CN113356978A - HC adsorption system and method for controlling heat flow and temperature of exhaust gas of cold start of engine - Google Patents

HC adsorption system and method for controlling heat flow and temperature of exhaust gas of cold start of engine Download PDF

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CN113356978A
CN113356978A CN202110852807.8A CN202110852807A CN113356978A CN 113356978 A CN113356978 A CN 113356978A CN 202110852807 A CN202110852807 A CN 202110852807A CN 113356978 A CN113356978 A CN 113356978A
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heat
heat flow
exhaust gas
exhaust
temperature
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CN113356978B (en
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邓元望
冯长岭
韩丹丹
鄂加强
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Hunan University
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Hunan University
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N5/00—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy
    • F01N5/02—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy the devices using heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
    • F01N2240/02—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being a heat exchanger
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
    • F01N2240/10—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being a heat accumulator
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

The invention discloses an HC adsorption system and method for controlling exhaust heat flow and temperature of cold start of an engine, wherein the system comprises the engine, an HC adsorber and a three-way catalyst, and also comprises a heat flow divider, a heat flow collector and a heat flow transfer structure; the heat flow transfer structure is connected with the heat flow diverter and the heat flow collector. The invention controls the temperature of the exhaust gas entering the HC adsorber by shunting the heat of the exhaust gas, thereby controlling the adsorption process. The exhaust heat is shunted before the HC adsorber, so that the heat entering the HC adsorber during cold start is reduced, the temperature rise rate of the HC adsorber is reduced, and the adsorption temperature can be kept for a long time; the heat of reposition of redundant personnel joins before the three-way catalyst converter, can increase the heat that gets into the three-way catalyst converter, increases the temperature rise rate of three-way catalyst converter, shortens the time of starting combustion.

Description

HC adsorption system and method for controlling heat flow and temperature of exhaust gas of cold start of engine
Technical Field
The invention relates to the technical field of engine exhaust aftertreatment, in particular to an HC adsorption system and method for controlling exhaust heat flow and temperature of an engine during cold start.
Background
HC adsorption technology is mainly applied at home and abroad aiming at HC emission in the cold start stage of the engine. The HC adsorption technology usually uses a three-way catalyst and an HC adsorber, and improves the pollutant emission control capacity by optimizing and upgrading the three-way catalyst in the existing aftertreatment system, but the technical difficulty of the existing three-way catalyst is increased, noble metal schemes, coating technologies, structures and carriers need to be correspondingly improved, the technical difficulty of matching with an engine is increased, and the aftertreatment system cost is increased. The HC adsorber comprises series-connected adsorbers and parallel-connected adsorbers, the adsorption process of the HC adsorber in the cold starting process of an engine is not controlled, the parallel-connected adsorbers control exhaust gas in the cold starting process of the engine to enter the adsorber, the exhaust gas does not enter the adsorber after the cold starting is finished, the purpose of controlling the adsorption time of the adsorber is achieved by controlling an exhaust path, the adsorption process is not controlled, and the low-temperature adsorption performance and the high-temperature desorption performance of the HC adsorption material are required to be improved. When the engine is started in a cold state, the exhaust temperature is low, the HC emission is large, and the low-temperature adsorption capacity of the adsorption material is insufficient; in the later period of cold start, although the exhaust temperature is continuously increased, when the catalyst in the catalyst does not reach the light-off temperature, part of HC may begin to be desorbed from the adsorption material and enter the catalyst, and the high-temperature performance of the adsorption material is difficult to meet the requirement.
Disclosure of Invention
Accordingly, the present invention is directed to overcoming the above-mentioned shortcomings in the art, and providing a HC adsorption system and method for engine cold start exhaust gas heat flow and temperature control.
The invention provides an HC adsorption system for controlling heat flow and temperature of exhaust gas of cold start of an engine, which comprises the engine, an HC adsorber and a three-way catalyst, and also comprises a heat flow divider, a heat flow collector and a heat flow transfer structure; the heat flow transfer structure is connected with the heat flow diverter and the heat flow collector.
Preferably, the thermal splitter is configured to split exhaust heat into the HC adsorber and the thermal flow transfer structure, and the thermal collector is configured to merge exhaust heat from the HC adsorber and the thermal flow transfer structure into the three-way catalyst.
