RU2262780C1 - Method for tightness checkup of metal-hydrogen storage batteries - Google Patents

Abstract

FIELD: electrical engineering; in-service tightness checkup of metal-hydrogen storage batteries.

SUBSTANCE: proposed method includes measurement of battery case internal pressure and external temperature, comparison of measurement data with permissible values, and evaluation of battery tightness by compliance of measured parameters with specified range; novelty is measurement of gas density within battery space, evaluation of coefficients of thermal expansion of battery case for mentioned measured temperatures and pressures, evaluation of battery degree of charge within which hydrogen is liberated during battery charge so as to check battery for leakage, primary charging of battery in the range of its degree of charge within which only hydrogen is liberated, and measurement of rated charging current; in the process check leakage of hydrogen from battery gas space is made and additional calibrating value of charging current compensating for absolute statistical error in above-given measured parameters of battery and its charging current is determined by amount of leaks; check leakage is ceased upon exit from its tightness check range, whereupon battery is discharged; then, in the course of battery charges with rated current within degree of battery charge in which only hydrogen is liberated during its charging period, battery is given thermostatic control similar to its primary charge, mean volumetric temperature of hydrogen within battery is evaluated for given range, and electrochemical hydrogen flow within battery (Q_ech) is determined by charge currents measured during each recharge and by charge current variation value correction, as well as by definite values of mean volumetric hydrogen temperatures; at the same time, barometric hydrogen flow (Q_bar) within battery is evaluated in same range, for same measured temperatures and pressures as during primary charge, as well as for definite coefficients of thermal expansion of battery case at mentioned measured temperatures and pressures within battery degree of charge in which only hydrogen is liberated during battery charge, and battery tightness is considered adequate provided condition Q_ech - Q_bar < Q_ad is satisfied, where Q_ad is admissible leakage from battery.

EFFECT: provision for in-service tightness check of battery by hydrogen leakage within battery admissible sensitivity level.

2 cl, 5 dwg

Description

The invention relates to electrical engineering and can be used in the operation of a metal-hydrogen battery (MVA) to check for leaks.

A known method of monitoring the tightness of pneumohydrosystems [1], used in space technology and adopted as an analogue.

The essence of the method lies in the fact that the spacecraft (SC) is placed in a vacuum chamber connected to a leak detector, while the volume of the vacuum chamber communicates with the internal cavity of the compartment. The chamber and compartment are evacuated by means of pumping to the maximum residual pressure in the vacuum chamber. Then a calibrated flow of control gas of a given value is fed there. The difference in the concentration of the control gas in the vacuum chamber from the calibrated flow is measured. After measurements, the supply of a calibrated flow of control gas to the vacuum chamber is stopped. The pneumohydrosystem is charged with control gas. The change in the concentration of the control gas in the vacuum chamber from micro-leaks in the units and highways of the pneumatic system is measured, and the tightness of the pneumatic system is judged by the ratio of the measured changes in the concentration of the control gas.

The indicated control method can be used for MVA only if it is inoperative, and only to control the tightness of the body (vessel) that is not under working pressure. In this case, only hydrogen can be used as a control gas, which for such tests in vacuum technology, due to its explosiveness, is not used. The use of other gases for such purposes, including neutral ones (for example, helium), cannot further guarantee the regular operation of the MVA electrochemical battery (ECB), since the remnants of the control gas can further interfere with the main electrochemical processes occurring in the battery.

It is known that for control of MVA during operation, the most used are the parameters of pressure, temperature and voltage [2, p. 266]. The specified parameters are also used to control the tightness of the MBA. A method of monitoring the tightness of a metal-hydrogen battery, including measuring the pressure inside its case and the temperature on the battery case, comparing the measured values with the maximum allowable and determining the tightness by finding the measured parameters in the acceptable range, is taken as a prototype [2, p.265-266].

Acceptable gradients of growth or pressure drop inside the battery housing can be judged on its tightness. In case of leaks, the specified tolerances are exceeded, up to the mechanical rupture of the vessel. However, this method of control is rather rough, and the situation associated with the rupture of the vessel is prevented by the choice of margin of safety of the material in the manufacture of cases [2, p. 266].

