Exhaust gas treatment system and model for controlling hydrocarbon adsorption / desorption in hydrocarbon trap

Abstract

An exhaust gas treatment system includes a hydrocarbon storage model and a controller operably connected to the hydrocarbon storage model, the controller configured to perform a method for determining a hydrocarbon storage level of a hydrocarbon trap, the method including determining a first reaction rate indicative of a hydrocarbon adsorption rate at a non-acidic site of the hydrocarbon trap; determining a second reaction rate indicative of a rate of hydrocarbon desorption at a non-acidic site of the hydrocarbon trap; determining a third reaction rate indicative of a hydrocarbon adsorption rate at an acid site of the hydrocarbon trap; determining a fourth reaction rate indicative of a hydrocarbon desorption rate at an acid site of the hydrocarbon trap; and determining a hydrocarbon storage level in the hydrocarbon trap based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

Description

Technical Field

[0001] This disclosure relates to an exhaust emission control system for an internal combustion engine, and more specifically, to minimizing hydrocarbon emissions during engine cold start. Background Technology

[0002] Exhaust gases emitted from internal combustion engines contain gaseous emissions such as carbon monoxide (“CO”), unburned hydrocarbons (“HC”), and nitrogen oxides (“NO”). x These are heterogeneous mixtures of exhaust gases. Many of these emission components are highly regulated. Catalyst components, typically mounted on a catalyst support or substrate, are provided in the engine exhaust system as part of an aftertreatment system to convert some or all of these exhaust components into unregulated compounds.

[0003] Exhaust gas treatment systems typically include one or more catalyst-based treatment units, such as three-way catalytic converters (TWCs). The purpose of a catalyst, such as a TWC, is to convert the main emissions from the engine into carbon dioxide, water, and nitrogen. For a catalyst or TWC to function effectively as a catalyst for hydrocarbon oxidation, high operating temperatures must be reached, which can be difficult during cold start operations. Therefore, hydrocarbon traps (HCTs) are typically used to store hydrocarbons during cold starts and release them when the catalyst or TWC reaches a sufficient temperature to catalyze the oxidation of hydrocarbons. However, HCTs may reach the hydrocarbon release temperature before the catalyst or TWC reaches a temperature sufficient for catalytic oxidation of hydrocarbons, resulting in inefficient and / or insufficient hydrocarbon oxidation.

[0004] Therefore, it is desirable to allow sufficient time for the catalyst or TWC to reach the operating temperature before a large amount of hydrocarbon contaminants enter the catalytic system. Summary of the Invention

[0005] One aspect provides an exhaust gas treatment system. The exhaust gas treatment system includes a first catalyst downstream of an exhaust outlet of an internal combustion engine, wherein the first catalyst receives exhaust gas output from the exhaust outlet. A hydrocarbon trap is downstream of the first catalyst, wherein the hydrocarbon trap receives exhaust gas output from the first catalyst. An air injection port is configured to deliver an airflow upstream of the hydrocarbon trap and downstream of the first catalyst. An exhaust gas heating unit is located downstream of the hydrocarbon trap, wherein the exhaust gas heating unit receives exhaust gas output from the hydrocarbon trap. A second catalyst is located downstream of the exhaust gas heating unit, wherein the second catalyst receives exhaust gas output from the exhaust gas heating unit. The exhaust gas treatment system also includes a hydrocarbon storage model and a controller operatively connected to the hydrocarbon storage model, wherein the controller is configured to perform a method for determining the hydrocarbon storage level of the hydrocarbon trap. A method for determining the hydrocarbon storage level in a hydrocarbon trap includes determining a first reaction rate representing the rate of hydrocarbon adsorption at non-acidic sites of the hydrocarbon trap, a second reaction rate representing the rate of hydrocarbon desorption at non-acidic sites of the hydrocarbon trap, a third reaction rate representing the rate of hydrocarbon adsorption at acidic sites of the hydrocarbon trap, and a fourth reaction rate representing the rate of hydrocarbon desorption at acidic sites of the hydrocarbon trap. The hydrocarbon storage level in the hydrocarbon trap is determined based on the first, second, third, and fourth reaction rates.

[0006] In another embodiment, the controller is also configured to adjust the post-processing operation on hydrocarbons released from the hydrocarbon trap based on hydrocarbon storage levels, the net reaction rate of hydrocarbon desorption from the hydrocarbon trap, or a combination thereof. The net reaction rate of hydrocarbon desorption from the hydrocarbon trap is determined based on a first reaction rate, a second reaction rate, a third reaction rate, and a fourth reaction rate.

[0007] In another embodiment, the steps of adjusting the aftertreatment operation include selectively operating the exhaust gas heating unit, selectively delivering an airflow or a combination thereof at the air injection port.

[0008] In another embodiment, the exhaust gas treatment system also includes a first temperature sensor for determining the temperature of the hydrocarbon trap.

[0009] In another embodiment, the exhaust gas treatment system further includes a second temperature sensor for determining the temperature of the second catalyst.

[0010] In another embodiment, the first reaction rate is represented by Equation 1:

[0011]

[0012] The second reaction rate is expressed by Equation 2:

[0013]

[0014] The third reaction rate is expressed by Equation 3:

[0015]

[0016] The fourth reaction rate is expressed by Equation 4:

[0017]

[0018] In equations 1 to 4, [HC] represents the concentration of hydrocarbons obtained through the hydrocarbon trap, and q represents the concentration of hydrocarbons obtained through the hydrocarbon trap. Z It is the site density of non-acidic sites that are not bound by hydrocarbons in the hydrocarbon trap, q ZHC It is the site density of non-acidic sites that are not bound by hydrocarbons in the hydrocarbon trap, q ZH It is the site density of unbound acidic sites in the hydrocarbon trap, q ZHHC It is the site density of acidic sites bound to hydrocarbons in the hydrocarbon trap, A 1Z A is the pre-exponential factor for the non-acidic sites of hydrocarbon traps used for hydrocarbon adsorption. -1Z A is the pre-exponential factor for the non-acidic site of a hydrocarbon trap used for hydrocarbon desorption. 1ZH A is the pre-exponential factor for the acidic sites of hydrocarbon traps used for hydrocarbon adsorption. -1ZH It is the pre-exponential factor of the acidic site of the hydrocarbon trap used for hydrocarbon desorption, Ea z Ea is the activation energy of the adsorption reaction at the non-acidic site of the hydrocarbon trap. zH It is the activation energy of the adsorption reaction at the acidic site of the hydrocarbon trap, ΔH. Z It is the heat of adsorption of hydrocarbons at the non-acidic sites of the hydrocarbon trap, ΔH ZH R is the heat of adsorption of hydrocarbons at the acidic sites of the hydrocarbon trap, where R is the universal gas constant and T is the temperature.

[0019] In another embodiment, the exhaust gas heating unit operates selectively when the net reaction rate of hydrocarbon desorption from the hydrocarbon trap is greater than zero, wherein the net reaction rate of hydrocarbon desorption from the hydrocarbon trap is determined based on a first reaction rate, a second reaction rate, a third reaction rate, and a fourth reaction rate.

