JP7352336B2 - Apparatus and method for replenishing containers with pressurized gas - Google Patents

Description

The present invention relates to an apparatus and method for replenishing a container with pressurized gas.

The invention more particularly relates to a device for refueling containers with pressurized gas, in particular for refueling gaseous hydrogen tanks, comprising a source of pressurized gas and one upstream gas connected to said gas source. and a transfer circuit comprising at least one downstream end (6) intended to be removably connected to a container, said device cooling gas flowing from a gas source before entering said container. the refrigeration system comprises a refrigerant cooling loop circuit comprising a compressor, a condenser section, an expansion valve, and an evaporator section arranged in series, the refrigeration system having a heat exchanger with the condenser section; and a heat exchanger disposed within the transfer circuit and including a heat exchange section between the gas flowing within the transfer circuit and the evaporator section.

Hydrogen refueling stations are designed for rapid refueling (in minutes) of fuel cell electric vehicles (FCEVs) with high pressure (eg, 70 MPa or higher) hydrogen. To avoid overheating in the tank, it is necessary to pre-cool the hydrogen (generally below -33° C.) at the dispenser refueling nozzle.

Known cooling or refrigeration systems supply a hydrogen-cooled heat exchanger with refrigerant in a refrigerant cooling loop circuit.

The refrigerant is _CO2 . For example, see the documents JP20150921108A or US2016348840A. Please also refer to WO2018104983A.

Generally, a heat exchanger includes a mass or block of material that stores cold heat to meet high demand. Refrigeration systems can provide nearly constant cooling, with cooling energy stored in the thermal inertia of the heat exchanger (high thermal inertia).

However, thermal inertia may not be sufficient in some situations to provide the required cooling. Furthermore, when using other types of heat exchangers (e.g. compact diffusion bonded heat exchangers), the thermal inertia is small. In that case, cooling energy must be supplied when it is demanded. This demand can change from zero to full cooling power within seconds.

The most efficient use of cooling power is made using countercurrent heat exchangers. In that case, it is desirable that the temperature of the refrigerant at the inlet to the heat exchanger remains within a predetermined temperature range.

For that purpose, a certain evaporation pressure range must be maintained at the inlet of the heat exchanger. Also, sufficient superheat must be maintained during suction of the compressor. Superheating is, for example, a predetermined amount of heat added to the refrigerant after it has already vaporized. It can be defined by the temperature at a given pressure and can be measured at the outlet of the heat exchanger or at the inlet of the compressor. The evaporation temperature of the refrigerant depends on the pressure.

The reason superheating is controlled is to ensure that the liquid refrigerant in the evaporator section has completely changed from liquid to vapor (gas) (this is because we want only vapor to return to the compressor suction/suction )

The refueling device (or station) may also be set in standby mode (ready for refueling) for an extended period of time. Also, even if refueling occurs, the amount of gas may be less than the maximum design value. In these cases, the refrigeration system operates at low load.

One goal is to overcome or reduce at least one of the aforementioned problems.

For this purpose, according to the above general definition, the device according to the invention comprises a refrigerant cooling loop circuit with an upstream end connected to the outlet of the compressor and a refrigerant cooling loop circuit upstream of the inlet of the compressor a bypass conduit having a downstream end connected to the compressor and bypassing the condenser section and the expansion valve, the apparatus further comprising a bypass regulating valve for regulating the flow of refrigerant flowing through the bypass conduit; The device comprises a pressure sensor for sensing the refrigerant pressure in the refrigerant cooling loop circuit between the inlet and the heat exchanger outlet, in particular at the inlet of the compressor, the device being connected to a bypass regulating valve to detect the opening of said bypass regulating valve. the compressor is a variable speed compressor, the electronic controller is connected to the compressor and is configured to control the speed of the compressor, and in particular the compressor is a variable speed compressor; is essentially characterized in that it is arranged to regulate the suction pressure at the inlet of the compressor by controlling the compressor speed and the opening of the bypass regulating valve.

Additionally (or alternatively), embodiments may include one or more of the following features.
the electronic controller is configured to adjust the suction pressure at the inlet of the compressor to a predetermined value or pressure setpoint or within a predetermined pressure range;
the electronic controller is configured to calculate the predetermined suction pressure at the inlet of the compressor by a correlation based on the fluid state equation and/or the desired evaporation temperature of the refrigerant, i.e. the temperature of the refrigerant after the expansion valve;
The device is equipped with a temperature sensor that measures the temperature of the refrigerant at the inlet of the heat exchanger,
the electronic controller is configured to use the refrigerant temperature measured by the temperature sensor at the inlet of the heat exchanger to reduce the predetermined suction pressure control to compensate for the pressure loss;
an electronic controller configured to receive the cooling power request and control the opening of the expansion valve, and in particular to increase the opening of the expansion valve when the cooling demand increases;
the electronic controller is configured to reduce the bypass refrigerant flow rate and/or increase the speed of the compressor (8) when the opening of the expansion valve increases;
The device comprises a temperature sensor for sensing the refrigerant temperature in the refrigerant cooling loop circuit between the compressor inlet and the heat exchanger outlet, in particular at the compressor inlet;
The electronic controller is configured to adjust the temperature of the refrigerant at the inlet of the compressor to a predetermined temperature set point by controlling the compressor speed and the opening of the bypass valve; is configured to generate or receive a signal indicative of the cooling power required by the heat exchanger to cool the gas flow therein, and to control the cooling power produced by the refrigeration system accordingly.