The most probable cause of the MBA leak is the leakage of hydrogen from the battery both through its body and through the assembly sites of additional structural elements that make up the battery. Monitoring of hydrogen leakage can be carried out by the voltage of the battery and by the temperature on its housing [2, p. 265]. The fact of a partial loss of hydrogen is established by the voltage drop during the charge. On a nickel-hydrogen battery, for example, the voltage drop is from 1.4 ... 1.6 V to 0.5 ... 0.6 V.

In addition, the MBA is very hot, since almost all the power supplied to it goes into heat.

The main disadvantages of the prototype method are as follows. It is practically impossible to control the MVA tightness by pressure drop inside the housing for micro-leaks, this is due to the fact that the process of converting chemical energy directly to electric energy in the accumulator is accompanied by pressure changes associated not only with the ongoing thermodynamic processes, but also with electrochemical processes. Therefore, in addition to the pressures and temperatures in the closed volume of the battery, it is necessary to take into account to control the flow of emitted gases (oxygen and hydrogen) and the magnitude of the battery currents. In many ways, the gas evolution process also depends on the design of the battery itself, the construction of its ECB, the scheme for removing excess battery heat, and other features.

The parametric manifold characterizing the operation of the MBA introduces an error in the process of monitoring its tightness by pressure, while the magnitude of this error does not allow to bring the sensitivity of the method to control the values of small leaks (~ 0.1 μm Hg · l / s).

Temperature tightness control on the battery case also has a significant drawback, since it is not the process of leakage from the battery that is controlled, but the consequences of this leakage. Thus, it is not possible to take into account the negative process in the operational strategy of the MBA and it is necessary to react only to the consequences of this leak.

In addition, for MVA with a common gas collector [3] and with elements connected in series, it is not possible to control the temperature and voltage on an individual element, since the voltage on the ECB, measured as the sum of the voltages of each element, can generally be estimated by in different ways. On the one hand, when it falls, one of the elements may fail, on the other, a voltage drop on each of the elements associated with a hydrogen leak from the battery case. A temperature control system (STR) of ECB, for example, using heat pipes closed to radiators, heat exchangers (RTOs) [3], can provide the necessary heat release from MVA.

Thus, as in the case of pressure, leakage can be judged with a significant degradation of the battery as a whole, when the load on the CTP will not increase in proportion to the heat capacity of the battery associated with its regular operation.

The challenge facing the proposed method is to ensure ongoing monitoring of the tightness of the metal-hydrogen battery during its operation for hydrogen leakage within the sensitivity range at a level acceptable for the battery.

The problem is solved in that in a method for monitoring the tightness of a metal-hydrogen battery, including measuring pressure inside its case and temperatures on the case, comparing the measured values with the maximum allowable and determining the tightness by finding the measured parameters in the allowable range, measure the volume of the gas-metal hydrogen cavity accumulator, determine the expansion coefficients of the metal-hydrogen accumulator case for the indicated measured values of temperatures and pressures, determine for for the tightness of the metal-hydrogen accumulator, the range of values of the degree of its charge, within which hydrogen is released when the metal-hydrogen battery is charged, the primary charge of the metal-hydrogen battery is produced in the range of the values of the degree of its charge, within which only hydrogen is released and the nominal charge current, while producing a control flow of hydrogen from the volume of the gas cavity of the metal-hydrogen battery and its value determine the calibration additional value of the charging current, which compensates for the absolute statistical error of the above measured parameters of the metal-hydrogen battery and the charging current, upon leaving the tightness control range, they cease to control the leak and discharge the metal-hydrogen battery, then, during repeated charges of the metal-hydrogen battery with a nominal current in the range of the degree of charge of the metal-hydrogen battery, within which only hydrogen is released and when it is charged, thermostatting of the metal-hydrogen battery is performed, similar to its primary charge, volumetric average temperatures of hydrogen in the metal-hydrogen battery are determined for the indicated range and by the values of the charge currents measured at each repeated charge and the correction for the calibration value of the charge current, and defined as volume average value of the hydrogen temperature is determined electrochemical hydrogen stream in the accumulator (Q _Ah) simultaneously in the same range for the same measured zna temperature and pressure, as with the initial charge, as well as certain values of the expansion coefficients of the metal-hydrogen battery housing for the indicated measured temperatures and pressures in the range of the degree of charge of the metal-hydrogen battery, within which only hydrogen is released when the metal hydrogen battery, determine barometric flow of hydrogen into the metal-hydrogen battery (Q _bar) and sealing metal-hydrogen battery formed judged by nd conditions

Q _eh -Q _bar <Q _add

Q _add - allowable leakage value of a metal-hydrogen battery.

