Apparatus and method for filling pressurized gas tank

Abstract

The invention relates to a method (100) for filling a tank (1) of pressurized gas by means of a filling device (10) comprising a gas source (2), a filling tube (3) connecting the source (2) to the tank (1), a flow and / or pressure control valve (4), an electronic control member (5) configured to control the flow and / or pressure of the gas present in the tank (1) when an estimated temperature (or density) of the gas reaches a temperature limit value (or accordingly, the estimated temperature (or density) reaches the temperature limit value. The method comprises a step (S1) of determining the ambient temperature (Tamb) at the filling device (10) before filling the tank (1), a step (S2) of determining the pressure (Pini) of the gas present in the tank (1), and a preliminary step (S3) of estimating the initial temperature (Tini) of the gas present in the tank (1), the initial temperature (Tini) of the gas present in the tank is a value estimated on the basis of the ambient temperature (Tamb) and on the basis of the pressure (P) of the gas present in the tank prior to filling the tank, the initial temperature (Tini) of the gas present in the tank being higher than or equal to or lower than or equal to the ambient temperature (Tamb).

Description

[0001] The present invention relates to an apparatus and a method for filling a pressurized gas tank.

[0002] The invention is particularly suitable for filling hydrogen tanks.

[0003] More specifically, the present invention relates to a device for filling a pressurized gas tank, the device comprising a gas source, a filling pipe connecting the source to the tank, a flow and / or pressure control valve located in the filling pipe, a sensor configured to measure the pressure in the tank and / or the ambient temperature on the filling device, and an electronic control unit configured to:

[0004] - stopping the filling when the estimated temperature (respectively, density) of the gas present in the tank reaches a temperature limit value (respectively, density limit value);

[0005] -Estimation of the initial temperature of the gas present in the tank before filling the tank.

[0006] In the device described above, the temperature of the gas present in the tank and in particular the temperature before filling remains difficult to obtain. In a known manner, the initial temperature used in existing filling schemes is derived from the SAE ("Society of Automotive Engineers") recommendations related to filling fuel cell vehicles. The initial temperature is provided as a function of the ambient temperature, according to a predefined curve for hot conditions and a predefined curve for cold conditions.

[0007] However, it has been shown in practice that the initial temperature of the tank to be filled does not always vary according to these curves recommended by the SAE. Therefore, the tank is particularly exposed to the risk of overheating or overfilling if the initial temperature of the tank is outside the safety corridor formed by the curve recommended by the SAE.

[0008] The risk of overheating increases in the case of successive fillings. In fact, although filling generally causes an increase in the temperature of the gas present in the tank, the current schemes consider that, for subsequent fillings, the initial temperature of the tank remains within the safety limits defined by the SAE. Therefore, since the initial temperature of the gas is underestimated during subsequent fillings, contrary to the predictions of the models deployed in the current filling schemes, the temperature limits may be exceeded quickly.

[0009] The object of the present invention is to overcome all or some of the above-mentioned disadvantages of the prior art.

[0010] To this end, the essential feature of the device according to the invention and according to the general definition provided in the above preamble is that the initial temperature is a value estimated based on the ambient temperature and based on the pressure of the gas present in the tank before filling, wherein the initial temperature of the gas in the tank is greater than or equal to or less than or equal to the ambient temperature.

[0011] The invention thus improves the accuracy of estimating the initial temperature of the gas present in the tank, thus limiting the risk of overheating or overfilling the tank.

[0012] The invention also relates to a method for filling a pressurized gas tank, the method being implemented by a filling device comprising a gas source, a filling pipe connecting the source to the tank, a flow and / or pressure control valve located in the filling pipe, and an electronic control unit configured to stop the filling when the estimated temperature (or density) of the gas present in the tank reaches a temperature limit value (or, respectively, a density limit value). The method comprises a step of determining the ambient temperature on the filling device before filling the tank, a step of determining the pressure of the gas present in the tank, and a preliminary step of estimating the initial temperature of the gas present in the tank. The initial temperature of the gas in the tank is a value estimated according to the ambient temperature and according to the pressure of the gas present in the tank before filling, wherein the initial temperature of the gas in the tank is greater than or equal to or less than or equal to the ambient temperature.

[0013] Furthermore, embodiments of the method according to the invention may include one or more of the following features:

[0014] - dividing the initial temperature of the gas in the tank into a first calculated initial temperature corresponding to a state of the tank considered to be most recently filled to a first initial density and a second calculated initial temperature corresponding to a state of the tank considered to be most recently drained to a second initial density;

[0015] the first initial temperature of the gas present in the tank is within a high temperature range having a lower limit determined to be greater than or equal to the ambient temperature and an upper limit corresponding to a determined maximum temperature limit, for example equal to 85° C.;

[0016] - the first initial temperature is determined according to a first predetermined prediction curve "TPgas_hot" provided by a predetermined physical model simulating a reference filling of the tank in the high temperature range;

[0017] - a second initial temperature of the gas present in the tank is within a low temperature range having an upper limit determined to be less than or equal to the ambient temperature and a lower limit corresponding to a determined minimum temperature limit, the determined minimum temperature limit ranging, for example, between zero and -5°C;

[0018] - the second initial temperature is determined according to a second predetermined prediction curve "TPgas_cold" provided by a predetermined physical model simulating a reference discharge of the tank in the low temperature range;

[0019] - the method comprises a step of modeling a first temperature variation curve (or respectively, a first density variation curve) of the gas present in the tank during filling, the first temperature variation curve (or respectively, a first density variation curve) having as starting condition the first initial temperature (or respectively, the first initial density) of the gas present in the tank, and / or a second temperature variation curve (or respectively, a second density variation curve) of the gas present in the tank having as starting condition the second initial temperature (or respectively, the second initial density) of the gas present in the tank;

[0020] - the method comprises a step of estimating the temperature variation curve (or respectively the density variation curve) of the gas present in the tank during filling, wherein said curve ranges between the first temperature variation curve (respectively the first density variation curve) and the second temperature variation curve (respectively the second density variation curve); - during filling, recalculating the first initial temperature and / or the second initial temperature of the tank as a function of the flow rate and as a function of the temperature of the gas present in the filling pipe, wherein said flow rate and said temperature are determined by calculation and / or by sensors on the filling device;

