DE102019131405A1 - Method for filling a pressure vessel of a motor vehicle - Google Patents

Abstract

The technology disclosed here relates, according to the invention, to a method for filling a pressure vessel (10) of a motor vehicle with a fluid fuel for driving the motor vehicle, the method comprising the following step: introducing the fuel into the pressure vessel (10) through a filling device of the pressure vessel (10) with a pressure difference between the interior (12) of the pressure vessel (10) and a filling device from which the fuel is introduced into the pressure vessel (10) of approx. 10 to approx. 30 bar such that when the fuel flows in from the Filling device in the interior (12) of the pressure vessel (10) forms a turbulent flow.

Description

The technology disclosed here relates to a method for filling a pressure vessel of a motor vehicle and a pressure vessel for a motor vehicle.

In previously known pressure vessels for storing fuel for motor vehicles, in particular cryogenic hydrogen, an electric tank heat exchanger is often used, which heats hydrogen by means of electricity. To fill the pressure vessel, the pressure vessel has a fueling rod which extends over a large part of the length of the pressure vessel. The fueling rod has a large number of holes or recesses on its circumference, through which the fuel flows or arrives in the pressure vessel. As a result, the fuel is introduced relatively evenly into the interior of the pressure vessel.

The disadvantage of previously known pressure vessels is that the fueling rod has to be mechanically supported in order to prevent or reduce swinging of the loose end of the fueling rod. It is also disadvantageous that the refueling rod makes the manufacture of the pressure vessel more expensive. In addition, the refueling rod increases the weight of the pressure vessel.

It is a preferred object of the technology disclosed here to reduce or eliminate at least one disadvantage of a previously known solution or to propose an alternative solution. In particular, a preferred object of the technology disclosed here is to show a method for filling a pressure vessel of a motor vehicle or a pressure vessel for a motor vehicle in which the fuel in the pressure vessel is technically simply mixed while the fuel is being introduced into the pressure vessel. Further preferred objects can result from the advantageous effects of the technology disclosed here. The object (s) is / are achieved by the subject matter of claim 1 or claim 4 of the independent claims. The dependent claims represent preferred configurations.

In particular, the object is achieved by a method for filling a pressure vessel of a motor vehicle with a fluid fuel for driving the motor vehicle, the method comprising the following step: introducing the fuel into the pressure vessel through a filling device of the pressure vessel with a pressure difference between the interior of the pressure vessel and a filling device, from which the fuel is introduced into the pressure vessel, from approx. 10 to approx. 30 bar in such a way that a turbulent flow is formed when the fuel flows into the interior of the pressure vessel from the filling device.

One advantage of this is that the fuel in the pressure vessel is mixed by the introduction of fuel into the pressure vessel, since the fuel flows into the pressure vessel in different directions over time. As a result, temperature gradients within the pressure vessel are reduced or a temperature equalization takes place over the interior of the pressure vessel. In addition, no fueling rod or the like is required. This saves costs and weight. In particular, no larger structure, such as a fueling rod or the like, has to be arranged in the interior space for introducing the fuel into the pressure vessel. The change in the direction of flow of the fuel over time is typically not precisely predictable. However, it is sufficient that the inflow direction changes randomly or chaotically over time (e.g. every few minutes).

In particular, the object is also achieved by a pressure vessel for a motor vehicle for storing fuel, the pressure vessel having a filling device for filling the fluid fuel into the pressure vessel, the filling device being designed in such a way that in the event of a pressure difference between the interior of the pressure vessel and a Filling device, from which the fuel is introduced into the pressure vessel, from approx. 10 to approx. 30 bar, a turbulent flow is formed when the fuel flows into the pressure vessel from the filling device.

