DE102016216551A1 - Method for determining the insulation quality of a pressure vessel for storing a fuel, in particular hydrogen, in a vehicle and pressure vessel system for a vehicle, comprising a pressure vessel for storing a fuel, in particular hydrogen - Google Patents

Abstract

The invention relates to a method for determining an insulation quality of a pressure vessel (10) for storing a fuel, in particular hydrogen, in a vehicle, the amount of heat input per unit of time from the environment into the fuel in the pressure vessel (10), taking into account the removal that may be required of fuel from the pressure vessel (10), wherein the isolation quality of the pressure vessel (10) is determined by the determined amount of heat input per unit time in relation to the temperature of the fuel in the pressure vessel (10) or in relation to the difference between the ambient temperature and the Temperature of the fuel in the pressure vessel (10) is set.

Description

The invention relates to a method for determining the insulation quality of a pressure vessel for storing a fuel, in particular hydrogen, in a vehicle and a pressure vessel system for a vehicle, comprising a pressure vessel for storing a fuel, in particular hydrogen.

In particular, cryogenic pressure vessels are not in thermodynamic equilibrium with the environment, but the fuel in the pressure vessel is at lower temperatures than the environment. In previously known pressure vessel systems in vehicles, the entry of heat / heat input per unit time from the environment into the fuel in the pressure vessel (s) is detected. Depending on the quality of insulation and thermodynamic state of the pressure vessel, the heat input per unit time from the environment into the fuel is different. The heat input per unit time usually changes with time (eg, when removing fuel from the pressure vessel, by reducing thermal mass, expanding cooling, and by degrading the evacuated space located between an inner vessel and an outer vessel of the pressure vessel).

The mere statement of the heat input per unit time in the fuel, however, may be insufficient in certain cases, since this information does not always allow reliable statements about the isolation quality of the pressure vessel.

It is a preferred object of the technology disclosed herein to reduce or eliminate at least some of the disadvantages of the previously known solutions. Other preferred objects may result from the beneficial effects of the technology disclosed herein. The object (s) is / are solved by the subject matter of patent claim 1 of the independent claims and by the subject matter of claim 8 of the independent claims. The dependent claims are preferred embodiments.

In particular, the object is achieved by a method for determining an isolation quality of a pressure vessel for storing a fuel, in particular hydrogen, in a vehicle, wherein the heat quantity entry per unit time from the environment into the fuel in the pressure vessel taking into account the possibly taking place of fuel from the pressure vessel is determined, the insulation quality of the pressure vessel is determined by the determined amount of heat per unit time is set in relation to the temperature of the fuel in the pressure vessel or in relation to the difference between the ambient temperature and the temperature of the fuel in the pressure vessel.

An advantage of this is that for sure, d. H. taking into account the ambient temperature, it can be determined how good the insulation or insulation quality of the pressure vessel is. Thus, it can be decided at which point in time the density in the evacuated space of the pressure vessel between the inner container and the outer container of the pressure vessel should be reduced by evacuating the space again, or the evacuated space should be (again) evacuated in order to increase the isolation quality to restore the original insulation quality of the pressure vessel. When deciding when to evacuate the evacuated space, it may be considered whether vehicle journeys are planned over longer distances (eg more than 100 km or more than 200 km at a time) and / or if one is Filling the pressure vessel with warm (ie non-cryogenic) fuel is sufficient for the time being. In particular, "ratioing" may include calculating the isolation quality based on the determined amount of heat input per unit time taking into account the temperature of the fuel in the pressure vessel or taking into account the difference between the ambient temperature and the temperature of the fuel in the pressure vessel. The determination of the isolation quality does not have to take place by forming a fixed ratio between the stated values, but the isolation quality can be determined on the basis of the stated values by a formula / an algorithm and / or by means of characteristic curves.

The determination of the amount of heat input per unit time can be carried out during the operation of the vehicle. An advantage of this is that the vehicle need not be parked or taken out of service to determine the isolation quality. This leads to more recent values of the insulation quality.

In order to take into account the optionally taking of fuel from the pressure vessel in the determination of the amount of heat input per unit time, the temperature and / or the mass of the fuel removed from the pressure vessel can be determined. As a result, the removal of fuel from the pressure vessel can be taken into account particularly precisely in the determination of the insulation quality. Thus, the isolation quality can be determined even more precisely.