[0020] In another embodiment, when the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is greater than zero, an air stream is selectively delivered to the air injection port, wherein the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is determined based on a first reaction rate, a second reaction rate, a third reaction rate, and a fourth reaction rate.

[0021] In another embodiment, the amount of air delivered at the air inlet is proportional to the calculated oxygen deficiency at the second catalyst.

[0022] On the other hand, a method for treating exhaust gases from an internal combustion engine in a motor vehicle is provided. The method includes operating the internal combustion engine to provide an exhaust gas fluid at the exhaust gas outlet of the internal combustion engine; and guiding the exhaust gas fluid through an exhaust gas treatment system. The exhaust gas treatment system includes a first catalyst downstream of the exhaust gas outlet of the internal combustion engine, wherein the first catalyst receives the exhaust gas output from the exhaust gas outlet. The exhaust gas treatment system includes a hydrocarbon trap downstream of the first catalyst, wherein the hydrocarbon trap receives the exhaust gas output from the first catalyst. The exhaust gas treatment system includes an air injection port configured to deliver an airflow upstream of the hydrocarbon trap and downstream of the first catalyst. The exhaust gas treatment system includes an exhaust gas heating unit downstream of the hydrocarbon trap, wherein the exhaust gas heating unit receives the exhaust gas output from the hydrocarbon trap. The exhaust gas treatment system includes a second catalyst downstream of the exhaust gas heating unit, wherein the second catalyst receives the exhaust gas output from the exhaust gas heating unit. The exhaust gas treatment system also includes a hydrocarbon storage model and a controller operatively connected to the hydrocarbon storage model, wherein the controller is configured to perform a method for determining the hydrocarbon storage level of the hydrocarbon trap. The method further includes determining a first reaction rate representing the hydrocarbon adsorption rate at non-acidic sites of the hydrocarbon trap, a second reaction rate representing the hydrocarbon desorption rate at non-acidic sites of the hydrocarbon trap, a third reaction rate representing the hydrocarbon adsorption rate at acidic sites of the hydrocarbon trap, and a fourth reaction rate representing the hydrocarbon desorption rate at acidic sites of the hydrocarbon trap. The method also includes determining the hydrocarbon storage level in the hydrocarbon trap based on the first, second, third, and fourth reaction rates.

[0023] In another embodiment, the method further includes adjusting the post-processing operation on hydrocarbons released from the hydrocarbon trap based on hydrocarbon storage levels, the net reaction rate of hydrocarbons desorbed from the hydrocarbon trap, or a combination thereof, wherein the net reaction rate of hydrocarbons desorbed from the hydrocarbon trap is determined based on a first reaction rate, a second reaction rate, a third reaction rate, and a fourth reaction rate.

[0024] In another embodiment, the steps of adjusting the aftertreatment operation include selectively operating the exhaust gas heating unit, selectively delivering an airflow or a combination thereof at the air injection port.

[0025] In another embodiment, in a method for treating exhaust gases from an internal combustion engine in a motor vehicle, the first reaction rate is represented by Equation 1:

[0026]

[0027] The second reaction rate is expressed by Equation 2:

[0028]

[0029] The third reaction rate is expressed by Equation 3:

[0030]

[0031] The fourth reaction rate is expressed by Equation 4:

[0032]

[0033] In equations 1 to 4, [HC] represents the concentration of hydrocarbons obtained through the hydrocarbon trap, and q represents the concentration of hydrocarbons obtained through the hydrocarbon trap. Z It is the site density of non-acidic sites that are not bound by hydrocarbons in the hydrocarbon trap, q ZHC It is the site density of non-acidic sites that are not bound by hydrocarbons in the hydrocarbon trap, q ZH It is the site density of unbound acidic sites in the hydrocarbon trap, q ZHHC It is the site density of acidic sites bound to hydrocarbons in the hydrocarbon trap, A 1Z A is the pre-exponential factor for the non-acidic sites of hydrocarbon traps used for hydrocarbon adsorption. -1Z A is the pre-exponential factor for the non-acidic site of a hydrocarbon trap used for hydrocarbon desorption. 1ZH A is the pre-exponential factor for the acidic sites of hydrocarbon traps used for hydrocarbon adsorption. -1ZH It is the pre-exponential factor of the acidic site of the hydrocarbon trap used for hydrocarbon desorption, Ea z Ea is the activation energy of the adsorption reaction at the non-acidic site of the hydrocarbon trap. zH It is the activation energy of the adsorption reaction at the acidic site of the hydrocarbon trap, ΔH. Z It is the heat of adsorption of hydrocarbons at the non-acidic sites of the hydrocarbon trap, ΔH ZH R is the heat of adsorption of hydrocarbons at the acidic sites of the hydrocarbon trap, where R is the universal gas constant and T is the temperature.

[0034] In another embodiment, the method further includes operating the exhaust gas heating unit when the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is greater than zero, wherein the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is determined based on a first reaction rate, a second reaction rate, a third reaction rate, and a fourth reaction rate.

[0035] In another embodiment, the exhaust gas heating unit does not operate when the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is zero.

[0036] In another embodiment, the method further includes supplying an air stream at an air inlet when the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is greater than zero, wherein the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is determined based on a first reaction rate, a second reaction rate, a third reaction rate, and a fourth reaction rate.

[0037] In another embodiment, in a method for treating exhaust gas from an internal combustion engine in a motor vehicle, the amount of air delivered at the air injection port is proportional to the calculated oxygen deficiency at the second catalyst.

[0038] In another embodiment, in a method for treating exhaust gas from an internal combustion engine in a motor vehicle, no airflow is supplied before the hydrocarbon trap reaches the hydrocarbon desorption temperature.

[0039] In another embodiment, in a method for treating exhaust gas from an internal combustion engine in a motor vehicle, no airflow is supplied until the second catalyst reaches the hydrocarbon oxidation temperature.

[0040] In another embodiment, in a method for treating exhaust gas from an internal combustion engine in a motor vehicle, no air stream is delivered when the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is zero.

[0041] The above-described features and advantages, as well as other features and advantages of this disclosure, will become apparent when taken in conjunction with the accompanying drawings and the following detailed description. Attached Figure Description

[0042] Other features, advantages, and details appear by way of example only in the following detailed description, which refers to the accompanying drawings, wherein:

[0043] Figure 1 A motor vehicle including an internal combustion engine and an emission control system according to one or more embodiments is shown;

[0044] Figure 2 It is a schematic plan view of an exhaust gas treatment system according to one or more embodiments;

[0045] Figure 3 A flowchart illustrating a method according to one or more embodiments is shown;

[0046] Figure 4 A flowchart illustrating a method according to one or more embodiments is shown;

[0047] Figure 5A This is a graph showing the hydrocarbon (HC) concentration (parts per million, ppm) versus time (seconds) measured at the inlet and outlet of the hydrocarbon trap according to one or more embodiments, and a graph showing the temperature (°C) versus time (seconds) measured at the inlet and at the second catalyst of the hydrocarbon trap; and

[0048] Figure 5B It is a graph of the surface coverage of the hydrocarbon trapping material relative to time, measured for acidic and non-acidic sites, according to one or more embodiments, and a graph of the temperature (°C) relative to time, measured at the inlet of the hydrocarbon trap and at the second catalyst. Detailed Implementation

[0049] The following description is exemplary in nature and is not intended to limit this disclosure, its application or use.

