Device and method for filling a container with compressed gaseous hydrogen

Abstract

The invention relates to a device for filling a container, in particular a vehicle tank, with compressed gaseous hydrogen, comprising a gas supply system (2) for providing compressed gaseous hydrogen, a connection mechanism (4) for producing a fluidic connection to a container (10) to be filled, and a cooling device (15, 46) for cooling the hydrogen to be supplied to the container, said cooling device comprising a cooling unit for cooling the hydrogen. The invention is characterized in that the cooling device has a buffering medium (17, 38a, 38b) which functions as a latent heat accumulator and which is thermally connected to the gaseous hydrogen to be supplied to the container on a first heat exchanger surface (18, 39a, 39b) and to the cold source (21, 44) on a second heat exchanger surface (19, 42a, 42b).

Description

[0001] Device and method for filling a container with compressed gaseous hydrogen

[0002] The invention relates to a device for refueling a container with compressed, gaseous hydrogen, comprising a gas supply system for providing compressed, gaseous hydrogen, a line system equipped with a connecting mechanism for establishing a flow connection between the gas supply system and a container to be filled, and a cooling device for cooling the hydrogen to be supplied to the container. The invention further relates to a corresponding method.

[0003] When filling a container, such as a vehicle tank or a transport container, with compressed, gaseous hydrogen, the pressure increase in the tank and the negative Joule-Thomson coefficient in the relevant temperature range cause the hydrogen in the container to heat up considerably. Since this heat can only be inadequately dissipated through the container walls during the refueling process, pre-cooling is required to ensure that the temperatures in the tank remain within legal requirements, such as those of SAE J2601. This standard stipulates that refueling of hydrogen-powered vehicles to a final pressure of 350 bar or 700 bar under reference conditions must be completed within ten or three minutes, respectively, without the temperature of the vehicle tank rising above 85°C.At the same time, it is required that the temperature of the hydrogen during refueling upon entering the tank to be filled remains within a specified temperature window, which may not be exceeded or undercut. For example, for refueling category T40, which allows refueling of cars with hydrogen at minus 40°C, the upper and lower temperature limits upon entering the tank to be filled are minus 33°C and minus 40°C, respectively. Other categories allow refueling at higher temperatures (T30, T20). Furthermore, the standard stipulates that this temperature window must be reached no later than 30 seconds after the start of the refueling process. The required cooling capacity is usually provided by a refrigeration machine.However, the short-term peak power demand, especially at the beginning of refueling, is critical. This can be many times higher than the average power demand. Consequently, such cooling systems must be equipped with very powerful refrigeration units, which, however, represent a considerable investment.

[0004] WO 2015 001 208 A2 discloses a method for refueling with hydrogen, in which the hydrogen supplied to a tank is tempered by a cold reservoir. The cold reservoir is a container filled with a cryogenic liquefied gas, such as liquid nitrogen, which is thermally connected to a heat exchanger via a cooling circuit. A heat transfer medium pumped through the cooling circuit is brought into thermal contact with the hydrogen gas. A disadvantage here, however, is that the system technology must be adapted to a short-term peak demand.

[0005] It has also already been proposed to store the hydrogen on site in a cryogenically liquefied state and to use the low temperature of the liquid hydrogen in whole or in part to achieve the required target temperature of the hydrogen gas intended for refueling. Devices of this type are known, for example, from WO 2013 020 665 A1, WO 2018 220 303 A1 or WO 2019 002 724 A1. For example, in the subject matter of WO 2013 020665 A1, cryogenic liquid hydrogen is stored in a storage tank. Before refueling begins, a portion of the liquid hydrogen is withdrawn and compressed to the respective filling pressure using a cryopump, although it is initially still at a low temperature of approximately 50K to 60K compared to the required filling temperature. By heating a partial flow and then combining it with the unheated partial flow, a target temperature between -33°C and -40°C can be achieved.However, storing hydrogen in cryogenic liquefied form is associated with significant evaporation losses, which are particularly noticeable during periods of extended downtime, such as weekends. Furthermore, the investment costs are considerable.

[0006] The invention is therefore based on the object of providing a possibility for refueling a container with hydrogen, which is characterized by high availability and an instantly available and adjustable cooling capacity, and which is at the same time associated with a comparatively low investment expenditure.

[0007] This object is achieved by a device having the features of patent claim 1 and by a method having the features of patent claim 12. Advantageous embodiments of the invention are specified in the dependent claims.