The invention also relates to a method for refueling a container with pressurized gas, in particular a method for refueling a gaseous hydrogen tank, comprising a gas source and a transfer circuit for transferring the compressed gas from said gas source to the container. and the method includes the step of cooling a heat exchanger disposed within the transfer circuit, the heat exchanger exchanging heat with gas flowing from the gas source to the vessel, The steps generate cooling power in an evaporator section of a refrigerant cooling loop circuit, the refrigerant cooling loop circuit comprising a compressor, a condenser section, an expansion valve, and an evaporator section arranged in series, the condenser section being a refrigeration section. The method includes controlling the compressor speed and the amount of refrigerant compressed by the compressor that is re-injected through a bypass conduit upstream of the compressor without flowing through the condenser section and expansion valve. The method comprises the step of adjusting the suction pressure at the inlet of the compressor by controlling the compressor.

According to other embodiments, the invention may include one or more of the following features.
the suction pressure at the inlet of the compressor is adjusted to a predetermined value or pressure setpoint or within a predetermined range;
The method includes calculating a predetermined suction pressure at the inlet of the compressor by a fluid equation of state and/or a correlation based on a desired evaporation temperature of the refrigerant, i.e., the temperature of the refrigerant after the expansion valve;
The method includes adjusting the temperature of the refrigerant at the inlet of the compressor to a predetermined temperature set point through control of the speed of the compressor and the opening of the bypass regulating valve;
The method includes directing some of the refrigerant in the refrigerant cooling loop circuit to an expansion vessel to reduce the pressure in the refrigerant cooling loop circuit below a predetermined value;
The method includes providing cold heat to the refrigerant cooling loop circuit through the cold source and extracting gas from the expansion container to the refrigerant cooling loop circuit when the pressure in the expansion vessel is greater than a predetermined value;
The method comprises an expansion vessel including an inlet connected to a refrigerant cooling loop circuit downstream of a compressor outlet and an outlet connected to a refrigerant cooling loop circuit upstream of a compressor inlet, the apparatus comprising: A set of valves is provided to control the flow of refrigerant from the vessel and to control the pressure within the refrigerant cooling loop circuit and within the expansion vessel.

The invention may also relate to any alternative device or method comprising any combination of the above or below features within the scope of the claims.

Other features or advantages will become apparent from the following description with reference to the drawings.
1 is a schematic diagram and a partial diagram showing the structure and operation of a refueling device according to a first embodiment; FIG. FIG. 7 is a schematic diagram and a partial diagram showing the structure and operation of a refueling device according to a second embodiment. FIG. 7 is a schematic diagram and a partial diagram showing the structure and operation of a refueling device according to a third embodiment. FIG. 7 is a schematic diagram and a partial diagram showing the structure and operation of a refueling device according to a fourth embodiment. 2A and 2B are schematic and partial illustrations of different possible operations of the apparatus and process that may be implemented (independently or in combination); FIG. Figure 3 is a schematic and partial diagram illustrating the structure and operation of a refueling device according to a further embodiment;

As shown in the drawing, a device 1 for refueling a container 3 is used for refueling the tank of a motor vehicle with pressurized gas (for example hydrogen, but also other gases such as natural gas). It may also be a refueling station.

The device 1 comprises a pressurized gas source 2, one upstream end 5 connected to the gas source 2 and at least one downstream end 6 (intended to be removably connected to the container or tank 3 to be filled). For example, a transfer circuit 4 comprising a nozzle) is provided.

The gas source 2 may, for example, include at least one of a pressurized gas reservoir or buffer, a compressor, a pressurized gas cylinder or bundle of tube trailers, a liquefied gas source and vaporizer, an electrolytic cell, a gas network outlet. can.

The transfer circuit 4 is controlled by an electronic controller according to a predetermined refueling strategy (pressure increase or rate of pressure increase and/or injection volume control and/or control of the density in the tank 3 and/or control of the temperature increase in the tank 3). A set of valves may be provided.

The apparatus 1 comprises a refrigeration system for cooling the gas flowing from the gas source 2 (for example to a predetermined temperature below 0°C, in particular between -33°C and -40°C) before entering the vessel 3. The cooled gas temperature varies depending on the refueling conditions (temperature and/or pressure in the tank 3, rate of pressure increase in the tank 3, gas flow rate in the transfer circuit 4, ambient temperature...). It can also be controlled.