[0021] the temperature limit value (respectively the density limit value) is a determined fixed value, for example 85° C. (respectively 24.1 kg / m3 or 40.2 kg / m3) or a value provided by a reference temperature curve “TPgas_max” (respectively by a reference density curve “RHO_cold”), wherein said curve is provided by a predetermined physical model simulating the thermodynamic conditions of the gas during a reference filling of the tank;

[0022] The physical model is based on a system of equations comprising at least one of the following:

[0023] The internal energy balance equation applied to the gas present in the tank;

[0024] The mass balance equation applied to the gas present in the tank;

[0025] The energy conservation equation in the tank wall; the heat flow continuity equation between the gas present in the tank and the tank wall; the heat flow continuity equation between the tank wall and the surrounding air; and

[0026] a flow equation that connects the mass flow of the filling device to the pressure difference between the filling device and the tank;

[0027] - the first initial temperature of the tank (respectively, the second initial temperature) and the initial pressure of the gas present in the tank are obtained by solving the system of equations, for example using a tridiagonal matrix type algorithm;

[0028] - the ambient temperature of the filling device and the initial pressure of the gas present in the tank are determined by calculation and / or measured by sensors on the filling device;

[0029] - the electronic control component is configured to control the flow and / or pressure control valve so as to generate a predetermined pressure curve or ramp during filling;

[0030] The electronic control means are configured to simulate and estimate the density variation profile (and / or the temperature variation profile) of the gas present in the tank in a dynamic manner when filling the tank and / or in an anticipatory manner (ie before filling).

[0031] The invention may also relate to any alternative device or method comprising any combination of the above or below mentioned features within the scope of the claims.

[0032] Further specific features and advantages will become apparent from a reading of the following description provided with reference to the accompanying drawings, in which:

[0033] [ Figure 1 ] schematically and partially illustrates a filling device according to the invention;

[0034] [ Figure 2 ] schematically illustrates the steps of a filling method by a filling device;

[0035] [ Figure 3 ] shows a reference temperature curve which, for a given ambient temperature, provides the temperature limits of a gas as a function of its pressure;

[0036] [ Figure 4 ] shows the variation of the lower limit (respectively, the upper limit) associated with the high temperature range (respectively, the low temperature range) in which the reference filling occurs relative to the ambient temperature;

[0037] [ Figure 5 ] shows curves which, for a simulated reference filling at a given ambient temperature, provide the variation in the temperature of a tank considered to have been recently filled (and, accordingly, considered to have been recently emptied), the variation in the temperature, density and pressure of the gas present in said tank, the variation in the temperature and pressure of the gas at the outlet of the filling device;

[0038] [ Figure 6 ] shows surface curves corresponding to several reference temperature curves established for different ambient temperatures;

[0039] [ Figure 7 ] shows[ Figure 1], where the reduced "temperature" variable is between 0 (zero) and 1 (one);

[0040] [ Figure 8 ] showing a reference temperature curve and a predicted curve of a first initial temperature of a tank or a gas present in said tank;

[0041] [ Fig. 9 ] shows a curve representing the variation of the temperature of a tank and of the temperature of the gas present in said tank, wherein said variation is associated with the thermal diffusion after a reference filling;

[0042] [ Fig.10 ] shows the [ Figure 8 ] curve;

[0043] [ Fig.11 ] shows a predicted curve of a second initial temperature of a tank or a gas present in said tank;

[0044] [ Fig.12 ] shows the [ Fig.11 ] curve;

[0045] [ Fig.13 ] presents an embodiment of a temperature profile of a gas in order to control the filling of a tank and prevent the tank from overheating;

[0046] [ Fig.14 ] presents an embodiment of a temperature profile of a gas in combination with a reference temperature profile in order to control the filling of a tank and prevent overheating of the tank;

[0047] [ Fig.15 ] shows an example of radial discretization of the tank wall;

[0048] [ Fig.16 ] shows that in [ Fig.15 ] details of the mesh obtained after discretization.

[0049] The device 10 for filling pressurized gas tanks 1 is, for example, a station for filling pressurized hydrogen tanks.

[0050] The device 10 includes a gas source 2, a filling pipe 3 connecting the source 2 to the tank 1, a flow and / or pressure control valve 4 located in the filling pipe 3, and a group of one or more sensors 6a, 6b, which are configured to measure the pressure in the tank 1 and / or the ambient temperature Tamb on the filling device 10.

[0051] Furthermore, the device 10 comprises an electronic control member 5 configured to control the filling and in particular to stop the filling when the estimated temperature (respectively, density) of the gas present in the tank 1 reaches a temperature limit value (respectively, density limit value). The control member 5 is also configured to estimate the initial temperature of the gas present in the tank 1 before filling it.

[0052] The electronic control component 5 comprises, for example, a microprocessor, a computer or any suitable electronic controller.

[0053] According to the present invention, the initial temperature Tini of the gas present in the tank 1 is a value estimated based on the ambient temperature Tamb and based on the pressure Pini of the gas present in the tank 1 before filling, wherein the initial temperature Tini is greater than or equal to or less than or equal to the ambient temperature Tamb.

[0054] Therefore, for a given ambient temperature Tamb, the initial temperature Tini of the gas present in the tank is no longer a fixed quantity as provided in the prior art, but a quantity that depends on the initial pressure Pini of the gas present in the tank 1 .

[0055] Advantageously, the initial temperature Tini of the gas present in the tank 1 is divided into a first calculated initial temperature Tini_1 corresponding to a state of the tank 1 considered to have been recently filled to a first initial density ρini_1 and a second calculated initial temperature Tini_2 corresponding to a state of the tank 1 considered to have been recently drawn out to a second initial density ρini_2.

[0056] The ambient temperature Tamb and the initial pressure Pini are determined during steps S1 and S2 of the filling method for the filling device, respectively, and are determined in [ Figure 2 ] is schematically shown in. Step S1 and step S2 may be performed simultaneously or may not be performed simultaneously. With respect to the initial temperature Tini divided into the first initial temperature Tini_1 and the second initial temperature Tini_2, in [ Figure 2 ] The initial temperature is determined during step S3 shown in .