The advantage of this is that, in the pressure vessel, the fuel is mixed by introducing fuel into the pressure vessel, since the fuel flows into the pressure vessel in different directions over time. By changing the direction of flow, temperature gradients within the pressure vessel are reduced or temperature equalization takes place over the interior of the pressure vessel. The pressure vessel also does not require a fueling rod or the like. As a result, the pressure vessel can have a low weight and can be manufactured inexpensively. In particular, there is no need to arrange a larger structure such as a fueling rod or the like in the interior of the pressure vessel for introducing the fuel into the pressure vessel. The change in the direction of flow of the fuel over time is typically not precisely predictable. However, it is sufficient that the inflow direction changes randomly or chaotically over time (e.g. every few minutes).

In particular, the object is also achieved by a motor vehicle with a pressure vessel described above.

According to one embodiment of the method, the fuel is introduced into the pressure vessel through the filling device in such a way that the Reynolds number is greater than approximately 3 * 10 ⁵ . One advantage of this is that it is ensured that the direction of flow of the fuel into the pressure vessel changes often enough within a filling process or quickly enough. It is thus achieved that the inflow direction often changes even with a brief filling process, and consequently good mixing of the fuel in the pressure vessel takes place. It also ensures that the inflow is turbulent.

According to one embodiment of the method, the fuel is introduced into the pressure vessel through the filling device in such a way that the Reynolds number is less than approximately 3 * 10 ⁶ . The advantage here is that too great a pressure loss through the filling device of the pressure vessel is prevented. Thus, if the fuel is well mixed in the pressure vessel, it is ensured at the same time that the fuel flows into the pressure vessel with sufficient pressure.

According to one embodiment of the pressure vessel, the filling device is designed such that with a pressure difference between the interior of the pressure vessel and a filling device from which the fuel is introduced into the pressure vessel, the Reynolds number is greater than approx . 3 * 10 ⁵ is. The advantage of this is that in the case of the pressure vessel it is ensured that the direction of flow of the fuel into the pressure vessel changes often enough within a filling process or quickly enough. What is achieved hereby is that the inflow direction often changes even with a brief filling process and consequently the fuel in the pressure vessel is thoroughly mixed. It is also ensured that the flow of fuel into the pressure vessel is turbulent.

According to one embodiment of the pressure vessel, the filling device is designed in such a way that, in the event of a pressure difference between the interior of the pressure vessel and a filling device from which the fuel is introduced into the pressure vessel, the Reynolds number is less than approx 3 * 10 ⁶ is. One advantage of this is that an excessive pressure loss in the pressure vessel due to the filling device of the pressure vessel is prevented. Consequently, if the fuel is well mixed in the pressure vessel, it is ensured at the same time that the fuel flows into the pressure vessel with sufficient pressure.

According to one embodiment of the pressure vessel, the filling device comprises a filling pipe which has an inside diameter of approximately 1 mm to approximately 3 mm. One advantage of this is that the Reynolds number required, at which a turbulent flow occurs and the direction of flow of the fuel into the pressure vessel changes over time, can be achieved in a technically particularly simple manner, especially at low flow velocities.

According to one embodiment of the pressure vessel, the filling device protrudes into the interior of the pressure vessel. The advantage of this is that the area through which the filling device or the filling pipe passes is thermally insulated so that this area is not cooled excessively by the inflowing fuel. This prevents mechanical stresses from occurring due to large temperature differences between parts of the pressure vessel.

According to one embodiment of the pressure vessel, the filling device is designed at least partially at a distance from a receiving element for a valve of the pressure vessel. One advantage of this is that the receiving element for the valve or the boss is technically simply thermally insulated from the filling device or the filling pipe. This prevents the boss from cooling down significantly compared to the rest of the pressure vessel, which could lead to strong mechanical stresses.

According to one embodiment of the pressure vessel, the filling device is fixed in a receiving element for a valve of the pressure vessel by means of stamping. The advantage here is that the filling device or the filling pipe is thereby technically simply attached or firmly locked with good thermal insulation. This reliably prevents the filling device or the filling pipe from moving or fidgeting while fuel is being introduced into the pressure vessel.