[0050] For cold-start hydrocarbon (HC) control, hydrocarbon traps (HCTs), such as those utilizing zeolite as the hydrocarbon trapping component, have been investigated. In these systems, the molecular sieve zeolite component adsorbs and stores hydrocarbons during startup and rapidly releases the stored hydrocarbons when the exhaust gas temperature is high enough to desorb them. The desorbed hydrocarbons are then converted by a hydrocarbon oxidation catalyst, such as a three-way catalyst (TWC) component downstream of the HCT. However, during cold start, even when the exhaust gas heater (EH) is used to heat the TWC, the HCT can reach the hydrocarbon desorption (release) temperature before the TWC reaches a suitable temperature for HC oxidation. As disclosed herein, injecting air after the first catalyst and before the hydrocarbon trap according to a specific schedule provides a cooling effect to the HCT to delay the release of hydrocarbons from the HCT, which allows the EH additional time to heat the TWC to a suitable operating temperature for hydrocarbon oxidation. The cooling effect of injecting air before the HCT can also be used to maximize the temperature difference between the HCT and the second catalyst, thereby improving hydrocarbon oxidation efficiency.

[0051] Internal combustion engines are typically said to be able to produce gases including (e.g., NO) x CO x This disclosure pertains to any apparatus that emits exhaust gases containing NO (NO2) and / or particulate matter, and therefore should be construed as applicable to all such apparatuses. As used herein, “exhaust gas” means any chemical substance or mixture of chemical substances that may require treatment, and includes gaseous, liquid, and / or solid substances. For example, an exhaust gas stream may contain one or more NOs. x A mixture of substances, one or more liquid hydrocarbon (HC) substances, carbon dioxide, and / or carbon monoxide. It should also be understood that the embodiments disclosed herein are applicable to treating effluent streams that do not contain carbonaceous and / or particulate matter. Particulate matter in exhaust gases typically includes carbonaceous soot and other solid and / or liquid carbonaceous substances.

[0052] According to an exemplary embodiment, an exhaust gas treatment system for motor vehicles is provided. Figure 1In this diagram, motor vehicle 10 is shown in the form of a pickup truck. It should be understood that motor vehicle 10 can take various forms, including automobiles, commercial transport vehicles, marine vehicles, etc. Motor vehicle 10 includes a body 12, which has an engine compartment 14 and optionally a passenger compartment 15 and / or a cargo box 17. The engine compartment 14 houses an internal combustion engine 24. The internal combustion engine 24 includes an exhaust gas system 30, which is fluidly connected to an exhaust gas treatment system 34. The internal combustion engine 24 may also be connected to other engine components 26. The exhaust gases produced by the internal combustion engine 24 are reduced and / or converted by the exhaust gas treatment system 34 to discharge emissions into the ambient atmosphere through an exhaust gas outlet pipe 36.

[0053] Although Figure 1 The internal combustion engine 24 shown is depicted as the sole power source of the vehicle 10, but it could also represent a second main engine source used in conjunction with another power source, such as in a hybrid electric motor.

[0054] According to one aspect, and as Figure 2 As shown, a system 200 is provided, which includes an internal combustion engine 201, the internal combustion engine 201 including an exhaust outlet 203, wherein the internal combustion engine 201 delivers exhaust gas through the exhaust outlet 203. The internal combustion engine 201 may include one or more exhaust outlets 203. For example, Figure 2 A pair of exhaust outlets 203 are shown for guiding combustion gases from an internal combustion engine 201.

[0055] A first catalyst (e.g., a first three-way catalyst or TWC) 205 is disposed downstream of the exhaust outlet 203. The first catalyst 205 is in fluid communication with the exhaust outlet 203 to receive the exhaust gas output (exhaust gas flow) from the exhaust outlet 203 of the internal combustion engine 201.

[0056] The first catalyst 205 can be capable of oxidizing CO and HC and reducing NO. xThis is one of various flow-through catalyst devices. In some embodiments, the first catalyst 205 may include a flow-through metal or ceramic monolithic substrate. The substrate may be encapsulated in a stainless steel shell or tank having an inlet in fluid communication with an exhaust outlet 203 and an outlet in fluid communication with an exhaust duct 207. The substrate may include a catalyst compound disposed thereon. The catalyst compound may be applied as a carrier coating and may contain platinum group metals such as platinum (Pt), palladium (Pd), rhodium (Rh), or other suitable oxidation catalysts or combinations thereof. The carrier coating layer comprises layers of materials that are different in composition on the surface of the carrier coating layer disposed on or beneath the monolithic substrate. The catalyst may contain one or more carrier coating layers, and each carrier coating layer may have a unique chemocatalytic function. In the first catalyst 205, the catalyst composition for oxidation and reduction functions may be present in discrete carrier coating layers on the substrate, or alternatively, the composition for oxidation and reduction functions may be present in discrete longitudinal regions on the substrate.

[0057] The exhaust gas treatment system 200 includes a hydrocarbon trap (HCT) 209 located downstream of a first catalyst 205. The HCT 209 is in fluid communication with the first catalyst 205 and receives exhaust gas output from the first catalyst 205. For example, as described herein, the first catalyst 205 may be in fluid communication with the HCT 209 via a section of an exhaust gas duct 207.

[0058] Suitable HCT storage materials for hydrocarbons include microporous solids, so-called molecular sieves, with zeolite materials representing suitable microporous solids for HC capture. Storage materials such as zeolite (or zeolite-type) materials have a porosity suitable for storing or capturing hydrocarbons at least up to the desired desorption temperature. That is, hydrocarbons are adsorbed when the exhaust gas is cold (e.g., during cold start-up) and desorbed when a higher exhaust gas temperature is reached. Zeolites are microporous crystalline aluminosilicate materials characterized by a well-ordered 3D structure with a uniform pore / channel / cage structure, for example, 3 to 12 Å or 3 to 10 Å (depending on the framework type), and the ability to perform ion exchange so that catalytically active cations can be dispersed throughout the structure. Zeolite-type zeolites are structural isomorphous / isocrystalline forms of zeolites, and instead of the framework structure derived from linked silica and alumina tetrahedra, they are based on, for example, alumina-phosphate (ALPO), silica-alumina-phosphate (SAPO), metal-alumina-phosphate (M-ALPO), or metal-silica-alumina-phosphate (M-APSO). Exemplary zeolite materials include, for example, mordenite (MOR), γ-zeolite (FAU), ZSM-5 (MFI), β-zeolite (BEA), or combinations thereof. These are preferably used in the H- or NH4- form exchanged with transition metals.