[0057] Hereafter, a tank 1 considered to have been recently filled will also be compared to a tank recently exposed to direct sunlight or in a relatively hot environment, or even a tank that was hot filled. To refill such a tank, the fluid already present is considered to have been compressed and therefore the temperature has increased far above the ambient temperature.

[0058] A tank that is considered to have been recently drawn out will also be compared to a tank that has recently been exposed to a relatively cold environment or a tank that is cold filled. In order to fill such a tank, the remaining fluid is considered to have previously undergone significant expansion and therefore significant cooling.

[0059] The tank that is considered to have been recently filled and the tank that is considered to have been recently drawn are modeled virtual tanks that may or may not be the same. In the second case, the tank that is considered to have been recently drawn may have a larger surface area: volume ratio than the surface area: volume ratio of the tank that is considered to have been recently filled, which makes it more capable of rejecting heat and cooling.

[0060] Advantageously, the first initial temperature Tini_1 of the gas present in the tank is within a high temperature range having a determined lower limit TLgas_min_1 greater than or equal to the ambient temperature and an upper limit TLgas_max_1 corresponding to a determined maximum temperature limit. The variation of the lower limit TLgas_min_1 with the ambient temperature of the filling device is derived, for example, from the curve "Thotsoak" derived from the SAE recommendations for filling hot tanks (see [ Figure 4 ]). The upper limit TLgasmax_1 is set to, for example, 85° C. This value takes into account the thermophysical properties of the tank.

[0061] Advantageously, the second initial temperature Tini_2 of the tank is within a low temperature range having a determined upper limit TLgas_max_2 less than or equal to the ambient temperature Tamb and a lower limit TLgas_min_2 corresponding to a determined minimum temperature limit, for example ranging between zero and -5°C. In particular, the upper limit TLgas_max_2 varies with the ambient temperature and follows a curve "Tcoldsoak" derived, for example, from the SAE recommendations for filling cold tanks (see [ Figure 4 ]).

[0062] Advantageously, the temperature limit value (respectively, the density limit value) is a determined fixed value or a value provided by a reference temperature curve "Tpgasmax" (respectively, a reference density curve). In particular, the reference temperature curve "Tpgasmax" (respectively, a reference density curve) allows estimating the temperature limit value (respectively, the density limit value) for a given pressure of the gas in the tank.

[0063] [ Figure 3 An example of a reference temperature curve "Tpgas_max" is shown in FIG. 1. For the maximum pressure of the gas present in tank 1, the temperature limit value is 85°C and coincides with the upper limit TLgasmax_1 of the high temperature range. For the minimum pressure of the gas in the tank, the temperature limit value is approximately 20°C and coincides with the lower limit TLgasmin_1 of the high temperature range.

[0064] The density limit value depends on the service pressure of the tank. For example, for a service pressure of 350 barg, the density limit value is set to, for example, 24.1 kg / m3. For a service pressure of 700 barg, the limit density value is set to, for example, 40.2 kg / m3. Typically, the density limit value may be defined by a state of fill "SOC" ("state of charge") percentage defining a recommended maximum amount of hydrogen in the tank.

[0065] Determine the reference temperature curve "Tpgasmax" and the reference density curve.

[0066] Advantageously, the reference temperature curve "Tpgasmax" (respectively, the reference density curve) is provided by a first physical model which simulates a reference filling of the tank in the high temperature range (respectively, in the low temperature range) with precooling at the source. The reference filling is simulated from a minimum pressure, set in this case to 5 barg, up to a maximum pressure corresponding to the service pressure of the tank.

[0067] In particular, the reference temperature curve "Tpgasmax" (respectively, the reference density curve) is obtained from the curve "Pgashot" providing the variation of the pressure of the gas present in the tank over time and from the curve "Tgasmax" (respectively, the curve "RHO_cold") providing the variation of the temperature (respectively, the variation of the density) of the gas contained in the tank over time. The curves "Pgashot", "Tgasmax" (respectively "RHO_cold") are also provided by the first predetermined physical model. They are in [ Figure 5 ] is displayed in ].

[0068] For different ambient temperatures, the first predetermined physical model provides as many reference temperature curves "Tpgasmax" (respectively, as many reference density curves) forming a reference temperature surface curve (respectively, a reference density surface curve). [ Figure 6 ] shows an example of a reference temperature surface curve.

[0069] To facilitate the use of the reference temperature curve "Tpgasmax" (and accordingly the reference density curve), the "temperature" variable is reduced between a value of zero (0) corresponding to a lower limit TLgasmin_1 and a value of one (1) corresponding to an upper limit TLgasmax_1. Figure 7 ] shows the curve “Reduc_TPgasmax” obtained after reducing the “temperature” variable on the reference temperature curve “TPgasmax”.

[0070] Determine the first initial temperature Tini_1 of the gas.

[0071] The first initial temperature Tini_1 of the gas present in the tank is provided by a second predetermined prediction curve "TPgashot" which varies with the initial pressure Pini of the gas (see [ Figure 8 ]). In other words, for a given initial pressure Pini of the gas present in the tank, the prediction curve "Tpgashot" allows determining a first initial temperature Tini_1.

[0072] The prediction curve "Tpgashot" is drawn according to a second physical model which simulates a reference filling of the tank in a high temperature range, optionally with pre-cooling of the gas supplied by the source. Preferably, the second physical model also simulates the heat diffusion on the tank and / or on the gas present in the tank. Thus, the second physical model may differ from the first physical model by taking into account the heat diffusion.

[0073] The heat diffusion takes place after a reference filling of the tank and precooling of the source. Advantageously, the heat diffusion is simulated over a period of 2 minutes corresponding to the minimum time required between two consecutive fillings of a tank at a filling station. Still advantageously, during the heat diffusion period, the pressure of the gas in the tank is assumed to be constant.

[0074] For a given ambient temperature, thermal diffusion causes a drop in the temperature of the gas present in the tank. This drop is given by [ Fig. 9 ] is shown in the curve “Stgasmax”.

[0075] It should be noted that the curve "TPgashot" is obtained from the curve "Pgashot" and the curve "Tgashot" both established for the same ambient temperature. In particular, the curve "Tgashot" is obtained by subtraction performed between the curve "Tgasmax" and the curve "STgasmax".