The refrigeration system includes a refrigerant cooling loop circuit 20 including a compressor 8, a condenser section 9, an expansion valve 10 and an evaporator section 11 arranged in series. The refrigerant flowing through the refrigerant cooling loop circuit 20 is preferably carbon dioxide, but another refrigerant such as R717 (ammonia), R22, R134a, R404a, R507, or any refrigerant capable of reaching at least -40° C. may be used.

The condenser section 9 may include a heat exchanger that cools the refrigerant compressed by the compressor 8.

The refrigeration system includes a cold source 12 that exchanges heat with a condenser section 9 . The cold source 12 may include a cooling fluid circuit, such as a loop. For example, air, water, nitrogen, or any suitable cooling fluid or refrigerant. The cold source may include any other refrigeration apparatus or device capable of cooling the refrigerant, such as a heat convector, cooling tower, or secondary refrigeration cycle. The cooling fluid from cold source 12 can exchange heat with condenser section 9 in a heat exchanger.

The refrigeration system preferably comprises a heat exchanger 7 arranged within the transfer circuit 4 and comprising a heat exchange section between the gas flowing within the transfer circuit 4 and the evaporator section 11 . The evaporator section 11 comprises a circuit (e.g. a coil) for heat exchange with the transfer circuit 4 and/or a block (e.g. a few centimeters) of material (e.g. aluminum) forming an organ with high thermal inertia for storing low temperatures. thick metal or aluminum blocks and/or other materials such as phase change materials).

According to an advantageous feature, the refrigerant cooling loop circuit 20 includes an upstream end connected to the outlet of the compressor 8 and a downstream end connected upstream of the compressor 8 in the refrigerant cooling loop circuit 20 and condensing. A bypass conduit 13 that bypasses the vessel section 9 and the expansion valve 10 is provided. The refrigeration system includes a bypass regulating valve 15 for controlling the flow of refrigerant into the bypass conduit 13.

As shown in FIG. 1, at least a portion of the compressor 8, the condenser section 9, the cold source 12, the bypass regulating valve, and possibly the expansion valve 10 can be arranged within the refrigeration module 14.

As shown in FIG. 1, the downstream end of the bypass conduit 13 (upstream connected to the compressor outlet) can be connected directly to the suction line of the compressor 8. This means that the hot compressed bypassed refrigerant is reinjected directly into the inlet of the compressor 8.

In another embodiment (FIG. 2), the downstream end of the bypass conduit 13 can be connected upstream of the inlet of the heat exchanger 7. This second solution allows mixing of the hot compressed bypassed refrigerant with a cooler refrigerant stream that is regulated by the expansion valve 10 before entering the heat exchanger 7. This allows the expansion valve 10 to maintain a superheat level (sufficient temperature) within the circuit. This also allows higher fluid velocities in the heat exchanger 7 and the suction line of the compressor.

If the compressor is an oil-lubricated piston compressor, this makes it possible to better transport oil that would have leaked and accumulated in the refrigerant cooling loop circuit, in particular in the heat exchanger 7. However, when the evaporator load is low, keeping the heat exchanger inlet temperature constant can be more difficult to control.

In the preferred embodiment shown in FIGS. 3 and 4, the downstream end of the bypass conduit 13 is connected to the outlet of the heat exchanger 7 of the transfer circuit 4. That is, the hot compressed bypassed refrigerant is reinjected and mixed with the refrigerant exiting the heat exchanger 7.

This means that the hot compressed bypassed refrigerant is not injected into the inlet or suction line of the compressor 8, but is injected more upstream, preferably closer to the refrigerant outlet of the heat exchanger 7.

For example, the downstream end of the bypass conduit 13 is fixed (fixed) in the refrigerant cooling loop circuit 20 immediately after the evaporator section 11, e. connected). It is also preferred that this connection of the hot gas bypass conduit 13 is not too close to the refrigerant temperature measurement at the outlet of the evaporator section 11 (temperature sensor 17) .

This makes it possible to avoid or limit the influence of the bypass fluid on the measured temperature (temperature sensor 17) . Preferably, therefore, the temperature measurement (temperature sensor 17) is as close as possible to the outlet of the evaporator 11 (for example approximately 5-10 cm from the outlet depending on the necessary fittings) and the connection of the bypass conduit 13 to said outlet. approximately 20-40 cm downstream or 20-30 cm downstream of said temperature sensor 17 (eg, 20-30 cm downstream of the first bend of the refrigerant cooling loop circuit/bypass conduit). However, since the evaporator section 11 is generally mounted inside the dispenser and the pipe comes from below, its position is almost automatically defined by the available space.

Compared to the solution described in Figure 2, this solution prevents or reduces the problem of temperature fluctuations at the inlet of the heat exchanger 7, since hot and cold refrigerants are not mixed at the inlet of the heat exchanger 7. do. Compared to the solution described in FIG. prevent.