Preferably, the thermal shunt and the thermal collector are made of high-thermal-conductivity materials and have a honeycomb structure with high heat transfer efficiency; the heat flow transmission structure is made of a heat insulation material, and a high-heat-conductivity material is arranged inside the heat flow transmission structure.
Preferably, the heat diverter and the heat collector are micro baffle type heat exchangers; the heat flow transmission structure is made of heat insulation materials, and high-heat-conductivity fluid is arranged inside the heat flow transmission structure.
Preferably, the heat splitter and the heat collector are micro baffle type heat exchangers, and the heat flow transfer structure is a heat pipe.
The invention also provides a method for controlling the exhaust temperature in the exhaust system during the cold start of the engine, which utilizes the HC adsorption system for controlling the heat flow and the temperature of the exhaust gas during the cold start of the engine, and specifically comprises the following steps:
s1: in the cold starting process of the engine, the heat of the exhaust enters the HC absorber and the heat flow transfer structure through the heat flow divider1Representing the heat of the exhaust gas before entering the thermal splitter, phi z1Indicating the heat of exhaust gas entering the HC adsorber, phi r1Representing the heat of exhaust entering the heat flow transfer structure, [ phi ]1＝Фz1+Фr1；
S2: the exhaust heat enters the heat confluence device after passing through the HC absorber and the heat flow transfer structure2Representing the heat of exhaust gas, after passing through the HC adsorber, entering the heat flow combiner2Representing the heat of exhaust gas entering the heat collector after passing through the heat flow transfer structure, phi2Representing the heat of the exhaust gas after passing through the heat collector, phi z2+Фr2＝Ф2；
S3: the exhaust heat enters the three-effect catalyst after passing through the heat collector.
Preference is given toThe ground heat diverter has anisotropic heat conduction performance, phi z1Less than phi r1，
Figure BDA0003182971590000021
Thermal conductivity lambdaz1Less than the thermal conductivity lambdar1，
Figure BDA0003182971590000022
Preferably, the structure of the heat sink satisfies:
Figure BDA0003182971590000023
in the formula, Bi is a Beaut number, and delta is a structural characteristic length;
in the heat collector, the heat confluence is satisfied:
Figure BDA0003182971590000024
wherein the volume of the heat sink is V, the surface area is A, t represents the temperature of the heat sink∞Representing the temperature of the exhaust entering the heat sink, the heat transfer coefficient of the inner surface of the heat sink is h.
Preferably, [ phi ] z1<Ф1Smaller exhaust heat amount phi z1And the adsorption temperature and the adsorption process can be kept for a long time by entering the HC adsorber to slow down the temperature rise rate of the HC adsorber.
Preferably, [ phi ] z2<Ф2After the exhaust heat enters the heat collector, the larger phi2The rate of temperature rise of exhaust gas entering the three-way catalyst is increased, and the light-off time of the three-way catalyst is shortened.
The HC adsorption system and the method for controlling the heat flow and the temperature of the exhaust gas of the cold start of the engine control the temperature of the exhaust gas entering an HC adsorber through the diversion of the heat of the exhaust gas, thereby controlling the adsorption process. The exhaust heat is shunted before the HC adsorber, so that the heat entering the HC adsorber during cold start is reduced, the temperature rise rate of the HC adsorber is reduced, and the adsorption temperature can be kept for a long time; the heat of reposition of redundant personnel joins before the three-way catalyst converter, can increase the heat that gets into the three-way catalyst converter, increases the temperature rise rate of three-way catalyst converter, shortens the time of starting combustion.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic structural diagram of an HC adsorption system with engine cold start exhaust heat flow and temperature control provided by the present invention;
fig. 2 is a schematic diagram of a thermal shunt, a thermal sink and a heat flow transfer structure according to the present invention;
FIG. 3 is a schematic diagram of another heat splitter, heat sink, and heat flow transfer configuration in accordance with the present invention;
fig. 4 is a schematic diagram of another thermal splitter, thermal collector, and heat flow transfer structure according to the present invention.
