Apparatus and method for filling pressurized gas tanks

Abstract

The present invention relates to a method (100) for filling a pressurized gas tank (1) by means of a filling device (10) comprising a gas source (2), a filling pipe (3) connecting the gas source (2) to the tank (1), a flow and / or pressure control valve (4) in the filling pipe, and an electronic control element (5) configured to stop filling if the estimated temperature (or density) of the gas present in the tank (1) reaches a temperature limit (or, i.e., a density limit), the method comprising determining the ambient temperature (Tamb) of the filling device (10) before filling the tank (1). The method includes a step (S1) of determining the pressure (Pini) of the gas present in 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), 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, and the initial temperature (Tini) of the gas present in the tank (1) is above or below the ambient temperature (Tamb).

Description

[Technical Field]

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

[0002] The invention is particularly applicable to filling hydrogen tanks.

[0003] More specifically, the present invention relates to a gas supply system comprising a gas source, a filling pipe connecting the gas source to a tank, a flow and / or pressure control valve in the filling pipe, a sensor configured to measure the pressure in the tank and / or the ambient temperature of the filling device, and - Stop filling if the estimated temperature (i.e. density) of the gas present in the tank reaches a temperature limit (i.e. density limit); - A device for filling a pressurized gas tank, comprising an electronic control element configured to estimate the initial temperature of the gas present in the tank before filling the tank. [Background technology]

[0004] In such devices, it remains difficult to obtain the temperature of the gas present in the tank, in particular the temperature before filling. In a known manner, the initial temperature used in existing filling protocols is derived from the SAE ("Society of Automotive Engineers") recommendations for filling fuel cell vehicles. The initial temperature is given as a function of the ambient temperature according to a predetermined curve corresponding to a high temperature and a predetermined curve corresponding to a low temperature. Summary of the Invention [Problem to be solved by the invention]

[0005] However, practice has shown that the initial temperature of a tank being filled does not always follow these curves recommended by SAE, and therefore, if the initial temperature of the tank is outside the area defined by the curves recommended by SAE, the tank is often at risk of overheating or overfilling.

[0006] The risk of overheating increases in the case of successive fills. Indeed, fills generally lead to an increase in the temperature of the gas present in the tank, but current protocols assume that the initial temperature of the tank during subsequent fills will remain within the region defined by the SAE. Therefore, the initial gas temperature during subsequent fills may be underestimated, leading to premature exceedance of the temperature limit, contrary to the predictions of the models employed in current fill protocols.

[0007] SUMMARY OF THE INVENTION It is an object of the present invention to overcome all or some of the above-mentioned disadvantages of the prior art. [Means for solving the problem]

[0008] For this purpose, the device according to the invention is further characterized in accordance with the general definition given in the preamble above, essentially in that the initial temperature is a value estimated as a function of the ambient temperature and as a function of the pressure of the gas present in the tank before filling, the initial temperature of the gas in the tank being above or below the ambient temperature.

[0009] The present invention therefore reduces the risk of overheating or overfilling the tank by improving the accuracy of estimating the initial temperature of the gas present in the tank.

[0010] The present invention also relates to a method for filling a pressurized gas tank, carried out by a filling device including a gas source, a filling pipe connecting the gas source to the tank, a flow and / or pressure control valve in the filling pipe, and an electronic control element configured to stop filling if the estimated temperature (i.e., density) of the gas present in the tank reaches a temperature limit (or density limit). The method includes the steps of determining the ambient temperature of the filling device, determining the pressure of the gas present in the tank, and estimating an initial temperature of the gas present in the tank, before filling the tank, the initial temperature of the gas in the tank being a value estimated as a function of the ambient temperature and as a function of the pressure of the gas present in the tank before filling, said initial temperature of the gas in the tank being above or below the ambient temperature.

