CN114961945B - A method and device for calculating ammonia storage quality - Google Patents

Abstract

The present application provides a method and device for calculating the mass of ammonia storage. The change of ammonia storage on the catalyst is calculated by a kinetic equation; the change of ammonia storage on the catalyst is used to obtain the ammonia storage mass conservation calculation formula; the ammonia storage mass conservation calculation formula and the forward Euler discrete formula are used to construct the ammonia storage mass formula, and the ammonia storage mass formula is used to calculate the ammonia storage mass. In this way, the change of ammonia storage on the catalyst is calculated by a kinetic equation, which simplifies the selective catalytic reduction model; the ammonia storage mass formula is constructed by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula, which simplifies the calculation workload of the model and ensures the calculation accuracy of the model. The effect of simplifying the selective catalytic reduction model while accurately obtaining the mass of the ammonia storage is achieved. In this way, the injection amount of ammonia can be dynamically controlled according to the mass of the ammonia storage and the actual nitrogen oxide emissions of the engine and the conversion efficiency of the catalyst in the selective catalytic reduction system to improve the conversion efficiency of the selective catalytic reduction system.

Description

A method and device for calculating ammonia storage quality

Technical Field

The present application relates to the technical field of atmospheric pollutant treatment, and in particular to a method and device for calculating ammonia storage quality.

Background technique

With the continuous development of science and technology, the requirements for technology are also constantly increasing. For engines, higher requirements are placed on the conversion efficiency of the Selective Catalyst Reduction (SCR) system. The improvement of the conversion efficiency of the SCR system is conducive to meeting the demand for higher conversion efficiency on the one hand, and on the other hand, it is conducive to the engine to improve the NOx level and thus reduce fuel consumption; at the same time, there are higher requirements for the control accuracy of the SCR system, and model-based SCR control has become a necessary means.

However, the establishment of a one-dimensional SCR model requires a large amount of electronic control unit resources, and some solutions may require more SCR models. Therefore, how to design a simple and implementable SCR model has become a technical problem that needs to be solved urgently in this field.

Summary of the invention

In view of this, an embodiment of the present application provides a method and apparatus for calculating ammonia storage quality, aiming to simplify the SCR model and simplify the calculation workload of the SCR model.

In a first aspect, an embodiment of the present application provides a method for calculating ammonia storage quality, the method comprising:

The change of ammonia storage on the catalyst is calculated by the kinetic equation;

Using the change of ammonia storage on the catalyst, a calculation formula for ammonia storage mass conservation is obtained;

The mass formula of ammonia storage is constructed by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula;

The mass of the ammonia storage is calculated using the mass formula of the ammonia storage.

Optionally, the calculation of the change of ammonia storage on the catalyst by a kinetic equation specifically includes:

The change of ammonia storage on the catalyst is calculated using the first formula;

The first formula is: NH3 _add = NH3 _us - NH3 _cnv - NH3 _ds - NH3 _oxd - NH3 _n2o ;

Where NH3 _add is the change of ammonia storage on the catalyst; NH3 _us is the _NH3 flow rate upstream of the selective catalytic reduction system; NH3 _cnv is the ammonia flow rate converted by the selective catalytic reduction system; NH3 _ds is the _NH3 flow rate escaping downstream of the selective catalytic reduction system; NH3 _oxd is the _NH3 flow rate oxidized by the selective catalytic reduction system; NH3 _n2o is the _NH3 flow rate consumed by the selective catalytic reduction system to generate _N2O .

Optionally, the change of ammonia storage on the chemical agent is used to obtain a calculation formula for conservation of ammonia storage mass, and the specific formula is: Wherein Ω=aNH3 _max , a is the standardized coefficient, and NH3 _max is the maximum ammonia reserve.

Optionally, the mass formula of ammonia storage is constructed by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula, specifically including:

The mass formula of ammonia storage is constructed by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula. The mass formula of ammonia storage is: Wherein, Ω=aNH3 _max , θ(t _n-1 ) is the ammonia storage mass output value of the n-1th module in the selective catalytic reduction model; θ(t _n ) is the ammonia storage mass output value of the nth module in the selective catalytic reduction model.