[0059] The exhaust gas treatment system 200 includes an exhaust gas heating unit 213 located downstream of the HCT 209. The exhaust gas heating unit 213 is in fluid communication with the HCT 209 and receives exhaust gas output from the HCT 209. For example, as described herein, the exhaust gas heating unit 213 may be in fluid communication with the HCT 209 via a section of the exhaust gas duct 207. Any suitable exhaust gas heating unit 213 may be used. For example, the exhaust gas heating unit 213 may be an electric heater. If the vehicle is a conventional vehicle powered solely by the internal combustion engine 201, the exhaust gas heating unit 213 is powered by the engine 201 after startup (i.e., post-start heating after the engine 201 has already started). If the vehicle is a hybrid vehicle powered by the internal combustion engine 201 and / or a separate ICE / electric motor combination (not shown), the exhaust gas heating unit 213 may be powered by either the engine 201 or the ICE / electric motor combination.

[0060] The exhaust gas treatment system 200 includes a second catalyst (e.g., a second TWC) 215 located downstream of the exhaust gas heating unit 213. The second catalyst 215 is in fluid communication with the exhaust gas heating unit 213 and receives exhaust gas output from the exhaust gas heating unit 213. For example, as described herein, the second catalyst 215 may be in fluid communication with the exhaust gas heating unit 213 via a section of the exhaust gas duct 207. The second catalyst 215 may be capable of oxidizing CO and HC and reducing NO. x It is one of the various flow-through catalyst devices, and any suitable catalyst can be used, such as those described herein with respect to the first catalyst 205.

[0061] The exhaust gas treatment system 200 includes an air inlet 211 configured to selectively deliver an airflow upstream of the HCT 209 and downstream of the first catalyst 205. The location of the air inlet 211 is not particularly limited. In some embodiments, the airflow may be combined with exhaust gas output from the first catalyst 205 near its outlet. In other embodiments, the air inlet 211 may be located near the inlet of the HCT 209.

[0062] The air injection source can be provided by an auxiliary pump, or it can be tapped from the engine's compressor using valves and / or choke nozzles. For vehicles with turbochargers, boost pressure and turbocharged air can be used as the source. In other embodiments, the air source can be from the crankcase, using the energy generated therein to provide air injection. In some embodiments, the air source can be a turbocharger compressor or another air pumping device included in the engine.

[0063] A technical challenge associated with the use of the HCT 209 system is determining the state or stock level of the HCT 209 unit and the rate at which HC is released from the HCT 209. Specifically, the use of an electric heater and / or air injection should be optimally correlated with the state of the HCT unit (HC stock) and a predicted hydrocarbon release profile as a function of time and temperature. The exhaust gas treatment system also includes a hydrocarbon storage model (not shown) and a controller 217 operatively connected to the hydrocarbon storage model. The controller 217 is configured to perform a method for determining the hydrocarbon storage level of the HCT 209. The controller 217 can then activate or operate HER 213, supply an airflow upstream of the HCT 209, or a combination thereof, based on the hydrocarbon storage level of the HCT 209, as further detailed herein.

[0064] A method for determining the hydrocarbon storage level of HCT 209 includes determining a first reaction rate representing the rate of hydrocarbon adsorption at non-acidic sites of HCT 209; determining a second reaction rate representing the rate of hydrocarbon desorption at non-acidic sites of HCT 209; determining a third reaction rate representing the rate of hydrocarbon adsorption at acidic sites of HCT 209; determining a fourth reaction rate representing the rate of hydrocarbon desorption at acidic sites of HCT 209; and determining the hydrocarbon storage level in HCT 209 based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

[0065] The determination of the first, second, third, and fourth reaction rates can be achieved using a two-site (acidic / non-acidic site) hydrocarbon trap modeling approach to determine the molar adsorption and desorption behavior of hydrocarbons. This model assumes two primary interactions between the HCT material and the hydrocarbons. The first is the storage of HC within the pores of, for example, zeolite materials, referred to as the non-acidic sites of the HCT material. The second is the interaction between HC and, for example, the Brønsted acidic sites of zeolite materials, referred to as the acidic sites of the HCT material. Therefore, the combination of the first and third reaction rates provides the total adsorption of HC at the HCT material, while the combination of the second and fourth reaction rates provides the total desorption of HC at the HCT material.

[0066] The equilibrium reaction between the non-acidic site (Z) of HCT 209 and the hydrocarbon (HC) to form a hydrocarbon-occupied site (ZHC) can be represented by the following relationship:

[0067]

[0068] Similarly, the equilibrium reaction between the acidic site (ZH) and the hydrocarbon (HC) of HCT 209 to form a hydrocarbon-occupied site (ZHHC) can be represented by the following relationship:

[0069]

[0070] In one or more embodiments, the first reaction rate representing HC adsorption at the non-acidic site of HCT can be expressed by Equation 1:

[0071]

[0072] The second reaction rate for HC desorption at the non-acidic site of HCT can be represented by Equation 2:

[0073]

[0074] The third reaction rate for HC adsorption at the acidic site of HCT can be represented by Equation 3:

[0075]

[0076] The fourth reaction rate for HC desorption at the acidic site of HCT can be represented by Equation 4:

[0077]

[0078] In equations 1 to 4, [HC] is the hydrocarbon concentration via HCT, expressed in moles per liter (mol / L, or parts per million, ppm); q Z It is the site density (0-1) of the unbound, non-acidic sites (Z) of HCT; q ZHC It is the site density of non-acidic sites (ZHC) of HCTs bound to hydrocarbons (0 to 1); q ZH This represents the site density (0 to 1) of unbound acidic sites (ZH) in HCT; q ZHHC This is the site density of acidic sites (ZHHC) of HCTs bound to hydrocarbons (0 to 1). q Z and q ZHC The sum of q is 1, and q ZH and q ZHHC The sum is 1. A 1Z It is the pre-exponential factor of the non-acidic site (Z) of HCT for hydrocarbon adsorption; A -1Z It is the pre-exponential factor of the non-acidic site (ZHC) of HCT used for hydrocarbon desorption; A 1ZH It is the pre-exponential factor of the acidic site (ZH) of HCT used for hydrocarbon adsorption; A -1ZH It is the pre-exponential factor of the acidic site (ZHHC) of the HCT used for hydrocarbon desorption; Ea z It is the activation energy of the adsorption reaction at the non-acidic site (Z) of HCT; Ea zH It is the activation energy of the adsorption reaction at the acidic site (ZH) of HCT; ΔH ZΔH is the heat of adsorption of hydrocarbons at the non-acidic site (Z) of the HCT, expressed in kilojoules per mole (kJ / mol); ZH R is the heat of adsorption of hydrocarbons at the acidic site (ZH) of HCT, expressed in kJ / mol; R is the universal gas constant; T is the temperature in Kelvin. It can be assumed that HC adsorption is not an activation process at the non-acidic site (Z) and acidic site (ZH), such that the activation energy is zero. This can be achieved by assuming that for each r at the non-acidic site (Z) and acidic site (ZH)... ads =r des To calculate balanced storage. Therefore, when r ads <r des At this time, HCT desorbs HC. Note that Z and ZH are determined by the type of HCT material. In one or more embodiments, Equations 1 to 4 can be used to fit ΔH for each HC substance. Z ΔH ZH A 1Z A -1Z A 1ZH and A -1ZH The parameters.