According to one embodiment of the pressure vessel, the pressure vessel further comprises an electrical heat exchanger. One advantage of this is that the fuel in the pressure vessel can be heated in a technically simple manner. Since the pressure vessel does not have to have a fueling rod, the electrical heat exchanger can be arranged in the pressure vessel without mechanical restrictions.

The technology disclosed here relates to a fuel cell system with at least one fuel cell. The fuel cell system is intended, for example, for mobile applications such as motor vehicles (for example passenger cars, motorcycles, utility vehicles), in particular for providing the Energy for at least one prime mover for locomotion of the motor vehicle. In its simplest form, a fuel cell is an electrochemical energy converter that converts fuel and oxidizing agents into reaction products, producing electricity and heat in the process. The fuel cell comprises an anode and a cathode, which are separated by an ion-selective and ion-permeable separator, respectively. The anode is supplied with fuel. Preferred fuels are: hydrogen, low molecular weight alcohol, biofuels, or liquefied natural gas. The cathode is supplied with oxidizing agent. Preferred oxidizing agents are, for example, air, oxygen and peroxides. The ion-selective separator can be designed, for example, as a proton exchange membrane (PEM). A cation-selective polymer electrolyte membrane is preferably used. Materials for such a membrane are, for example: Nafion®, Flemion® and Aciplex®.

In addition to the at least one fuel cell, a fuel cell system comprises peripheral system components (also called balance of plant components or BOP components) that can be used when operating the at least one fuel cell. As a rule, several fuel cells are combined to form a fuel cell stack.

The technology disclosed here relates to a pressure vessel system (compressed hydrogen storage system) for a motor vehicle (e.g. passenger cars, motorcycles, commercial vehicles). The pressure vessel system is used to store fuel which is gaseous under ambient conditions. The pressure vessel system can be used, for example, in a motor vehicle that is operated with compressed (also called compressed natural gas or CNG) or liquefied (also called liquid natural gas or LNG) natural gas or with hydrogen.

Such a pressure vessel system comprises at least one pressure vessel. The pressure vessel can be, for example, a cryogenic pressure vessel or a high-pressure gas vessel.

High-pressure gas container systems are designed, essentially at ambient temperatures, fuel (e.g. hydrogen) permanently at a nominal operating pressure (also called nominal working pressure or NWP) of over approx. 350 barg (= overpressure compared to atmospheric pressure), further preferably of over approx. 500 barg particularly preferred to store from over approx. 700 barg.

The cryogenic pressure vessel system includes a cryogenic pressure vessel. The cryogenic pressure vessel can store fuel in the liquid or supercritical state. A supercritical aggregate state is a thermodynamic state of a substance that has a higher temperature and a higher pressure than the critical point. The critical point describes the thermodynamic state at which the densities of gas and liquid of the substance coincide, i.e. the substance is single-phase. While one end of the vapor pressure curve is identified in a pT diagram by the triple point, the critical point represents the other end. In the case of hydrogen, the critical point is 33.18 K and 13.0 bar. A cryogenic pressure vessel is particularly suitable for storing the fuel at temperatures that are well below the operating temperature (meaning the temperature range of the vehicle environment in which the vehicle is to be operated) of the motor vehicle, for example at least 50 Kelvin, preferably at least 100 Kelvin or . at least 150 Kelvin below the operating temperature of the vehicle (usually approx. - 40 ° C to approx. + 85 ° C). The fuel can be hydrogen, for example, which is stored in the cryogenic pressure vessel at temperatures of approx. 34 K to 360 K. The cryogenic pressure vessel can in particular comprise an inner vessel which is designed for a nominal operating pressure (also called nominal working pressure or NWP) of approx. 350 barg (= overpressure compared to atmospheric pressure), preferably of approx. 500 bar, and particularly preferably of approx 700 barg or more. The fuel is stored in the inner container. The outer container preferably closes off the pressure container from the outside. The cryogenic pressure vessel preferably comprises a vacuum with an absolute pressure in the range from 10 ^-9 mbar to 10 ^-1 mbar, further preferably from 10 ^-7 mbar to 10 ^-3 mbar and particularly preferably from about 10 ^-5 mbar, that at least in some areas between the inner container and the outer container in an evacuated (intermediate) space or vacuum V is arranged. Storage at temperatures (just) above the critical point has the advantage over storage at temperatures below the critical point that the storage medium is single-phase. So there is no interface between liquid and gaseous, for example.