The isolation quality can be displayed to the driver in a display, in particular graphically, preferably in a color-differentiated display become. As a result, the driver and / or a workshop employee can detect the insulation quality technically simple and fast. Thus, the decision as to when the evacuated space of the pressure vessel is evacuated again can be made even easier. In addition, in an unforeseen event (eg, an accident, a collision with low speed, damage to the underbody of the vehicle or the like) quickly and safely, even by laymen, the insulation quality and / or the change in the insulation quality (before the accident / after the accident) are detected. Based on this information, the decision can then be made as to whether a workshop should be visited promptly. Even for a layman is by a graphic display, which in particular a color gradient of the color "red" (low isolation quality) to the color "green" (high isolation quality), quickly and easily recognizable how high or low the insulation quality of the pressure vessel ,

The determination of the amount of heat input per unit of time can be repeatedly determined, in particular at predetermined time intervals. As a result, the detected or indicated insulation quality always essentially corresponds to the insulation quality actually present.

If it is determined that the isolation quality is below a threshold value, the filling of the pressure vessel with cold fuel can be prevented or a filling process of the pressure vessel with fuel can be ended before the maximum possible fuel density in the pressure vessel. An advantage of this is that cryogenic fuel is prevented from being introduced into the pressure vessel, although the quality of isolation of the pressure vessel is insufficient or not sufficiently high. The filling with cryogenic fuel or with a large amount of cryogenic fuel with insufficient isolation quality of the pressure vessel would lead to a rapid heating of the fuel and then to a pressure increase of the fuel in the pressure vessel up to the maximum operating pressure of the pressure vessel. If the maximum operating pressure of the pressure vessel is reached or exceeded, then fuel would have to be blown off (and reacted, for example, with a blow-off management system). Consequently, fuel would be wasted as it would be introduced into the pressure vessel, although it is foreseeable that it will not be consumed (eg by the fuel cell) before fuel has to be blown off due to excessive pressure of the fuel in the pressure vessel -off or boil-off). Thus fuel is saved. The limit value can be fixed or calculated.

If it is determined that the isolation quality is below a threshold value, an evacuated space between an inner tank for storing the fuel and an outer tank of the pressure vessel can be evacuated by means of a vacuum pump to increase the insulation quality. The advantage of this is that the isolation quality of the pressure vessel, especially during travel or operation of the vehicle, can be increased again without bringing the vehicle to a workshop and / or connect to the vehicle without further devices or vacuum pumps. The evacuated space can alternatively be evacuated at intervals or in fixed predetermined cycles by means of the vacuum pump or when the insulation quality falls below a limit. The limit value can be fixed or calculated.

In particular, the object is also achieved by a pressure vessel system for a vehicle, comprising a pressure vessel for storing a fuel, in particular hydrogen, comprising: a measuring device for determining the amount of heat input per unit time taking into account the optionally taking out of fuel from the pressure vessel; and a control device for determining the insulation quality of the pressure vessel by means of the heat quantity input per unit time, wherein the control device is designed such that the isolation quality can be determined by the heat quantity input per unit time in relation to the temperature of the fuel in the pressure vessel or in relation to the difference between the ambient temperature and the temperature of the fuel in the pressure vessel is set.

An advantage of this is that for sure, d. H. taking into account the ambient temperature, it can be determined how good the insulation or insulation quality of the pressure vessel is. Thus, it can be decided at which time the density in the evacuated space of the pressure vessel between the inner vessel and the outer vessel of the pressure vessel is to be reduced by (re) evacuating the space to increase the isolation quality or restore the original isolation quality of the pressure vessel. In deciding when to evacuate the evacuated space, it may be taken into account whether trips of the vehicle are planned over long distances (eg more than 100 km or more than 200 km at a time) and / or whether Operation of the pressure vessel with warm (ie non-cryogenic) fuel is sufficient for now.

The pressure vessel system may further comprise a display device, in particular a graphic display, preferably a color-differentiated display, for displaying the insulation quality of the Include driver of the vehicle. Thus, the decision as to when the evacuated space of the pressure vessel is evacuated again can be made even easier. In addition, in an unforeseen event (eg, an accident, a collision with low speed, damage to the underbody of the vehicle or the like) quickly and safely, even by laymen, the insulation quality and / or the change in the insulation quality (before the accident / after the accident) are detected. Based on this information, the decision can then be made as to whether a workshop should be visited promptly. Even for a layman is by a graphic display, which in particular a color gradient of the color "red" (low isolation quality) to the color "green" (high isolation quality), quickly and easily recognizable how high or low the insulation quality of the pressure vessel ,