[0011] Furthermore, embodiments of the method according to the invention include the following features: the initial temperature of the gas in the tank is divided into a first calculated initial temperature corresponding to a state of the tank considered recently filled to a first initial density and a second calculated initial temperature corresponding to a state of the tank considered recently drained to a second initial density; the first initial temperature of the gas present in the tank is within a high temperature range, the upper limit of which corresponds to a determined maximum temperature limit, the upper limit being, for example, equal to 85°C; the first initial temperature is determined from a first predetermined prediction curve "TPgas_hot" given by a predetermined physical model simulating a reference fill of the tank over a high temperature range, the second initial temperature of the gas present in the tank is within a low temperature range corresponding to a predetermined minimum temperature limit, for example in the range of 0 to -5°C, with an upper limit determined to be equal to or lower than the ambient temperature; the second initial temperature is determined from a second predetermined prediction curve "TPgas_cold" provided by a predetermined physical model simulating a reference discharge of the tank over a low temperature range; the method comprises the step of modelling, during filling, a first temperature variation curve (i.e. a first density variation curve) of the gas present in the tank starting from a first initial temperature (or i.e. a first initial density) of the gas present in the tank and / or a second temperature variation curve (i.e. a second density variation curve) of the gas present in the tank starting from a second initial temperature (i.e. a second initial density) of the gas present in the tank, the method comprises a step of estimating, during filling, a temperature variation curve (or, i.e., density variation curve) of the gas present in the tank, said curve lying between a first temperature variation curve (i.e., first density variation curve) and a second temperature variation curve (i.e., second density variation curve), the first initial temperature and / or the second initial temperature of the tank are recalculated during filling as a function of the flow rate and as a function of the temperature of the gas present in the filling pipe, said flow rate and said temperature being determined by calculation and / or by sensors of the filling device, the temperature limit (i.e. the density limit) is a predetermined fixed value, for example 85°C (i.e. for example 24.1 kg / m3 or 40.2 kg / m3), or a value given by a reference temperature curve "TPgas_max" (i.e. a reference density curve "RHO_cold"), said curve being given by a predetermined physical model simulating the thermodynamic conditions of the gas during a reference filling of the tank, The physical model is The internal energy balance equation applied to the gas present in the tank, The mass balance equation applied to the gas present in the tank, The energy conservation equation within 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 based on a system of equations including at least one flow equation connecting the mass flow rate of the filling device to the pressure difference between the filling device and the tank; the first initial temperature of the tank (i.e. the second initial temperature) and the initial pressure of the gas present in the tank are obtained by solving said system of equations, for example using a triangular matrix algorithm; 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; the electronic control element is configured to control the flow and / or pressure control valve to generate a predetermined pressure curve or ramp during filling; The electronic control element is configured to simulate and estimate the density variation curve (and / or temperature variation curve) of the gas present in the tank dynamically and / or in a predictive manner when filling the tank, i.e. before filling.

[0012] The invention may also relate to any alternative apparatus or method including any combination of the features set out above or below within the scope of the claims.

[0013] Further particular features and advantages will become apparent from the following description, given in conjunction with the drawings. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 shows diagrammatically and partially a filling device according to the invention. [Figure 2] FIG. 2 shows a schematic diagram of the steps of the filling method using the filling device. [Figure 3] FIG. 3 shows a reference temperature curve giving the change in the limit temperature of a gas as a function of pressure for a given ambient temperature. [Figure 4] FIG. 4 shows the variation with ambient temperature of the lower (ie, upper) limit associated with the higher (ie, lower) temperature range in which the reference fill occurs. [Figure 5] Figure 5 shows curves representing the change in temperature of a tank that is considered to have been recently filled (i.e., recently discharged), the change in temperature, density and pressure of the gas present in said tank, and the change in temperature and pressure of the gas at the outlet of the filling device, for a simulated reference filling at a given ambient temperature. [Figure 6] FIG. 6 shows surface curves corresponding to several reference temperature curves established for various ambient temperatures. [Figure 7] FIG. 7 shows the reference temperature curve of FIG. 1 normalized between 0 and 1 for the "Temperature" variable. [Figure 8] FIG. 8 shows a reference temperature curve and a predicted curve for a first initial temperature of the tank or gas present in the tank. [Figure 9] FIG. 9 shows a curve representing the change in the temperature of the tank and the temperature of the gas present in the tank, said change being linked to the thermal diffusion after the reference fill. [Figure 10] FIG. 10 shows the curves of FIG. 8 after normalizing the "temperature" variable. [Figure 11] FIG. 11 shows a predicted curve of the second initial temperature of the tank or gas present in said tank. [Figure 12] FIG. 12 shows the curves of FIG. 11 after normalizing the "Temperature" and "Pressure" variables between 0 and 1. [Figure 13] FIG. 13 shows one embodiment of a gas temperature curve for controlling the filling of the tank to prevent overheating. [Figure 14] FIG. 14 shows one embodiment of a gas temperature variation curve combined with a reference temperature curve to control the filling of the tank and prevent overheating. [Figure 15] Figure 15 shows an example of discretization in the radial direction of the tank wall. [Figure 16] FIG. 16 shows a detail of the mesh obtained after the discretization of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] The filling device 10 for pressurized gas tanks 1 is, for example, a filling station for pressurized hydrogen tanks.

[0016] The device 10 includes a gas source 2, a filling pipe 3 connecting the gas source 2 to the tank 1, a flow and / or pressure control valve 4 in the filling pipe 3, and a set of one or more sensors 6a, 6b configured to measure the pressure in the tank 1 and / or the ambient temperature Tamb of the filling device 10.

[0017] Furthermore, the device 10 includes an electronic control element 5 configured to control the filling and in particular to stop the filling if the estimated temperature (i.e. density) of the gas present in the tank 1 reaches a temperature limit (i.e. density limit). The control element 5 is also configured to estimate the initial temperature of the gas present in the tank 1 before filling the tank 1.

[0018] The electronic control element 5 may include, for example, a microprocessor, a computer, or any suitable electronic control device.

[0019] According to the invention, the initial temperature Tini of the gas present in the tank 1 is a value estimated as a function of the ambient temperature Tamb and as a function of the pressure Pini of the gas present in the tank 1 before filling, said initial temperature Tini being greater than or less than the ambient temperature Tamb.

[0020] Thus, for a given ambient temperature Tamb, the initial temperature Tini of the gas present in the tank is no longer a fixed quantity as given by the prior art, but rather a quantity that depends on the initial pressure Pini of the gas present in the tank 1.