The pressure vessel can comprise a liner. The liner forms the hollow body in which the fuel is stored. The liner can be made, for example, of aluminum or steel or of their alloys. Furthermore, the liner can preferably be made from a plastic. A linerless pressure vessel can also be provided.

The filling device can typically comprise or be a filling station for filling the pressure vessel with fuel. The filling device can be a hydrogen filling station, for example. The Filling device can provide cryogenic hydrogen for refueling the pressure vessel.

In other words, the technology disclosed here relates to a method or a pressure vessel in which the fuel is introduced through a filling device, in particular a filling pipe with a predetermined diameter, at usual inflow velocities or pressure differences, so that the fuel has such a high Reynolds number which leads to the formation of a turbulent flow and the inflow direction of the fuel changing over time when it leaves the filler pipe (e.g. the inflow direction changes every 30 seconds).

• 1 eine schematische Ansicht eines Druckbehälters gemäß der hier offenbarten Technologie;
• 2 eine Detailansicht der Einfülleinrichtung des Druckbehälters aus 1;
• 3 eine schematische Seitenansicht des Druckbehälters aus 1 zu einem ersten Zeitpunkt;
• 4 eine schematische Aufsicht des Druckbehälters aus 1 zu dem ersten Zeitpunkt;
• 5 eine schematische Seitenansicht des Druckbehälters aus 1 bzw. 3 zu einem zweiten Zeitpunkt;
• 6 eine schematische Aufsicht des Druckbehälters aus 1 bzw. 3 zu einem zweiten Zeitpunkt; und
• 7 eine Querschnittsansicht der Einfülleinrichtung aus 2 entlang der Linie VII-VII.

The technology disclosed here will now be explained with reference to the figures. Show it:

• 1 a schematic view of a pressure vessel according to the technology disclosed herein;
• 2 a detailed view of the filling device of the pressure vessel 1 ;
• 3rd a schematic side view of the pressure vessel from 1 at a first point in time;
• 4th a schematic plan view of the pressure vessel 1 at the first time;
• 5 a schematic side view of the pressure vessel from 1 or. 3rd at a second point in time;
• 6th a schematic plan view of the pressure vessel 1 or. 3rd at a second point in time; and
• 7th a cross-sectional view of the filling device 2 along the line VII-VII.

1 shows a schematic view of a pressure vessel 10 according to the technology disclosed herein. 2 shows a detailed view of the filling device of the pressure vessel 10 out 1 .

The pressure vessel 10 is designed to store a fuel, in particular cryogenic hydrogen. The pressure vessel 10 is designed to be arranged in a motor vehicle. The fuel drives the motor vehicle. In particular, the hydrogen can drive a fuel cell that provides the motor vehicle with electrical power for locomotion.

The motor vehicle can be a car, a truck, a bus, a motorcycle, a train, a ship, a helicopter or an airplane.

The pressure vessel 10 is cigar-shaped. At one longitudinal end of the pressure vessel 10 is a receiving element for a valve of the pressure vessel 10 educated. The receiving element also becomes boss 15th called. The boss 15th can be made of metal or a metal alloy such as steel. By the boss 15th leads a filling device. The filling device can be a filling pipe 35 or comprise a nozzle. Via the filler pipe 35 gets cryogenic hydrogen in the interior 12th of the pressure vessel 10 brought in.

The filler pipe 35 has a substantially circular cross-section. The diameter of the filler pipe 35 can be in the range between approx. 1 mm and approx. 3 mm. For example, the filler pipe 35 a diameter of approx. 2 mm.