Reference numerals: 1. an engine; 2. an HC adsorber; 3. a three-way catalyst; 4. a thermal shunt; 5. a heat sink; 6. a heat flow transfer structure; 7. and (4) exhausting the gas.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Example 1
As shown in fig. 1 and fig. 2, the present embodiment provides an HC adsorption system with engine cold start exhaust heat flow and temperature control, which includes an engine 1, an HC adsorber 2, a three-way catalyst 3, a heat splitter 4, a heat sink 5, and a heat flow transfer structure 6; the heat flow divider 4 is arranged on an exhaust pipe 7 between the engine 1 and the HC adsorber 2, the heat flow collector 5 is arranged on the exhaust pipe 7 between the HC adsorber 2 and the three-way catalyst 3, and the heat flow transfer structure 6 is connected with the heat flow divider 4 and the heat flow collector 5. The thermal flow divider 4 is used for dividing exhaust gas heat into the HC adsorber 2 and the heat flow transfer structure 6, and the thermal flow collector 5 is used for merging the exhaust gas heat in the HC adsorber 2 and the heat flow transfer structure 6 into the three-way catalyst 3. The heat diverter 4 and the heat collector 5 are made of materials with high thermal conductivity and have a honeycomb structure with high heat transfer efficiency; the heat flow transmission structure 6 is made of a heat insulation material, and a high-heat-conductivity material is arranged inside the heat flow transmission structure.
In the present embodiment, during cold start of the engine 1, the exhaust gas passes through the thermal shunt 4, which functions to shunt the heat of the exhaust gas, neglecting the heat capacity of the thermal shunt 4 itself, and having Φ1＝Фz1+Фr1，Фz1<Ф1The heat amount of exhaust gas Φ z entering the HC adsorber 21The decrease, the rate of rise of the exhaust gas temperature becomes small, enabling the HC adsorber 2 to maintain the adsorption temperature for a sufficiently long time, completing the adsorption of HC in the exhaust gas. Another partial heat amount r1Into the heat flow transfer structure 6 and then to the heat sink 5.
After the exhaust heat passes through the heat collector 5, the function is to collect the exhaust heat, namely phi z2+Фr2＝Ф2，Фz2<Ф2Phi greater behind the heat sink2The rate at which the temperature of the exhaust gas entering the three-way catalyst 3 rises can be increased, shortening the light-off time of the three-way catalyst 3.
The heat flow transfer structure 6 has the function of p phi r1And the high-efficiency and quick heat transfer is carried out. Let the exhaust gas temperature at the heated splitter 4 be t1The exhaust gas temperature at the heat collector 5 is t2，t1>t2. Heat loss in the heat transfer process is reduced as much as possible, so that phi r1And phi r2Of substantially equal magnitude, i.e. r1≈Фr2。
The heat spreader 4 is designed as a heat spreader with anisotropic heat conduction properties, which is realized by materials and structures, according to the basic law of heat conduction:
Figure BDA0003182971590000041
material and structural requirements: phi z thermal flow in z direction1Smaller, can be represented as
Figure BDA0003182971590000042
Thus, the thermal conductivity λz1Should be small and the z-dimension of the structure is large, i.e.
Figure BDA0003182971590000051
Is smaller.
Heat flow phi r in r direction1Is larger, can be represented as
Figure BDA0003182971590000052
Thus, the thermal conductivity λr1Should be larger and the structure dimension in the r-direction smaller, i.e.
Figure BDA0003182971590000053
Is relatively large.
After passing through the hot splitter 4, the exhaust heat flow phi z is smaller1And the gas enters the HC adsorber 2 along the exhaust pipe, so that the temperature rise rate of the HC adsorber 2 is reduced, and the adsorption temperature and the adsorption process can be kept for a long time.
Large exhaust heat amount z corresponding to this2The heat is transferred to the heat collector 5 along the heat flow transfer structure 6, the heat flow transfer structure 6 requires a material and a structure having a sufficiently large thermal conductivity in the heat transfer direction compared with the exhaust gas thermal conductivity, and the thermal conductivity in other directions is close to zero, so that the rapid heat transfer can be ensured, and the heat loss can be prevented. I.e. heat is transferred in the direction indicated by the arrow in figure 1, and r1≈Фr2。
The heat collector 5 functions to adjust the heat value phi z of the exhaust gas having passed through the HC adsorber 22With the heat phi r passing through the heat flow transferring structure 62Converging, i.e. phi z2+Фr2＝Ф2. The heat collector 5 should use a material and a structure having a large thermal diffusivity a, such as
Figure BDA0003182971590000054
In the formula, lambda is the material thermal conductivity; rho is the material density; and c is the specific heat capacity of the material.