[0021] As an advantageous feature, 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 possible state of the tank 1 having recently been filled and having a first initial density ρini_1, and a second calculated initial temperature Tini_2 corresponding to a possible state of the tank 1 having recently been discharged and having a second initial density ρini_2.

[0022] The ambient temperature Tamb and the initial pressure Pini are determined during steps S1 and S2, respectively, of the filling method for operating the filling device, as shown schematically in Figure 2. Steps S1 and S2 may or may not be performed simultaneously. The initial temperature Tini, divided into a first initial temperature Tini_1 and a second initial temperature Tini_2, is determined during step S3, also shown in Figure 2.

[0023] Hereinafter, examples of tanks 1 that are considered to be recently filled include tanks that have recently been exposed to direct sunlight or a relatively hot environment, or tanks that have been hot filled. To refill such a tank, the fluid already there is compressed and therefore considered to have risen in temperature to well above ambient temperature.

[0024] An example of a tank that would be considered recently drained would be one that has recently been exposed to a relatively cold environment, or one that is undergoing a cold fill. To fill such a tank, the residual fluid would have previously expanded significantly, and therefore cooled significantly.

[0025] The tank considered recently filled and the tank considered recently drained are modeled virtual tanks that may or may not be the same. In the second case, the tank considered recently drained has a larger surface area to volume ratio than the tank considered recently filled, and is therefore more likely to give off heat and cool.

[0026] Advantageously, the first initial temperature Tini_1 of the gas present in the tank is within an upper temperature range having a lower limit TLgas_min_1 equal to or greater than the ambient temperature and an upper limit TLgas_max_1 corresponding to a predetermined maximum temperature limit. The variation of the lower limit TLgas_min_1 as a function of the ambient temperature of the filling device is given, for example, by the curve "Thotsoak" (see FIG. 4), derived from the SAE recommendations for filling high-temperature tanks. The upper limit TLgasmax_1 is set, for example, to 85°C. This value takes into account the thermophysical properties of the tank.

[0027] Advantageously, the second initial temperature Tini_2 of the tank is within a low temperature range having an upper limit TLgas_max_2 determined to be equal to or less than the ambient temperature Tamb, and a lower limit TLgas_min_2 corresponding to a predetermined minimum temperature limit, for example between 0 and -5° C. In particular, the upper limit TLgas_max_2 is a function of the ambient temperature, for example according to the curve "Tcoldsoak" (see FIG. 4) derived from the SAE recommendations for filling cryogenic tanks.

[0028] Advantageously, the temperature limit (i.e., density limit) is a predetermined fixed value or a value given by a reference temperature curve "Tpgasmax" (i.e., reference density curve), which in particular allows the temperature limit (i.e., density limit) to be estimated for a given pressure of the gas in the tank.

[0029] An example of the reference temperature curve "Tpgas_max" is shown in Figure 3. For the maximum pressure of gas present in tank 1, the temperature limit is 85°C, which corresponds to the upper limit of the upper temperature range TLgasmax_1. For the minimum pressure of gas in the tank, the temperature limit is about 20°C, which corresponds to the lower limit of the upper temperature range TLgasmin_1.

[0030] The density limit depends on the operating pressure of the tank. For example, if the operating pressure is 350 barg, the density limit is set at, for example, 24.1 kg / m3. If the operating pressure is 700 barg, the density limit is set at, for example, 40.2 kg / m3. Generally, the density limit can be defined in terms of a State of Charge (SOC) percentage, which defines the recommended maximum amount of hydrogen in the tank.

[0031] Determination of the reference temperature curve "Tpgasmax" and the reference density curve As an advantageous feature, the reference temperature curve "Tpgasmax" (i.e., the reference density curve) is provided by a first physical model that simulates a reference fill of the tank over a high temperature range (i.e., a low temperature range) with pre-cooling at the gas source. The reference fill is simulated from a minimum pressure, in this case 5 barg, to a maximum pressure corresponding to the operating pressure of the tank.

[0032] In particular, the reference temperature curve "Tpgasmax" (i.e., the reference density curve) is obtained from the curve "Pgashot" representing the change in pressure of the gas present in the tank as a function of time, and from the curve "Tgasmax" (i.e., the curve "RHO_cold") giving the change in temperature (i.e., the change in density) of the gas contained in the tank as a function of time. The curves "Pgashot", "Tgasmax" (i.e., "RHO_cold") are also given by a first predetermined physical model. These are shown in Figure 5.

[0033] For various ambient temperatures, the first predetermined physical model provides as many reference temperature curves "Tpgasmax" (i.e., as many reference density curves as possible) that form a reference temperature surface curve (i.e., a reference density surface curve). Figure 6 shows an example of a reference temperature surface curve.

[0034] To facilitate the use of the reference temperature curve "Tpgasmax" (i.e. the reference density curve), the "Temperature" variable is normalized between the value 0 corresponding to the lower limit TLgasmin_1 and the value 1 corresponding to the upper limit TLgasmax_1. Figure 7 shows the curve "Reduc_TPgasmax" obtained after normalizing the "Temperature" variable of the reference temperature curve "TPgasmax".