In addition, in the specified method for monitoring the tightness of a metal-hydrogen battery, a control discharge of hydrogen in the process of its initial charge is carried out by Q _extra for various conditions of temperature control of the metal-hydrogen battery within the permissible temperature values, a calibration additional charge current value is determined for each discharge, which take into account when determining Q _eh for similar thermostating conditions during repeated charges of a metal-hydrogen battery.

To describe the proposed method introduced figure 1 ... figure 5, which presents:

figure 1 - device Nickel-hydrogen storage battery with a common gas collector;

figure 2 - placement of current leads on the housing of a Nickel-hydrogen battery with a common gas collector;

figure 3 - placement of pressure sensors on the housing of a Nickel-hydrogen battery with a common gas manifold;

figure 4 - graphs of the measured telemetric parameters of the Nickel-hydrogen battery during the charging test;

figure 5 - dynamic errors of the measured and calculated parameters of the Nickel-hydrogen storage battery.

To explain the essence of the proposed technical solution, let us consider, as an example, a nickel-hydrogen storage battery (NVAB) designed to directly convert electrical energy into chemical energy of the reaction of interaction between nickel hydroxide and hydrogen, storing it in this form for the necessary time and reverse direct conversion of the chemical energy of the reactants into electrical energy.

The NVAB device is presented in figure 1-figure 3, where the conventions are introduced:

1 - ECB;

2, 3 - parts of the power housing: the first and second hemispheres, respectively;

4 - pressure sensors (three in total);

5 - current leads with pressure sockets (only two);

6 - nozzle for refueling with hydrogen;

7 - seat installation of heat pipes;

8 - a nut;

9 - a central hairpin;

10 - adapter of the central stud;

11 - current lead;

12 - power terminals of current leads;

13 is a cylindrical insert.

ECB 1, located in a welded power case, consisting of two parts 2 and 3 of a spherical shape and a cylindrical insert 13, performs the functions of an energy converter.

When assembled, the casing is a high-pressure cylinder, which is filled with hydrogen. Three pressure sensors 4 are installed on the cylinder, providing pressure measurement inside the NVAB housing and controlling the operation of ECB 1, two current leads with pressure connectors 5, which allow supplying and removing electric energy from ECB 1, and a nozzle 6 for testing and filling the NVAB with hydrogen.

In addition, temperature measurements are made on the NVAB housing, installing (gluing) from three to six temperature sensors in different places on the housing surface. The same sensors are installed on heat pipes [3].

In the axial part of the NVAB there are two cylindrical seats 7 for installing the evaporative part of two heat pipes [3], which provide heat transfer from ECB 1 to the heat pipes. To increase heat transfer, the gap between the design of ECB 1 and the seats for installing heat pipes 7 is filled with heat-conducting paste.

The ECB 1 is fastened to the first hemisphere 2 using a nut 8, followed by welding of the joints between the central pin 9 and the adapter of the central pin of the housing 10.

The second fulcrum of the ECB 1 in the second hemisphere 3 is sliding, providing movement of the housing along the stud when pressure and temperature inside the housing change. After installing the ECB in the hemisphere 2, the corresponding power terminals 12 of the current leads 11 are connected to the buses "+" and "-" ECB.

NVAB is made with a common gas collector, which ensures high stored energy per unit mass (not less than 50 W · h / kg) and volume (not less than 100 W · h / l), high reliability and safety.

ECB 1 contains electrical groups consisting of a negative hydrogen gas diffusion electrode made in the form of a metal gilded nickel grid with a catalyst embedded in it (platinum with fluoroplastic), a positive oxide-nickel electrode (ONE), which is a highly porous nickel structure filled with hydroxide nickel.

The thickness of the positive electrode (mass) determines the total stored energy of the battery and electron carrier.

The electrolyte is an aqueous solution of alkali (KOH), which is contained in a special porous matrix.