Optionally, the method for calculating each parameter in the first formula specifically includes:

The NH3 _us is calculated based on the urea injection amount;

The NH3 _cnv is calculated according to the second formula and the ratio of NO ₂ /NO _x upstream of the selective catalytic reduction system; the second formula is: is the _NOx concentration downstream of the selective catalytic reduction system; is the concentration of NO _x gas reactant upstream of the selective catalytic reduction system; /> is the frequency factor of NO _x reaction; θ is the ammonia coverage concentration of the selective catalytic reduction system; /> is the activation energy of NO _x chemical reaction; R is the uniform gas constant; T is the temperature; sv represents the space velocity, which is the exhaust gas volume flow divided by the SCR catalyst volume;

The NH3 _ds is calculated according to the third formula and the exhaust gas volume; the third formula is: Among them,/> is the escape concentration of NH ₃ ; K _des is the frequency factor of the desorption reaction; _Kads is the frequency factor of the adsorption reaction; E _ads is the chemical reaction activation energy of the adsorption reaction; E _des is the chemical reaction activation energy of the desorption reaction; ε is the correlation coefficient between the desorption reaction activation energy parameter and the ammonia storage;

The NH3 _oxd is calculated according to the fourth formula; the fourth formula is: r _oxd is the reaction rate of the oxidation reaction; K _oxd is the frequency factor of the oxidation reaction; E _oxd is the chemical reaction activation energy of the oxidation reaction;

The _NH3n2o is calculated according to the fifth formula; the fifth formula is:

r _n2o is the reaction rate of NO ₂ ; K _n2o is the frequency factor of NO ₂ reaction; E _n2o is the chemical reaction activation energy of NO ₂ reaction.

In a second aspect, an embodiment of the present application provides a device for calculating the quality of an ammonia storage, the device comprising: an ammonia storage change calculation module, an ammonia storage quality formula construction module, and an ammonia storage quality calculation module;

The ammonia storage change calculation module is used to calculate the change of ammonia storage on the catalyst through a kinetic equation;

The mass formula construction module of the ammonia storage is used to obtain the ammonia storage mass conservation calculation formula by using the change of the ammonia storage on the catalyst; and to construct the ammonia storage mass formula by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula;

The ammonia storage mass calculation module is used to calculate the mass of the ammonia storage using the ammonia storage mass formula.

Optionally, the ammonia storage change calculation module is specifically used to:

The change of ammonia storage on the catalyst is calculated using the first formula;

The first formula is: NH3 _add = NH3 _us - NH3 _cnv - NH3 _ds - NH3 _oxd - NH3 _n2o ;

Where NH3 _add is the change of ammonia storage on the catalyst; NH3 _us is the _NH3 flow rate upstream of the selective catalytic reduction system; NH3 _cnv is the ammonia flow rate converted by the selective catalytic reduction system; NH3 _ds is the _NH3 flow rate escaping downstream of the selective catalytic reduction system; NH3 _oxd is the _NH3 flow rate oxidized by the selective catalytic reduction system; NH3 _n2o is the _NH3 flow rate consumed by the selective catalytic reduction system to generate _N2O .

Optionally, the mass formula building module of the ammonia storage is specifically used for:

The change of ammonia storage on the catalyst is used to obtain the ammonia storage mass conservation calculation formula, and the specific formula is: Wherein Ω=aNH3 _max , a is the standardized coefficient, and NH3 _max is the maximum ammonia reserve.

Optionally, the mass formula building module of the ammonia storage is specifically used for:

The mass formula of ammonia storage is constructed by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula. The mass formula of ammonia storage is: Wherein, Ω=aNH3 _max , θ(t _n-1 ) is the ammonia storage mass output value of the n-1th module in the selective catalytic reduction model; θ(t _n ) is the ammonia storage mass output value of the nth module in the selective catalytic reduction model.

Optionally, the ammonia storage change calculation module is specifically used to calculate the parameters in the first formula:

The NH3 _us is calculated based on the urea injection amount;

The NH3 _cnv is calculated according to the second formula and the ratio of NO ₂ /NO _x upstream of the selective catalytic reduction system; the second formula is: is the _NOx concentration downstream of the selective catalytic reduction system; is the concentration of NO _x gas reactant upstream of the selective catalytic reduction system; /> is the frequency factor of NO _x reaction; θ is the ammonia coverage concentration of the selective catalytic reduction system; /> is the activation energy of NO _x chemical reaction; R is the uniform gas constant; T is the temperature; sv represents the space velocity, which is the exhaust gas volume flow divided by the SCR catalyst volume;

The NH3 _ds is calculated according to the third formula and the exhaust gas volume; the third formula is: Among them,/> is the escape concentration of NH ₃ ; K _des is the frequency factor of the desorption reaction; _Kads is the frequency factor of the adsorption reaction; E _ads is the chemical reaction activation energy of the adsorption reaction; E _des is the chemical reaction activation energy of the desorption reaction; ε is the correlation coefficient between the desorption reaction activation energy parameter and the ammonia storage;

The NH3 _oxd is calculated according to the fourth formula; the fourth formula is: r _oxd is the reaction rate of the oxidation reaction; K _oxd is the frequency factor of the oxidation reaction; E _oxd is the chemical reaction activation energy of the oxidation reaction;

The _NH3n2o is calculated according to the fifth formula; the fifth formula is:

r _n2o is the reaction rate of NO ₂ ; K _n2o is the frequency factor of NO ₂ reaction; E _n2o is the chemical reaction activation energy of NO ₂ reaction.