[0035] Determination of the first initial temperature Tini_1 of the gas. The first initial temperature Tini_1 of the gas present in the tank is given as a function of the initial pressure Pini of the gas by a second predetermined prediction curve "TPgashot" (see Fig. 8). In other words, for a given initial pressure Pini of the gas present in the tank, the first initial temperature Tini_1 can be determined by the prediction curve "Tpgashot".

[0036] A prediction curve "Tpgashot" is derived from a second physical model that simulates a reference fill of the tank over a wide temperature range, with optional pre-cooling of the gas supplied by the gas source. Preferably, the second physical model also simulates thermal diffusion for the tank and / or for the gas present in the tank. Thus, the second physical model may differ from the first physical model by taking into account thermal diffusion.

[0037] The thermal diffusion takes place after a reference filling of the tank and a pre-cooling of the gas source. Advantageously, the thermal diffusion is simulated for two minutes, which corresponds to the shortest time required between two successive fillings of the tank at the filling station. Also advantageously, the pressure of the gas in the tank is assumed to be constant during the thermal diffusion period.

[0038] For a given ambient temperature, thermal diffusion causes a decrease in the temperature of the gas present in the tank, which is shown by the curve "Stgasmax" in Figure 9.

[0039] It should be noted that the curve "Tpgashot" is obtained from the curves "Pgashot" and "Tgashot", both established for the same ambient temperature. In particular, the curve "Tgashot" is obtained from a subtraction carried out between the curves "Tgasmax" and "STgasmax".

[0040] As an advantageous feature, to make the curve "TPgashot" easier to use, the "Temperature" variable can be normalized between the value 0, corresponding to the lower limit TLgasmin_1, and the value 1, corresponding to the upper limit TLgasmax_1. The curve thus obtained, "Reduc_TPgashot", is shown in FIG. 10.

[0041] Determination of the second initial temperature of the gas, Tini_2. The second initial temperature Tini_2 of the gas can be obtained as a function of the initial pressure Pini of the gas from the third curve "TPgascold" (see Fig. 11). In other words, based on the initial pressure Pini of the gas present in the tank, the second initial temperature Tini_2 of the gas present in the tank can be determined by the curve "Tpgascold".

[0042] The curve "TPgascold" can be given by a third predetermined physical model (described below) that simulates the reference discharge of the tank over the low temperature range, ie between an upper limit TLgasmax_2 and a lower limit TLgasmin_2.

[0043] The upper limit TLgasmax_2 corresponds to the start of the reference discharge, when the tank is at least partially filled, preferably 100% full. At this upper limit TLgasmax_2 there is a corresponding maximum pressure Pgasmax_2, called the operating pressure ("nominal operating 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 through the following formula taken from the literature: Pgasmax_2[barg]=A*TLgasmax_2[℃]+B Here, A is in the range of 1-2 and B is in the range of 300-400.

[0044] The lower limit TLgasmin_2 corresponds to the end of the reference discharge at which the tank has a minimum pressure Pgasmin_2, set in this case to 5 barg, and a minimum density ρgasmin_2, called the second initial density ρini_2. Furthermore, the lower limit TLgasmin_2 can be obtained from the following formula, taken from the third physical model: Tgasmin_2=A*Tamb+B Here Tamb is the ambient temperature of the filling device, A is in the range of 0.5 to 1.5, B is in the range of -30 to -15.

[0045] For various ambient temperatures, the third physical model provides a number of curves "Tpgascold" that form a surface curve (not shown). To make these curves "TPgascold" easier to use, each "Temperature" variable is normalized between the value 0, which corresponds to a lower limit TLgasmin_2, and the value 1, which corresponds to an upper limit TLgasmax_2. Similarly, the "Pressure" variable can be normalized between the value 0, which corresponds to a minimum pressure Pgasmin_2, and the value 1, which corresponds to a maximum pressure Pgasmax_2, before the tank is emptied. The curve "Reduc_TPgascold" shown in Figure 12 is the result of such a reduction performed on the curve "TPgascold".

[0046] Finally, for an initial pressure Pini measured in the tank and an ambient temperature Tamb obtained from the filling device, at least one predetermined physical model considers this initial pressure Pini to be the final pressure of the previous filling ("hot case") or the final pressure of the previous discharge ("cold case"). These two hypotheses respectively define values for a first initial temperature Tini_1 (corresponding to the hot case) and a second initial temperature Tini_2 (corresponding to the cold case). The values of the first initial temperature Tini_1 and the second initial temperature Tini_2 thus defined may differ from the values of the initial temperatures determined by prior art techniques, for example, may deviate from the ambient temperature by 10-20°C.

[0047] Estimation of the temperature change curve of the gas between the first temperature change curve of the gas (hot case) and the second temperature change curve of the gas (cold case). As an advantageous feature, the control element 5 can be configured to estimate, during filling, the temperature variation curve of the gas present in the tank as a function of the initial temperature of the gas present in the tank, i.e. with the initial temperature of the gas present in the tank as a starting point (or starting condition).

[0048] More specifically, the control element 5 can 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), so that for a given pressure of the gas present in the tank, the corresponding temperature is estimated to be between a first temperature located on the first temperature variation curve of the gas (hot case) and a second temperature located on the second temperature variation curve of the gas (cold case).