The control device may be designed to compare the insulation quality with a limit, in particular depending on the temperature of the fuel or on the difference between the ambient temperature and the temperature of the fuel, the control device being further configured such that the control device, if determined, that the insulation quality is below the limit value, prevents the filling of the pressure vessel with cold fuel or terminates a filling process of the pressure vessel with fuel before reaching the maximum possible fuel density in the pressure vessel. An advantage of this is that cryogenic fuel is prevented from being introduced into the pressure vessel, although the quality of isolation of the pressure vessel is insufficient or not sufficiently high. The filling with cryogenic fuel or with a large amount of cryogenic fuel with insufficient isolation quality would lead to a rapid heating of the fuel, then to a pressure increase of the fuel in the pressure vessel up to the maximum operating pressure of the pressure vessel. If the maximum operating pressure of the pressure vessel is reached or exceeded, then fuel would have to be blown off (and reacted, for example, with a blow-off management system). Consequently, fuel would be wasted as it would be introduced into the pressure vessel, although it is foreseeable that it will not be consumed (eg, by the fuel cell) before fuel has to be blown off due to excessive fuel pressure (so-called blow-off or boil-off). Thus fuel is saved.

The pressure vessel system may further comprise a temperature measuring device for measuring the temperature of the fuel removed from the pressure vessel and / or a flow measuring device for measuring the flow mass flow of fuel through a withdrawal line to take account of any removal of fuel from the pressure vessel when determining the amount of heat input per unit time. As a result, the removal of fuel from the pressure vessel can be taken into account particularly precisely in the determination of the insulation quality. Thus, the isolation quality can be determined even more precisely.

The pressure vessel may include an inner container for storing the fuel, an outer container and an evacuated space between the inner container and the outer container for heat insulation, the pressure container system further comprising a vacuum pump for increasing the isolation quality of the pressure container by evacuating the evacuated space. The advantage of this is that the isolation quality of the pressure vessel can be increased again, without bringing the vehicle in a workshop and / or connect without further devices or vacuum pumps to the vehicle. The evacuated space can be evacuated at intervals or in fixed predetermined cycles by means of the vacuum pump or if the insulation quality falls below a limit.

By cold fuel is meant in particular cryogenic fuel. By non-cold or warm fuel is meant in particular non-cryogenic fuel.

The fuel may be a (at standard pressure of 1,000 bar and standard temperature of 0 ° C) gaseous fuel, in particular hydrogen.

The amount of heat input per unit of time into the fuel in the pressure vessel can be described in particular by a method which is described in US Pat DE 10 2016 216 525.9 is described. Alternatively, the amount of heat input per unit time can be determined by the slope of the amount of heat of the fuel in the pressure vessel per unit time.

The technology disclosed herein relates to a compressed hydrogen storage (CHS) system for storing gaseous fuel under ambient conditions. Such a pressure vessel is in particular a pressure vessel which is installed or can be installed in a motor vehicle. The pressure vessel can be used in a motor vehicle, which is operated for example with compressed ("compressed natural gas" = CNG) or liquefied (LNG) natural gas or with hydrogen. Such a pressure vessel may be, for example, a cryogenic pressure vessel (= CcH2 system) or a high-pressure gas vessel (= CGH2 system).

High-pressure gas container systems (= CGH2 systems) are designed, essentially at ambient temperatures, fuel (eg hydrogen) permanently at a max. Operating pressure (also called maximum operating pressure or MOP) of about 350 barü (= overpressure relative to the atmospheric pressure), further preferably of about 500 barü and more preferably of about 700 barü store.

The cryogenic pressure vessel system (= CcH2 system) comprises a cryogenic pressure vessel. The cryogenic pressure vessel may store fuel in the liquid or supercritical state. A supercritical state of aggregation is a thermodynamic state of a substance which has a higher temperature and a higher pressure than the critical point. The critical point denotes the thermodynamic state in which the densities of gas and liquid of the substance coincide, that is, it is single-phase. While one end of the vapor pressure curve in a pT diagram is marked by the triple point, the critical point represents the other end. For 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 significantly 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 motor vehicle (usually about -40 ° C to about + 85 ° C). The fuel may be, for example, hydrogen, which is stored at temperatures of about 34 K to 360 K in the cryogenic pressure vessel. The cryogenic pressure vessel may in particular comprise an inner container which is designed for max. Operating pressures (also called maximum operating pressure or MOP) to about 350 barü (= overpressure relative to the atmospheric pressure), preferably up to about 500 barü, and particularly preferably up to about 700 barü. The fuel is stored in the inner container. The outer container preferably closes off the pressure vessel to the outside. Preferably, the cryogenic pressure vessel comprises a vacuum with an absolute pressure in the range of 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 partially 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 present in a single phase. For example, there is no interface between liquid and gaseous.