For filling the pressure vessel 10 becomes the pressure vessel 10 or the interior 12th of the pressure vessel 10 via the filler pipe 35 with a refueling point for filling the pressure vessel 10 fluidly connected with cryogenic hydrogen.

The pressure vessel 10 has a filling device, which is a refueling line 30th and a thin metal pipe 35 or has a nozzle, wherein the refueling line 30th into the thin metal tube 35 transforms. The metal pipe 35 or the nozzle faces the rest of the filling device or the refueling line 30th a slightly smaller cross-section or diameter. The difference can be in the range between approx. 0.2 mm and approx. 0.5 mm.

The metal pipe 35 is at a distance from the boss 15th , which is usually made of stainless steel, arranged. This is the boss 15th opposite the filler pipe 35 or metal pipe or nozzle or the cryogenic hydrogen that flows through the filler pipe 35 or metal pipe or the nozzle flows, thermally insulated.

The metal pipe 35 stands something, for example approx. 0.1 mm to approx. 1.5 mm, for example approx. 1 mm, above the boss 15th in the interior 12th of the pressure vessel 10 in front. This is in 2 clearly visible. This means that the metal pipe 35 in the interior 12th of the pressure vessel 10 protrudes. This prevents the inflowing hydrogen from being the boss 15th cools significantly more than the rest of the pressure vessel 10 . This creates greater mechanical stresses in the boss 15th prevented.

The refueling point pumps the cryogenic hydrogen through the filler pipe 35 or metal pipe or the nozzle into the interior 12th of the pressure vessel 10 . Typically, a pump at the refueling point ensures a pressure difference of approx. 20 bar between the pump and the hydrogen in the pressure vessel 10 .

The filling device or the metal pipe 35 of the pressure vessel 10 is designed in such a way that the hydrogen has a high Reynolds number when flowing in, so that a turbulent flow of the fuel occurs when flowing into the interior 12th of the pressure vessel 10 trains. The Reynolds number can be in the range from approx. 3 * 10 ⁵ to approx. 3 * 10 ⁶ . The direction of inflow changes due to the Reynolds number or the turbulent flow 50 of the hydrogen in the interior 12th of the pressure vessel 10 over time. The flow of hydrogen into the interior 12th of the pressure vessel 10 is unstable due to the Reynolds number.

A Reynolds number above 3 * 10 ⁶ would also change the direction of flow 50 of the hydrogen in the pressure vessel 10 lead over time, but then there is the pressure drop through the filler pipe 35 or the nozzle is typically undesirably high.

3rd shows a schematic side view of the pressure vessel 10 out 1 at a first point in time. 4th shows a schematic top view of the pressure vessel 10 out 1 at the first time.

In 3rd is the upper part of the pressure vessel 10 seen above and the lower part of the pressure vessel 10 can be seen below. In 4th is the left part of the pressure vessel 10 seen above and the right part of the pressure vessel 10 can be seen below.

At the first point in time when hydrogen flows into the interior 12th of the pressure vessel 10 through the filler pipe 35 or the metal pipe or the nozzle, the fuel flows down to the left. The "bottom left" direction is to be understood based on an observer who is walking along the center line of the metal pipe 35 towards the interior 12th of the pressure vessel 10 looks.

This direction of flow 50 is typically maintained for a few seconds to a few tens of seconds or a few minutes. Then changes due to the change in the pressure conditions or the density of the hydrogen in the pressure vessel 10 the direction of flow 50 of the hydrogen in the pressure vessel 10 .

5 shows a schematic side view of the pressure vessel 10 out 1 or. 3rd at a second point in time. 6th shows a schematic top view of the pressure vessel 10 out 1 or. 3rd at a second point in time.

In 5 is the upper part of the pressure vessel 10 seen above and the lower part of the pressure vessel 10 can be seen below. In 6th is the left part of the pressure vessel 10 seen above and the right part of the pressure vessel 10 can be seen below.

At the second point in time, the direction of inflow is different from the first point in time 50 of the hydrogen in the interior 12th of the pressure vessel 10 changed. At the second point in time, the hydrogen flows in an inflow direction 50 , which points to the top right, into the interior 12th of the pressure vessel 10 .