[0049] The first temperature variation curve (i.e., the second curve) of the gas has as a starting point (or starting condition) a first initial temperature Tini_1 (i.e., a second initial temperature Tini_2) of the gas. Furthermore, the first temperature variation curve (i.e., the second curve) of the gas is provided by a predetermined physical model that simulates a reference filling of the tank from the first initial temperature Tini_1 (i.e., from the second initial temperature Tini_2) of the gas, said filling being accompanied by pre-cooling at the gas source, followed by thermal diffusion.

[0050] It should be noted that the physical model giving the prediction curve "Tpgashot" of the first initial temperature Tini_1 of the gas is preferably identical to the physical model giving the first temperature change curve of the gas, the two curves being distinguished by their starting points, i.e. the lower limit TLgasmin_1 (in the case of the prediction curve "TPgashot" of the first initial temperature Tini_1) and the first initial temperature Tini_1 (in the case of the first temperature change curve of the gas), respectively.

[0051] Estimation of the density of the gas present in the tank between the first density curve (hot case) and the second density curve (cold case). As an advantageous feature, the control element 5 can 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 starts from the initial density of the gas present in the tank. It should be noted that the initial density can be calculated by the ideal or real gas equations knowing the volume of the tank (known or estimated by known methods, for example based on pressure pulses before filling), the pressure and temperature of the gas.

[0052] More specifically, the control element 5 can be configured to estimate a 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), such that for a given pressure of the gas present in the tank, the corresponding density is estimated to be 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).

[0053] The first density variation curve (i.e., the second curve) starts from a first initial density (i.e., the second initial density) of the gas present in the tank, and the first density variation curve (i.e., the second density variation curve) of the gas is given by a physical model simulating a reference fill of the tank with pre-cooling at the gas source from the first initial density (i.e., from the second initial density) of the gas.

[0054] Determination of the tank's reference temperature curve and temperature change curve. As an advantageous feature, the tank filling stop condition related to the temperature limit of the gas present in the tank can be replaced by a stop condition related to the tank temperature limit.

[0055] The temperature limits of the tank can be given by reference temperature curves of the tank, which are given by the first physical model. In particular, for a tank made up of several layers, for example an inner layer called "liner" that is in contact with the gas and an outer layer called "composite" that is in contact with the outside air, the first physical model gives three reference temperature curves as shown in Figure 8: a first curve "TPgasliner_max" corresponding to the inner wall, a second curve "TPlinercompo_max" corresponding to the inner / outer layer interface, and a third curve "TPexternal_max" corresponding to the outer wall.

[0056] The curves "TPgasliner_max", "TPexternal_max", and "TPlinercompo_max" can be obtained from the curve "Pgashot" by combining them with the curves "Tgasliner_hot", "Texternal_hot", and "Tlinercompo_hot", which represent the temperature change as a function of time at the inner wall, the inner / external interface, and the outer wall, respectively. The curves "Tgasliner_hot" and "Texternal_hot" are shown in Figure 5.

[0057] Furthermore, for ease of use, the curves "TPgasliner_max", "TPexternal_max", and "TPlinercompo_max" can be converted into the curves "Reduc_TPgasliner_max", "Reduc_TPexternal_max", and "Reduc_TPlinercompo_max", respectively, which are defined between the value 0 corresponding to the lower temperature limit TLgasmin_1 and the value 1 corresponding to the upper temperature limit TLgasmax_1.

[0058] An estimate of the initial temperature of the tank between the first initial temperature (hot case) and the second initial temperature (cold case) of the tank. The control element 5 can be configured to estimate an initial temperature of the tank between a first initial temperature of the tank corresponding to a state of the tank that is considered to have been recently filled to a first initial density (hot case) and a second initial temperature of the tank corresponding to a state of the tank that is considered to have been recently drained to a second initial density (cold case).

[0059] The first initial temperature Tini_1 of the tank can be given as a function of the initial pressure Pini of the gas by the prediction curves "TPgasliner_hot", "TPlinercompo_hot", "Tpexternal_hot" (see Fig. 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 the first initial temperature Tini_1 of the tank to be determined.

[0060] The curves "TPgasliner_hot", "TPexternal_hot", and "Tplinercompo_hot" can be given by a second physical model. More specifically, these curves can be obtained from the curve "Pgashot" in combination with the curves "Tgasliner_hot_bis", "Texternal_hot_bis", and "Tlinercompo_hot_bis" (not shown), which represent the temperature change as a function of time for the inner wall, the outer wall, and the inner / external interface of the tank, respectively.

[0061] The curve "Tgasliner_hot_bis" is obtained by modulating the curve "Tgasliner_hot" with the curve "STgasliner". The curve "Texternal_hot_bis" is obtained by modulating the curve "Texternal_hot" with the curve "STexternal". The curve "Tlinercompo_hot_bis" can be obtained by modulating the curve "Tlinercompo_hot" with the curve "STlinercompo". The curves "STgasliner", "STexternal", and "STlinercompo" are shown in Figure 9. These represent the thermal diffusion that occurs near the inner wall, outer wall, and inner / outer layer interface of the tank after the reference filling.

[0062] In the example shown in Figure 9, thermal diffusion corresponds to a decrease in temperature over time at the inner wall of the tank, but at the outer wall of the tank and the inner / outer layer interface, thermal diffusion corresponds to an increase in temperature.