The embodiment of the present application provides a method for calculating the mass of ammonia storage. When executing the method, the change of ammonia storage on the catalyst is first calculated by a kinetic equation; then the change of ammonia storage on the catalyst is used to obtain the ammonia storage mass conservation calculation formula; then the ammonia storage mass conservation calculation formula and the forward Euler discrete formula are used to construct the ammonia storage mass formula, and finally the ammonia storage mass formula is used to calculate the ammonia storage mass. In this way, the change of ammonia storage on the catalyst is calculated by a kinetic equation, which simplifies the selective catalytic reduction model; the ammonia storage mass conservation calculation formula and the forward Euler discrete formula are used to construct the ammonia storage mass formula, which simplifies the calculation workload of the model and ensures the calculation accuracy of the model. The effect of simplifying the selective catalytic reduction model while accurately obtaining the mass of the ammonia storage is achieved. In this way, the injection amount of ammonia can be dynamically controlled according to the mass of the ammonia storage and the actual nitrogen oxide emissions of the engine and the conversion efficiency of the catalyst in the selective catalytic reduction system to improve the conversion efficiency of the selective catalytic reduction system.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in this embodiment or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

FIG1 is a schematic diagram of the SCR hardware layout architecture provided in an embodiment of the present application;

FIG2 is a block diagram of an SCR model provided in an embodiment of the present application;

FIG3 is a flow chart of a method for calculating ammonia storage quality provided in an embodiment of the present application;

FIG4 is a schematic diagram of an SCR model architecture provided in an embodiment of the present application;

FIG5 is a schematic diagram of the structure of a device for calculating ammonia storage quality provided in an embodiment of the present application.

Detailed ways

With the continuous development of science and technology, the requirements for technology are also constantly increasing. For engines, higher requirements are placed on the conversion efficiency of the Selective Catalyst Reduction (SCR) system. The improvement of the conversion efficiency of the SCR system is conducive to meeting the demand for higher conversion efficiency on the one hand, and on the other hand, it is conducive to the engine to improve the NOx level and thus reduce fuel consumption; at the same time, there are higher requirements for the control accuracy of the SCR system, and model-based SCR control has become a necessary means.

However, the establishment of a one-dimensional SCR model requires a large amount of electronic control unit resources, and some solutions may require more SCR models. Therefore, how to design a simple and implementable SCR model has become a technical problem that needs to be solved urgently in this field.

In view of this, the inventors of the present application considered that if the dynamic equation is used for solving, the NOx efficiency model and the _NH3 leakage model can be simplified, and then the SCR model can be simplified; and if the mass recursive formula of the ammonia storage is constructed by using the ammonia storage mass conservation and the forward Euler method, the calculation workload of the SCR model can be simplified and the accuracy of the SCR model can be guaranteed. In this way, the effect of simplifying the SCR model can be achieved.

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

Before introducing the solution of the present application, the relevant technology in the field is first introduced to facilitate the understanding of the solution of the present application.

The basic principle of selective catalytic reduction (SCR) technology is to inject fuel or add a reductant into the exhaust gas, and use a suitable catalyst to promote the reaction between the reductant and NOx, while inhibiting the non-selective oxidation reaction between the reductant and oxygen. Commonly used urea-SCR catalysts include V ₂ O ₅ /W ₂ O ₃ /TiO ₂ and metal oxide/zeolite.

Vanadium-based catalysts have high selectivity for NOx and a wide high-efficiency temperature window, as well as high sulfur resistance. However, their disadvantage is that they are easily poisoned by phosphorus components in the lubricating oil and fail at high temperatures. Zeolite-type catalysts have extremely strong adsorption capacity for _NH3 , but at low temperatures, zeolite also has a strong adsorption capacity for HC, and the adsorption of HC affects the low-temperature performance of the catalyst. At the same time, zeolite has poor hydrothermal stability and sulfur resistance, so its actual use is limited and low-sulfur fuel is required.

Sulfur oxides will form sulfates in copper-based SCR, which will reduce the active sites of the catalyst, block small holes, and reduce the conversion efficiency of SCR to NOx. Therefore, when a certain amount of sulfur oxides are captured in the SCR, they need to be desulfurized. There are two mechanisms of sulfur poisoning: (NH4)SO4, etc., which will reduce the active sites of the SCR catalyst and block small holes, thereby reducing the NOx conversion efficiency; SO2 and SO3 compete with NOx for adsorption, reducing the adsorption of NOx.