When charged, hydrogen is restored on the hydrogen electrode and fills the total volume of the battery, while the pressure in the tank (the barodynamic dependence of NAB) increases approximately in proportion to the charged battery capacity. Each temperature value measured on the NVAB housing has its own schedule of permissible pressure increase inside the battery case at rated charging current [2, Fig. XI.5 p. 259].

Comparing the measured values with the maximum permissible values, the tightness of the housing can be determined by finding the measured parameters in the acceptable range.

During the discharge, hydrogen is ionized and the electrochemical formation of Ni (OH) ₂ occurs, while the hydrogen pressure decreases approximately in proportion to the consumed battery capacity. The average potential of one element during a discharge is ~ 1.25 ... 1.3 V.

For example, we take ECB1 in the form of a package [3], consisting of eighteen battery cells connected in series, interconnecting electrical groups.

We also take for monitoring the tightness of the battery in the charging cycle. The indicated cycle is the most dangerous in case of the shell’s internal gas pressure, the growth of which can amount to tens of atmospheres during the charge up to a maximum value of ~ 60 kgf / cm ² .

Let us write down a system of equations describing the calculation of the leakage rate of an NLAB.

1) Electrochemical flow of hydrogen (generalized Faraday law in differential form - [4], p. 388).

Where

μ _H2 = 2 - kilomol mass of hydrogen, [kg / kmol];

n = 18 - the number of cells connected in series in NVAB, [-];

Z _H2 = 2 is the valence of hydrogen, [-];

F = 9.6485 · 10 ⁷ is the Faraday number, [A · s / kmol];

I (τ) is the measured current value in the charge-discharge cycles of NVAB, [A];

η = η (С / С _HOM , T _ECB , I; n _C ) - calculated value of current efficiency in charge mode (a complex empirical function of many variables), [-];

С / С _HOM - calculated degree of charge of NVAB, [-];

T _ECB - calculated _volumetric average temperature of the electrochemical battery (ECB), [° C];

n _C - the number of charge-discharge cycles at the current time of the resource operation of the NVAB, [-].

2) The barometric flow rate of hydrogen (Mendeleev-Clapeyron equation in differential form - [4], p. 151).

Where

V _H2 (P, T _K ) - calculated volume occupied by gaseous hydrogen in NVAB (technical measurement system), [l];

R _O = 8314 is the universal gas constant, [J / (kmol · K)];

P (τ) is the measured pressure of hydrogen in NVAB (technical measurement system), [kgf / cm ² ];

T _H2 (τ) is the calculated volumetric average temperature of hydrogen in NVAB, [° С];

T _K (τ) - the measured temperature of the housing NVAB, [° C];

k _P = 9.81 · 10 - conversion factor for measuring pressure in the SI system, [(N / m ² ) kgf / cm ² )];

k _V = 10 ^-3 - conversion factor for measuring volume in the SI system, [m ³ / l].

3) Hydrogen flow (leak) through the gas-permeable shell of the NVAB housing and sealing structural elements (expense balance).

4) The calculated value of the average (integral) temperature over the internal volume of the NVAB ([5], p. 31) in the general form

In private form for cylindrical layers of ECB and gas cavity we have:

Where

T (r) is the calculated distribution of temperature along the radius in the cylindrical layers of NVAB;

r ₀ , r ₁ , r ₂ are the radii of the inner surface of the ECB, the outer surface of the ECB and the inner surface of the NVAB housing, respectively.

5) The calculated volume of gaseous hydrogen, taking into account the "respiration" of the spherical housing of the NVAB, from temperature and pressure factors.

Where

V ₀ - the measured volume of the gas cavity NVAB during acceptance tests with temperature T ₀ and pressure P ₀ the environment, (the value of the volume entered in the form), [l];

ΔV _T is the volume increment from the temperature factor, [l];

ΔV _P is the increment of volume from the pressure factor, [l];

β _T - temperature coefficient of linear expansion of the material of the body, [1 / ° C];

- the calculated coefficient of expansion of the housing from the pressure factor, [kgf / cm ² ] ^-1 ;

Δt = (T _K -T ₀ ) - change in temperature of the housing, [° C];

ΔP = (P-P ₀ ) is the change in hydrogen pressure, [kgf / cm ² ];

T ₀ , P ₀ - measured environmental parameters when determining the volume V ₀ for the gas cavity NVAB (parameter values are entered in the form);

R _K - excess test pressure to determine the coefficient β _P at T _K = T ₀ = Const;

ΔL _K is the measured linear elongation of the circumference of the body under the influence of the test pressure factor P _K , [mm];

D ₀ - the measured diameter of the housing NVAB with parameters T ₀ and P ₀ , [mm].