[0008] A device according to the invention thus comprises a gas supply system by means of which gaseous hydrogen is provided at a pressure that is higher than a target pressure of the hydrogen in a container to be filled. The container to be filled is, for example, a tank of a vehicle, in particular a road or rail vehicle, a ship, or an aircraft, or a mobile transport container for hydrogen (trailer), or a pressure container for storing gaseous hydrogen, such as a gas cylinder or a bundle of compressed gas cylinders. The gas supply system is, for example, one or more pressure containers, such as a storage tank or a bundle of cylinders, or a high-pressure line.The gas supply system can also comprise a conditioning container in which, at the beginning of a refueling process, hydrogen is present. This hydrogen has been taken from a low-pressure tank or pipeline and compressed by a compressor, and / or taken from a liquid supply and vaporized by an evaporator. Furthermore, the device comprises a line system equipped with a connection mechanism for establishing a flow connection between the gas supply system and a container to be filled. The connection mechanism is adapted to the respective container type or the type of connection.For example, this involves a coupling by means of which the container to be filled is firmly but detachably connected to the pipe system, thereby establishing a flow connection; in the case of a hydrogen filling station, the container to be filled is a vehicle tank, and the connection mechanism includes, for example, a fuel pump equipped with a filling line and filling gun for connection to a filler neck of the vehicle tank.

[0009] Furthermore, the device according to the invention comprises a cooling device for cooling the hydrogen to be supplied to the container. The cooling device is equipped with a buffer medium acting as a latent heat storage device, which is thermally connected at a first heat exchanger surface to at least a partial flow of the hydrogen to be supplied to the container during a refueling process and at a second heat exchanger surface to a cold source. At the second heat exchanger surface, the buffer medium is cooled to a temperature that is below a required temperature of the hydrogen to be supplied to the container (hereinafter referred to as the "target temperature"), while at the first heat exchanger surface, the hydrogen is cooled by thermal contact with the cooled buffer medium to a filling temperature that preferably corresponds to the target temperature.

[0010] The buffer medium, which acts as a latent heat storage device, enables the hydrogen supplied to the tank, which is provided in the gas supply system at ambient temperature, for example, to be cooled to a substantially constant temperature throughout an entire refueling process, without the need to simultaneously cool the buffer medium to the same extent, or at all. Thus, the cooling of the hydrogen is decoupled from the cooling of the buffer medium.The energy that can be stored in the latent heat storage system in the form of conversion enthalpy is determined by the quantity and type of buffer medium. In particular, with a suitable design, it is possible to dimension the heat storage capacity of the buffer medium such that the hydrogen to be released during one or more refueling operations is cooled to a substantially constant temperature corresponding to the target temperature, for example, minus 40°C. Cooling of the buffer medium via the second heat exchanger, on the other hand, can take place continuously over a longer period of time, which can include intermediate breaks instead of or in addition to the duration of one or more refueling operations. Therefore, it is possible to cool the buffer medium with a comparatively low cooling capacity, for example, with a comparatively low-performance refrigeration machine.

[0011] The buffer medium is preferably a medium that at least partially undergoes a solid-to-liquid phase transition during operation of the device, i.e., during thermal contact with the hydrogen during the refueling process. The buffer medium is therefore at least partially in a solid state before the refueling process and gradually begins to melt as the hydrogen passes through the first heat exchanger. The phase transition temperature or phase transition temperature range (melting point) of the buffer medium is therefore below the temperature of the hydrogen supplied to the first heat exchanger, but higher than the lowest temperature to which the buffer medium can be cooled by thermal contact with the cold source at the second heat exchanger. During the phase transition, the enthalpy of fusion prevents a significant increase in the temperature of the buffer medium, even with continued heat supply.This makes it possible to cool the hydrogen to an essentially constant temperature throughout the entire refueling process, or even during several consecutive refueling processes, while at the same time reliably preventing the hydrogen from falling below a certain minimum temperature.

[0012] In a first advantageous embodiment of the invention, a pure substance is used as the buffer medium, the melting point of which is below a target temperature required for the respective tank application, for example, below a temperature range between minus 40°C and minus 60°C. Octane, for example, is considered as such a pure substance.

[0013] Another preferred buffer medium consists of a mixture of substances, in particular a mixture of miscible liquids, whose composition also allows for the adjustment of its solid-liquid phase transition temperature. The composition of the mixture can thus be selected depending on the target temperature required for the respective tank task; for example, a composition is selected whose phase transition temperature is within the range of the target temperature. Preferred mixtures are mixtures of water and ethylene glycol or of water and propylene glycol, in which the solid-liquid phase transition temperature can be selected within a wide range by varying the ratio between the two substances.