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

1 a schematic view of the pressure vessel system disclosed herein;

2 the display device of the pressure vessel system 1 ; and

3 a diagram of the amount of heat input per unit time against the difference between the ambient temperature and the fuel temperature.

1 shows a schematic view of the pressure vessel system disclosed here 5 , 2 shows the display device 60 of the pressure vessel system 5 out 1 , The pressure vessel system 5 includes a pressure vessel 10 for storing the fuel, in particular hydrogen. The pressure vessel 10 has an inner container and an outer container. Between the inner container and the outer container, an evacuated space is arranged. The fuel is stored in the inner container.

The hydrogen can be cryogenic hydrogen. The pressure vessel may be a cryogenic hydrogen pressure vessel. Non-cryogenic hydrogen or CNG are also conceivable as fuel.

The insulation quality of the pressure vessel 10 indicates the amount of heat input per unit of time (eg, per second or per minute) from the environment into that in the pressure vessel 10 stored fuel is. The greater the amount of heat input per unit time, the lower the thermal insulation and thus the insulation quality of the pressure vessel 10 ,

The amount of heat input per unit time corresponds to the time rate of change of the amount of heat stored in the fuel, i. H. z. For example, how much Joule per minute are introduced into the fuel due to the temperature difference between the fuel and the environment. The higher the difference or the difference between the ambient temperature and the temperature of the fuel, the greater the amount of heat input (with the same insulation quality).

The amount of heat input per unit time or the time rate of change is determined by a controller 40 detected. To record variables of the extracted fuel and the consideration of the extracted fuel (lower amount of fuel in the pressure vessel 10 , lower temperature of the remaining fuel, lower pressure of the fuel) is a flow meter 47 in the withdrawal line 15 arranged. The sampling line 15 connects the pressure vessel 10 via a tank shut-off valve 17 with the fuel cell 30 or with a fuel consumption device for driving the vehicle. The flowmeter 47 captures the amount of fuel passing through the sampling line 15 flows. A temperature measuring device 43 measures the temperature of the fuel in the pressure vessel 10 , In addition, a pressure measuring device, the pressure of the fuel in the pressure vessel 10 measure up. The control device is via measuring lines 44 . 49 with the temperature measuring device 43 or the flow measuring device 47 connected. The control device 40 is via a control line 48 with the tank shut-off valve 17 connected. This allows the Tankabsperrventil 17 be opened and closed.

By means of the detected values of the fuel, the amount of heat input per unit time from the environment into the fuel, taking into account the optionally taking out of fuel from the pressure vessel 10 be determined. This amount of heat input per unit time is now set in relation to the ambient temperature. Alternatively, the amount of heat input per unit time may be related to the difference between the ambient temperature and the temperature of the fuel in the pressure vessel 10 be set. For this purpose, the control device 40 a characteristic field and / or a database, which for each ratio of heat input and ambient temperature (or difference between the ambient temperature and the temperature of the fuel in the pressure vessel 10 ) indicates a value of the insulation quality. The value of the isolation quality can z. B. in a range between 0 (virtually no isolation, very low isolation quality) to 100 (very good or high insulation, high isolation quality) amount.

The amount of heat input per unit time can be described in particular by a method that is described in the DE 10 2016 216 525.9 is described. Alternatively, the heat input per unit time by the slope of the amount of heat of the fuel in the pressure vessel 10 be determined per unit of time.

The of the control device 40 certain isolation quality may be on a graphical display device 60 be displayed in the same way. A digital display is also conceivable. In the 2 shown display device 60 has a pointer 62 on whose tip moves in front of a display background. The pointer 62 indicates the specific insulation quality. The better the insulation quality, the further to the left is the pointer 62 , Different areas of the ad background are labeled "very good", "ok" and "bad" and "unacceptably bad" to give the driver a linguistic equivalent expression for the particular value. The display background may have a color gradient from "green" (far left) to "red" (far right). The more the background, in front of the top of the pointer 62 is located, corresponds to the color green, the better the insulation quality of the pressure vessel 10 , In the right area is through a dividing line 66 a region indicating heat input that is "improperly poor".