The reaction principle of SCR technology:

Urea is hydrolyzed into ammonia: (Urea injection system)

(NH2)2CO+H2O→2NH3+CO2;

SCR post-treatment reaction: (SCR catalytic converter)

NO+NO2+2NH3→2N2+3H2O;

4NO+O2+4NH3→4N2+6H2O;

2NO2+O2+4NH3→3N2+6H2O;

The reducing agent actually involved in the selective catalytic reduction reaction in SCR is ammonia (NH ₃ ), but due to the high corrosiveness of ammonia, liquid ammonia and ammonia water are difficult to store and transport, so they cannot be directly used in vehicle-mounted SCR systems. At present, urea aqueous solution is generally used as a reducing agent. Compared with other concentrations of urea aqueous solution, 32.5% urea aqueous solution has the lowest freezing point of -11°C, so 32.5% urea aqueous solution is generally used as the standard reducing agent for SCR internationally.

In order to prevent the waste of reducing agent and the leakage of NH ₃ after SCR catalysis, the injection amount of reducing agent must be dynamically controlled according to the actual NOx emission of the engine and the conversion efficiency of the SCR catalyst. Since urea aqueous solution is only a carrier of NH ₃ , the process of urea aqueous solution decomposing into NH ₃ has an important influence on the performance of SCR.

See FIG. 1 , which is a schematic diagram of the SCR hardware layout architecture provided in an embodiment of the present application.

Before the SCR are the urea nozzle DM and the temperature sensor T, the NOx1 sensor is located before the SCR, and the NOx2 sensor is located after the SCR.

See Figure 2, which is a schematic diagram of the SCR model block provided in the embodiment of the present application. The SCR is divided into blocks along the airflow direction, and the number of blocks is between 5 and 10. The output of the previous block is the input of the next block. For each block, the ammonia reserve is calculated according to the method provided in the present application. The specific scheme is as follows:

Referring to FIG. 3 , FIG. 3 is a flow chart of a method for calculating ammonia storage quality provided in an embodiment of the present application, which specifically includes:

S301. Calculate the change of ammonia storage on the catalyst through a kinetic equation.

The change of ammonia storage on the catalyst is calculated using the first formula;

The first formula is: NH3 _add = NH3 _us - NH3 _cnv - NH3 _ds - NH3 _oxd - NH3 _n2o ;

Where NH3 _add is the change of ammonia storage on the catalyst; NH3 _us is the _NH3 flow rate upstream of the selective catalytic reduction system; NH3 _cnv is the ammonia flow rate converted by the selective catalytic reduction system; NH3 _ds is the _NH3 flow rate escaping downstream of the selective catalytic reduction system; NH3 _oxd is the _NH3 flow rate oxidized by the selective catalytic reduction system; NH3 _n2o is the _NH3 flow rate consumed by the selective catalytic reduction system to generate _N2O .

The calculation method of each parameter in the first formula specifically includes:

The NH3 _us is calculated based on the urea injection amount; the urea injection amount can be directly obtained.

The NH3 _cnv is calculated according to the second formula and the ratio of NO ₂ /NO _x upstream of the selective catalytic reduction system; the second formula is: is the _NOx concentration downstream of the selective catalytic reduction system; is the concentration of NO _x gas reactant upstream of the selective catalytic reduction system; /> is the frequency factor of NO _x reaction; θ is the ammonia coverage concentration of the selective catalytic reduction system; /> is the activation energy of the NO _x chemical reaction; R is the uniform gas constant; T is the temperature; sv represents the space velocity, which is the exhaust gas volume flow divided by the catalyst volume in the selective catalytic reduction system;

The NH3 _ds is calculated according to the third formula and the exhaust gas volume; the third formula is: Among them,/> is the escape concentration of NH ₃ ; K _des is the frequency factor of the desorption reaction; _Kads is the frequency factor of the adsorption reaction; E _ads is the chemical reaction activation energy of the adsorption reaction; E _des is the chemical reaction activation energy of the desorption reaction; ε is the correlation coefficient between the desorption reaction activation energy parameter and the ammonia storage;

The NH3 _oxd is calculated according to the fourth formula; the fourth formula is: r _oxd is the reaction rate of the oxidation reaction; K _oxd is the frequency factor of the oxidation reaction; E _oxd is the chemical reaction activation energy of the oxidation reaction;

The _NH3n2o is calculated according to the fifth formula; the fifth formula is:

r _n2o is the reaction rate of NO ₂ ; K _n2o is the frequency factor of NO ₂ reaction; E _n2o is the chemical reaction activation energy of NO ₂ reaction.