Isotropic materials with a larger λ and smaller ρ, c should be chosen. The structure of the heat collector 5 meets the following requirements:
Figure BDA0003182971590000055
in the formula, Bi is the Beaudo number; δ is the structural feature length.
In the heat collector 5, the heat confluence satisfies:
Figure BDA0003182971590000056
wherein the volume of the heat sink 5 is V, the surface area is A, t represents the heat sink temperature, t∞The temperature of the exhaust gas entering the heat sink 5, the heat transfer coefficient h of the inner surface of the heat sink 5, is shown, from which the temperature and heat of the exhaust gas after passing the heat sink 5 can be determined.
In this embodiment, the exhaust heat flow and temperature control system composed of the heat splitter 4, the heat collector 5 and the heat flow transfer structure 6 may also adopt a multi-time splitting and converging manner to control the exhaust temperature and optimize the performance of the exhaust aftertreatment system.
The exhaust gas enters the three-way catalyst 3 after passing through the heat collector 5. The exhaust heat flow and temperature control system composed of the heat flow divider 4, the heat flow collector 5 and the heat flow transfer structure 6 controls the adsorption temperature of the HC adsorber 2. Compared with an exhaust heat flow and temperature control system which is not composed of the heat flow divider 4, the heat flow collector 5 and the heat flow transfer structure 6, the exhaust gas passing through the heat flow collector 5 carries more heat, so that the exhaust temperature entering the three-way catalyst 3 is higher, the three-way catalyst 3 can reach the ignition temperature quickly, and the ignition time is shortened.
Example 2
As shown in fig. 1 and fig. 3, the present embodiment provides an HC adsorption system with engine cold start exhaust heat flow and temperature control, which includes an engine 1, an HC adsorber 2, a three-way catalyst 3, a heat splitter 4, a heat sink 5, and a heat flow transfer structure 6; the heat flow divider 4 is arranged on an exhaust pipe 7 between the engine 1 and the HC adsorber 2, the heat flow collector 5 is arranged on the exhaust pipe 7 between the HC adsorber 2 and the three-way catalyst 3, and the heat flow transfer structure 6 is connected with the heat flow divider 4 and the heat flow collector 5. The thermal flow divider 4 is used for dividing exhaust gas heat into the HC adsorber 2 and the heat flow transfer structure 6, and the thermal flow collector 5 is used for merging the exhaust gas heat in the HC adsorber 2 and the heat flow transfer structure 6 into the three-way catalyst 3. The heat shunt 4 and the heat collector 5 are micro baffle type heat exchangers; the heat flow transmission structure 6 is made of a heat insulation material, and a high-heat-conductivity fluid is arranged inside the heat flow transmission structure.
In the present embodiment, during cold start of the engine 1, the exhaust gas passes through the thermal shunt 4, which functions to shunt the heat of the exhaust gas, neglecting the heat capacity of the thermal shunt 4 itself, and having Φ1＝Фz1+Фr1，Фz1<Ф1The heat amount of exhaust gas Φ z entering the HC adsorber 21The decrease, the rate of rise of the exhaust gas temperature becomes small, enabling the HC adsorber 2 to maintain the adsorption temperature for a sufficiently long time, completing the adsorption of HC in the exhaust gas. Another partial heat amount r1Into the heat flow transfer structure 6 and then to the heat sink 5.
After passing through the heat collector 5, the exhaust gas has the function of collecting the heat of the exhaust gas, namely phi z2+Фr2＝Ф2，Фz2<Ф2Phi greater behind the heat sink2The rate at which the temperature of the exhaust gas entering the three-way catalyst 3 rises can be increased, shortening the light-off time of the three-way catalyst 3.