[0076] Advantageously, in order to facilitate the use of the curve "TPgashot", the "temperature" variable can be reduced between a value of zero (0) corresponding to a lower limit TLgasmin_1 and a value of one (1) corresponding to an upper limit TLgasmax_1. The curve "Reduc_TPgashot" thus obtained is in [ Fig.10 ] is displayed in ].

[0077] Determine the second initial temperature Tini_2 of the gas.

[0078] The second initial temperature Tini_2 of the gas is obtained by the third curve "TPgascold" which varies with the initial pressure Pini of the gas (see [ Fig.11]). In other words, based on the initial pressure Pini of the gas present in the tank, the curve "TPgascold" allows determining a second initial temperature Tini_2 of the gas present in the tank.

[0079] The curve “TPgascold” may be provided by a third predetermined physical model (described below) which simulates a reference discharge of the tank in a low temperature range (ie, between an upper limit TLgasmax_2 and a lower limit TLgasmin_2).

[0080] The upper limit TLgasmax_2 corresponds to the start of the reference discharge, in which the tank is at least partially filled, and preferably 100% filled. At this upper limit TLgasmax_2, there is a corresponding maximum pressure Pgasmax_2, called the service pressure ("nominal working pressure"), and a maximum density ρgasmax_2. It should be noted that the maximum pressure Pgasmax_2 can be written as a function of the upper limit TLgasmax_2 by the following mathematical expression taken from the literature:

[0081] Pgasmax_2[barg]=A*TLgasmax_2[℃]+B

[0082] Where A ranges between 1 and 2, and B ranges between 300 and 400.

[0083] The lower limit TLgasmin_2 corresponds to the end of the reference discharge, where the tank has a minimum pressure Pgasmin_2 (set to 5 barg in this case) and a minimum density ρgasmin_2 (called the second initial density ρini_2). In addition, the lower limit TLgasmin_2 can be obtained from the following mathematical expression taken from the third physical model:

[0084] Tgasmin_2=A*Tamb+B

[0085] in

[0086] Tamb is the ambient temperature on the filling device;

[0087] A ranges between 0.5 and 1.5;

[0088] The range of B is between -30 and -15.

[0089] For different ambient temperatures, the third physical model provides as many curves "TPgascold" forming surface curves (not shown). To facilitate the use of these curves "TPgascold", the "temperature" variable on each of them is reduced between a zero (0) value corresponding to a lower limit TLgasmin_2 and a one (1) value corresponding to an upper limit TLgasmax_2. Similarly, the "pressure" variable can be reduced between a zero (0) value corresponding to a minimum pressure Pgasmin_2 and a one (1) value corresponding to a maximum pressure Pgasmax_2 before the tank is discharged. [ Fig.12 The curve “Reduc_TPgascold” shown in ] is the result of this reduction performed on the curve “TPgascold”.

[0090] Finally, for the initial pressure Pini measured in the tank and the ambient temperature Tamb taken from the filling device, at least one predetermined physical model considers that this initial pressure Pini is the final pressure of the previous filling ("hot case") or the previous extraction ("cold case"). These two assumptions define the value of the first initial temperature Tini_1 (corresponding to the hot case) and the value of the second initial temperature Tini_2 (corresponding to the cold case), respectively. The value of the first initial temperature Tini_1 and the value of the second initial temperature Tini_2 thus defined can be different from the initial temperature values ​​determined according to the prior art, for example, deviating from the ambient temperature by 10°C to 20°C.

[0091] The temperature profile of the gas is estimated between a first temperature profile of the gas (hot case) and a second temperature profile of the gas (cold case).

[0092] Advantageously, the control means 5 may be configured to estimate the temperature variation curve of the gas present in the tank during filling as a function of the initial temperature of the gas present in the tank (ie taking the initial temperature of the gas present in the tank as a starting point (or starting condition).

[0093] More specifically, the control means 5 may be configured to estimate such a curve between a first temperature variation curve of the gas (hot case) and a second temperature variation curve of the gas (cold case). Thus, for a given pressure of the gas present in the tank, a corresponding temperature is estimated between a first temperature situated on the first temperature variation curve of the gas (hot case) and a second temperature situated on the second temperature variation curve of the gas (cold case).

[0094] The first temperature variation curve (respectively, the second curve) of the gas has the first initial temperature Tini_1 (respectively, the second initial temperature Tini_2) of the gas as a starting point (or starting condition). In addition, the first temperature variation curve (respectively, the second curve) of the gas is supplied by a predetermined physical model, which simulates a reference filling of the tank from the first initial temperature Tini_1 (respectively, from the second initial temperature Tini_2) of the gas, wherein the filling is accompanied by precooling at the source and followed by heat diffusion.

[0095] It should be noted that the physical model from which the prediction curve "TPgashot" for the first initial temperature Tini_1 of the gas is derived is preferably the same as the physical model from which the first temperature variation curve of the gas is derived. The two curves are distinguished by their starting points, which are respectively the lower limit TLgasmin_1 (for the prediction curve "TPgashot" for the first initial temperature Tini_1) and the first initial temperature Tini_1 (for the first temperature variation curve of the gas).

[0096] The density of the gas present in the tank is estimated between the first density profile (hot case) and the second density profile (cold case).

[0097] Advantageously, the control means 5 may be configured to estimate (e.g. calculate) the density variation curve of the gas present in the tank during filling as a function of the initial density of the gas present in the tank. This means that the density variation curve has as a starting point the initial density of the gas present in the tank. It should be noted that, knowing the volume of the tank (known or estimated, for example, via known techniques based on a pressure pulse before filling), the pressure and the temperature of the gas, the initial density can be calculated by an ideal or real gas equation.

[0098] More specifically, the control means 5 may be configured to estimate the density variation curve of the gas between a first density variation curve of the gas (hot case) and a second density variation curve of the gas (cold case). Thus, for a given pressure of the gas present in the tank, a corresponding density is estimated between a first density located on the first density variation curve (hot case) and a second density located on the second density variation curve (cold case).

[0099] The first density variation curve (respectively, the second curve) has as a starting point a first initial density (respectively, the second initial density) of the gas present in the tank. Furthermore, the first density variation curve (respectively, the second curve) of the gas is provided by a physical model which simulates a reference filling of the tank from the first initial density (respectively, from the second initial density) of the gas, wherein precooling is performed at the source.