6) Norm of leakage (leak).

Equation {3} describes the material balance of gas consumption, expressed in units of mass. In a vacuum technique, a calculated gas flow is used to measure a leak, expressed in arbitrary units of the flow determined by an expression that is valid at a constant temperature (calculated gas flow is [6, p. 156]):

Where

- the calculated average value of the temperature of hydrogen in NVAB during the implementation of the control method, [K];

τ ₁ and τ ₂ - the measured time of the beginning and end of the method of monitoring leaks, respectively, [s];

Δτ = (τ ₂ -τ1) - the duration of the method of tightness control, [s];

k _P = 7.5 · 10 ³ - conversion factor for measuring gas flows in the technical measurement system, [(μm mercury column · l / s) / (W)].

Consider in detail the application of the proposed method for monitoring the tightness of a metal-hydrogen (nickel-hydrogen) battery.

Before using the battery, measure the volume of the gas cavity V ₀ .

For this, the technological connection 6 is used (see figure 1). Through it, for example, the battery is charged with a calibrated mass of hydrogen. Next, the volume of the gas cavity of the battery is measured by the known mass of hydrogen, the measured temperature on the housing and the pressure inside the housing.

We determine the coefficients β _t and β _p (see {6}), while taking into account the operating range of temperatures and pressures of the battery obtained during its operation. We determine the range of values of the degree of charge of the battery (C / C _nom ), within which only hydrogen is released when the battery is charged. For this, we use the well-known dependences on the pressure change in the function of the relative charge capacity (degree of charge) at various temperatures, (see [2], p. 259).

From the indicated dependences, we determine the areas only for hydrogen evolution, characterized by a constant gradient of pressure change. For example, C-band / S _SG of from 0.1 to 0.5 (see [2]., Ris.XI.5, p. 259), hydrogen is released at a temperature of from 0 ° to 40 ° C.

For the indicated region of the degree of charge, an almost constant value η≈1 is guaranteed to be realized. This greatly simplifies the determination of G _EH from the measured charging current when charging the battery within the specified range. In addition, the choice of the region of hydrogen evolution leads to an increase in the accuracy of the control method, since this region is characterized by the minimum intrinsic heat release of the NAB and, as a consequence, the stability and uniformity of the temperature distribution over the battery design, which allows the accuracy of replacing the calculated value of the average volumetric temperature of hydrogen T _H2 to the measured value of the housing temperature T _K.

Based on these prerequisites, figure 4 made the selection of the specified area for NVAB installed on the spacecraft "Yamal-100" and located in the charging cycle.

In Fig. 4, the following notation is introduced:

_{TT TT} is the temperature of the heat pipes in the zone of their installation on the PTO (see [3]);

W - current values of the level of charge of the NVAB, determined by the expression:

where k is the coefficient of proportionality;

P ₀ - pressure in NVAB at the end of a full discharge, [kgf / cm ² ];

P - working pressure in NVAB, [kgf / cm ² ].

To implement the method, the value of the relative charge W = (0.1 ... 03) W _NOM ) in the time interval Δτ≈1.5 hours

The area of practical implementation is highlighted by a rectangle. As can be seen from the fragments of the graphs belonging to the region, a linear increase in P and W is observed at I≈const, Т _K ≈const and Т _TT ≈const.

Thus, this region is limited by the limits for the released hydrogen in the process of charge, with η≈1.

For the presented domain of definition, taking into account the assumptions made, after the transformation of the above system of equations {1} ... {8}, the final expression for the calculated current leak rate is:

Where

a certain value of the flow of hydrogen in the battery from an electrochemical reaction;

a certain value of the barometric flow of hydrogen in the battery.