The heat flow transfer structure 6 has the function of p phi r1And the high-efficiency and quick heat transfer is carried out. Let the exhaust gas temperature at the heated splitter 4 be t1The exhaust gas temperature at the heat collector 5 is t2，t1>t2. Heat loss in the heat transfer process is reduced as much as possible, so that phi r1And phi r2Of substantially equal magnitude, i.e. r1≈Фr2。
The heat diverter 4 is designed as a miniature baffle type heat exchanger with
ΔΦ＝kAΔtm
Then phiz1＝Φ1-ΔΦ
Φr1＝ΔΦ
Large exhaust heat amount z corresponding to this2The heat is transferred to the heat collector 5 along the heat flow transfer structure 6, the heat flow transfer structure 6 requires a material and a structure having a sufficiently large thermal conductivity in the heat transfer direction compared with the exhaust gas thermal conductivity, and the thermal conductivity in other directions is close to zero, so that the rapid heat transfer can be ensured, and the heat loss can be prevented. I.e. heat is transferred in the direction indicated by the arrow in figure 1, and r1≈Фr2. The heat collector 5 can likewise be designed as a micro baffle heat exchanger.
In this embodiment, the exhaust heat flow and temperature control system composed of the heat splitter 4, the heat collector 5 and the heat flow transfer structure 6 may also adopt a multi-time splitting and converging manner to control the exhaust temperature and optimize the performance of the exhaust aftertreatment system.
The exhaust gas enters the three-way catalyst 3 after passing through the heat collector 5. The exhaust heat flow and temperature control system composed of the heat flow divider 4, the heat flow collector 5 and the heat flow transfer structure 6 controls the adsorption temperature of the HC adsorber 2. Compared with an exhaust heat flow and temperature control system which is not composed of the heat flow divider 4, the heat flow collector 5 and the heat flow transfer structure 6, the exhaust gas passing through the heat flow collector 5 carries more heat, so that the exhaust temperature entering the three-way catalyst 3 is higher, the three-way catalyst 3 can reach the ignition temperature quickly, and the ignition time is shortened.
Example 3
As shown in fig. 1 and fig. 4, the present embodiment provides an HC adsorption system with engine cold start exhaust heat flow and temperature control, which includes an engine 1, an HC adsorber 2, a three-way catalyst 3, a heat splitter 4, a heat sink 5, and a heat flow transfer structure 6; the heat flow divider 4 is arranged on an exhaust pipe 7 between the engine 1 and the HC adsorber 2, the heat flow collector 5 is arranged on the exhaust pipe 7 between the HC adsorber 2 and the three-way catalyst 3, and the heat flow transfer structure 6 is connected with the heat flow divider 4 and the heat flow collector 5. The thermal flow divider 4 is used for dividing exhaust gas heat into the HC adsorber 2 and the heat flow transfer structure 6, and the thermal flow collector 5 is used for merging the exhaust gas heat in the HC adsorber 2 and the heat flow transfer structure 6 into the three-way catalyst 3. The heat shunt 4 and the heat collector 5 are miniature baffle type heat exchangers, and the heat flow transfer structure 6 is a heat pipe.
In the present embodiment, during cold start of the engine 1, the exhaust gas passes through the thermal shunt 4, which functions to shunt the heat of the exhaust gas, neglecting the heat capacity of the thermal shunt 4 itself, and having Φ1＝Фz1+Фr1，Фz1<Ф1The heat amount of exhaust gas Φ z entering the HC adsorber 21The decrease, the rate of rise of the exhaust gas temperature becomes small, enabling the HC adsorber 2 to maintain the adsorption temperature for a sufficiently long time, completing the adsorption of HC in the exhaust gas. Another partial heat amount r1Into the heat flow transfer structure 6 and then to the heat sink 5.
After passing through the heat collector 5, the exhaust gas has the function of collecting the heat of the exhaust gas, namely phi z2+Фr2＝Ф2，Фz2<Ф2Phi greater behind the heat sink2The rate at which the temperature of the exhaust gas entering the three-way catalyst 3 rises can be increased, shortening the light-off time of the three-way catalyst 3.