[0079] In some embodiments, the controller may also be configured to regulate the post-treatment operation of hydrocarbons released from the hydrocarbon trap based on hydrocarbon storage levels, the net reaction rate of hydrocarbon desorption from the hydrocarbon trap, or a combination thereof. The net reaction rate of hydrocarbon desorption from the hydrocarbon trap may be determined based on a first reaction rate, a second reaction rate, a third reaction rate, and a fourth reaction rate. For example, regulation of the post-treatment operation may include selectively operating the exhaust gas heating unit 213, selectively delivering an airflow at the air inlet 211, or a combination thereof. For example, the control unit 217 may be configured to deliver an airflow upstream of HCT 209 after HCT 209 stops adsorbing or capturing hydrocarbons and before HCT 209 begins desorbing or releasing hydrocarbons. In some embodiments, the control unit 217 may be configured to deliver an airflow upstream of HCT 209 while HCT 209 is desorbing hydrocarbons. For example, in one or more embodiments, the control unit 217 may be configured to deliver an airflow upstream of HCT 209 after HCT 209 stops adsorbing hydrocarbons and while HCT 209 is desorbing hydrocarbons.

[0080] In some embodiments, the exhaust gas heating unit 213 can be selectively operated when the net reaction rate of hydrocarbon desorption from HCT 209 is greater than zero, wherein the net reaction rate of hydrocarbon desorption from HCT 209 can be determined based on a first reaction rate, a second reaction rate, a third reaction rate, and a fourth reaction rate. In some embodiments, when the net reaction rate of hydrocarbon desorption from HCT 209 is greater than zero, an air stream can be selectively supplied at the air injection port 211, wherein the net reaction rate of hydrocarbon desorption from HCT 209 can be determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate. In some embodiments, the amount of air supplied at the air injection port 211 can be proportional to the calculated oxygen deficiency at the second catalyst 215.

[0081] In some embodiments, control unit 217 may be operatively connected via multiple sensors to monitor exhaust gas treatment system 200. The control unit may include a control module (not shown). As used herein, the term module refers to application-specific integrated circuits (ASICs), electronic circuitry, processors (shared, dedicated, or grouped), and memory executing one or more software or firmware programs, combinational logic circuitry, and / or other suitable components providing the described functionality. Exemplary sensors include hydrocarbon sensors, oxygen sensors, temperature sensors, pressure sensors, etc., or combinations thereof. Signals generated by the sensors may be transmitted to and interpreted by control unit 217, for example, for the operation or regulation of exhaust gas treatment system 200.

[0082] In some embodiments, the exhaust gas treatment system 200 may include a first sensor 221 disposed upstream of the HCT 209 and downstream of the first catalyst 205. The first sensor 221 may be used, for example, to measure the concentration of one or more gases (e.g., oxygen, carbon dioxide, hydrocarbons, etc., or combinations thereof) present in the exhaust gas duct 207. The first sensor 221 may also be used, for example, to measure the temperature and / or pressure present in the exhaust gas duct 207. For example, the first sensor 221 may be located near the inlet of the HCT 209 to determine the gas concentration, temperature, and / or pressure at the inlet of the HCT 209.

[0083] In some embodiments, the exhaust gas treatment system 200 may include a second sensor 223 disposed downstream of the HCT 209 and upstream of the exhaust gas heating unit 213. The second sensor 223 may be used, for example, to measure the concentration of one or more gases (e.g., oxygen, carbon dioxide, hydrocarbons, etc., or combinations thereof) present in the exhaust gas duct 207. The second sensor 223 may also be used, for example, to measure the temperature and / or pressure present in the exhaust gas duct 207. For example, the second sensor 223 may be located near the outlet of the HCT 209 to determine the gas concentration, temperature, and / or pressure at the outlet of the HCT 209.

[0084] Control unit 217 is operatively connected to the hydrocarbon storage model and is used to assess or determine the storage state of HCT 209 based on a first reaction rate, a second reaction rate, a third reaction rate, and a fourth reaction rate. For example, the storage state of HCT 209 can be assessed based on time, temperature, and / or hydrocarbon concentration. In some embodiments, the storage state and / or model can be adjusted based on measured parameters (e.g., gas concentration, temperature, and / or pressure). For example, in some embodiments, the storage state can be further assessed by comparing the gas concentration, temperature, and / or pressure at the inlet of HCT 209 with the gas concentration, temperature, and / or pressure at the outlet of HCT 209. In some embodiments, the storage state of HCT 209 can be further assessed based on the timing of engine events (e.g., time elapsed since a cold start of the engine).

[0085] As used herein, the term "storage state" refers to the state of a hydrocarbon trap and can be an active, inactive, or released state. The term "active state" indicates that hydrocarbons are stored (e.g., adsorbed) in HCT 209, the term "released state" indicates that hydrocarbons are released from HCT 209, and the term "inactive state" indicates that hydrocarbons are neither stored nor released at HCT 209. For example, an active state can be indicated when the hydrocarbon concentration at the HCT 209 inlet is determined to be greater than the hydrocarbon concentration at the HCT 209 outlet; a released state can be indicated when the hydrocarbon concentration at the HCT 209 outlet is determined to be greater than the hydrocarbon concentration at the HCT 209 inlet; and an inactive state can be indicated when the hydrocarbon concentration at the HCT 209 inlet is determined to be substantially the same as the hydrocarbon concentration at the HCT 209 outlet. The storage stage can be determined based on a hydrocarbon storage model and / or by using any number of parameters (e.g., gas concentration, time, pressure, and / or temperature).

[0086] Alternatively, one or more sensors may be located within various components of the exhaust gas treatment system 200. In some embodiments, the one or more sensors may include one or more temperature sensors 225, 227, 229 in contact with components of the exhaust gas treatment system 200. For example, the exhaust gas treatment system 200 may include a first temperature sensor 225 configured to measure the temperature of the HCT 209, a second temperature sensor 227 configured to measure the temperature of the exhaust gas heating unit 213, and / or a third temperature sensor 229 configured to measure the temperature of the second catalyst 215. In some embodiments, the temperature signals generated by the temperature sensors may be transmitted to a control unit 217 and interpreted by the control unit 217 according to the operational needs of the exhaust gas treatment system 200. The temperature sensors may be in fluid communication with the exhaust gas within the corresponding components and / or may be measurements of component temperature.

[0087] As described above, the exhaust gas treatment system 200 may include an exhaust gas duct 207, which may include several sections for conveying exhaust gas from the internal combustion engine 201 to various exhaust gas treatment devices within the exhaust gas treatment system 200. For example, such as Figure 2 As shown, the exhaust gas treatment system 200 includes a section of exhaust gas duct 207, which is fluidly connected to a first catalyst 205, an HCT 209, an exhaust gas heating unit 213, and a second catalyst 215. The outlet of the second catalyst 215 may include a tailpipe for discharging the treated exhaust gas into the ambient atmosphere.