[0014] Carbon dioxide, which is present in the cooling device at its triple point temperature (-57°C) or below, is also an advantageous buffer medium. For example, in this case, the cooling device comprises a container filled with carbon dioxide as a buffer medium, in the headspace of which gaseous CO2 is present at a largely constant pressure of 5.2 bar(a). If complete freezing occurs during continued cooling, the pressure suddenly drops; the aggregate state of the carbon dioxide can be easily determined by measuring the CO2 pressure, thus enabling a control device to regulate the cold supply to the buffer medium depending on the measured pressure. If, in addition, a temperature lower than its melting point is permitted in the CO2 serving as the buffer medium, then CO2 de-sublimates from the gas phase and becomes solid.Since the specific sublimation enthalpy of CO2 is about twice as large as the heat of fusion, the heat absorption capacity of the carbon dioxide used as a buffer medium can be significantly increased by appropriate dimensioning of the gas space.

[0015] The cooling device comprises, for example, a container filled with the buffer medium (buffer tank), in which the first and second heat exchanger surfaces, for example in the form of coiled tubes, are arranged. The hydrogen to be delivered flows through the first heat exchanger surface during a refueling process. The second heat exchanger surface, together with the cold source, is part of a cooling system for cooling the buffer medium. A refrigeration machine is preferably used as the cold source. The second heat exchanger surface is either part of the refrigeration machine itself and forms, for example, an evaporator arranged in a cooling circuit of the refrigeration machine, or the second heat exchanger surface is thermally connected to a refrigeration machine via a separate cooling circuit. Furthermore, a plurality of buffer tanks filled with the buffer medium, each equipped with first and second heat exchanger surfaces, can also be provided.

[0016] Alternatively or additionally, the cooling system comprises a cooling line connected to a tank for a cryogenic cooling medium. In this case, the cryogenic medium stored in the tank serves as the cold source, which is fed to the second heat exchanger via the cooling line and thus cools the buffer medium. Liquid or cold gaseous nitrogen or another cryogenically liquefied gas, for example, is used as the cryogenic cooling medium. Furthermore, any residual cold of the cryogenic cooling medium still present after thermal contact at the second heat exchanger can advantageously be used to cool other areas of the device according to the invention.For example, a double pipe and / or a further heat exchanger and / or a cold storage device can be arranged in the cooling line downstream of the second heat exchanger surface, at which the cryogenic cooling medium can be brought into thermal contact with the hydrogen, upstream of the first heat exchanger surface, which is transported through the line system between the pressure storage system and the container to be filled.

[0017] If latent heat is stored in the cooling device by utilising a phase transition in the buffer medium, the cooling device should be designed in such a way that the buffer medium can be brought to a temperature below the corresponding phase transition temperature by thermal contact with the cold source at the second heat exchanger.

[0018] The cooling device is expediently equipped with means for generating a flow in the buffer medium to improve heat transfer in the partially liquefied buffer medium. These are, for example, means that generate a convective flow within a buffer tank filled with the buffer medium, such as a stirring device or a circulation line, by means of which, during operation of the device, liquid buffer medium is continuously withdrawn from a first region of the buffer tank filled with the buffer medium and fed into another region of the buffer tank by means of a pump.

[0019] A suitable embodiment of the invention provides that the cooling device is equipped with at least two separate buffer media, each having different solid-liquid phase transition temperatures and independently of one another, which can be brought into thermal contact with the hydrogen to be supplied to the container. The line system transporting the hydrogen from the gas supply system to the container thus branches into two or more sub-lines, each of which passes through a first heat exchanger in a buffer container filled with a buffer medium. The buffer containers are each equipped with a second heat exchanger, by means of which the buffer media in the buffer containers can be cooled simultaneously or separately through thermal contact with the cold source.The buffer media in the buffer tanks are designed as latent heat storage devices, but each has different solid-liquid phase transition temperatures. For example, these are mixtures of substances with different compositions, such as ethylene glycol-water mixtures with different mixing ratios. The sub-lines can be controlled separately by a controller, allowing different buffer media to be used to cool the hydrogen depending on the required target temperature. This ensures consistent cooling of the hydrogen to the respective target temperature, even for different refueling tasks, and the required minimum temperature for the hydrogen is not undercut.