The heat flow transfer structure 6 has the function of p phi r1And the high-efficiency and quick heat transfer is carried out. Let the exhaust gas temperature at the heated splitter 4 be t1The exhaust gas temperature at the heat collector 5 is t2，t1>t2. Heat loss in the heat transfer process is reduced as much as possible, so that phi r1And phi r2Of substantially equal magnitude, i.e. r1≈Фr2。
The heat diverter 4 is designed as a miniature baffle type heat exchanger with
ΔΦ＝kAΔtm
Then phiz1＝Φ1-ΔΦ
Φr1＝ΔΦ
Large exhaust heat amount z corresponding to this2Along the heat flow transfer structure 6 to the heat sink 5, heatThe flow transfer structure 6 requires a material and a structure having a sufficiently large thermal conductivity in the heat transfer direction compared to the exhaust gas thermal conductivity, and the thermal conductivity in the other directions is close to zero, so that not only can the rapid transfer of heat be ensured, but also the loss of heat can be prevented. I.e. heat is transferred in the direction indicated by the arrow in figure 1, and r1≈Фr2. The heat collector 5 can likewise be designed as a micro baffle heat exchanger.
In this embodiment, the exhaust heat flow and temperature control system composed of the heat splitter 4, the heat collector 5 and the heat flow transfer structure 6 may also adopt a multi-time splitting and converging manner to control the exhaust temperature and optimize the performance of the exhaust aftertreatment system.
The exhaust gas enters the three-way catalyst 3 after passing through the heat collector 5. The exhaust heat flow and temperature control system composed of the heat flow divider 4, the heat flow collector 5 and the heat flow transfer structure 6 controls the adsorption temperature of the HC adsorber 2. Compared with an exhaust heat flow and temperature control system which is not composed of the heat flow divider 4, the heat flow collector 5 and the heat flow transfer structure 6, the exhaust gas passing through the heat flow collector 5 carries more heat, so that the exhaust temperature entering the three-way catalyst 3 is higher, the three-way catalyst 3 can reach the ignition temperature quickly, and the ignition time is shortened.
Example 4
The embodiment provides a method for controlling the exhaust temperature in an exhaust system during the cold start of an engine, which utilizes the HC adsorption system for controlling the heat flow and the temperature of the exhaust gas during the cold start of the engine, and specifically comprises the following steps:
s1: in the cold starting process of the engine 1, the heat of the exhaust enters the HC absorber 2 and the heat flow transfer structure 6 through the heat flow divider 4, and phi1Representing the heat of the exhaust gas before entering the thermal splitter 4, phi z1Denotes the heat quantity of exhaust gas, Φ r, entering the HC adsorber 21Representing the heat of the exhaust gas, phi, entering the heat flow transferring structure 61＝Фz1+Фr1；
S2: the heat of the exhaust gas enters a heat collector 5 after passing through an HC absorber 2 and a heat flow transfer structure 6, and phi z2Showing the heat quantity of exhaust gas entering the heat collector 5 after passing through the HC adsorber 2，Фr2Representing the heat of the exhaust gas entering the heat collector 5 after passing through the heat flow transferring structure 6, phi2Denotes the heat of exhaust gas after passing through the heat collector 5, phi z2+Фr2＝Ф2；
S3: the exhaust heat enters the three-way catalyst 3 after passing through the heat collector 5.
Фz1<Ф1Smaller exhaust heat amount phi z1And the temperature of the HC adsorber 2 is slowed down by entering the HC adsorber 2, so that the adsorption temperature and the adsorption process can be maintained for a long time.
Фz2<Ф2The larger phi after the exhaust gas enters the heat collector 52The rate of rise of the temperature of the exhaust gas entering the three-way catalyst 3 is increased, shortening the light-off time of the three-way catalyst 3.
In the present embodiment, the temperature of the exhaust gas entering the HC adsorber 2, and thus the adsorption process itself, is controlled by exhaust heat diversion. The exhaust heat is divided before the HC adsorber 2, so that the heat entering the HC adsorber 2 during cold start is reduced, the temperature rise rate of the HC adsorber 2 is reduced, and the adsorption temperature can be kept for a long time; the heat of reposition of redundant personnel joins before three-way catalyst converter 3, can increase the heat that gets into three-way catalyst converter 3, increases three-way catalyst converter 3's temperature rise rate, shortens the time of starting combustion.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims (10)

1. An HC adsorption system for controlling heat flow and temperature of exhaust gas of cold start of an engine comprises the engine (1), an HC adsorber (2) and a three-way catalyst (3), and is characterized by further comprising a heat flow divider (4), a heat flow collector (5) and a heat flow transfer structure (6); the heat flow diverter is characterized in that the heat flow diverter (4) is installed on an exhaust pipe (7) between the engine (1) and the HC adsorber (2), the heat flow collector (5) is installed on the exhaust pipe (7) between the HC adsorber (2) and the three-way catalyst (3), and the heat flow transfer structure (6) is connected with the heat flow diverter (4) and the heat flow collector (5).