[0063] It should be noted that the curves "TPgasliner_hot", "TPexternal_hot", and "TPlinercompo_hot" can be normalized to the curves "Reduc_TPgasliner_hot", "Reduc_TPexternal_hot", and "Reduc_TPlinercompo_hot", respectively, defined between the value 0 corresponding to the lower temperature limit Tlgas_min_1 and the value 1 corresponding to the upper temperature limit Tlgas_max_1 (see Figure 10).

[0064] The second initial temperature Tini_2 of the tank is given as a function of the initial gas pressure Pini by the prediction curves "TPgasliner_cold", "TPexternal_cold", "TPlinercompo_cold" (see Fig. 11). In other words, for a given initial gas pressure Pini, the second initial tank temperature Tini_2 can be determined by the prediction curves "TPgasliner_cold", "TPexternal_cold", "TPlinercompo_cold".

[0065] It should be noted that the prediction curves "TPgasliner_cold", "TPexternal_cold" and "TPlinercompo_cold" are provided by a third physical model simulating the reference discharge of the tank. Once this reference discharge is complete, the tank temperature reaches a minimum value that varies across the thickness of the tank. For a two-layer tank, the minimum temperature Tmin near the inner wall, the outer wall or the inner / external interface can be given by a linear law of the type Tmin=A*Tamb+B, for example: Here Tamb is the ambient temperature A is in the range of 0.5 to 1.5, B is in the range of -20 to -10.

[0066] The prediction curves "TPgasliner_cold", "TPexternal_cold", and "TPlinercompo_cold" can be obtained by combining the curve "Pgascold" (showing the change in gas pressure as a function of time) and the curves "Tgasliner_cold", "Texternal_cold", and "Tlinercompo_cold" (low temperature case) showing the change in tank temperature as a function of time. The curves "Tgasliner_cold", "Texternal_cold", and "Pgas_cold" are shown in Figure 5.

[0067] Estimation of the temperature change curve of the tank between the first temperature change curve of the tank (hot case) and the second temperature change curve of the tank (cold case). The control element 5 can be configured to estimate the temperature variation curve of the tank during filling (see step S5 of the method shown in Figure 2). 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). Said first and second curves are determined in step S4 of the method shown in Figure 5.

[0068] The first curve starts from a first initial temperature Tini_1 of the tank, and the second curve starts from a second initial temperature Tini_2 of the tank.

[0069] A first temperature change curve (i.e., the second curve) of the tank can be obtained from a model simulating a reference fill from a first initial temperature Tini_1 of the tank (i.e., from a second initial temperature Tini_2), with pre-cooling at the gas source and heat diffusion after the reference fill.

[0070] The effect of thermal diffusion on the predicted curve of the first initial temperature Tini_1 of the tank or gas in the tank. An analysis of Figure 8, which gives the reference temperature curves of the tank or the gas present in the tank (i.e. the curves "TPgasliner_max", "TPlinercompo_max", "TPexternal_max", "TPgas_max") and the predicted curves of the first initial temperature Tini_1 of the tank or the gas in the tank (i.e. TPgasliner_hot", "TPlinercompo_hot", "TPexternal_hot", "TPgas_hot"), shows that the temperature of the gas and the inner wall of the tank decreases following thermal diffusion, while the temperature of the outer wall of the tank and the inner / outer interface increases following thermal diffusion.

[0071] By taking into account the above-mentioned specific changes in the tank temperature following thermal diffusion, the accuracy of the reference temperature curve of the tank and / or of the gas present in the tank can be improved. The invention therefore improves safety during filling by limiting the risk of exceeding temperature limits.

[0072] 10 shows several embodiments of the reference temperature curve "Tgas_max" and the first temperature change curve "Tgas_hot_bis" of a gas. To prevent overheating when filling the tank, the first temperature change curve of the gas present in the tank "Tgas_hot_bis" can be used alone (see example in Figure 13) or in combination with the reference temperature curve of the gas present in the tank "Tgasmax" (see example in Figure 14).

[0073] As shown in each of the above examples, after connecting the vehicle to the end of the filling pipe (step 1) and initializing filling with the filling device (step 2), an incipient overheating of the gas present in the tank is detected (step 3). In the example of Figure 13, an overheating is detected when the curve "Tgas_hot_bis" reaches the temperature limit, which in this case is represented by a horizontal line at 85°C. In the example of Figure 14, an incipient overheating is detected below the temperature limit (85°C). This overheating corresponds to the moment when the curve "Tgas_hot_bis" "catches up" with the curve "Tgas_max".

[0074] Following the initial overheating described above, the control element stops the filling even though the tank is not filled to its maximum capacity. The stop is extended for a certain time required before a new filling cycle (step 4). Steps 5, 6 and 7 correspond to this new filling cycle, in which the initial temperature of the gas present in the tank is determined as a function of the temperature reached by the same gas at the end of the previous cycle, but also as a function of the pressure of the same gas at the start of the new cycle.

[0075] By taking into account the temperature reached in the previous filling cycle and the temperature reached during the subsequent filling cycle, the invention reduces the risk of overheating and allows the maximum load in the tank to be reached.