Preferably, the bypass regulating valve 15 can be set to a closed position or multiple open positions for a regulated period of time (e.g., pulse width modulation of a solenoid valve), or can be set to an open position or a plurality of open positions (e.g., fully open and It is a controlled valve that can be set to fully closed. Thereby, the flow rate of the refrigerant flowing through the bypass conduit 13 can be interrupted or changed. The device 1 may comprise an electronic controller 21 connected to the bypass regulating valve 15 and configured (eg programmed) to control the opening of said bypass regulating valve 15 (see FIG. 4).

Electronic controller 21 may include equipment for storing procedures for receiving and/or transmitting data. For example, it includes a microprocessor and/or calculator and/or computer. Electronic controller 21 may be located within the device or station or may be remote. This electronic controller 21 can also control the flow of gas in the transfer circuit 4 to the tank 3.

Compressor 8 is preferably a variable speed compressor. The electronic controller 21 may be connected to the compressor 8 and configured to control the compressor 8 (on/off state) and the speed of the compressor 8.

The cooling power of the refrigeration system can be controlled mainly by the opening degree of the expansion valve 10. The controller 21 is preferably connected to the expansion valve 10 and configured to control the cooling power generated by the refrigeration system by controlling the opening of the expansion valve 10 .

In order to maintain a constant evaporation pressure, the suction pressure upstream of the compressor 8, in particular at the inlet of the heat exchanger 7, must be maintained within a predetermined range.

Therefore, the evaporation pressure can be controlled by controlling the bypass regulating valve 15 and the speed of the compressor 8.

The evaporation temperature, ie the temperature of the refrigerant after the expansion valve, depends on the pressure downstream of the expansion valve 10.

Based on the desired evaporation temperature (for a given cooling of the refueling gas), the required suction pressure can be calculated (by appropriate state or correlation equations).

The pressure can be measured in the heat exchanger 7 or preferably on the suction side of the compressor 8. As shown in FIG. 4, the device includes a pressure sensor for sensing the refrigerant pressure in the refrigerant cooling loop circuit 20 between the inlet of the compressor 8 and the outlet of the heat exchanger 7, in particular at the inlet of the compressor 8. 16 can be provided.

To compensate for the pressure loss, the measurement of the temperature at the inlet of the heat exchanger 7 (temperature sensor 18) can be used to reduce the set point of the suction pressure control.

As shown in FIG. 4, the device may be equipped with a temperature sensor 18 for sensing the refrigerant temperature in the evaporator section 11 upstream of the heat exchanger 7, in particular at the inlet of the heat exchanger 7.

The temperature at the inlet (temperature sensor 18) is equal to the evaporation temperature given by the suction pressure. Inlet temperature calculated via suction pressure instead of measurement reacts faster and gives better control.

In this context, the term <<temperature sensor>> means a device for directly or indirectly measuring temperature and/or for calculating temperature on the basis of suitable parameters.

The suction pressure of the compressor 8 can be controlled by controlling the flow rate of hot gas entering the bypass conduit 13 and the speed of the compressor 8.

Refrigerant flow through heat exchanger 7 may be zero when compressor 8 is at minimum speed (or stopped) and bypass regulating valve 15 is fully open.

The maximum flow of refrigerant through the heat exchanger 7 is obtained when the bypass regulating valve 15 is closed and the compressor 8 is at its maximum speed.

This relationship can be controlled with a split range control technique (signal amplitude sequence control technique).

This makes it possible to ensure that there is always sufficient superheat on the suction side of the compressor 8.

Rapid load changes can result in rapid reactions of the expansion valve 10. This affects the suction pressure of the compressor 8. For quick response of the pressure control, the opening of the expansion valve 10 may be associated with a feed forward signal to the pressure control output (i.e., the bypass regulator valve 15 and the speed setpoint of the compressor 8). .

As the cooling demand increases, the opening degree of the expansion valve 10 increases. The signal to the expansion valve 10 can also be used to calculate a feedforward signal to the suction pressure control to keep the evaporation pressure constant. This means that an increase in the opening of the expansion valve may command a reduction in the bypassed refrigerant flow and/or an increase in the speed of the compressor 8.

In a typical refrigeration application, superheat (refrigerant temperature) can be measured directly after the evaporator section 11 (at the outlet of the heat exchanger 7).

Alternatively or additionally, it is possible to measure the superheat (refrigerant temperature) close to the inlet of the compressor 8, for example at the inlet of the refrigeration module 14 (refrigeration module can also be called a refrigerator). be.

The main reason for measuring the temperature close to the evaporator section 11 (heat exchanger 7) is energy consumption. In this device, the distance between the refrigerator and the dispenser 6 can be used to subcool the liquid refrigerant and increase the temperature of the gaseous refrigerant on the suction side of the compressor 8. For example, referring to FIG. 4, this means that the lines between the outlet of the condenser section 9 and the expansion valve 10, as well as the lines between the evaporator section 11 and the superheat control (temperature sensor 22) , are made of the same insulating material. or can be achieved by running within an insulated structure. For this reason, it is preferable that superheat control be performed closer to the compressor 8 than to the heat exchanger 7.