Determine the average value of the temperature of hydrogen during the implementation of the method for Q _SEC :

Where

T _K (τ) is the measured temperature of the housing;

τ ₁ and τ ₂ - the measured time of the beginning and end of the method of monitoring leaks, respectively, [h].

We determine the average value of the calculated pressure gradient (taking into account the "respiration" of the case from temperature and pressure factors) during the implementation of the method for Q _BAR :

Where

P (τ) is the measured hydrogen pressure;

- the analytical dependence of the relative volume of hydrogen on the current parameters of the hydrogen pressure and the temperature of the housing;

Δt = Т _K (τ) -Т ₀ - current temperature difference, [° С];

ΔР = Р (τ) -Р _О - current pressure difference, [kgf / cm ² ];

τ ₁ and τ ₂ - the measured time of the beginning and end of the method of monitoring leaks, respectively, [h].

Determine the average measured value of the charging current during the implementation of the method for Q _EL :

where I _i - current measured values of the charging current in the field of implementation

Comparison of current and permissible leak rates:

If condition {19} is fulfilled, one can judge the tightness of the MBA. To increase the sensitivity of the control method, an additionally agreed calibration of the measured parameters I, P, T _K for compliance with the actual leak rate at the time of the start of standard (resource) operation in order to eliminate the static absolute measurement error is proposed.

The calibration is as follows.

On the nozzle 6 (see Fig. 1), a bypass valve with a calibrated nozzle for the control leak (Q _TAP ) is installed and during the initial charge of the battery within the previously considered range with the release of only hydrogen, open the valve. Thus produce a control flow of hydrogen from the volume of the gas cavity of the battery. In this case, the charging current is measured (I _ISM ).

Calibration additive ΔI _TAP for the charging current, which compensates for the absolute statistical error of the complex of measured parameters, is determined by the actually measured and calculated parameters obtained during the initial charge from the identity equation {10} with the substitution {11, 12} for the actual leak rate (Q _TAP ) :

After the specified initial charge, the battery is discharged. In this case, the losses of hydrogen from the volume of the gas cavity, in view of their smallness, are neglected.

Next, enter the value of the calibrated average value of the charging current (I _CP ) to implement the method:

From the expression {20} it follows that the indicated calibration value will most closely correspond to the temperature (temperature range) T _cf for which the tests were carried out. Therefore, in the process of recharging the battery with a rated current in the range of the degree of charge of the battery, within which only hydrogen is released, we perform thermostating of the battery, similar to its initial charge.

The indicated thermostating is carried out using the STR means of both the battery itself (see [3]) and, for example, the spacecraft compartment in which the MBA is located.

In the process of repeated charges of the battery, the expression {10} with the substitution {11, 12, 21} for the calculated current leak rate will look like:

where Q _EC is the hydrogen flow in the battery from the electrochemical reaction, taking into account the correction for the calibration value of the charge current.

A comparison of the current and permissible leak rates must be made by the expression

If condition {19} is fulfilled, one can judge the tightness of the MBA. An example of calculating the degree of tightness of NVAB spacecraft "Yamal-100" taking into account ΔI _{TAP is} shown in Fig.5.

In this case, the following calculated values are accepted:

Q _TAP = Q _DOP = 0.08 [μm Hg · l / s];

I _MOD = 8.320534, [A];

T _CP = 8.977064, [C];

(P · θ) Δτ = 5.5144, [(kgf / cm ² ) h]; V ₀ = 16, [l].

Substituting the indicated values into the calculated expression {20}, we obtain

ΔI _TAP = 2.674078 [A].

The indicated value was obtained during ground tests.

NVAB for the temperature range [T ' _CP ] ≈ [8 ... 30 ° C].

Further, according to the expression {22}, substituting the measured values obtained in the selected area of the practical implementation of the method (see figure 4):

I _MOD = 8.49138, [A];

T _CP = 13.1667, [° C]; T _CP ∈ [T ^' _CP ]

(P · θ) Δτ = 5.6833, [(kgf / cm ² ) h],

we obtain the value of Q _LEAK = 0.0672 μm Hg · l / s. We compare the obtained value with the permissible one and draw a conclusion on the tightness of the NVAB.

To increase the accuracy in determining the actual leak rate, the "dynamic noise level" of the measured parameters was smoothed out.