[0100] Determine the reference temperature curve of the tank and the temperature variation curve of the tank.

[0101] Advantageously, the condition for stopping the filling of the tank, which is related to a limit value of the temperature of the gas present in the tank, can be replaced by a stop condition related to a limit value of the temperature of the tank.

[0102] The limit value of the temperature of the tank can be provided by a reference temperature curve of the tank, wherein the curve is provided by the first physical model. In particular, for a tank formed by a plurality of layers (e.g., an inner layer in contact with the gas (referred to as a "liner" layer) and an outer layer in contact with the surrounding air (referred to as a "composite" layer), the first physical model provides [ Figure 8 ] shows three reference temperature curves, namely, the first curve "TPgasliner_max" for the inner wall, the second curve "TPlinercompo_max" for the inner / outer layer interface, and the third curve "TPexternal_max" for the outer wall.

[0103] The curves "TPgasliner_max", "TPexternal_max", and "TPlinercompo_max" can be obtained by combining the curve "Pgashot" with the curves "Tgasliner_hot", "Texternal_hot", and "Tlinercompo_hot" which respectively provide the temperature variation of the inner wall, the inner layer / outer layer interface, and the outer wall over time. Figure 5 ] shows the curves "Tgasliner_hot", "Texternal_hot".

[0104] In addition, for ease of use, the curves “TPgasliner_max”, “TPexternal_max” and “TPlinercompo_max” may be converted into curves “Reduc_TPgasliner_max”, “Reduc_TPexternal_max” and “Reduc_TPlinercompo_max”, each defined between a zero (0) value corresponding to the lower limit temperature TLgasmin_1 and a one (1) value corresponding to the upper limit temperature TLgasmax_1.

[0105] The initial temperature of the tank is estimated between a first initial temperature of the tank (hot case) and a second initial temperature of the tank (cold case).

[0106] The control component 5 can be configured to estimate the initial temperature of the tank between a first initial temperature of the tank corresponding to a state in which the tank is considered to have been recently filled to a first initial density (hot condition) and a second initial temperature of the tank corresponding to a state in which the tank is considered to have been recently drawn out to a second initial density (cold condition).

[0107] The first initial temperature Tini_1 of the tank can be obtained by the prediction curves "TPgasliner_hot", "TPlinercompo_hot", "TPexternal_hot" which vary with the initial pressure Pini of the gas (see [ Figure 8 In other words, for a given initial pressure Pini of the gas present in the tank, the prediction curves "TPgasliner_hot", "TPlinercompo_hot", "TPexternal_hot" allow determining a first initial temperature Tini_1 of the tank.

[0108] The curves "TPgasliner_hot", "TPexternal_hot", and "TPlinercompo_hot" can be provided by the second physical model. More specifically, these curves are obtained by combining the curve "Pgashot" with the curves "Tgasliner_hot_bis", "Texternal_hot_bis", and "Tlinercompo_hot_bis" (not shown) that respectively provide the temperature changes of the inner wall, the outer wall, and the inner layer / outer layer interface of the tank over time.

[0109] The curve "Tgasliner_hot_bis" is obtained by modulating the curve "Tgasliner_hot" by the curve "STgasliner". The curve "Texternal_hot_bis" is obtained by modulating the curve "Texternal_hot" by the curve "STexternal". The curve "Tlinercompo_hot_bis" is obtained by modulating the curve "Tlinercompo_hot" by the curve "STlinercompo". [ Fig. 9 The curves "STgasliner", "STexternal", "STlinercompo" are shown in Figure 3. They represent the heat diffusion after reference filling and occurring near the inner wall, outer wall and inner layer / outer layer interface of the tank.

[0110] exist[ Fig. 9 In the example shown in FIG. 1 , the thermal diffusion corresponds to a decrease in temperature over time for the inner wall of the tank. However, for the outer wall of the tank and the inner / outer interface, the thermal diffusion corresponds to an increase in temperature.

[0111] It should be noted that the curves "TPgasliner_hot", "TPexternal_hot", and "TPlinercompo_hot" can be reduced to the curves "Reduc_TPgasliner_hot", "Reduc_TPexternal_hot", and "Reduc_TPlinercompo_hot" respectively defined between a value of zero (0) corresponding to the lower limit temperature TLgas_min_1 and a value of one (1) corresponding to the upper limit temperature TLgas_max_1 (see [ Fig.10 ]).

[0112] The second initial temperature Tini_2 of the tank is provided by the prediction curves "TPgasliner_cold", "TPexternal_cold", "TPlinercompo_cold" which vary with the initial pressure Pini of the gas (see [ Fig.11 ]). In other words, for a given initial pressure Pini of the gas, the prediction curves "TPgasliner_cold", "TPexternal_cold", "TPlinercompo_cold" allow determining the second initial temperature Tini_2 of the tank.

[0113] It should be noted that the prediction curves "TPgasliner_cold", "TPexternal_cold", "TPlinercompo_cold" may be provided by a third physical model simulating a reference discharge of the tank. At the completion of this reference discharge, the temperature of the tank reaches a minimum value which varies with the thickness of the tank. For a tank consisting of two layers, the minimum temperature Tmin near the inner wall, the outer wall or the inner / outer layer interface may be provided, for example, by a linear law of the type Tmin=A*Tamb+B,

[0114] in

[0115] Tamb is the ambient temperature;

[0116] A ranges between 0.5 and 1.5;

[0117] The range of B is between -20 and -10.

[0118] The prediction curves "TPgasliner_cold", "TPexternal_cold", and "TPlinercompo_cold" can be obtained by combining the curve "Pgascold" (which provides the change of gas pressure over time) with the curves "Tgasliner_cold", "Texternal_cold", and "Tlinercompo_cold" (cold condition) which provide the change of tank temperature over time. Figure 5 ] shows the curves "Tgasliner_cold", "Texternal_cold" and "Pgas_cold".

[0119] The temperature profile of the tank is estimated between a first temperature profile of the tank (hot case) and a second temperature profile of the tank (cold case).

[0120] The control means 5 may be configured to estimate the temperature profile of the tank during filling (see [ Figure 2 ] step S5 of the method shown in ]. This estimation is performed between a first temperature variation curve of the tank (hot case) and a second temperature variation curve of the tank (cold case). The first curve and the second curve are in [ Figure 5 ] is determined during step S4 of the method shown in .