[0020] In a further advantageous embodiment of the invention, the line system between the gas supply system and the container to be filled branches into two sub-lines, of which a first sub-line is routed to the first heat exchanger surface for conveying a first partial flow of hydrogen, and a second sub-line is routed as a bypass line for conveying a second partial flow of hydrogen, bypassing the cooling device. The two sub-lines rejoin downstream of the cooling device. A control device enables the quantitative ratio between the first and second partial flows to be controlled depending on the temperature of the hydrogen supplied to the container.In this way, the temperature of the hydrogen can be easily adapted to different target temperatures required by the respective container, even if no different buffer media with different phase transition temperatures, as described above, are available.

[0021] The object of the invention is also achieved by a method having the features of patent claim 12.

[0022] A method for refueling a container with compressed, gaseous hydrogen provides that gaseous hydrogen is provided under pressure in a gas supply system and fed via a line system to a container for refueling and is cooled in a cooling device before being fed to the container. According to the invention, before the start of a refueling process, a buffer medium present in the cooling device, which acts as a latent heat store, is cooled by continuous thermal contact with a cold source and is thereby brought to a temperature below its solid-liquid phase transition temperature. During the refueling process, the buffer medium is then brought into thermal contact with at least a partial flow of the hydrogen to be fed to the container, whereby the hydrogen cools and the buffer medium in the solid state at least partially melts.The container to be filled (fuelled) is, for example, a tank of a vehicle, in particular a road or rail vehicle, a ship or an aircraft, a mobile transport container for hydrogen (trailer) or a pressure container for storing gaseous hydrogen, such as a gas cylinder or a bundle of compressed gas cylinders.

[0023] According to the invention, the conversion enthalpy of the buffer medium is used to cool hydrogen to a substantially constant temperature during one refueling process or during several consecutive refueling processes, without the buffer medium having to be cooled to the same extent at the same time. The buffer medium is preferably cooled continuously. For example, the buffer medium is cooled over a period of time that can be many times longer, for example five to ten times the average duration of a refueling process, thereby enabling the use of a correspondingly low-performance cooling system involving comparatively low investment expenditure. The filling temperature to which the hydrogen is cooled in the cooling device is, for example, between minus 40°C and minus 60°C.Higher filling temperatures are made possible, for example, by a lower heat transfer capacity of the cooling device, the choice of a different buffer medium or by adding correspondingly warmer hydrogen gas.

[0024] The invention enables a refueling system with low installation and maintenance costs. The buffer medium, which acts as a latent heat storage device, enables uniform cooling of the hydrogen during a refueling process and effectively prevents the temperature from falling below a prescribed minimum. The device and method according to the invention are particularly suitable for refueling motor vehicles, work vehicles, such as industrial trucks, at a logistics site, for bus fleets, or regional railway networks served by hydrogen-powered vehicles, although the possible applications are not limited to these.

[0025] An embodiment of the invention will be explained in more detail with reference to the drawing. The schematic views show:

[0026] Fig. 1: A device according to the invention in a first embodiment, Fig. 2: A device according to the invention in a second embodiment.

[0027] The device 1 according to the invention shown in Fig. 1 is used for refueling a container, for example a vehicle tank, with hydrogen. The device 1 has a gas supply system 2 for storing gaseous hydrogen. In the exemplary embodiment shown here, the gas supply system 2 comprises a plurality of pressure vessels 3a, 3b, 3c in which hydrogen is stored at different pressures. For example, the pressure vessel 3a is a high-pressure vessel in which hydrogen is stored at 700 bar or more, the pressure vessel 3b is a medium-pressure vessel in which hydrogen is stored at a pressure between 450 bar and 500 bar, and the pressure vessel 3c is a low-pressure vessel for storing hydrogen at a pressure between 20 bar and 200 bar. Furthermore, the gas supply system 2 can have more or fewer pressure vessels than shown here.The term “pressure vessel” is to be understood very generally here and includes any type of storage from which gaseous hydrogen can be withdrawn at the appropriate pressure, such as pressure tanks or compressed gas cylinder bundles.

[0028] The invention is not limited to a gas supply system with pressure vessels 3a, 3b, 3c; rather, other possibilities for supplying hydrogen gas can also be used, for example, the front line section 5 can be fluidly connected in a manner not shown here to a high-pressure hydrogen line (pipeline) or, via an evaporation unit, to a source of liquid hydrogen or, via a compressor, to a low-pressure vessel or a low-pressure line.