By solving the above kinetic equations, the NOx efficiency model and _NH3 leakage model are simplified.

S302, using the change of ammonia storage on the catalyst to obtain a calculation formula for conservation of ammonia storage mass.

The NH3 _add obtained in step S101 is used to obtain the ammonia storage mass conservation calculation formula, which is: Wherein Ω=aNH3 _max , a is the standardized coefficient, and NH3 _max is the maximum ammonia reserve.

S303, constructing a mass formula for ammonia storage using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula.

The mass formula of ammonia storage is constructed by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula. The mass formula of ammonia storage is: Among them, Ω=aNH3 _max , θ(t _n-1 ) is the ammonia storage mass output value of the n-1th module in the SCR model; θ(t _n ) is the ammonia storage mass output value of the nth module in the SCR model. It can be understood that the output of the previous module is used as the input of the next module.

S304, calculating the mass of the ammonia storage using the mass formula of the ammonia storage.

Using the mass formula for ammonia storage Calculate the mass of ammonia storage. The mass recursive formula of ammonia storage is constructed by using the ammonia storage mass conservation law and the forward Euler method, which simplifies the calculation workload of the model and ensures the accuracy of the model.

The embodiment of the present application provides a method for calculating the mass of ammonia storage. When executing the method, the change of ammonia storage on the catalyst is first calculated by a kinetic equation; then the change of ammonia storage on the catalyst is used to obtain the ammonia storage mass conservation calculation formula; then the ammonia storage mass conservation calculation formula and the forward Euler discrete formula are used to construct the ammonia storage mass formula, and finally the ammonia storage mass formula is used to calculate the ammonia storage mass. In this way, the change of ammonia storage on the catalyst is calculated by a kinetic equation, which simplifies the selective catalytic reduction model; the ammonia storage mass conservation calculation formula and the forward Euler discrete formula are used to construct the ammonia storage mass formula, which simplifies the calculation workload of the model and ensures the calculation accuracy of the model. The effect of simplifying the selective catalytic reduction model while accurately obtaining the mass of the ammonia storage is achieved. In this way, the injection amount of ammonia can be dynamically controlled according to the mass of the ammonia storage and the actual nitrogen oxide emissions of the engine and the conversion efficiency of the catalyst in the selective catalytic reduction system to improve the conversion efficiency of the selective catalytic reduction system.

Referring to FIG. 4 , FIG. 4 is a schematic diagram of the SCR model architecture provided in an embodiment of the present application. In the NOx efficiency model, the SCR upstream NOx flow, the SCR upstream _NH3 flow, the air velocity and temperature of the SCR system, and the output value of the previous SCR model block, namely, NOx-us(0), NH3-us(0), SV/T(0), θ(1) are input. After calculation by the NOx efficiency model, the SCR downstream NOx flow and NOx conversion efficiency, namely, NOx_ds(1), η(1) are output. In the _NH3 leakage model, the SCR system air velocity and temperature, and the output value of the previous SCR model block, namely, SV/T(0), θ(1) are input. After calculation by the _NH3 leakage model, the SCR system downstream _NH3 flow, NH3_ds(1) is output. In the oxidation model, the SCR system air velocity and temperature, and the output value of the previous SCR model block, namely, SV/T(0), θ(1) are input. After calculation by the oxidation module, the _NH3 flow participating in the oxidation reaction and the NH3 reacting with _N2O are output. ₃ flow rates, namely NH3_oxd and NH3_n2o(1); and NOx_ds(1), η(1), NH3_ds(1), NH3_oxd and NH3_n2o(1) are input into the calculation model of the change of ammonia storage on the catalyst, the change of ammonia storage on the catalyst is calculated, and the calculation result is input into the calculation model of ammonia storage, and finally the mass of ammonia storage of the current SCR block is output, and the output of this block is used as the input of the next block.

Using the SCR model shown in Figure 4, the NOx efficiency model and NH3 leakage model are simplified by solving the kinetic equations. The mass recursive formula of ammonia storage is constructed using the ammonia storage mass conservation and forward Euler method, which simplifies the calculation workload of the model and ensures the accuracy of the model.

The above are some specific implementations of a method for calculating ammonia storage quality provided in the embodiment of the present application. Based on this, the present application also provides a device for calculating ammonia storage quality. The device provided in the embodiment of the present application will be introduced from the perspective of functional modularization.