[0121] The first variation curve takes the first initial temperature Tini_1 of the tank as a starting point. The second variation curve takes the second initial temperature Tini_2 of the tank as a starting point.

[0122] The first temperature variation curve of the tank (respectively, the second curve) can be obtained from a model which simulates a reference filling of the tank from a first initial temperature Tini_1 of the tank (respectively, from a second initial temperature Tini_2), wherein the gas is pre-cooled at the source and there is heat diffusion after the reference filling.

[0123] Influence of thermal diffusion on the prediction curve of the first initial temperature Tini_1 of the tank or the gas present in the tank.

[0124] [ Figure 8] provides a reference temperature curve of the tank or the gas present in the tank (i.e. the curves "TPgasliner_max", "TPlinercompo_max", "TPexternal_max", "TPgas_max") and a predicted curve of the first initial temperature Tini_1 of the tank or the gas in the tank (i.e. the curves "TPgasliner_hot", "TPlinercompo_hot", "TPexternal_hot", "TPgas_hot") The analysis shows that after thermal diffusion, the temperature of the gas and the inner wall of the tank experiences a decrease, while after thermal diffusion, the temperature of the outer wall of the tank and the inner layer / outer layer interface experiences an increase.

[0125] Taking into account this singular variation of the temperature of the tank after thermal diffusion allows improving the accuracy of the reference temperature curve of the tank and / or of the gas present in the tank. The invention thus allows improving safety during filling by limiting the risk of exceeding temperature limit values.

[0126] Example of a reference temperature profile “Tgas_max” and a first temperature profile “Tgas_hot_bis” of a gas.

[0127] To prevent any overheating when filling the tank, a first temperature profile "Tgas_hot_bis" of the gas present in the tank can be used alone (see [ Fig.13 ]), or in combination with the reference temperature curve "Tgasmax" of the gas present in the tank (see [ Fig.14 ]).

[0128] As shown in each of these examples, after the vehicle is connected to the end of the filling pipe (step 1) and the filling is initiated by the filling device (step 2), the initial superheat in the gas present in the tank is detected (step 3). Fig.13 In the example of [ ], overheating is detected when the curve "Tgas_hot_bis" reaches the temperature limit value (which in this case is represented by a horizontal line at 85°C). Fig.14 In the example of ], an initial overheating below the temperature limit value (85° C.) is detected. This overheating corresponds to the moment when the curve “Tgas_hot_bis” “catches up” with the curve “Tgas_max”.

[0129] After this initial overheating, the control unit stops the filling, while the tank is not filled to its maximum value. The stop is extended (step 4) by a certain period of time required before a new filling cycle. Steps 5, 6, 7 correspond to this new filling cycle, for which the initial temperature of the gas present in the tank is determined according to the temperature reached by the same gas at the end of the previous cycle, and also according to the pressure of the same gas at the beginning of the new cycle.

[0130] By taking into account the temperature reached during the preceding filling cycle, then during the subsequent filling cycle, the invention limits the risk of overheating and opens up the possibility of achieving a maximum charge in the tank.

[0131] Of course, the curves "Tgas_max" and "Tgas_hot_bis" of the above example can be replaced by the curves "TPgasmax" and "TPgas_hot" in order to control the filling of the tank. When the stop condition is related to an extreme value of the temperature of the tank, one of the curves (thermal conditions) providing a temperature variation of the tank (for example, the curve "TPgasliner_hot") can be used to control the filling. This variation curve can be used alone or in combination with an associated reference temperature curve (for example, the curve "TPgasliner_max").

[0132] Introduction to the physical model.

[0133] The above-mentioned physical model, which is the source of the different prediction curves presented in this specification, is based on a set of energy balance equations applied to the tank and the gas present in the tank. These equations are introduced below.

[0134] a. The internal energy balance equation of the gas in the tank is written as follows:

[0135]

[0136] This balance uses the mass m of the gas in the tank g , the mass internal energy u of the gas in the tank g , the heat exchange between the gas in the tank and its inner wall (where the exchange coefficient is k i and the inner surface of these tanks is S i ), total hydrogen density and the entry mass enthalpy of the gas in the tank h g inlet . T g and T wi are the spatially average temperatures of the gas in the volume of these tanks and their inner walls, respectively.

[0137] One of the two safety criteria not to be exceeded concerns the density in the model. Since the PLC knows the total volume V of the tank of the vehicle CHSS(Compressed hydrogen storage system), so equation (1) can be used with m g =V CHSS ρ g Written as:

[0138]

[0139] To solve equation (2), it is necessary to discretize the equation by replacing the time derivative with a finite difference. Therefore, by dividing by V CHSS Get the equation:

[0140]

[0141] where Δt is the value of the time step (approximately one second).

[0142] The material balance equation in the tank is used to write:

[0143] V CHSS ρ g (t+Δt)=V CHSS ρ g (t)+Q (4)

[0144] That is, by dividing by V CHSS :

[0145]

[0146] Equation (5) allows to obtain ρ g (t+Δt). Therefore, equation (3) allows to obtain the internal energy u g The value of (t+Δt):

[0147]

[0148] b. The energy conservation equation in the wall is written as follows:

[0149]

[0150] This balance involves the density of the wall, p, its heat capacity, c p and its thermal conductivity λ, and the radius r from the center of the tank.

[0151] At the interface between the gas and the liner, the flow continuity equation is written as follows:

[0152]

[0153] At the interface between the composite and the surroundings, the flow continuity equation is written as follows:

[0154]

[0155] where k e is the heat exchange coefficient between the surrounding environment and the outer wall of the tank, S e are the outer surfaces of these tanks, and T amb is the ambient temperature.

[0156] Finally, at the interface between the two liners and the composite material inside the wall, the flow continuity equation is written as follows:

[0157]

[0158] c. Discretization of the equations in the wall

[0159] In order to solve equations (7), (8), (9) and (10), the wall needs to be discretized radially into various meshes. The number of meshes in the liner n_liner and the number of meshes in the composite n comp can be different. The wall temperature is calculated at each node, then n_mesh = n_liner + n_comp + 1nodes. Therefore, the size of the mesh is (δr) in the liner liner =e liner / n liner and (δr) in the complex comp =e comp / n comp ,like Fig.13 The thickness of the mesh at the interface is (δr) / 2. In the example shown, 3 meshes are set in the liner and 3 other meshes are set in the composite.