[0029] The device 1 further comprises a line system connected to the gas supply system 2, having a front line section 5 and a rear line section 6 equipped with a connecting mechanism 4 for establishing a flow connection with a container to be filled, in the exemplary embodiment shown here, a vehicle tank 10. The connecting mechanism is adapted to the respective container to be filled; in the exemplary embodiment shown here, the connecting mechanism 4 consists of a fuel pump 7 with a filling hose 8, which, in a conventional manner, has a filling gun 9 for connecting to a corresponding connection on the vehicle tank 10 of a vehicle 11. In the exemplary embodiment shown here, the vehicle 11 is a motor vehicle; however, it could also be, for example, a rail vehicle, an aircraft, or a ship. Suitable motor vehicles to be refueled include, in particular, cars, trucks, or buses.It should be expressly noted that the connecting mechanism shown here, consisting of the filling pump 7, filling hose 8, and filling gun 9, represents only one possibility for establishing a flow connection between a gas supply system 2 and a container to be filled, which is particularly suitable for hydrogen filling stations for vehicles. If other types of containers are to be filled with gaseous hydrogen using the device 1, a different type of connecting mechanism can be used, such as a coupling suitable for the passage of gases.

[0030] In the embodiment shown in Fig. 1, the front line section 5 extending from the gas supply system 2 branches into two sub-lines 12, 13, which rejoin at the rear line section 6. A cooling device 15 for cooling the hydrogen conveyed through the sub-line 12 is arranged in the sub-line 12. Its construction and operation are described in more detail below.

[0031] The cooling device 15 comprises a buffer tank 16, which, during operation of the device 1, is filled with a buffer medium 17 acting as a latent heat storage device. Two heat exchanger surfaces 18, 19, each designed as a coiled tube, are arranged within the buffer tank 16. While the first heat exchanger surface 18 is integrated into the partial line 12, the second heat exchanger surface 19 is fluidly connected to a container 20 for a cryogenic cooling medium, for example, liquid nitrogen, via a cooling line 21. In order to utilize the residual cold of the cooling medium still present after passing through the cooling device 15, the cooling line 21 is thermally connected to the front line section 5 via a double pipe 23. Instead of the double pipe 23, a heat exchanger or a cold storage device can also be provided, although these are not shown here.

[0032] The buffer medium 17 is a medium that undergoes a solid-liquid phase transition during operation of the device 1, whereby its enthalpy of fusion is used for the cooling process. The buffer medium 17 is selected such that its phase transition temperature (melting point) is, on the one hand, below the temperature of the hydrogen entering the heat exchanger surface 18, for example, ambient temperature (20°C), and, on the other hand, above the temperature to which the buffer medium 17 can be cooled by thermal contact with the second heat exchanger surface 19, for example, minus 60°C. The phase transition temperature is preferably equal to or lower than a target temperature for the hydrogen to be supplied to the vehicle tank 11, for example, between minus 40°C and minus 50°C.For example, the buffer medium is octane, carbon dioxide or a mixture of substances, such as a water-glycol mixture, whose melting point can be specified by choosing a suitable mixing ratio of the two components.

[0033] During operation of the device 1, the buffer medium 17 present in the buffer tank 16 is cooled by thermal contact with the cooling medium conveyed through the cooling line 20 before the start of a refueling process to such an extent that it solidifies completely or partially in the buffer tank 16. The cooling process can also be continued during the refueling process, as well as between successive refueling processes or during operational breaks. If the volume of the buffer medium 17 increases during this process, a gas phase 22 present in the buffer tank 16 serves as a compensating volume.

[0034] To refuel the vehicle tank 10, the filling gun 9 is connected to a filler neck of the vehicle tank 10. The filling data (total quantity and pressure of the hydrogen to be filled) are entered at the filling pump 7. Sensors not shown here can also automatically record additional information required and / or appropriate for the filling process, such as the type, current fill level, volume, and / or maximum filling pressure of the vehicle tank 10 and / or the existence of a secure and gas-tight connection between the filling gun 9 and the vehicle tank 10.

[0035] The information thus obtained is transmitted to a control unit 24. Depending on the input and / or recorded information, the control unit 24 issues a control command for releasing hydrogen from the pressure vessels 3a, 3b, 3c according to a predetermined program. For this purpose, the control unit is in data communication with valves 25a, 25b, 25c at the outlets of the pressure vessels 3a, 3b, 3c and with a pressure sensor 26 in the rear line section 6. During refueling, the control unit 24 continuously determines the best possible pressure value for supply from the gas supply system 2 and automatically ensures that the corresponding valve 25a, 25b, 25c is opened or closed. In this way, in particular, the sequence of supplying compressed gas from the pressure vessels 3a, 3b, 3c to the vehicle tank 10 can be controlled with minimal time and energy expenditure.