If the isolation quality has a value in the range "unacceptably bad", the control device 40 a filling of the pressure vessel 10 Prevent with cold or cryogenic fuel or prematurely terminate the filling process before reaching the maximum filling density of fuel. Refueling may occur upon reaching a predetermined density value of the fuel in the pressure vessel system 5 or in the pressure vessel 10 to be ended.

In addition, if the insulation quality has a value in the range of "improperly poor", a vacuum pump disposed in the vehicle can be started, and the evacuated space can be (re) evacuated to increase the insulation performance. Also, an interval-like operation (regardless of the specific insulation quality) of the vacuum pump is conceivable. In determining when to activate the vacuum pump, it may be considered that by cold refueling, i. H. a refueling with cryogenic fuel or hydrogen, the vacuum or the evacuated space is improved and thus the insulation quality is increased.

Through the graphic display device 60 the driver or workshop personnel can at any time about the current status of the insulation quality or the insulation quality of the pressure vessel 10 technically easy to inform. The user does not need to have any technical or thermodynamic knowledge in order to be able to interpret the insulation quality of the pressure vessel (eg a purely displayed numerical value). The maintenance of the vehicle is thus facilitated.

The driver or the workshop personnel can decide on the basis of the specific display quality or the display, whether the current insulation quality or insulation quality of the pressure vessel 10 is sufficient and the renewed evacuation of the evacuated space between inner container and outer container (so-called "vacuum pull") take place at a later date. A high isolation quality is z. B. required if a lot of fuel to be stored and / or longer lossless life, ie without blow-off, are required.

If the current insulation quality is sufficient, the pressure vessel 10 only be filled with warm, ie non-kroygenem or gaseous fuel.

The specific isolation quality can be achieved via a wireless connection, eg. As Internet and / or mobile, be sent to a workshop. The workshop can then inform the driver if a new evacuation of the evacuated space is necessary or useful.

The determination of the insulation quality, ie how well the heat insulation of the pressure vessel 10 is, can take place permanently or at timed intervals.

3 FIG. 12 shows a plot of heat input per unit time from the environment into the fuel in the pressure vessel versus the difference between the ambient temperature and the fuel temperature. FIG. Here, the difference or the difference between the ambient temperature and the fuel temperature, ie the temperature of the fuel, and on the y-axis of the heat quantity entry per unit time is shown on the x-axis.

Three characteristic curves (characteristic low heat input per unit time 70 , Characteristic mean heat input per unit time 75 , Characteristic high heat input per unit time 80 ) provide the insulation quality of the pressure vessel 10 Is the determined ratio between the heat quantity input per unit time and the difference between the ambient temperature and the fuel temperature (or alternatively the ambient temperature) on the characteristic low heat input per unit time 70 or the ratio is close to this, the pressure vessel 10 a high insulation quality. Is the determined ratio between the amount of heat input per unit time and the difference between the ambient temperature and the fuel temperature (or alternatively the ambient temperature) on the characteristic high heat input per unit time 80 or the ratio is close to this, the pressure vessel 10 a low or low isolation quality. The values in between each characterize insulation qualities between "very good" or "good" and "bad" or "unacceptably bad". If the ratio is close to the characteristic high heat input per unit time 80 , shows the pointer 62 in 2 corresponding to the area labeled "bad" or "unacceptably bad" (orange to red area).

Accordingly, the pointer points 62 on the green area or the area labeled "very good" if the ratio at or near the characteristic low heat input per unit time 70 lies. Accordingly, the pointer points 62 to the orange area or the area labeled "ok" if the ratio is at or near the characteristic average heat input per unit time 75 lies.

The characteristics 70 . 75 . 80 rise from a small difference between the temperature of the fuel and the ambient temperature or vice versa equidistantly to each other and each reach a horizontally extending plateau. The plateaus are also equidistant from each other. Continue to the right in 3 fall the characteristics 70 . 75 . 80 from the plateau, the characteristic high heat input per unit time 80 Steep falls, as the characteristic average heat input per unit time 75 and as the characteristic low heat input per unit time 70 , The characteristic curve mean heat input per unit time 75 Falls steeper or faster than the characteristic high heat input per unit time 80 , The characteristics 70 . 75 . 80 meet at a large difference between the ambient temperature and between the temperature of the fuel in the pressure vessel 10 ,

For the sake of legibility, the term "at least one" has been omitted for simplicity. If a feature of the technology disclosed here is described in the singular or indefinite (eg the / a pressure vessel), then at the same time its plurality should also be disclosed (eg the at least one pressure vessel).