The device 1 thus comprises a temperature sensor 17 for sensing the refrigerant temperature in the refrigerant cooling loop circuit 20 between the inlet of the compressor 8 and the outlet of the heat exchanger 7, and in particular a temperature sensor at the inlet of the compressor 8. 22.

The electronic controller 21 can be configured to adjust the temperature of the refrigerant at the inlet of the compressor 8 to a predetermined temperature range by controlling the speed of the compressor 8 and the opening degree of the bypass regulating valve 15.

Based on the actual measured or calculated pressure P and the pressure set point PS (required pressure), the electronic controller acts on the bypass regulating valve 15 and the compressor 8, as shown in FIG.

Control of the cooling power may be based on temperature measurement at the outlet of the heat exchanger 7 (superheat control). This control scheme works well with only slowly changing cooling demands. However, in the case of tank refueling stations, rapid load changes can occur. Simple temperature control strategies cannot keep the gas temperature to be cooled (e.g. H ₂ ) in the correct temperature range for refueling (typically between -33°C and -40°C). .

In typical refrigeration applications, cooling demand changes very slowly. In these cases, the reaction rate of the refrigerator is not important.

For refueling stations, cooling demands can change from zero to full cooling power within seconds. For this reason, a single temperature-based control may not be sufficient.

Preferably, the device measures the temperature difference between the temperature of the refrigerant in the refrigerant cooling loop circuit 20 at the outlet of the heat exchanger 7 and the temperature of the refrigerant in the refrigerant cooling loop circuit 20 at the inlet of the heat exchanger 7. Equipped with a sensor system. Electronic controller 21 may be configured to control the cooling power generated as a function of this temperature difference.

For example, the temperature difference is calculated based on temperature sensors 17, 18 at the outlet and inlet of the heat exchanger 7.

The expansion valve 10 can be controlled via closed-loop control of the refrigerant temperature difference between the inlet (temperature sensor 18) and outlet (temperature sensor 17) of the heat exchanger 8. If the required cooling power is absent or low (for example, a cold heat exchanger in standby mode), the temperature difference will be very low. As the cooling demand increases, the temperature difference increases and the control opens the expansion valve 10 as necessary.

Since the actual cooling power is directly related to the opening degree of the expansion valve 10 (typically with a proportional and/or regulated opening time), therefore to control whether the supplied cooling power is too high or too low. The measurement of can be the temperature difference between the refrigerant inlet and the refrigerant outlet to the heat exchanger 7.

The device 1 may be switched to refueling mode when there is a refueling request.

For example, refueling mode may be activated upon generating or receiving a signal or command at electronic controller 21. For example, upon payment/request from the user and/or when the refueling nozzle 6 is removed from the base dispenser.

After the nozzle 6 is removed, it may take some time (eg, 10 to 20 seconds) for the user to attach the nozzle 6 to the vehicle and activate the refueling sequence.

Once the connection of the nozzle to the tank 3 is made, a pressure pulse test (for example about 30 seconds) is performed and the actual refueling begins.

A predetermined low gas temperature (eg, about -33° C.) should be reached at the dispenser outlet 6 within a short time (eg, 30 seconds) after refueling is initiated.

The device can be designed such that the heat exchanger 7 is cooled to a predetermined temperature (eg -38° C.) within a certain time (eg 60 seconds) after the nozzle is removed from its base. .

This means that the heat exchanger is subcooled before the gas in the transfer circuit 4 flows to the tank 3.

When cooling of heat exchanger 11 is required prior to gas flow, and the system is in standby mode (described below), electronic controller 21 starts compressor 8 and controls expansion valve 10 and bypass regulator valve 15. can be controlled as described above. This causes rapid cooling.

Refueling the tank 3 takes, for example, 150 seconds to 500 seconds. Meanwhile, the actual cooling demand changes rapidly. These rapid changes are typically too fast for classical control. Preferably, feedforward control is implemented to maintain a stable temperature of the hydrogen.

For example, the operating parameters of a refrigeration system are based on the actual cooling energy required.

Therefore, once the actual refueling begins, refueling generates a cooling demand. Based on the actual cooling demand, the required cooling power can be calculated/provided.

The electronic controller 21 is able to calculate and control the required refrigerant flow rate within the heat exchanger 7 (since as the cooling demand increases, the refrigerant flow rate must be increased).

The compressor 8 can be started immediately after the start of refueling. In order to reduce power consumption, the refrigeration system may cool the internal heat exchanger 9 (condenser section) and the heat exchanger 7 as much as possible from the beginning.

As the cooling demand increases, first the bypass regulating valve 15 is closed and then the speed of the compressor 8 is increased as necessary. This can be done via split range control (signal amplitude sequence control).

In order to react faster to load changes, the required cooling power can be calculated based on the gas flow to be cooled. The calculated cooling demand can act as an offset to the electronic controller 21. Therefore, the expansion valve 10 can open before a significant change in temperature difference occurs in the heat exchanger 7.