The direction "top right" is to be understood based on an observer who is walking along the center line of the metal pipe 35 towards the interior 12th of the pressure vessel 10 looks.

By changing the direction of flow 50 thermal mixing of the fuel or the hydrogen takes place in the interior 12th of the pressure vessel 10 instead of. This creates mechanical stresses in the pressure vessel 10 prevented or reduced by larger temperature differences.

The change in the direction of flow 50 typically takes place several times during a filling process or a refueling process. An almost empty pressure vessel 10 Filling it completely takes about 5 minutes, for example, with the direction of flow changing every 20 to 40 seconds 50 of the hydrogen in the pressure vessel 10 .

The filler pipe 35 or the nozzle does not move, neither actively nor passively. The change in the direction of flow 50 is mainly caused by pressure changes and / or temperature changes and / or changes in the inflow velocity of the hydrogen.

At the beginning of the filling of an essentially empty pressure vessel 10 is the inflow speed of the hydrogen into the interior 12th of the pressure vessel 10 through the filler pipe 35 or metal pipe or the nozzle approx. 800 m / s to approx. 2000 m / s. Here the Reynolds number is in the order of magnitude of approx. 1 * 10 ⁶ .

By increasing the pressure or the density of the fuel in the pressure vessel 10 the inflow velocity in the filler pipe decreases 35 or metal pipe or the nozzle during the refueling process. When the pressure vessel 10 is almost full during the refueling process, the inflow velocity is, for example, only approx. 50 m / s to approx. 100 m / s. This reduces the Reynolds number. At the end of the refueling process, the Reynolds number is typically in the range of approx. 0.5 * 10 ⁵ . Also at the end of the filling process of the pressure vessel 10 with fuel there is a turbulent flow.

The Reynolds number is above or significantly above the critical Reynolds number, so that a turbulent flow develops.

Thus, the inflow velocity can change faster or more often at the beginning of a refueling process than towards the end of a (complete) refueling process. This is also desirable since there is little hydrogen in the pressure vessel at the beginning 10 is located, which serves as a thermal buffer, while at the end of the refueling process there is a lot of hydrogen in the pressure vessel 10 and thus a lot of hydrogen can serve as a thermal buffer. The thermal buffer prevents major temperature differences between different parts of the pressure vessel 10 and thus prevents the development of mechanical stresses, especially in the metallic liner and in the carbon fiber reinforced plastic (CFRP) of the pressure vessel 10 .

The high Reynolds number has the effect that one direction of flow of the hydrogen fidgets back and forth in all directions. The direction of flow 50 is not always horizontally in the middle, but sometimes a few degrees upwards, shortly afterwards a few degrees downwards, shortly afterwards a few degrees to the left and shortly afterwards a few degrees to the right. These changes of direction very often happen in the course of refueling.

7th FIG. 13 shows a cross-sectional view of the filling device from FIG 2 along the line VII-VII. The cross-section is perpendicular to the center line of the filler pipe 35 or the nozzle.

The filling device points in the area of the metal pipe 35 or the nozzle on an embossing. At 3 points in the circumferential direction of the metal pipe 35 are equidistant from each other (so to speak at 12 o'clock, 4 o'clock and 8 o'clock of a clock), the metal tube 35 in each case a projection or an embossing element 40-42 on the outside and a corresponding depression on the inside. These depressions are compared to the inner diameter of the metal pipe 35 slightly, for example, they have a depth or height in the range from approx. 0.2 mm to approx. 0.5 mm.

The protrusions contact the inner surface of a cylindrical recess of the boss 15th of the pressure vessel 10 . The rest of the outer surface of the metal pipe 35 touches the boss 15th of the pressure vessel 10 Not. This is the boss 15th opposite the metal pipe 35 thermally insulated.