[0160] Equation (7) is discretized and applied to each of the various grids forming the wall so that it can be solved. Fig.14 The radial discretization used to solve the equation is shown. In this figure, the grid centered at point P is surrounded by points W to the west and E to the east, with the interior of the tank located to the west. An imaginary surface w is defined between points W and P, and a second imaginary surface e is defined between points P and E. The distances between points W and P on the one hand and between points P and E on the other hand are denoted as (δr) w and (δr) e . Surface w and surface e are separated by Δr P Point W, point P and point E are located at a distance r from the center of the tank. W 、r P and r E Place.

[0161] Equation (7) is integrated over the time step and spatially from west to east to obtain:

[0162]

[0163] The left term is called A and the right term is called B.

[0164] Assume that density ρ and heat capacity c p There is almost no change between time t and t+Δt, so the left term is written as follows:

[0165]

[0166] Assume that the temperature difference T(r, t+Δt)-T(r, t) between points w and e remains constant and equal to T(r P , t+Δt)-T(r P , t). Term A is written as follows:

[0167]

[0168] By writing: Item A is finally written as follows:

[0169]

[0170] Term B, i.e., the right-hand side of equation (11), can be written as follows:

[0171]

[0172] Assumptions and Assuming that the thermal conductivity λ barely changes between times t and t+△t, term B is written as follows:

[0173]

[0174] The value obtained at time t is marked with index 0, and the value obtained at time t+△t is marked with index 1 The values ​​obtained at points W, P, and E are indicated by indexes. W , P and E For example, the value T(r p , t+Δt) is marked as

[0175] The implicit format is used, and thus equation (11) becomes:

[0176]

[0177] At the interface between the gas and the liner, the flow continuity equation (8) is discretized as follows:

[0178]

[0179] At the interface between the composite and the surrounding environment, the flow continuity equation (9) is discretized as follows:

[0180]

[0181] Finally, at the interface between the two liners and the composite material inside the wall, the flow continuity equation (10) is discretized as follows:

[0182]

[0183] The following system of equations can be solved by the Thomas algorithm (also known as TDMA (Tridiagonal Matrix Algorithm)): (17) for each point P that is not at the interface; and (18), (19) and (20).

[0184] Physical properties and coefficients.

[0185] a. Tg and Pg from ρ and u

[0186] For each time step, the model calculates the temperature and pressure of the gas based on its density ρ and internal energy u:

[0187] T g =f1(ρ,u) (21)

[0188] P g =f2(ρ,u) (22)

[0189] These functions f1 and f2 are adjusted so as to best correspond to the thermophysical properties of the gas.

[0190] b. Heat transfer coefficients ki and ke

[0191] The model also requires a heat transfer coefficient k i and k e For the internal transfer coefficient k i , using a function calibrated based on the correlation proposed by Bourgeois, T. et al. (see "Bourgeois T., Ammouri F., Weber M., Knapik C. 'Evaluating the temperature inside a tank during a filling with highly-pressurized gas', Int. J. Hydrogen Energ. 2015; 40: 11748-55").

[0192]

[0193] For the external transfer coefficient k e, using a function calibrated based on the correlation proposed by Massard, F. (see The Thermal Engineer's Checklist, ELSEVIER; 1997):

[0194]

[0195]

[0196]

[0197]

[0198]

[0199] Advantageously, the above-mentioned physical model can be associated with a heat transfer model between the filling device and the tank or tanks. Such a transfer model is described below.

[0200] The term h of the gas entry mass enthalpy in equation (1) is g The inlet is obtained based on the mass enthalpy of the gas on the dispenser with the aid of a heat transfer model. Its purpose is to estimate the heat exchange of the gas between the dispenser of the filling device and the inlet into the tank of the vehicle along the length of the hose and other elements connecting the dispenser to the tank.

[0201] For each elementary length dx along the pipe, the energy conservation equation applied to the gas inside the pipe is written in equation (25). In this case, the pipe is assumed to have a uniform temperature throughout its length:

[0202]

[0203] in is the gas density, c p，g is the mass heat capacity of the gas, x is the horizontal coordinate along the pipe, T gas，pipe is the temperature of the gas in the pipe which depends on x and t, k i，pipe is the internal exchange coefficient in the pipe, d inat，pipe is the average inner diameter of the pipe, and T pipe The temperature of the pipe depends only on t.

[0204] Equation (25) can be integrated between 0 (distributor) and position x along the pipeline to obtain T gas，pipe (x, t). For greater clarity, Marked as characteristic length:

[0205] dT gas，pipe / (T pipe (t)-T gas，pipe (x, t)) = 1 / L c(t)dx (26.1)

[0206]

[0207] (T pipe (t)-T gas，pipe (x, t)) / (T pipe (t)-T disp )=exp(-x / L C (t)) (26.3)

[0208] The energy conservation equation applied to the pipe is written in equation (27):

[0209]

[0210] Where (mc p ) pipe is the heat capacity of the pipe, Δh pipe is the energy transferred from the gas to the pipe, k e，pipe is the external exchange coefficient of the pipe, and S e，pipe It is the outer surface of the pipe.

[0211] By means of equation (26.3), the term We can write:

[0212]

[0213]

[0214]

[0215] Where L pipe is the length of the pipe.

[0216] Equation (27) is discretized:

[0217]

Claims

1. A method (100) for filling a pressurized gas tank (1), the method being implemented by a filling device (10), the filling device comprising a gas source (2), a filling pipe (3) connecting the source (2) to the tank (1), a flow and / or pressure control valve (4) located in the filling pipe, and an electronic control unit (5) configured to stop the filling when the estimated temperature (or density) of the gas present in the tank (1) reaches a temperature limit value (or, respectively, a density limit value), The method comprises, before filling the tank (1), a step (S1) of determining the ambient temperature (Tamb) on the filling device (10), a step (S2) of determining the pressure (Pini) of the gas present in the tank (1), and a preliminary step (S3) of estimating the initial temperature (Tini) of the gas present in the tank (1), wherein the initial temperature (Tini) of the gas present in the tank (1) is a value estimated based on the ambient temperature (Tamb) and based on the pressure (Pini) of the gas present in the tank (1) before filling, wherein the initial temperature (Tini) of the gas present in the tank (1) is greater than or equal to or less than or equal to the ambient temperature (Tamb).