The highest level of dynamic error of the measured parameters is noted for the charging current. Therefore, as the I _ISM , the spent measured current value of the charging current Ii is accepted, taking into account the approximation reliability value (R ² ). Smoothing the "dynamic noise level" was carried out using a mathematical apparatus using the least squares method.

The control leakage of the Q _tap battery can be selected in different ways, based on the subsequent planned strategy for battery operation. For example, if periodic monitoring is available using external controls (mass spectrometers, exemplary pressure gauges, etc.) that are not installed on the battery itself, the sensitivity of the method can be reduced by increasing Q _tap , until the condition

The indicated approach can make it possible to reduce several requirements for the accuracy of measurements of the parameters I, P, T _K , Δτ. Remove the requirement for conducting individual calibration tests for each NVAB (for example, for a large batch to reduce the cost of the test process), etc.

In case of increased requirements, to fulfill the condition

the requirements for measuring equipment are increasing, control algorithms are becoming more complicated in terms of the mathematical processing of the measured parameters (approximation and smoothing in order to eliminate dynamic error). It may be necessary to conduct several calibration tests (“primary charges”) for statistical processing of the results obtained (for example, followed by refueling the battery with hydrogen, etc., which will increase the cost of testing and operating the MBA.

From the point of view of optimization, the ratio of price and quality is proposed to proceed from the necessary sufficiency of control and to control the hydrogen flow in the process of the initial charge of the battery by

for various conditions of temperature control of the battery within the permissible temperature values. Next, determine for each of the conditions a calibration incremental value of the charging current, which then should be taken into account when determining the Q _SEC for similar thermostating conditions during repeated charges of the battery.

The necessary accuracy and certification of the method for monitoring the tightness of NVAB during ground training and regular operation is achieved by the following measures:

- completing the NVAB with accurate measuring equipment, taking into account the secondary conversion of the output analog signal in the on-board control algorithm, including for the following parameters: I, P, T, Δτ;

- conducting individual calibration tests for each NVAB regarding the determination of technical characteristics with their entry in the form, including for the following parameters: V _o , T _o , P _o , β _p , β _t , η;

- development of an algorithm for determining the calculated parameters in terms of the temperature distribution T (g) along the radius in the cylindrical layers of the NVAB according to the input measured parameters;

- mathematical processing (approximation and smoothing) of the measured parameters I, P, T _K in order to eliminate the dynamic error from electromagnetic interference in the secondary signal conversion system - smoothing the "noise level". The performance of the MBA largely depends on the integrity and integrity of the design of its housing. Destruction of the housing design leads to a complete loss of performance. Possible irreversible leaks of the working fluid with an increased leak rate lead to accelerated degradation of its technical characteristics during normal (resource) operation. Moreover, the rate of degradation directly depends on the magnitude of these leaks. In the event of an MBA leak, the strategy for its further operation should accordingly change with the inevitable decrease in the technical characteristics of the battery in comparison with the standards of technical conditions for operation.

During the design and development of the MBA used on the spacecraft, the necessary leakage standards are established, which make it possible to provide technical characteristics for a given battery life. In ground testing and acceptance tests, various regulatory methods are used to determine and confirm the design tightness standard using special expensive ground equipment and fittings (vacuum stands, standard pressure gauges, mass spectrometer, etc.). However, the control methods used in this case are not suitable for the regular operation of the spacecraft in space flight conditions.

During long-term regular operation of the MBA as part of the spacecraft, it becomes necessary to verify the actual leak rate using simple means of measuring the parameters of the battery included in its composition. Such a check is necessary for the correct assessment of the technical condition of the MBA and confirmation of its electrical resource characteristics, subject to the condition of permissible tightness of the ampouled volume with a gaseous working fluid (hydrogen).

The known method is a prototype of the control of the actual leakage rate of pressure drop is not acceptable for the regular operation of the MVA in the conditions of variable temperature control and various operating modes of the battery.

The proposed method allows for space flight to carry out current (operational) control of the tightness of the MBA sensitivity is comparable with the specified methods of ground control.

The availability of leakage information allows you to build an appropriate battery management strategy. So if there is a hydrogen leak above the permissible leakage value, in order to extend the battery life, it is necessary to increase the duration of its storage in the discharged state and charge it in cases of predicted demand for electricity from secondary power sources. For example, before passing through the “shadow” sections of the spacecraft’s orbit and before the end of the indicated sections, the battery is charged, then storage is in a discharged state. Other options are also possible in the MBA operation strategy.