Feedforward control based on actual cooling demand may be used. Based on the gas flow rate in the transfer circuit 4 and the (expected) inlet temperature, the required cooling power can be calculated. Based on the required cooling power, the required refrigerant flow rate can be calculated and then the required opening degree of the expansion valve 10 can be calculated. Therefore, the necessary opening degree of the expansion valve 10 can be used to generate a feedforward signal for cooling power control.

An estimate of the required cooling power can be calculated using the instruments available in the device 1. For example, the required cooling power can be set equal to the gas flow rate to be cooled multiplied by the difference between the enthalpy of the gas at the inlet of the heat exchanger 7 and the enthalpy of said gas at the outlet of the heat exchanger 7. . This can be calculated using the expected exit gas temperature at nozzle 6 (typically -40°C). At a minimum, an estimate of gas flow rate may be required. Preferably, this can be derived, for example, from a flow meter signal in the transfer circuit. However, it can also be calculated from other equipment signals (eg pressure drop or pressure change in the gas source 2, such as a buffer). In order to improve the accuracy of cooling power calculation, the gas pressure upstream of the heat exchanger 7, the gas pressure downstream of the heat exchanger 7, the gas temperature upstream of the heat exchanger, the ambient temperature, the temperature of the heat exchanger, etc. Other measurements can be taken into account.

As shown in FIG. 7, the cooling power request signal 24 causes the electronic controller 21 to act on the compressor 8 and expansion valve 10 to meet the request.

The device can also be placed in standby mode (between two fills).

During this standby mode, the heat exchanger 7 may be maintained at a temperature that allows a quick start of refueling (for example within a predetermined period of 60 seconds).

This requirement may define the maximum temperature of the heat exchanger 7 during standby mode. For example, if the refrigeration system is capable of cooling the heat exchanger 7 by 20 °C within 60 seconds, active cooling during standby mode will cause the temperature of the heat exchanger 7 to exceed a predetermined threshold, e.g. -18 °C. Start when.

If the system is at a low temperature (eg, a heat exchanger temperature below a first standby temperature threshold (eg, below −20° C.)), the system is placed/maintained in standby mode. The compressor is then preferably switched off.

During standby mode, the liquid refrigerant is warmed and the pressure within the refrigerant cooling loop circuit 20 increases.

To reduce the pressure within the refrigerant cooling loop circuit 20 (the pressure increases above a preset limit), the cold source 12 is activated to generate the refrigerant cooling loop circuit 20 or the refrigerant cooling loop circuit is 20 can be cooled down.

If the temperature of the heat exchanger 7 has to be reduced (or maintained at a low temperature), the compressor 8 can be started. Starting the compressor 8 creates a flow in the loop and reduces the pressure at its inlet.

Starting the compressor 8 creates a flow in the loop and reduces the pressure at its inlet.

If the heat exchanger 7 warms up too much during standby mode, the heat exchanger 7 is preferably cooled again.

In this operating scenario, the time to reach low temperature is not critical. Therefore, compressor 8 can be operated at the most efficient speed (typically the lowest speed).

At the lowest speed of the compressor 8, the cooling power is, for example, 10-20 kW. This is enough cooling power to cool a typical heat exchanger by 30°K within 120 seconds. The minimum operating time of the compressor 8 may be fixed (for example, 120 seconds). Therefore, during this standby cooling of the heat exchanger 7, a higher compressor speed may not be required.

For example, if the temperature T17 of the heat exchanger 7 (temperature sensor 19 in FIG. 8) is below the first standby temperature threshold ("TS1" in FIG. 8, for example -37°C), the refrigeration system (cooling) or compressor 8 can be switched off (kept switched off, see reference numeral 25 in FIG. 8). The temperature of the heat exchanger 7 may be measured via a temperature sensor 19, for example, or may be calculated based on other parameters.

However, if this temperature T17 exceeds a second standby temperature threshold TS2 (e.g. -20°C or higher, etc.), the refrigeration device is (or can be) switched on ("Y" in Figure 8 and reference numeral 26). ). Otherwise, the refrigeration system (cooling) or the compressor can be switched off (kept switched off, see reference numeral 25 in FIG. 8).

The electronic controller 21 may control the refrigeration system such that the refrigerant temperature set point at the heat exchanger inlet is a predetermined temperature, for example -40°C.

The electronic controller 21 is thus able to regulate the evaporation temperature, which is measured at the inlet of the heat exchanger 7, for example. If this temperature increases too much, the pressure set point at the inlet of the compressor 8 will decrease (ie the temperature achieved at the inlet of the heat exchanger).

The expected pressure drop through the heat exchanger 7 and the compressor suction line may be less than 1 bar. Therefore, when the refrigerant is _CO2 , it can be said that the influence on the evaporation temperature due to pressure loss is less than 2°K.

If a different refrigerant is used, the temperature effect can be much larger.