[0036] For refueling, the hydrogen present in the pressure vessels 3a, 3b, 3c, which is approximately at ambient temperature, must be cooled to a predetermined target temperature of, for example, between minus 20°C and minus 40°C. This is achieved by conducting at least a partial flow of the hydrogen taken from the corresponding pressure vessel 3a, 3b, 3c via the partial line 12, bringing it into indirect thermal contact with the buffer medium 17 at the first heat exchanger surface 18, and then feeding it, cooled, to the vehicle tank 10. Upon thermal contact with the hydrogen at the first heat exchanger surface 18, heat is supplied to the buffer medium 17, and it gradually melts. As long as a solid and a liquid phase of the buffer medium 17 is present in the buffer vessel 16, the temperature of the buffer medium 17 hardly changes, and the cooling capacity transferred to the hydrogen is essentially constant.At the same time, the temperature of the buffer medium 17 does not drop below its melting temperature, eliminating the need for an undertemperature safety shutdown, which would otherwise ensure that the hydrogen is not cooled below a minimum permissible temperature. With appropriate design of the buffer tank 16, this ensures that the temperature conditions in the buffer tank 16 remain essentially constant throughout the duration of a refueling operation or a plurality of consecutive refueling operations.

[0037] The heat supplied via the first heat exchanger surface 18 during the refueling process or during the refueling processes intermittently is continuously extracted from the buffer medium 17 at the second heat exchanger surface 19 through thermal contact with the cryogenic cooling medium conveyed through the cooling line 20. In particular, periods between successive refueling processes or during operational breaks, for example at night, can also be used to cool the buffer medium 17. The cooling capacity of the second heat exchanger surface 19 is selected such that the buffer medium 17 is at least partially in a solid state in the buffer tank 16 before the start of a refueling process, or the first of a series of successive refueling processes. If necessary, the flow rate of the cooling medium conveyed via the cooling line 20 can be adjusted by means of a valve 30 depending on a temperature in the buffer tank.A possible deviation of a temperature measured at a temperature sensor 31 in the buffer tank 16 from the phase transition temperature of the buffer medium 17 serves as a guideline.

[0038] Cooling by means of the cooling device 15 enables the refueling of the vehicle tank 10 with hydrogen, the temperature of which does not exceed the target temperature of the hydrogen in the vehicle tank 10 during the entire refueling process. If necessary, in the exemplary embodiment according to Fig. 1, the temperature of the hydrogen to be supplied to the vehicle tank 11 can be adjusted to different target temperatures. For this purpose, the temperature of the hydrogen in the rear line section 6 is determined using a temperature sensor 27 and compared with the target temperature. Depending on the temperature difference thus determined, the ratio of the partial hydrogen flows conducted through the partial lines 12, 13 can be adjusted by controlling valves 28, 29 in the partial lines 12, 13, and in this way the temperature of the hydrogen supplied to the vehicle tank 10 can be controlled. Such a procedure is, of course, not absolutely necessary within the scope of the invention.For example, if a constant target temperature is required for all refueling processes, sub-line 13 and the corresponding control technology can be dispensed with.

[0039] The device 35 shown in Fig. 2 differs from the device 1 shown in Fig. 1 essentially by a different cooling device. Otherwise identical features are therefore provided with the same reference numerals in Fig. 2 as in the embodiment shown in Fig. 1.

[0040] The cooling device 36 of the apparatus 35 has two buffer tanks 37a, 37b filled with different buffer media 38a, 38b, each acting as a latent heat storage device. The buffer media 38a, 38b have different solid-liquid phase transition temperatures; for example, these are water-glycol mixtures with different compositions. For example, the phase transition temperature of the buffer medium 38a is minus 40°C, and the phase transition temperature of the buffer medium 38b is minus 20°C. First heat exchanger surfaces 39a, 39b are arranged in the buffer tanks 37a, 37b, which are fluidly connected to the front line section 5 and the rear line section e of the line system via partial lines 40a, 40b. Valves 41a, 41b are arranged in the partial lines 40a, 40b and are in data communication with the controller 24.