Referring to FIG. 5 , FIG. 5 is a schematic diagram of the structure of a device for calculating the quality of ammonia storage provided in an embodiment of the present application, the device comprising an ammonia storage change calculation module 501, an ammonia storage quality formula construction module 502, and an ammonia storage quality calculation module 503;

The ammonia storage change calculation module 501 is used to calculate the change of ammonia storage on the catalyst through a kinetic equation;

The ammonia storage mass formula construction module 502 is used to obtain an ammonia storage mass conservation calculation formula using the change of ammonia storage on the catalyst; and construct an ammonia storage mass formula using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula;

The ammonia storage mass calculation module 503 is used to calculate the mass of the ammonia storage using the ammonia storage mass formula.

Furthermore, the ammonia storage change calculation module 501 is specifically used for:

The change of ammonia storage on the catalyst is calculated using the first formula;

The first formula is: NH3 _add = NH3 _us - NH3 _cnv - NH3 _ds - NH3 _oxd - NH3 _n2o ;

Where NH3 _add is the change of ammonia storage on the catalyst; NH3 _us is the _NH3 flow rate upstream of the selective catalytic reduction system; NH3 _cnv is the ammonia flow rate converted by the selective catalytic reduction system; NH3 _ds is the _NH3 flow rate escaping downstream of the selective catalytic reduction system; NH3 _oxd is the _NH3 flow rate oxidized by the selective catalytic reduction system; NH3 _n2o is the _NH3 flow rate consumed by the selective catalytic reduction system to generate _N2O .

Furthermore, the ammonia storage quality formula construction module 502 is specifically used for:

The change of ammonia storage on the catalyst is used to obtain the ammonia storage mass conservation calculation formula, and the specific formula is: Wherein Ω=aNH3 _max , a is the standardized coefficient, and NH3 _max is the maximum ammonia reserve.

Furthermore, the ammonia storage quality formula construction module 502 is specifically used for:

The mass formula of ammonia storage is constructed by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula. The mass formula of ammonia storage is: Wherein, Ω=aNH3 _max , θ(t _n-1 ) is the ammonia storage mass output value of the n-1th module in the selective catalytic reduction model; θ(tn) is the ammonia storage mass output value of the nth module in the selective catalytic reduction model.

Furthermore, the ammonia storage change calculation module 501 is specifically used to calculate the parameters in the first formula:

The NH3 _us is calculated based on the urea injection amount;

The NH3 _cnv is calculated according to the second formula and the ratio of NO ₂ /NO _x upstream of the selective catalytic reduction system; the second formula is: is the _NOx concentration downstream of the selective catalytic reduction system; is the concentration of NO _x gas reactant upstream of the selective catalytic reduction system; /> is the frequency factor of NO _x reaction; θ is the ammonia coverage concentration of the selective catalytic reduction system; /> is the activation energy of NO _x chemical reaction; R is the uniform gas constant; T is the temperature; sv represents the space velocity, which is the exhaust gas volume flow divided by the SCR catalyst volume;

The NH3 _ds is calculated according to the third formula and the exhaust gas volume; the third formula is: Among them,/> is the escape concentration of NH ₃ ; K _des is the frequency factor of the desorption reaction; _Kads is the frequency factor of the adsorption reaction; E _ads is the chemical reaction activation energy of the adsorption reaction; E _des is the chemical reaction activation energy of the desorption reaction; ε is the correlation coefficient between the desorption reaction activation energy parameter and the ammonia storage;

The NH3 _oxd is calculated according to the fourth formula; the fourth formula is: r _oxd is the reaction rate of the oxidation reaction; K _oxd is the frequency factor of the oxidation reaction; E _oxd is the chemical reaction activation energy of the oxidation reaction;

The _NH3n2o is calculated according to the fifth formula; the fifth formula is:

r _n2o is the reaction rate of NO ₂ ; K _n2o is the frequency factor of NO ₂ reaction; E _n2o is the chemical reaction activation energy of NO ₂ reaction.

The embodiment of the present application provides a device for calculating the mass of ammonia storage, which is used to execute a method for calculating the mass of ammonia storage. When executing the method, the change of ammonia storage on the catalyst is first calculated by a kinetic equation; then the change of ammonia storage on the catalyst is used to obtain the ammonia storage mass conservation calculation formula; then the ammonia storage mass conservation calculation formula and the forward Euler discrete formula are used to construct the ammonia storage mass formula, and finally the ammonia storage mass formula is used to calculate the ammonia storage mass. In this way, the change of ammonia storage on the catalyst is calculated by a kinetic equation, which simplifies the selective catalytic reduction model; the ammonia storage mass conservation calculation formula and the forward Euler discrete formula are used to construct the ammonia storage mass formula, which simplifies the calculation workload of the model and ensures the calculation accuracy of the model. The effect of simplifying the selective catalytic reduction model while accurately obtaining the mass of the ammonia storage is achieved. In this way, the injection amount of ammonia can be dynamically controlled according to the mass of the ammonia storage and the actual nitrogen oxide emissions of the engine and the conversion efficiency of the catalyst in the selective catalytic reduction system to improve the conversion efficiency of the selective catalytic reduction system.