The electronic controller 21 is able to control the temperature difference between the inlet (temperature sensor 18) and the outlet (temperature sensor 17) of the heat exchanger 7. If the heat exchanger warms up (given by the increase in the temperature difference ΔT), see reference numeral 27 and arrow "Y" in FIG. 6, the controller 21 can open the expansion valve 10 (see reference numeral 122 in FIG. reference).

As the heat exchanger 7 cools, the temperature difference decreases (see arrow "N" in FIG. 6) and the electronic controller 21 closes the expansion valve 10 (see reference numeral 23 in FIG. 6).

Thereby, the amount of refrigerant flowing into the heat exchanger 7 can be controlled based on this temperature difference (between the inlet and the outlet). As the temperature difference increases, the output of the controller 21 increases and more refrigerant is sent to the heat exchanger (and vice versa). This can be controlled as a feedforward control signal in the expansion valve 10.

The minimum power can be adjusted such that at zero load, the superheat temperature at the inlet of the compressor 8 is around a predetermined temperature (eg +10°K).

For "standby cooling" the set point can be higher, for example +20°K.

The electronic controller 21 can control the speed of the compressor 8 and the bypass regulating valve 15 to maintain a constant pressure at the inlet of the compressor 8.

The superheat control (temperature control) is preferably always active. If the superheat temperature drops too much, the expansion valve 10 can optionally be closed.

Preferably, if the superheat temperature at the compressor inlet is too low, the expansion valve 10 is closed regardless of the actual cooling demand.

If the superheat temperature rises too much, the expansion valve 10 can be opened as required.

If the superheat temperature at the compressor inlet is too low, the hot gas bypass regulating valve 15 can be opened.

In order to avoid complete closure of the expansion valve 10, a minimum opening of the expansion valve 10 can be set. This minimum opening degree can be set such that the suction temperature at the inlet of the compressor 8 is always sufficiently superheated by the injection of the high temperature bypass gas.

In addition to the above advantages, the device allows very fast changes in cooling power while maintaining a constant evaporation pressure and sufficient superheating at the suction of the compressor 8.

When the device 1 is on standby, the refrigerant (typically liquid CO2) downstream of the condenser heat exchanger 9 warms up and evaporates, leading to a pressure increase on the discharge side of the compressor 8. One solution is to turn on the cold source 12 to provide cooling and reduce refrigerant pressure. In order to reduce the number of starts of the cold source 12, as shown in FIG. 9, the device can be provided with an expansion vessel 29 with an inlet connected to the refrigerant cooling loop circuit 20 at the outlet on the side of the compressor 8. The expansion container 29 has an outlet connected to the refrigerant cooling loop circuit 20 at the outlet on the compressor 8 side. The device includes a set of valves 28 for controlling the flow of refrigerant from the circuit 20 (downstream of the compressor outlet) to the expansion vessel 29 and from the expansion vessel 29 to the circuit 20 (upstream of the compressor 8 inlet). , 30 included. The electronic controller 21 is configured to open the inlet valve 28 to the expansion vessel 29 until the pressure downstream of the compressor 8 is below a certain value (typically open at 35 barg) and close it at a preset value (eg 33 barg). can do.

If the temperature of the heat exchanger 7 is too high or the pressure in the expansion vessel 29 is too high (for example above 15 barg), the cold source 12 can be started and the compressor 8 can be started. The outlet valve 30 of the expansion vessel 29 is opened and the pressure within the expansion vessel 29 is reduced again to a suitable value (for example 10 barg).

Claims (11)