[0041] Furthermore, second heat exchanger surfaces 42a, 42b are arranged in each of the buffer tanks 37a, 37b, each of which is fluidly connected to a cooling source, in the embodiment shown here to a refrigeration machine 44, via a cooling circuit 43a, 43b. The cooling circuits 43a, 43b are equipped with valves 45a, 45b, with which they can be opened and closed independently of one another. The valves 45a, 45b are each connected to a temperature sensor 46a, 46b via a control system (not shown here), which, as shown here, is arranged in the buffer tank 37a, 37b or at another suitable location. This ensures that the supply of coolant to the second heat exchanger surfaces 42a, 42b is increased or throttled in the event of a temperature deviation from the respective phase transition temperature.As a heat transfer medium in the cooling circuits 43a, 43b, a substance can be considered whose melting temperature is below the melting temperature of the buffer medium 17, for example brine or an ethylene glycol-water mixture of suitable composition.

[0042] Furthermore (not shown here), the second heat exchanger surfaces 42a, 42b can also function as evaporators of a refrigeration machine, in which case no additional cooling circuits 43a, 43b are required to connect the heat exchanger surfaces 42a, 42b to the refrigeration machine 44. Likewise, in the embodiment according to Fig. 2, the buffer media 38a, 38b can be cooled with a cryogenic medium according to the design in Fig. 1, or conversely, in the embodiment according to Fig. 1, a cooling circuit connected to a refrigeration machine can be used to cool the buffer medium 17. During operation of the device 35, the buffer media 38a, 38b are first cooled by means of the cooling circuits 40a, 40b to such an extent that both buffer media 38a, 38b are at least partially in the solid state. Before starting a refueling process, a value for a target temperature for the hydrogen to be filled into the vehicle tank 10 is then entered into the control unit 24.The control unit 24 determines the buffer medium 38a, 38b suitable for this target temperature, hereinafter referred to as buffer medium 38a, for example, and then issues a control command to open the valve 41a and close the valve 41b. The hydrogen from the gas supply system 2 is then cooled using the buffer medium 38a in the manner described above for the exemplary embodiment shown in Fig. 1. Due to the ability of the buffer medium 38a to store absorbed heat in the form of fusion enthalpy, the hydrogen is cooled to a constant temperature throughout the entire refueling process. Furthermore, excessive cooling of the hydrogen is effectively prevented. The cooling of the buffer media 38a, 38b via the cooling circuits 43a, 43b can be continued or interrupted independently of the cooling of the hydrogen.

[0043] Furthermore, in the embodiment according to Fig. 2 (not shown here), a partial line similar to the partial line 13 in Fig. 1 and a corresponding temperature control can be provided, which makes it possible to add warm hydrogen gas to the hydrogen cooled in the cooling device 36 in the rear line section 6 if required.

[0044] Furthermore, means (not shown here) can be provided in the buffer tanks 16, 37a, 37b to generate a convective flow in the respective buffer tank 16, 37a, 37b to ensure good heat transfer. For example, buffer medium 17, 38a, 38b can be continuously withdrawn from the lower region of the buffer tank 16, 37a, 37b and returned to an upper region of the buffer tank 16, 37a, 37b by means of a pump.

[0045] The container to be filled is, in the case of the containers shown here,

[0046] Embodiments relate to the vehicle tank 10 of a vehicle 11. However, the invention is not limited thereto; in principle, the container to be filled can be any type of container in which hydrogen gas is transported and / or stored under pressure. For example, the container to be filled can also be a trailer, a compressed gas cylinder, or a bundle of compressed gas cylinders; in this case, in particular, the connection mechanism between the line system and the container is different from the connection mechanism 4 described here, which consists of a filling pump 7 with a filling hose 8 and a filling gun 9. For example, in such cases, a coupling suitable for hydrogen at the corresponding temperature can be considered, with which a flow-tight, yet detachable connection between the line system and the container to be filled is possible.