[0088] On the other hand, a method for treating exhaust gas using an exhaust gas treatment system 200 is provided. The method includes operating an internal combustion engine 201 to provide an exhaust gas fluid (e.g., exhaust gas flow) at an exhaust gas outlet 203. The exhaust gas fluid is directed or transported through the exhaust gas treatment system 200 and passes through a first catalyst 205, an HCT 209, an exhaust gas heating unit 213, and a second catalyst 215. The exhaust gas treatment system 200 also includes a hydrocarbon storage model and a controller 217 operatively connected to the hydrocarbon storage model. The controller 217 is configured to perform a method for determining the hydrocarbon storage level of HCT 209, as described above, by means of the following steps: determining a first reaction rate representing the hydrocarbon adsorption rate at non-acidic sites of HCT 209; determining a second reaction rate representing the hydrocarbon desorption rate at non-acidic sites of HCT 209; determining a third reaction rate representing the hydrocarbon adsorption rate at acidic sites of HCT 209; determining a fourth reaction rate representing the hydrocarbon desorption rate at acidic sites of HCT 209; and determining the hydrocarbon storage level in HCT 209 based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

[0089] In some embodiments of the method, as provided herein, the first reaction rate can be represented by Equation 1, the second reaction rate by Equation 2, the third reaction rate by Equation 3, and the fourth reaction rate by Equation 4.

[0090] In some embodiments, the method may further include adjusting the post-treatment operation on the hydrocarbons released from HCT 209 based on hydrocarbon storage levels, the net reaction rate of hydrocarbon desorption from HCT 209, or a combination thereof, wherein the net reaction rate of hydrocarbon desorption from HCT 209 may be determined based on a first reaction rate, a second reaction rate, a third reaction rate, and a fourth reaction rate. For example, adjusting the post-treatment operation may include selectively operating the exhaust gas heating unit 213, selectively delivering an airflow at the air injection port 211, or a combination thereof.

[0091] In some embodiments, the exhaust gas heating unit 213 can be operated when the net reaction rate of hydrocarbon desorption from HCT 209 is greater than zero, wherein the net reaction rate of hydrocarbon desorption from HCT 209 is determined based on a first reaction rate, a second reaction rate, a third reaction rate, and a fourth reaction rate. For example, in some embodiments, the exhaust gas heating unit does not operate when the net reaction rate of hydrocarbon desorption from HCT 209 is zero.

[0092] In some embodiments, the method may include supplying an air stream at air injection port 211 when the net reaction rate of hydrocarbon desorption from HCT 209 is greater than zero, wherein the net reaction rate of hydrocarbon desorption from HCT 209 is determined based on a first reaction rate, a second reaction rate, a third reaction rate, and a fourth reaction rate. The air stream may be injected via air injection port 211, as described herein. For example, the air stream may be combined with exhaust gas output from the first catalyst 205 at a location near the outlet of the first catalyst 205. In other embodiments, air injection port 211 may be located near the inlet of HCT 209.

[0093] In some embodiments, the method may include supplying an air stream after HCT 209 has stopped adsorbing hydrocarbons and before HCT 209 begins desorbing hydrocarbons. In some embodiments, the method may include supplying an air stream after HCT 209 has stopped adsorbing hydrocarbons and during HCT 209 desorbing hydrocarbons. In some aspects, the method may also include stopping the supply of air streams after HCT 209 has stopped desorbing hydrocarbons. For example, in some embodiments, no air stream is supplied until HCT 209 reaches its hydrocarbon desorption temperature. In some embodiments, no air stream may be supplied until the second catalyst 215 reaches its hydrocarbon oxidation temperature. In some embodiments, no air stream may be supplied when the net reaction rate of hydrocarbon desorption from HCT 209 is zero.

[0094] The method may optionally include measuring temperature, gas concentration, pressure, or a combination thereof using a first sensor 221 positioned upstream of HCT 209 and downstream of the first catalyst 205.

[0095] In some embodiments, the method may further include timing-selective delivery of an airflow based on engine events, wherein the airflow is delivered after the hydrocarbon trap has stopped adsorbing hydrocarbons and before the hydrocarbon trap begins desorbing hydrocarbons. For example, engine events may be measured from the start of a cold start of the engine.

[0096] In some embodiments, the method may also include measuring temperature, gas concentration, pressure, or a combination thereof using a second sensor 223 located downstream of HCT 209 and upstream of exhaust gas heating unit (HER) 213.

[0097] In some embodiments, the airflow can be delivered at any suitable air mass flow rate. For example, the airflow can be delivered at a flow rate sufficient to provide a suitable temperature difference between the hydrocarbon release temperature at HCT 209 and the hydrocarbon oxidation temperature at catalyst 215. As used herein, the term "hydrocarbon release temperature" refers to the temperature at which hydrocarbons are released (e.g., desorbed) from HCT 209. As used herein, the term "hydrocarbon oxidation temperature" refers to the temperature at which hydrocarbons are oxidized at catalyst 215.

[0098] In one or more embodiments, the airflow can be delivered at an air mass flow rate of 1 to 30 liters per second (L / s). For example, the airflow can be delivered at an air mass flow rate of 2.5 to 30 L / s, or 5 to 25 L / s, but the embodiments are not limited thereto. In some embodiments, the airflow is delivered at an air mass flow rate sufficient to provide a suitable temperature difference, wherein the temperature difference is the difference between the temperature of HCT 209 and the temperature of the second catalyst 215. In some embodiments, the airflow is delivered at an air mass flow rate sufficient to provide a suitable temperature difference, wherein the temperature difference is the difference between the temperature of HCT 209 and the temperature of the exhaust gas heating unit 213. In some embodiments, methods are provided for selecting the HCT material and the catalyst material to maximize the temperature difference.

[0099] In some embodiments, the airflow can be delivered at a mass flow rate sufficient to provide a temperature difference of at least 10°C, at least 25°C, at least 50°C, at least 100°C, at least 150°C, at least 180°C, or at least 200°C, wherein the temperature difference is the difference between the temperature of HCT 209 and the temperature of the second catalyst 215. In some embodiments, the airflow can be delivered at a mass flow rate sufficient to provide a temperature difference of at least 10°C, at least 25°C, at least 50°C, at least 100°C, at least 150°C, at least 180°C, or at least 200°C, wherein the temperature difference is the difference between the temperature of HCT 209 and the temperature of the exhaust gas heating unit 213.

[0100] Figure 3A flowchart 300 illustrating a method for treating exhaust gas from an internal combustion engine according to one or more embodiments is depicted. The flowchart begins at block 301, where it is determined whether the hydrocarbon trap has reached the hydrocarbon release temperature. If the hydrocarbon trap has not yet reached the release temperature, the process proceeds to block 302 and air injection remains closed. If the hydrocarbon trap has reached the release temperature, the process proceeds to block 303, where it is determined whether the second catalyst has reached the oxidation temperature. If the second catalyst has not yet reached the oxidation temperature, the process proceeds to block 304 and air injection remains closed. If the second catalyst has reached the oxidation temperature, the process proceeds to block 305, where it is determined whether the tailpipe EQR is greater than 1. If the tailpipe EQR is not greater than 1, the process proceeds to block 306 and air injection remains closed. If the tailpipe EQR is greater than 1, the process proceeds to block 307, where it is determined whether the hydrocarbon release rate from the hydrocarbon trap is zero. If the hydrocarbon release rate from the hydrocarbon trap is zero, the process proceeds to block 309 and air injection remains closed. If the hydrocarbon release rate from the hydrocarbon trap is not zero, proceed to box 308 and air injection is turned on.