Device (1) for refueling containers with pressurized gas, in particular for refueling gaseous hydrogen tanks, comprising:
a pressurized gas source (2);
a transfer circuit (4) comprising one upstream end (5) connected to said gas source (2) and at least one downstream end (6) intended to be removably connected to the container (3); ) and,
The apparatus (1) comprises a refrigeration system for cooling the gas flowing from the pressurized gas source (2) before entering the container (3);
The refrigeration system comprises a refrigerant cooling loop circuit (20) including a compressor (8), a condenser section (9), an expansion valve (10) and an evaporator section (11) arranged in series;
The refrigeration system includes a cold source (12) that exchanges heat with the condenser section (9), a cold source (12) disposed within the transfer circuit (4), and a gas flowing through the transfer circuit (4) and a cold source (12) that exchanges heat with the condenser section (9). 11); a heat exchanger (7) including a heat exchange section between the heat exchanger (7);
The refrigerant cooling loop circuit (20) has an upstream end connected to the outlet of the compressor (8);
a bypass conduit (13) having a downstream end connected to the refrigerant cooling loop circuit (20) upstream of the inlet of the compressor (8) and bypassing the condenser section (9) and the expansion valve (10); ),
The device further includes a bypass regulating valve (15) for controlling the flow of refrigerant flowing into the bypass conduit (13),
The device (1) is configured to cool the refrigerant in the refrigerant cooling loop circuit (20) between the inlet of the compressor (8) and the outlet of the heat exchanger (7), in particular at the inlet of the compressor (8). Equipped with a pressure sensor (16) for sensing pressure,
The device (1) comprises an electronic controller (21) connected to the bypass regulating valve (15) and configured to control the opening degree of the bypass regulating valve (15),
The compressor (8) is a variable speed compressor,
the electronic controller (21) is connected to the compressor (8) and configured to control the speed of the compressor (8), in particular the compressor (8);
The electronic controller (21) controls the suction pressure at the inlet of the compressor (8) to a predetermined value or pressure set value by controlling the speed of the compressor (8) and the opening degree of the bypass regulating valve (15). or within a predetermined pressure range ;
In standby mode or refueling mode, where the required cooling power is not available or is low, the electronic controller (21) receives the cooling power request and controls the opening degree of the expansion valve (10), in particular the cooling power The electronic controller (21) is configured to increase the opening of the expansion valve (10) when the demand increases, and the electronic controller (21) decreases the bypass refrigerant flow rate when the opening of the expansion valve (10) increases. , and/or increasing the speed of said compressor (8) . The electronic controller (21) determines the temperature at the inlet of the compressor (8) by a correlation based on the equation of state of the fluid and/or the desired evaporation temperature of the refrigerant, i.e. the temperature of the refrigerant after the expansion valve (10). Device according to claim 1, characterized in that it is configured to calculate a predetermined suction pressure. Device according to claim 1 or 2, characterized in that it comprises a temperature sensor (18) for measuring the temperature of the refrigerant at the inlet of the heat exchanger (7). The electronic controller (21) uses the refrigerant temperature measured by the temperature sensor (18) at the inlet of the heat exchanger (7) to reduce a predetermined suction pressure to compensate for the pressure loss. 4. Apparatus according to claim 3 , characterized in that it is configured. a temperature sensor for sensing the refrigerant temperature in the refrigerant cooling loop circuit (20) between the inlet of the compressor (8) and the outlet of the heat exchanger (7), particularly at the inlet of the compressor (8); 5. Device according to any one of claims 1 to 4 , characterized in that it comprises (17, 22). The electronic controller (21) sets the temperature of the refrigerant at the inlet of the compressor (8) to a predetermined temperature setting by controlling the speed of the compressor (8) and the opening degree of the bypass regulating valve (15). 6. Device according to claim 5 , characterized in that it is configured to adjust to a point. The electronic controller (21) cools the flow of gas in the transfer circuit (4) through the heat exchanger (7) and controls the cooling power produced by the refrigeration system accordingly. 7. A cooling device according to any one of claims 1 to 6 , characterized in that it is configured to generate or receive a signal indicative of the cooling power required in the heat exchanger (7) for Device. A method for refueling containers with pressurized gas, in particular for refueling gaseous hydrogen tanks, comprising:
comprising a gas source (2) and a transfer circuit (4) for transferring compressed gas from the gas source (2) to the container (3);
The method comprises the step of cooling a heat exchanger (7) arranged in the transfer circuit (4);
The heat exchanger (7) exchanges heat with the gas flowing from the gas source (2) to the container (3),
The cooling step generates cooling power in the evaporator section (11) of the refrigerant cooling loop circuit (20);
The refrigerant cooling loop circuit (20) includes a compressor (8), a condenser section (9), an expansion valve (10), and an evaporator section (11) arranged in series,
The condenser section (9) exchanges heat with a cold source (12),
The method includes controlling the speed of the compressor (8) and bypass conduit (13) upstream of the compressor (8) without flowing through the condenser section (9) and the expansion valve (10). control of the amount of refrigerant re-injected via the compressor (8) and compressed by the compressor (8) to bring the suction pressure at the inlet of the compressor (8) to a predetermined value or pressure setpoint or within a predetermined range. steps to adjust ,
In a standby mode or a refueling mode in which the required cooling power is not available or is low, a cooling power request is received and the opening degree of the expansion valve (10) is controlled, particularly when the cooling power request increases. increasing the opening of the expansion valve (10), decreasing the bypass refrigerant flow rate when the opening of the expansion valve (10) increases, and/or increasing the speed of the compressor (8); including,
Method. Calculating the predetermined suction pressure at the inlet of the compressor (8) by a correlation based on the equation of state of the fluid and/or the desired evaporation temperature of the refrigerant, i.e. the temperature of the refrigerant after the expansion valve (10). 9. A method according to claim 8 , characterized in that it comprises the steps of: The refrigerant at the inlet of the compressor (8) is controlled through the control of the opening of a bypass regulating valve (15) which controls the speed of the compressor (8) and the flow of refrigerant entering the bypass conduit (13). 10. A method according to claim 8 or 9 , characterized in that it comprises the step of adjusting the temperature of to a predetermined temperature set point. characterized in that it comprises the step of directing some of the refrigerant of the refrigerant cooling loop circuit (20) into an expansion vessel (29) to reduce the pressure within the refrigerant cooling loop circuit (20) below a predetermined value. , the method according to claim 8 or 9 .

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