[0047] List of reference symbols

[0048] 1 device 24 control unit

[0049] 2 Gas supply system 25a, 25b, 25c valve

[0050] 3a, 3b, 3c Pressure vessel 26 Pressure sensor

[0051] 4 Connection mimic 27 Temperature sensor

[0052] 5 Front line section 28 Valve

[0053] 6 Rear line section 29 Valve

[0054] 7 Fuel pump 30 Valve

[0055] 8 Filling hose 31 Temperature sensor

[0056] 9 Filling gun 32 -

[0057] 10 Vehicle tank 33 -

[0058] 11 Vehicle 34 -

[0059] 12 sub-line 35 device

[0060] 13 Partial line 36 Cooling device

[0061] 14 37a, 37b Container

[0062] 15 Cooling device 38a, 38b Buffer medium

[0063] 16 Tanks 39a, 39b First heat exchanger surface

[0064] 17 Buffer medium 40a, 40b sub-line

[0065] 18 First heat exchanger surface 41 a, 41 b Valve

[0066] 19 Second heat exchanger surface 42a, 42b Second heat exchanger surface

[0067] 20 Cooling line 43a, 43b Cooling circuit

[0068] 21 Container 44 Refrigeration machine

[0069] 22 Gas phase 45a, 45b valve

[0070] 23 Double pipe 46a, 46b Temperature sensor

Claims

Patent claims 1. Device for refueling a container with compressed gaseous hydrogen, comprising a gas supply system (2) for providing compressed gaseous hydrogen, a piping system (5, 6) equipped with a connection mechanism (4) for establishing a flow connection between the gas supply system (2) and a container (10) to be filled, and a cooling device (15, 36) for cooling the hydrogen to be supplied to the container (10), characterized in that the cooling device (15, 36) is equipped with a buffer medium (17, 38a, 38b) functioning as a latent heat storage medium, which is thermally connected at a first heat exchanger surface (18, 39a, 39b) to the gaseous hydrogen to be supplied to the container (10) and at a second heat exchanger surface (19, 42a, 42b) to a cold source (21, 44).

2. Device according to claim 1 , characterized in that the buffer medium (17, 38a, 38b) is selected such that it undergoes at least a partial solid-liquid phase transition during operation of the device (1 ).

3. Device according to claim 2, characterized in that a mixture of substances is used as the buffer medium (17, 38a, 38b) whose solid-liquid phase transition temperature can be varied depending on its composition.

4. Device according to claim 2, characterized in that carbon dioxide is used as the buffer medium (17, 38a, 38b), which can be controlled in the cooling device (15, 36) at a temperature equal to or below the temperature of its triple point.

5. Device according to one of the preceding claims, characterized in that the cold source (21, 44) comprises a refrigeration machine into which the second heat exchanger surface (19, 42a, 42b) is integrated or which is equipped with The second heat exchanger surface (19, 42a, 42b) is thermally connected via a cooling circuit (43a, 43b). Device according to one of the preceding claims, characterized in that the cooling source (21, 44) comprises a tank filled with a cryogenic cooling medium, which is thermally connected to the second heat exchanger surface (19, 42a, 42b) via a cooling line (20). Device according to claim 6, characterized in that a double pipe (23) and / or a further heat exchanger and / or a cold storage unit is arranged in the cooling line (20), downstream of the second heat exchanger surface (19), in which the cryogenic medium can be brought into thermal contact with the hydrogen in the piping system (5, 6), upstream of the first heat exchanger surface (18). Device according to one of the preceding claims, wherein the cooling device (15, 36) is equipped with means for generating a flow in the buffer medium (17, 38a, 38b).Device according to one of the preceding claims, characterized in that the cooling device (15, 36) is equipped with at least two separately provided buffer media (38a, 38b) each with different solid-liquid phase transition temperatures, which can be brought into thermal contact with the hydrogen to be supplied to the container (10) independently of one another at separate heat exchanger surfaces (39a, 39b). Device according to one of the preceding claims, characterized in that the piping system (5, 6) branches into two partial lines (12, 13), a first partial line (12) of which is supplied to the first heat exchanger surface (18, 39a, 39b) for conveying a first partial flow of hydrogen, and a second partial line (13) is routed as a bypass line for conveying a second partial flow of hydrogen, bypassing the cooling device (15, 36), wherein a control device (27) is provided for regulating the ratio between the first and second partial flows.The device is dependent on the temperature of the hydrogen supplied to the container (10). The device according to one of the preceding claims is characterized in that the container (10) is a vehicle tank and the connection mechanism (4) comprises a dispensing pump (7) connected to the piping system (5, 6) and equipped with a filling hose (8) and a filling nozzle (9).A method for refueling a container with compressed, gaseous hydrogen, wherein gaseous hydrogen is provided under pressure in a gas supply system (2) and supplied to a container (10) for refueling via a piping system (5, 6) and is cooled in a cooling device (15, 36) before being supplied to the container (10), characterized in that, prior to the start of a refueling process, a buffer medium (17, 38a, 38b) present in the cooling device (15, 36) and acting as a latent heat storage medium is cooled by thermal contact with a cold source and thereby brought to a temperature below its solid-liquid phase transition temperature, subsequently, during the refueling process, the buffer medium (17, 38a, 38b) is brought into thermal contact with at least a partial flow of the hydrogen to be supplied to the container (10) and cools it, wherein the buffer medium (17, 38a, 38b) in the solid state at least partially melts.

Images