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 NUMBERS

5

Pressure vessel system

10

pressure vessel

15

withdrawal line

17

tank shutoff valve

30

fuel cell

40

control device

43

Temperature measuring device

44

Measurement line

47

Flow measurement device

48

control line

49

Measurement line

60

display device

62

pointer

64

Display background

66

Dividing line

70

Characteristic low heat input per unit time

75

Characteristic mean heat input per unit time

80

Characteristic high heat input per unit time

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102016216525 [0021, 0035]

Claims (12)

Method for determining an insulation quality of a pressure vessel ( 10 ) for storing a fuel, in particular hydrogen, in a vehicle, the amount of heat input per unit of time from the environment into the fuel in the pressure vessel ( 10 ) taking into account any removal of fuel from the pressure vessel ( 10 ), the insulation quality of the pressure vessel ( 10 ) is determined by the determined amount of heat input per time unit in relation to the temperature of the fuel in the pressure vessel ( 10 ) or in relation to the difference between the ambient temperature and the temperature of the fuel in the pressure vessel ( 10 ) is set. The method of claim 1, wherein the determination of the amount of heat input per unit time during operation of the vehicle is performed. Method according to claim 1 or 2, wherein, in order to take into account the optionally taking off of fuel from the pressure vessel ( 10 ) in the determination of the amount of heat input per unit time, the temperature and / or the mass of the pressure vessel ( 10 ) is determined. Method according to one of the preceding claims, wherein the insulation quality of the driver in a display, in particular graphically, preferably in a color-differentiated display, is displayed. Method according to one of the preceding claims, wherein the determination of the amount of heat input per unit time, in particular at predetermined time intervals, repeatedly determined. Method according to one of the preceding claims, wherein, if it is determined that the insulation quality is below a limit value, the filling of the pressure vessel ( 10 ) prevented with cold fuel or a filling process of the pressure vessel ( 10 ) with fuel before reaching the maximum possible fuel density in the pressure vessel ( 10 ) is terminated. Method according to one of the preceding claims, wherein, when it is determined that the insulation quality is below a threshold, an evacuated space between an inner container for storing the fuel and an outer container of the pressure vessel ( 10 ) is evacuated by means of a vacuum pump to increase the insulation quality. Pressure vessel system ( 5 ) for a vehicle, comprising a pressure vessel ( 10 ) for storing a fuel, in particular hydrogen, comprising: a measuring device for determining the amount of heat input per unit of time, taking into account the optionally taking out of fuel from the pressure vessel ( 10 ); and a control device ( 40 ) for determining the insulation quality of the pressure vessel ( 10 ) by means of the heat quantity entry per unit of time, the control device ( 40 ) is designed such that the insulation quality can be determined by the heat quantity input per unit time in relation to the temperature of the fuel in the pressure vessel ( 10 ) or in relation to the difference between the ambient temperature and the temperature of the fuel in the pressure vessel ( 10 ) is set. Pressure vessel system ( 5 ) according to claim 8, further comprising a display device ( 60 ), in particular a graphic display, preferably a color-differentiated display, for displaying the insulation quality to the driver of the vehicle. Pressure vessel system ( 5 ) according to claim 8 or 9, wherein the control device ( 40 ) for comparing the insulation quality with a, in particular the temperature of the fuel or by the difference between the ambient temperature and the temperature of the fuel dependent, limit value is formed, wherein the control device ( 40 ) is further configured such that the control device ( 40 ), if it is determined that the insulation quality is below the limit, filling the pressure vessel ( 10 ) prevented with cold fuel or a filling process of the pressure vessel ( 10 ) with fuel before reaching the maximum possible fuel density in the pressure vessel ( 10 ) completed. Pressure vessel system ( 5 ) according to any one of claims 8-10, further comprising a temperature measuring device ( 43 ) for measuring the temperature of the pressure vessel ( 10 ) extracted fuel and / or a flow measuring device ( 47 ) for measuring the flow mass flow of fuel through a sampling line ( 15 ) to take account of any removal of fuel from the pressure vessel ( 10 ) in the determination of the amount of heat input per unit time. Pressure vessel system ( 5 ) according to any one of claims 8-11, wherein the pressure vessel ( 10 ) comprises an inner container for storing the fuel, an outer container and an evacuated space between the inner container and the outer container for heat insulation, and wherein the pressure vessel system ( 5 ) Further, a vacuum pump for Increasing the insulation quality of the pressure vessel ( 10 ) by evacuating the evacuated space.

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