[0076] Of course, the curves "Tgas_max" and "Tgas_hot_bis" in the above example can be replaced by the curves "TPgasmax" and "TPgas_hot" to control the filling of the tank. If the stop condition is related to the tank temperature limit, one of the curves showing the change in tank temperature (hot case) (e.g. the curve "TPgasliner_hot") can be used to control the filling. This change curve can be used alone or in combination with the associated reference temperature curve (e.g. the curve "TPgasliner_max").

[0077] Presentation of the physical model. The above-mentioned physical model that gives rise to the various prediction curves presented herein is based on a system of energy balance equations that apply to the tank and the gases present within it. These equations are presented below.

[0078] a.The internal energy balance equation for the gas in the tank is written as follows:

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[0079] This balance is determined by the mass of gas in the tank, m g , the mass internal energy of the gas in the tank, u g , the exchange coefficient is k i and the internal surface area of these tanks is S i The heat exchange between the gas in the tank and the tank inner wall, the total hydrogen density

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[0080] One of the two safety standards that must not be exceeded concerns the density within the model. CHSS Since the total volume of the tank (compressed hydrogen storage system) is known, equation (1) can be expressed as m g =V CHSS ρ g can be written as follows using

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[0081] To solve the above equation (2), it is necessary to discretize it by replacing the time derivative with finite differences. The equation thus obtained is therefore V CHSS It is obtained by dividing by

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[0082] According to equation (5), ρ g Therefore, the internal energy u g The value of (t+Δt) can be found.

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[0083] b. The energy conservation equation within the wall is written as follows:

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[0084] This balance involves the density of the wall ρ, its heat capacity v and its thermal conductivity λ, as well as the radius r from the center of the tank.

[0085] The continuity equation for flow at the gas-liner interface is written as follows:

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[0086] The continuity equation for flow at the interface between the composite and the surrounding environment is written as follows:

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[0087] Finally, the continuity equation for the flow at the interface between the two liners and the composite inside the wall is written as follows:

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[0088] c. Discretization of the in-wall equations

[0089] To solve equations (7), (8), (9) and (10), the wall needs to be discretized radially into various meshes. The number of meshes for the liner, n_liner, and the number of meshes for the composite, n_comp, can vary. The temperature of the wall is calculated at each node, then n_mesh = n_liner + n_comp + 1 nodes. Therefore, the size of the mesh is (δr) for the liner as shown in Figure 13. liner =e liner / n liner , in composite (δr) comp =e comp / n comp The thickness of the mesh at the interface is (δr) / 2. In the example shown, three meshes are placed on the liner and three on the composite.

[0090] Equation (7) is discretized so that it can be solved, and then applied to each of the various meshes that form the wall. Figure 14 shows the radial discretization used to solve the equation. In this figure, a mesh centered at point P is surrounded by point W on the west side and point E on the east side, with the tank interior located on the west side. An imaginary plane w is defined between points W and P, and a second imaginary plane e is defined between points P and E. The distance between point W and point P on the one hand, and the distance between point P and point E on the other hand, are respectively (δr) w , (δr) e The surface W and the surface e are spaced apart by Δr P Points W, P, and E are each r away from the center of the tank.W , r P and r E It is located in.

[0091] Equation (7) is integrated over the time step and spatially integrated from west to east to obtain

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[0092] The left side is called A and the right side is called B.

[0093] Density ρ and heat capacity c p Assuming that changes little between time t and t+Δt, the left-hand side can be written as follows:

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[0094] The temperature difference T(r,t+Δt)-T(r,t) remains constant between points w and e, and T(r P ,t+Δt)-T(r P ,t). The term A is written as follows:

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[0095]

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[0096] Term B, i.e., the right-hand side of equation (11), can be written as follows:

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[0097]

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[0098] The value obtained at time t is the exponential 0 The value obtained at time t+Δt is expressed as the exponent 1 The values obtained at points W, P, and E are denoted by the subscripts W , P and E For example, the value T(r p ,t+Δt) is

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[0099] Using the implicit scheme, equation (11) becomes:

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[0100] At the gas-liner interface, the flow continuity equation (8) is discretized as follows:

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[0101] Finally, at the interfaces between the two liners and the composite inside the wall, the flow continuity equation (10) is discretized as follows:

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[0102] The system of equations (17), (18), (19) and (20) for each point P not located on the interface can be solved by the Thomas algorithm, also known as TDMA (Tridiagonal Matrix Algorithm).

[0103] Physical Properties and Coefficients a. From ρ and u to Tg and Pg

[0104] At each time step, the model calculates the temperature and pressure of the gas based on its density ρ and internal energy u. T g =f1(ρ,u) (21) P g =f2(ρ,u) (22)

[0105] These functions f1 and f2 are adjusted to best match the thermophysical properties of the gas.

[0106] b. Heat transfer coefficients ki and ke

[0107] The model also calculates the heat transfer coefficient k i and k e We also need the value of the internal transfer coefficient k i For this, a function calibrated based on the correlation presented by Bourgeois, T. et al. is used (see "Bourgeois T., Ammouri F., Weber M., Knapik C., "Evaluating the temperature inside a tank during a filling with highly-pressurized gas". International Journal of Hydrogen Energy 2015;40:11748-55").

