, namely the total heat release of the hydrogen is not influenced by the double-stage precooling configuration. The single-stage precooling only has one heat exchanger without intermediate temperature, the COP of the single-stage precooling is about 1.09 only as a comparison reference, and the precooling energy consumption is 2.16 kWh;

in contrast, in the present embodiment, a dual precooling system (i.e., a dual-evaporation-temperature hydrogenation precooling system) is adopted, and the above control method is adopted, and the results show that as the intermediate temperature Tm increases, the power consumption of the compressor in the high-pressure state linearly decreases, and the power consumption index of the compressor in the low-pressure state increases, but the amplitude is small, the minimum value of 1.58kWh also appears in the total power consumption, which corresponds to 1.49 COP, and the energy is saved by 26.8% compared with single-stage precooling.

In general, under the condition of a certain total volume, compared with a single-evaporation precooling system, the precooling load of the double-evaporation-temperature heat exchanger adopting the corresponding control method of the embodiment is always lower than that of the single-evaporation precooling system. The method has the advantages that the total heat release quantity/precooling load of the hydrogen can not be influenced in the process of double-stage precooling, and the precooling load distribution among precooling heat exchangers can only be influenced by the intermediate temperature change; the energy consumption of the double-stage pre-cooling system in the embodiment is always lower than that of the single-stage pre-cooling system, and the energy of the double-stage pre-cooling system is saved by 20-30% compared with that of the single-stage pre-cooling system at a reasonable intermediate temperature.

The above-described embodiments are merely preferred embodiments of the present invention, and should not be construed as limiting the present invention, and features in the embodiments and examples in the present application may be arbitrarily combined with each other without conflict. The protection scope of the present invention is defined by the claims, and includes equivalents of technical features of the claims. I.e., equivalent alterations and modifications within the scope hereof, are also intended to be within the scope of the invention.