[0101] The term "EQR" refers to the equivalence ratio, which describes the air-fuel ratio in gasoline engines and aftertreatment systems. An EQR of 1 means that combustion occurs under stoichiometric conditions, where there is just enough air to burn all the fuel. An EQR > 1 means that there is more air than stoichiometric combustion is required, also known as lean (or fuel-lean) conditions. An EQR < 1 means that there is less air than stoichiometric combustion is required, also known as rich (or fuel-rich) conditions.

[0102] Figure 4 A flowchart 400 illustrating a method for treating exhaust gas from an internal combustion engine according to one or more embodiments is depicted. The flowchart begins at box 401, where it is determined whether the hydrocarbon release rate from the hydrocarbon trap is zero. If the hydrocarbon release rate from the hydrocarbon trap is zero, the process proceeds to box 403 and the electric heater is turned off. If the hydrocarbon release rate from the hydrocarbon trap is not zero, the process proceeds to box 402 and the electric heater is turned on.

[0103] Now for reference Figure 5A The figure shows the C1 hydrocarbon concentration (parts per million, ppm) measured at the inlet of HCT unit (501), the C1 hydrocarbon concentration measured at the outlet of HCT unit (502), and the C1 hydrocarbon concentration calculated using Equations 1 to 4 based on the time and temperature (503) from engine cold start. Data were collected using a laboratory reactor model. Figure 5AThe figure also shows the temperature at the HCT inlet (504) and the temperature at the second catalyst (505). Hydrocarbons are first released from the HCT unit in a time period of approximately 300 to approximately 450 seconds, followed by a second release of hydrocarbons from the HCT unit observed between approximately 475 to approximately 700 seconds. Now refer to... Figure 5B The figure shows the surface coverage (0 to 1) of the HCT material for each non-acidic site occupied by hydrocarbon (510) and acidic sites occupied by hydrocarbon (511) based on time and temperature. Figure 5B The graph also shows the temperature at the HCT inlet (504) and the temperature at the second catalyst (505). Figure 5B The timeline in the middle corresponds to Figure 5A The timeline shows that the first release of hydrocarbons from the HCT unit corresponds to the release of hydrocarbons from non-acidic sites, while the second release corresponds to the release of hydrocarbons from acidic sites. For the evaluation using Equations 1 to 4, the site density of Z is 2.5 mol / m². 3 Furthermore, the site density of ZH is 1.2 mol / m³. 3 Adsorption heat DH z It is 50.7 kJ / mol, DH ZH It is 67.2 kJ / mol; the pre-exponential factor is A. 1Z 6.983E5; A -1Z 9.85E11; A 1ZH 9.78E2; and A -1ZH 4.925E3.

[0104] The technical methods described herein contribute to improving emission control systems used in internal combustion engines, such as those used in vehicles. The technical features described herein improve conventional emission control systems by providing a control scheme based on the capture and release of hydrocarbons using a hydrocarbon trap. Advantageously, the control scheme reduces emissions during cold starts.

[0105] In terms of hardware architecture, the emission control system may be implemented in part using a computing device, which may include a processor, memory, and one or more input and / or output (I / O) device interfaces communicatively connected via a local interface. The local interface may include, for example, but not limited to, one or more buses and / or other wired or wireless connections. The local interface may have additional elements omitted for simplicity, such as controllers, buffers (caches), drivers, repeaters, and receivers, to enable communication. Furthermore, the local interface may include address, control, and / or data connections to enable appropriate communication between the aforementioned components.

[0106] When a computing device is in operation, the processor can be configured to execute software stored in memory, to transfer data to and from memory, and typically to control the operation of the computing device. The software in memory is read, in whole or in part, by the processor, possibly cached within the processor, and then executed. The processor can be a hardware device used to execute software (particularly software stored in memory). The processor can be a custom or commercially available processor, a central processing unit (CPU), an auxiliary processor among several processors associated with a computing device, a semiconductor-based microprocessor (in the form of a microchip or chipset), or any device typically used to execute software.

[0107] Memory may include any one or a combination of volatile memory elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, VRAM, etc.)) and / or non-volatile memory elements (e.g., ROM, hard disk drive, CD-ROM, etc.). Furthermore, memory may contain electronic, magnetic, optical, and / or other types of storage media. Note that memory may also have a distributed architecture, where components are located remotely to each other but are accessible by a processor.

[0108] Software in memory may include one or more individual programs, each comprising an ordered list of executable instructions for implementing logical functions. System components embodied as software may also be interpreted as source programs, executable programs (object code), scripts, or any other entity containing a set of instructions to be executed. When constructed as source programs, the programs are translated by compilers, assemblers, interpreters, etc., which may or may not be present in memory.

[0109] It should be noted that Figure 3 An architecture, functionality, and / or operational scheme that can be partially implemented using software is illustrated. In this regard, one or more blocks can be interpreted as modules, segments, or portions of code comprising one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions mentioned in the boxes may occur out of sequence and / or not at all. For example, two boxes shown consecutively may actually execute substantially simultaneously, or these boxes may sometimes execute in reverse order, depending on the functionality involved.

[0110] It should be noted that any functionality described herein can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device (such as a computer-based system, a processor-containing system, or other system that can fetch and execute instructions from and from an instruction execution system, apparatus, or device). In the context of this document, a “computer-readable medium” contains, stores, communicates, propagates, and / or transmits programs for use by or in connection with an instruction execution system, apparatus, or device. A computer-readable medium can be, for example, but not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices. More specific examples (not an exhaustive list) of computer-readable media include portable computer disks (magnetic), random access memory (RAM) (electronic), read-only memory (ROM) (electronic), erasable programmable read-only memory (EPROM or flash memory) (electronic), and portable optical disc read-only memory (CDROM) (optical).

[0111] The terms “a” and “an” do not indicate a limitation of quantity, but rather that at least one of the referenced items is present. Unless the context clearly indicates otherwise, the term “or” means “and / or”. Throughout the specification, reference to “aspect” means that a particular element described in connection with that aspect (e.g., a feature, structure, step, or characteristic) is included in at least one aspect described herein and may or may not be present in other aspects. Furthermore, it should be understood that the described elements may be combined in any suitable manner in the aspects.

[0112] When an element, such as a layer, film, region, or substrate, is referred to as being “on” another element, it can be directly on the other element, or there may be intermediate elements present. Conversely, when an element is referred to as being “directly” on another element, there are no intermediate elements present.

[0113] Unless otherwise stated herein, all test standards are the most recent standards in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which a test standard appears. Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0114] While the above disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes can be made and elements can be substituted with equivalents without departing from its scope. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of this disclosure without departing from the basic scope of this disclosure. Therefore, it is intended that this disclosure be limited to the specific embodiments disclosed, but will include all embodiments falling within its scope.