2. The method according to claim 1, characterized in that The initial temperature (Tini) of the gas present in the tank (1) is divided into a first calculated initial temperature (Tini_1) and a second calculated initial temperature (Tini_2), wherein the first calculated initial temperature corresponds to a state in which the tank (1) is considered to have been recently filled to a first initial density (ρini_1), and the second calculated initial temperature corresponds to a state in which the tank (1) is considered to have been recently drawn out to a second initial density (ρini_2).

3. The method according to claim 2, characterized in that The first initial temperature (Tini_1) of the gas present in the tank (1) is within a high temperature range having a lower limit (TLgas_max_1) determined to be greater than or equal to the ambient temperature (Tamb) and an upper limit (TLgas_max_2) corresponding to a determined maximum temperature limit, for example equal to 85°C.

4. The method according to any one of claims 2 or 3, characterized in that The first initial temperature (Tini_1) is determined according to a first predetermined prediction curve "TPgas_hot" provided by a predetermined physical model simulating a reference filling of the tank (1) in the high temperature range.

5. The method according to any one of claims 2 to 4, characterized in that The second initial temperature (Tini_2) of the gas present in the tank (1) is within a low temperature range having an upper limit (TLgas_max_2) determined to be less than or equal to the ambient temperature (Tamb) and a lower limit (TLgas_min_2) corresponding to a determined minimum temperature limit, the range of the determined minimum temperature limit being, for example, between zero and -5°C.

6. The method according to any one of claims 2 to 5, characterized in that The second initial temperature (Tini_2) is determined according to a second predetermined prediction curve "TPgas_cold" provided by a predetermined physical model simulating a reference discharge of the tank (1) within the low temperature range.

7. The method as claimed in any one of claims 2 to 6 comprises a step (S4) of modeling a first temperature change curve (or, respectively, a first density change curve) of the gas present in the tank (1) and / or a second temperature change curve (or, respectively, a second density change curve) of the gas present in the tank (1) during filling, the first temperature change curve (or, respectively, the first density change curve) having the first initial temperature (Tini_1) (or, respectively, the first initial density (ρini_1)) of the gas present in the tank (1) as a starting condition, and the second temperature change curve (or, respectively, the second density change curve) having the second initial temperature (Tini_2) (or, respectively, the second initial density (ρini_2)) of the gas present in the tank (1) as a starting condition.

8. The method as claimed in claim 7 comprises a step (S5) of estimating the temperature variation curve (or, respectively, the density variation curve) of the gas present in the tank (1) during filling, wherein the range of the curve is between the first temperature variation curve (or, respectively, the first density variation curve) and the second temperature variation curve (or, respectively, the second density variation curve).

9. The method according to any one of claims 2 to 8, characterized in that During filling, the first initial temperature (Tini_1) and / or the second initial temperature (Tini_2) are recalculated according to the flow rate and according to the temperature of the gas present in the filling pipe, wherein the flow rate and the temperature are determined by calculation and / or by sensors on the filling device (10).

10. The method according to any one of claims 1 to 9, characterized in that The temperature limit value (respectively, the density limit value) is a determined fixed value, for example 85°C (respectively 24.1 kg / m3 or 40.2 kg / m3) or a value provided by a reference temperature curve "TPgas_max" (respectively, by a reference density curve "RHO_cold"), wherein the curve is provided by a predetermined physical model simulating the thermodynamic conditions of the gas during a reference filling of the tank (1).

11. The method according to any one of claims 4 to 10, characterized in that The physical model is based on a system of equations including at least one of the following: - an internal energy balance equation applied to the gas present in the tank (1); - a mass balance equation applied to the gas present in the tank (1); -Energy conservation equation in the tank wall (1); - the continuity equation of the heat flow between the gas present in the tank (1) and the tank wall (1); - continuity equation of heat flow between the tank wall (1) and the surrounding air; as well as - a flow equation which connects the mass flow of the filling device (10) to the pressure difference between the filling device (10) and the tank (1).

12. The method according to claim 11, characterized in that The first initial temperature (Tini_1) (correspondingly, the second initial temperature (Tini_2)) and the initial pressure (Pini) of the gas present in the tank (1) are obtained by solving the system of equations, for example using a tridiagonal matrix type algorithm.

13. The method according to any one of claims 1 to 12, characterized in that The ambient temperature (Tamb) of the filling device (10) and the initial pressure (Pini) of the gas present in the tank (1) are determined by calculation and / or measured by sensors on the filling device (10).

14. The method according to any one of claims 1 to 13, characterized in that The electronic control component (5) is configured to control the flow and / or pressure control valve (4) so ​​as to generate a predetermined pressure curve or ramp during filling.

15. The method according to any one of claims 7 to 14, characterized in that The electronic control unit (5) is configured to simulate and estimate the temperature variation curve and / or the density variation curve of the gas present in the tank (1) dynamically when filling the tank (1) and / or in an anticipatory manner, ie before filling.

16. A device (10) for filling a pressurized gas tank (1), the device comprising a gas source (2), a filling pipe (3) connecting the source (2) to the tank (1), a flow and / or pressure control valve (3) located in the filling pipe (3), a set of one or more sensors (6a, 6b) configured to measure the pressure in the tank (1) and / or the ambient temperature on the filling device (10), and an electronic control unit (5), the electronic control unit being configured to; - stopping the filling when the estimated temperature (respectively, density) of the gas present in the tank (1) reaches a temperature limit value (respectively, a density limit value); - Estimation of the initial temperature (Tini) of the gas present in the tank (1) before filling the tank (1), characterized in that The initial temperature (Tini) of the gas present in the tank (1) is a value estimated based on the ambient temperature (Tamb) and based on the pressure (Pini) of the gas present in the tank (1) before filling, wherein the initial temperature (Tini) of the gas present in the tank (1) is greater than or equal to or less than or equal to the ambient temperature (Tamb).

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