The "first" and "second" in the names of "first formula", "second formula", etc. mentioned in the embodiments of the present application are only used as name identifiers and do not represent the first or second in order.

Through the description of the above implementation methods, it can be known that those skilled in the art can clearly understand that all or part of the steps in the above-mentioned embodiment method can be implemented by means of software plus a general hardware platform. Based on such an understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a storage medium, such as a read-only memory (ROM)/RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network communication device such as a router) to execute the methods described in each embodiment of the present application or some parts of the embodiments.

Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

The above description is merely an exemplary embodiment of the present application and is not intended to limit the protection scope of the present application.

Claims (9)

1. A method for calculating ammonia storage quality, characterized in that the method comprises: The change of ammonia storage on the catalyst is calculated by the kinetic equation; Using the change of ammonia storage on the catalyst, a calculation formula for ammonia storage mass conservation is obtained; The mass formula of ammonia storage is constructed by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula; Calculating the mass of the ammonia storage using the mass formula of the ammonia storage; The method of constructing the mass formula of ammonia storage by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula specifically includes: The mass formula of ammonia storage is constructed by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula. The mass formula of ammonia storage is: Wherein, Ω=aNH3 _max , θ(t _n-1 ) is the ammonia storage mass output value of the n-1th module in the selective catalytic reduction model; θ(t _n ) is the ammonia storage mass output value of the nth module in the selective catalytic reduction model, t _n is the nth moment, t _n-1 is the previous moment relative to the nth moment, a is a standardized coefficient, NH3 _max is the maximum ammonia storage, and NH3 _add is the change of ammonia storage on the catalyst. 2. The method according to claim 1, characterized in that the calculation of the change of ammonia storage on the catalyst by the kinetic equation specifically comprises: The change of ammonia storage on the catalyst is calculated using the first formula; The first formula is: NH3 _add = NH3 _us - NH3 _cnv - NH3 _ds - NH3 _oxd - NH3 _n2o ; Where NH3 _add is the change of ammonia storage on the catalyst; NH3 _us is the _NH3 flow rate upstream of the selective catalytic reduction system; NH3 _cnv is the ammonia flow rate converted by the selective catalytic reduction system; NH3 _ds is the _NH3 flow rate escaping downstream of the selective catalytic reduction system; NH3 _oxd is the _NH3 flow rate oxidized by the selective catalytic reduction system; NH3 _n2o is the _NH3 flow rate consumed by the selective catalytic reduction system to generate _N2O . 3. The method according to claim 1, characterized in that the ammonia storage mass conservation calculation formula is obtained by utilizing the change of ammonia storage on the catalyst, and the specific formula is: Wherein Ω=aNH3 _max , a is the standardized coefficient, and NH3 _max is the maximum ammonia reserve. 4. The method according to claim 2, characterized in that the method for calculating each parameter in the first formula specifically includes: The NH3 _us is calculated based on the urea injection amount; The NH3 _cnv is calculated according to the second formula and the ratio of NO ₂ /NO _x upstream of the selective catalytic reduction system; the second formula is: is the _NOx concentration downstream of the selective catalytic reduction system; c _NOx,us is the _NOx gas reactant concentration upstream of the selective catalytic reduction system; K _NOx is the frequency factor of the _NOx reaction; θ is the ammonia coverage concentration of the selective catalytic reduction system; E _NOx is the activation energy of the _NOx chemical reaction; R is the unified gas constant; T is the temperature; sv represents the space velocity, that is, the exhaust gas volume flow divided by the catalyst volume in the selective catalytic reduction system; The NH3 _ds is calculated according to the third formula and the exhaust gas volume; the third formula is: Among them,/> is the escape concentration of NH ₃ ; K _des is the frequency factor of the desorption reaction; _Kads is the frequency factor of the adsorption reaction; E _ads is the chemical reaction activation energy of the adsorption reaction; E _des is the chemical reaction activation energy of the desorption reaction; ε is the correlation coefficient between the desorption reaction activation energy parameter and the ammonia storage; The NH3 _oxd is calculated according to the fourth formula; the fourth formula is: r _oxd is the reaction rate of the oxidation reaction; K _oxd is the frequency factor of the oxidation reaction; E _oxd is the chemical reaction activation energy of the oxidation reaction; The _NH3n2o is calculated according to the fifth formula; the fifth formula is: r _n2o is the reaction rate of NO ₂ ; K _n2o is the frequency factor of NO ₂ reaction; E _n2o is the chemical reaction activation energy of NO ₂ reaction. 