If backup batteries are available, it is necessary to switch to them, using the leaky battery resource to the end, and also review the spacecraft’s energy balance in the direction of introducing energy saving modes, transferring electricity to other forms of energy - thermal, mechanical, compressed gas energy, etc. ., and in flight areas with an excess of generated energy on board the device and thereby reducing the cost of battery power in critical areas of its operation (reduce power consumption during heating construction, gases, etc.). These measures allow you to extend the life of the device. Thus, the presented method actually solves the problem of extending the spacecraft service life in the event of a gas (hydrogen) leak from MVA devices installed.

Literature

1. Lipnyak L.V., Panov N.G., Scherbakov E.V. A method of monitoring the tightness of pneumohydrosystems. RF patent 2086941.

2. Center B.I., Lyzlov N.Yu. Metal hydrogen electrochemical systems. Leningrad "Chemistry", Leningrad branch. 1989.

3. Chelyaev V.F., Nikitin V.A., Matrenin V.I., Tsedilkin A.P. Battery with metal-gas elements. RF patent 2118873.

4. B.M. Yavorsky, A.A. Detlaf. Handbook of Physics. Publishing House "Science", Main Edition of Physics and Mathematics, Moscow. 1979.

5. A.V. Lykov. Theory of thermal conductivity. Higher School Publishing House, Moscow. 1967.

6. L.N. Rozanov. Vacuum technology. Higher School Publishing House, Moscow. 1982.

Claims (2)

1. A method of monitoring the tightness of a metal-hydrogen battery, including measuring pressures inside its case and temperatures on the case, comparing the measured values with the maximum allowable and determining the tightness by finding the measured parameters in the acceptable range, characterized in that the volume of the gas cavity of the metal-hydrogen battery is measured determine the expansion coefficients of the housing of the metal-hydrogen battery for the specified measured values of temperatures and pressures, determine for control hermetically In the case of a metal-hydrogen accumulator, the range of values of the degree of its charge, within which hydrogen is released when the metal-hydrogen battery is charged, the primary charge of the metal-hydrogen battery is produced in the range of values of the degree of its charge, within which only hydrogen is released and the nominal charging current is measured at the same time, a control hydrogen leak is produced from the volume of the gas cavity of the metal-hydrogen accumulator and the calibration additional value is determined by its value the charge current, which compensates for the absolute statistical error of the above measured parameters of the metal-hydrogen battery and the charging current, upon leaving the tightness control range, stop the control leak and discharge the metal-hydrogen battery, then during repeated charges of the metal-hydrogen battery with a rated current in the range the degree of charge of the metal-hydrogen battery, within which only hydrogen is released when it is charged, Thermostatic control of the metal-hydrogen battery is carried out, similar to its initial charge, volumetric average temperatures of hydrogen in the metal-hydrogen battery are determined for the specified range and from the values of the charge currents measured at each repeated charge and the correction for the calibration value of the charge current, as well as a certain value of the average volumetric temperatures hydrogen, determine the electrochemical flow of hydrogen in the battery (Q _eh ) simultaneously in the same range for the same measured temperatures and pressures, as with the initial charge, as well as certain values of the expansion coefficients of the metal-hydrogen battery housing for the indicated measured temperatures and pressures in the range of the degree of charge of the metal-hydrogen battery, within which only hydrogen is released when the metal-hydrogen battery is charged, determine the barometric flow of hydrogen in the metal-hydrogen battery (Q _bar ) and the tightness of the metal-hydrogen battery is judged by the fulfillment of the condition Q _eh -Q _bar <Q _add , Q _add - allowable leakage value of a metal-hydrogen battery. 2. The method for monitoring the tightness of a metal-hydrogen battery according to claim 1, characterized in that the control discharge of hydrogen in the process of its initial charge is carried out by Q _extra for various conditions of temperature control of the metal-hydrogen battery within the permissible temperature values, calibration is determined for each discharge the additional value of the charging current, which is taken into account when determining Q _eh for similar thermostating conditions during repeated charges of a metal-hydrogen battery.

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