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[0108] External transfer coefficient k eFor this, we use a function calibrated based on the correlation presented by Massard, F. (see heat engineer's checklist. ELSEVIER; 1997):

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[0109] As an advantageous feature, the above-mentioned physical model can be associated with a heat transfer model between the filling device and one or more tanks, which heat transfer model is described below.

[0110] The gas inflow mass enthalpy term h in Eq. ginlet is determined based on the mass enthalpy of the gas at the dispenser by a heat transfer model, the purpose of which is to estimate the heat exchange of the gas between the dispenser of the filling device and the inlet to the tank of the vehicle, along the length of the hoses and other elements connecting the dispenser to the tank.

[0111] The energy conservation equation that applies to gas in a pipe is written for each elemental length dx along the pipe in equation (25). In this case, the pipe is assumed to be uniform in temperature along its entire length.

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[0112] formula T gas,pipe To obtain (x,t), equation (25) can be integrated between 0 (the dispenser) and the position x along the pipe. More specifically,

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[0113] The energy conservation equation that applies to piping is written in equation (27).

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[0114] term

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[0115] Equation (27) is discretized.

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Claims

1. 1. A method (100) for filling a pressurized gas tank (1) performed by a filling device (10) comprising a gas source (2), a filling pipe (3) connecting said gas source (2) to said tank (1), a flow and / or pressure control valve (4) in said filling pipe, and an electronic control element (5) configured to stop filling if the estimated temperature (or density) of the gas present in said tank (1) reaches a temperature limit (or, i.e., a density limit), 1. A method comprising the steps of: determining (S1) the ambient temperature (Tamb) of the filling device (10) before filling the tank (1); determining (S2) the pressure (Pini) of the gas present in the tank (1); and a preliminary step (S3) of estimating an 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 as a function of the ambient temperature (Tamb) and as a function of the pressure (Pini) of the gas present in the tank (1) before filling, and wherein the initial temperature (Tini) of the gas present in the tank (1) is greater than or equal to the ambient temperature (Tamb).

2. 2. The method of claim 1, wherein 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 with 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 discharged with a second initial density (ρini_2).

3. 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 between a lower limit (TLgas_max_1) determined to be equal to or greater than the ambient temperature (Tamb) and an upper limit (TLgas_max_2) corresponding to a predetermined maximum temperature limit, for example equal to 85°C.

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

5. The second initial temperature (Tini_2) of the gas present in the tank (1) is determined to be equal to or lower than the ambient temperature (Tamb) by an upper limit (TLgas_max_2) and a lower limit (TLgas_min) corresponding to a predetermined minimum temperature limit. ＿ 2 ） 5. The method according to claim 2, wherein the temperature is in the low temperature range of 0 to 5° C., for example in the range between 0 and −5° C.

6. The second initial temperature (T ＿ 6. The method according to claim 2, wherein the temperature difference TPgas_cold is determined from a second predetermined prediction curve "TPgas_cold" given by a predetermined physical model simulating a reference filling of the tank (1) over a low temperature range.

7. 7. The method according to claim 2, further comprising a step (S4) of modeling a first temperature variation curve (or, i.e., a first density variation curve) of the gas present in the tank (1) starting from the first initial temperature (Tini_1) (i.e., the first initial density (ρini_1)) of the gas present in the tank (1) during filling, and / or a second temperature variation curve (or, i.e., a second density variation curve) of the gas present in the tank (1) starting from the second initial temperature (Tini_2) (i.e., the second initial density (ρini_2)) of the gas present in the tank (1).

8. 8. The method according to claim 7, comprising a step (S5) of estimating a temperature variation curve (or, i.e., density variation curve) of the gas present in the tank (1) during filling, said curve lying between the first temperature variation curve (i.e., the first density variation curve) and the second temperature variation curve (i.e., the second density variation curve).

9. 9. The method according to claim 2, wherein the first initial temperature (Tini_1) and / or the second initial temperature (Tini_2) are recalculated during filling as a function of the flow rate and as a function of the temperature of the gas present in the filling tube, the flow rate and the temperature being determined by calculation and / or by sensors on the filling device (10).

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

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

12. 12. The method according to claim 11, characterized in that the first initial temperature (Tini_1) (i.e. 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 algorithm.

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

15. 15. Method according to any one of claims 7 to 14, characterized in that the electronic control element (5) is configured to simulate and estimate the temperature and / or density variation curves of the gas present in the tank (1) dynamically during filling of the tank (1) and / or in a predictable manner, i.e. before filling.

16. A device (10) for filling a pressurized gas tank (1) with gas, comprising: a gas source (2), a filling pipe (3) connecting the gas source (2) to the tank (1), a flow and / or pressure control valve (3) 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 of the filling device (10); - stopping the filling if the estimated temperature (i.e. density) of the gas present in said tank (1) reaches a temperature limit (i.e. density limit); - an electronic control element (5) configured to estimate 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 as a function of the ambient temperature (Tamb) and as a function of the pressure (Pini) of the gas present in the tank (1) before filling, the initial temperature (Tini) of the gas present in the tank (1) being greater than or less than the ambient temperature (Tamb).

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