Claims

1. A waste gas treatment system, comprising: A first catalyst downstream of the exhaust outlet of an internal combustion engine, wherein the first catalyst receives exhaust gas output from the exhaust outlet; A hydrocarbon trap downstream of the first catalyst, wherein the hydrocarbon trap receives exhaust gas output from the first catalyst; An air injection port is configured to deliver an airflow upstream of the hydrocarbon trap and downstream of the first catalyst; A waste gas heating unit downstream of the hydrocarbon trap, wherein the waste gas heating unit receives waste gas output from the hydrocarbon trap; A second catalyst downstream of the exhaust gas heating unit, wherein the second catalyst receives the exhaust gas output from the exhaust gas heating unit; Hydrocarbon storage models; as well as A controller, operatively connected to the hydrocarbon storage model, is configured to perform a method for determining the hydrocarbon storage level of the hydrocarbon trap, the method comprising: A first reaction rate representing the rate of hydrocarbon adsorption at the non-acidic sites of the hydrocarbon trap is determined; A second reaction rate representing the rate of hydrocarbon desorption at the non-acidic sites of the hydrocarbon trap is determined; A third reaction rate representing the rate of hydrocarbon adsorption at the acidic sites of the hydrocarbon trap was determined; Determine a fourth reaction rate representing the rate of hydrocarbon desorption at the acidic site of the hydrocarbon trap; and The hydrocarbon storage level in the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

2. The exhaust gas treatment system of claim 1, wherein the controller is further configured to adjust the post-treatment operation on the hydrocarbons released from the hydrocarbon trap based on the hydrocarbon storage level, the net reaction rate of hydrocarbons desorbed from the hydrocarbon trap, or a combination thereof, wherein the net reaction rate of hydrocarbons desorbed from the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

3. The waste gas treatment system according to claim 1, wherein... The first reaction rate is represented by Equation 1: The second reaction rate is expressed by Equation 2: The third reaction rate is expressed by Equation 3: The fourth reaction rate is expressed by Equation 4: in, In equations 1 to 4, [HC] is the concentration of hydrocarbons obtained through the hydrocarbon trap. q Z It is the site density of non-acidic sites in hydrocarbon traps that are not bound to hydrocarbons. q ZHC It is the site density of non-acidic sites in hydrocarbon traps that are bound to hydrocarbons. q ZH It is the site density of acidic sites in hydrocarbon traps that are not bound to hydrocarbons. q ZHHC It is the site density of acidic sites in hydrocarbon traps that are bound to hydrocarbons. A 1Z It is the pre-exponential factor for the non-acidic sites of hydrocarbon traps used for hydrocarbon adsorption. A -1Z It is the pre-exponential factor for the non-acidic sites of hydrocarbon traps used for hydrocarbon desorption. A 1ZH It is the pre-exponential factor for the acidic sites of hydrocarbon traps used for hydrocarbon adsorption. A -1ZH It is the pre-exponential factor of the acidic site of the hydrocarbon trap used for hydrocarbon desorption. Ea z It is the activation energy of the adsorption reaction at the non-acidic sites of the hydrocarbon trap. Ea zH It is the activation energy of the adsorption reaction at the acidic site of the hydrocarbon trap. ΔH Z It is the heat of adsorption of hydrocarbons at the non-acidic sites of the hydrocarbon trap. ΔH ZH It is the heat of adsorption of hydrocarbons at the acidic sites of the hydrocarbon trap. R is the universal gas constant, and T is temperature.

4. The waste gas treatment system according to claim 1, wherein the waste gas heating unit is selectively operated when the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is greater than zero, wherein the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

5. The exhaust gas treatment system according to claim 1, wherein when the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is greater than zero, an air stream is selectively delivered to the air injection port, wherein the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

6. A method for treating exhaust gas from an internal combustion engine in a motor vehicle, the method comprising: Operate the internal combustion engine to provide exhaust gas fluid at the exhaust outlet of the internal combustion engine; The waste gas fluid is guided through a waste gas treatment system, the waste gas treatment system comprising: A first catalyst is located downstream of the exhaust outlet of the internal combustion engine, wherein the first catalyst receives exhaust gas output from the exhaust outlet. A hydrocarbon trap, located downstream of the first catalyst, wherein the hydrocarbon trap receives exhaust gas output from the first catalyst; An air injection port is configured to deliver an airflow upstream of the hydrocarbon trap and downstream of the first catalyst; An exhaust gas heating unit is located downstream of the hydrocarbon trap, wherein the exhaust gas heating unit receives exhaust gas output from the hydrocarbon trap; The second catalyst is located downstream of the exhaust gas heating unit, wherein the second catalyst receives the exhaust gas output from the exhaust gas heating unit; Hydrocarbon storage models; and A controller, operatively connected to the hydrocarbon storage model, configured to perform a method for determining the hydrocarbon storage level of the hydrocarbon trap; A first reaction rate representing the rate of hydrocarbon adsorption at the non-acidic sites of the hydrocarbon trap is determined; A second reaction rate representing the rate of hydrocarbon desorption at the non-acidic sites of the hydrocarbon trap is determined; A third reaction rate representing the rate of hydrocarbon adsorption at the acidic sites of the hydrocarbon trap was determined; Determine a fourth reaction rate representing the rate of hydrocarbon desorption at the acidic site of the hydrocarbon trap; and The hydrocarbon storage level in the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

7. The method of claim 6, wherein The first reaction rate is represented by Equation 1: The second reaction rate is expressed by Equation 2: The third reaction rate is expressed by Equation 3: The fourth reaction rate is expressed by Equation 4: in, In equations 1 to 4, [HC] is the concentration of hydrocarbons obtained through the hydrocarbon trap. q Z It is the site density of non-acidic sites in hydrocarbon traps that are not bound to hydrocarbons. q ZHC It is the site density of non-acidic sites in hydrocarbon traps that are bound to hydrocarbons. q ZH It is the site density of acidic sites in hydrocarbon traps that are not bound to hydrocarbons. q ZHHC It is the site density of acidic sites in hydrocarbon traps that are bound to hydrocarbons. A 1Z It is the pre-exponential factor for the non-acidic sites of hydrocarbon traps used for hydrocarbon adsorption. A -1Z It is the pre-exponential factor for the non-acidic sites of hydrocarbon traps used for hydrocarbon desorption. A 1ZH It is the pre-exponential factor for the acidic sites of hydrocarbon traps used for hydrocarbon adsorption. A -1ZH It is the pre-exponential factor of the acidic site of the hydrocarbon trap used for hydrocarbon desorption. Ea z It is the activation energy of the adsorption reaction at the non-acidic sites of the hydrocarbon trap. Ea zH It is the activation energy of the adsorption reaction at the acidic site of the hydrocarbon trap. ΔH Z It is the heat of adsorption of hydrocarbons at the non-acidic sites of the hydrocarbon trap. ΔH ZH It is the heat of adsorption of hydrocarbons at the acidic sites of the hydrocarbon trap. R is the universal gas constant, and T is temperature.

8. The method of claim 6, further comprising operating the exhaust gas heating unit when the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is greater than zero, wherein the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

9. The method of claim 6, further comprising supplying the air stream at the air inlet when the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is greater than zero, wherein the net reaction rate of desorbing hydrocarbons from the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

10. The method of claim 6, wherein the air stream is not delivered before the hydrocarbon trap reaches the hydrocarbon desorption temperature.

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