Because the metal pipe 35 about the boss 15th in the interior 12th of the pressure vessel 10 protrudes, hydrogen remains more or less dormant in the area between the metal tube 35 and boss 15th near the interior 12th . This hydrogen contributes to the thermal insulation between the metal pipe 35 and boss 15th at.

For reasons of legibility, the expression “at least one” has been partially omitted for the sake of simplicity. If a feature of the technology disclosed here is described in the singular or indefinitely (e.g. the / a pressure vessel 10 , the one filling device, the filling pipe 35 , the / a boss 15th , the / a nozzle, the / an embossing, etc.), the plurality of these should also be disclosed at the same time (eg the at least one pressure vessel 10 , the at least one filling device, the at least one filling pipe 35 who is at least one boss 15th , the at least one nozzle, the at least one stamping, etc.).

The term “essentially” (eg “essentially vertical axis”) in the context of the technology disclosed here includes the exact property or the exact value (e.g. “vertical axis”) as well as deviations that are insignificant for the function of the property / value (eg “tolerable deviation from the vertical axis”).

The foregoing description of the present invention is for illustrative purposes only and not for the purpose of limiting the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents.

List of reference symbols

10

pressure vessel

12th

inner space

15th

boss

30th

Refueling line

35

Filler pipe (metal pipe)

40-42

Stamping element

50

Direction of flow

Claims (12)

A method for filling a pressure vessel (10) of a motor vehicle with a fluid fuel for driving the motor vehicle, the method comprising the following step: introducing the fuel into the pressure vessel (10) through a filling device of the pressure vessel (10) with a pressure difference between the interior space ( 12) des Pressure vessel (10) and a filling device from which the fuel is introduced into the pressure vessel (10) from approx. 10 to approx. 30 bar in such a way that when the fuel flows from the filling device into the interior (12) of the pressure vessel ( 10) forms a turbulent flow. Procedure according to Claim 1 , the fuel being introduced into the pressure vessel (10) through the filling device in such a way that the Reynolds number is greater than approx. 3 * 10 ⁵ . Procedure according to Claim 1 or 2 , the fuel being introduced into the pressure vessel (10) through the filling device in such a way that the Reynolds number is less than approx. 3 * 10 ⁶ . Pressure vessel (10) for a motor vehicle for storing fuel, wherein the pressure vessel (10) has a filling device for filling the fluid fuel into the pressure vessel (10), wherein the filling device is designed such that in the event of a pressure difference between the interior (12) of the pressure vessel (10) and a filling device from which the fuel is introduced into the pressure vessel (10), from approx. 10 to approx. 30 bar The flow of fuel from the filling device into the interior (12) of the pressure vessel (10) forms a turbulent flow. Pressure vessel (10) Claim 4 , wherein the filling device is designed such that with a pressure difference between the interior (12) of the pressure vessel (10) and a filling device from which the fuel is introduced into the pressure vessel (10), the Reynolds number is greater than approx. 3 * 10 ⁵ . Pressure vessel (10) Claim 4 or 5 , wherein the filling device is designed such that with a pressure difference between the interior (12) of the pressure vessel (10) and a filling device from which the fuel is introduced into the pressure vessel (10), the Reynolds number is less than approx. 3 * 10 ⁶ . Pressure vessel (10) according to one of the Claims 4 - 6th wherein the filling device comprises a filling tube (35) which has an inside diameter of approximately 1 mm to approximately 3 mm. Pressure vessel (10) according to one of the Claims 4 - 7th , wherein the filling device protrudes into the interior (12) of the pressure vessel (10). Pressure vessel (10) according to one of the Claims 4 - 8th wherein the filling device is at least partially spaced apart from a receiving element for a valve of the pressure vessel (10). Pressure vessel (10) according to one of the Claims 4 - 9 , wherein the filling device is fixed in a receiving element for a valve of the pressure vessel (10) by means of stamping. Pressure vessel (10) according to one of the Claims 4 - 10 , further comprising an electrical heat exchanger. Motor vehicle with a pressure vessel (10) according to one of the Claims 4 - 11 .

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