5. A device for calculating the quality of ammonia storage, characterized in that the device comprises: an ammonia storage change calculation module, an ammonia storage quality formula construction module, and an ammonia storage quality calculation module; The ammonia storage change calculation module is used to calculate the change of ammonia storage on the catalyst through a kinetic equation; The mass formula construction module of the ammonia storage is used to obtain the ammonia storage mass conservation calculation formula by using the change of the ammonia storage on the catalyst; and to construct the mass formula of the ammonia storage by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula; The mass calculation module of the ammonia storage is used to calculate the mass of the ammonia storage using the mass formula of the ammonia storage; The method of constructing the mass formula of ammonia storage by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula specifically includes: The mass formula of ammonia storage is constructed by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula. The mass formula of ammonia storage is: Wherein, Ω=aNH3 _max , θ(t _n-1 ) is the ammonia storage mass output value of the n-1th module in the selective catalytic reduction model; θ(t _n ) is the ammonia storage mass output value of the nth module in the selective catalytic reduction model, t _n is the nth moment, t _n-1 is the previous moment relative to the nth moment, a is a standardized coefficient, NH3 _max is the maximum ammonia storage, and NH3 _add is the change of ammonia storage on the catalyst. 6. The device according to claim 5, characterized in that the ammonia storage change calculation module is specifically used to: The change of ammonia storage on the catalyst is calculated using the first formula; The first formula is: NH3 _add = NH3 _us - NH3 _cnv - NH3 _ds - NH3 _oxd - NH3 _n2o ; Where NH3 _add is the change of ammonia storage on the catalyst; NH3 _us is the _NH3 flow rate upstream of the selective catalytic reduction system; NH3 _cnv is the ammonia flow rate converted by the selective catalytic reduction system; NH3 _ds is the _NH3 flow rate escaping downstream of the selective catalytic reduction system; NH3 _oxd is the _NH3 flow rate oxidized by the selective catalytic reduction system; NH3 _n2o is the _NH3 flow rate consumed by the selective catalytic reduction system to generate _N2O . 7. The device according to claim 5, characterized in that the mass formula building module of the ammonia storage is specifically used for: The change of ammonia storage on the catalyst is used to obtain the ammonia storage mass conservation calculation formula, and the specific formula is: Wherein Ω=aNH3 _max , a is the standardized coefficient, and NH3 _max is the maximum ammonia reserve. 8. The device according to claim 5, characterized in that the mass formula building module of the ammonia storage is specifically used for: The mass formula of ammonia storage is constructed by using the ammonia storage mass conservation calculation formula and the forward Euler discrete formula. The mass formula of ammonia storage is: Wherein, Ω=aNH3 _max , θ(t _n-1 ) is the ammonia storage mass output value of the n-1th module in the selective catalytic reduction model; θ(t _n ) is the ammonia storage mass output value of the nth module in the selective catalytic reduction model. 9. The device according to claim 6, characterized in that the ammonia storage change calculation module is specifically used to calculate the parameters in the first formula: The NH3 _us is calculated based on the urea injection amount; The NH3 _cnv is calculated according to the second formula and the ratio of NO ₂ /NO _x upstream of the selective catalytic reduction system; the second formula is: is the _NOx concentration downstream of the selective catalytic reduction system; c _NOx,us is the _NOx gas reactant concentration upstream of the selective catalytic reduction system; K _NOx is the frequency factor of the _NOx reaction; θ is the ammonia coverage concentration of the selective catalytic reduction system; E _NOx is the activation energy of the _NOx chemical reaction; R is the unified gas constant; T is the temperature; sv represents the space velocity, that is, the exhaust gas volume flow divided by the SCR catalyst volume; The NH3 _ds is calculated according to the third formula and the exhaust gas volume; the third formula is: Among them,/> is the escape concentration of NH ₃ ; K _des is the frequency factor of the desorption reaction; _Kads is the frequency factor of the adsorption reaction; E _ads is the chemical reaction activation energy of the adsorption reaction; E _des is the chemical reaction activation energy of the desorption reaction; ε is the correlation coefficient between the desorption reaction activation energy parameter and the ammonia storage; The NH3 _oxd is calculated according to the fourth formula; the fourth formula is: r _oxd is the reaction rate of the oxidation reaction; K _oxd is the frequency factor of the oxidation reaction; E _oxd is the chemical reaction activation energy of the oxidation reaction; The _NH3n2o is calculated according to the fifth formula; the fifth formula is: r _n2o is the reaction rate of NO ₂ ; K _n2o is the frequency factor of NO ₂ reaction; E _n2o is the chemical reaction activation energy of NO ₂ reaction.