2. An engine cold start exhaust gas heat flow and temperature controlled HC adsorption system according to claim 1, wherein the thermal splitter (4) is used for splitting exhaust gas heat into the HC adsorber (2) and the heat flow transfer structure (6), and the thermal collector (5) is used for collecting exhaust gas heat in the HC adsorber (2) and the heat flow transfer structure (6) into the three-way catalyst (3).
3. An engine cold start exhaust gas heat flow and temperature controlled HC adsorption system as claimed in claim 1 wherein the thermal splitter (4) and the thermal collector (5) are of high thermal conductivity material, honeycomb structure with high efficiency heat transfer efficiency; the heat flow transfer structure (6) is made of a heat insulation material, and a high-heat-conductivity material is arranged inside the heat flow transfer structure.
4. An engine cold start exhaust gas heat flow and temperature controlled HC adsorption system as claimed in claim 1 wherein the heat diverter (4) and heat sink (5) are micro baffled heat exchangers; the heat flow transfer structure (6) is made of a heat insulation material, and a high-heat-conductivity fluid is arranged in the heat flow transfer structure.
5. The HC adsorption system of engine cold start exhaust heat flow and temperature control according to claim 1, characterized in that the heat diverter (4) and the heat sink (5) are micro baffle heat exchangers, and the heat flow transfer structure (6) is a heat pipe.
6. A method of controlling the temperature of exhaust gas in an exhaust system at cold start of an engine, the method using a hot exhaust gas flow and temperature controlled HC adsorption system of any one of claims 1 to 5, comprising the steps of:
s1: hair-like deviceIn the cold starting process of the engine (1), the heat of the exhaust enters the HC adsorber (2) and the heat flow transfer structure (6) through the heat flow divider (4), and phi is1Denotes the heat of the exhaust gas before entering the thermal splitter (4), phi z1Denotes the heat quantity of exhaust gas entering the HC adsorber (2), phi r1Representing the heat of the exhaust gas entering the heat flow transfer structure (6), phi1＝Фz1+Фr1；
S2: the exhaust heat enters a heat confluence device (5) after passing through an HC absorber (2) and a heat flow transfer structure (6), and phi z2Denotes the amount of heat of exhaust gas, phi r, entering the heat collector (5) after passing through the HC adsorber (2)2Denotes the quantity of exhaust gas heat entering the heat collector (5) after passing through the heat flow transfer structure (6), phi2Denotes the heat of exhaust gas after passing through the heat collector (5), phi z2+Фr2＝Ф2；
S3: the exhaust heat enters the three-way catalyst (3) after passing through the thermal confluence device (5).
7. The HC adsorption system for hot flow and temperature control of exhaust gas for cold start of engine according to claim 6, wherein the thermal splitter (4) has anisotropic thermal conductivity, [ phi ] z1Less than phi r1，
Figure FDA0003182971580000021
Figure FDA0003182971580000022
Thermal conductivity lambdaz1Less than the thermal conductivity lambdar1，
Figure FDA0003182971580000023
Is less than
Figure FDA0003182971580000024
8. An engine cold start exhaust gas heat flow and temperature controlled HC adsorption system as claimed in claim 6 wherein the heat sink (5) is constructed to:
Figure FDA0003182971580000025
in the formula, Bi is a Beaut number, and delta is a structural characteristic length;
in the heat collector (5), the heat is converged to satisfy:
Figure FDA0003182971580000026
wherein the volume of the heat collector (5) is V, the surface area is A, t represents the temperature of the heat collector (5), t∞The temperature of the exhaust gas entering the heat collector (5) is shown, and the heat transfer coefficient of the inner surface of the heat collector (5) is h.
9. A method of controlling the temperature of exhaust gases in an exhaust system at cold start of an engine according to claim 6, where Φ z1<Ф1Smaller exhaust heat amount phi z1Enters the HC adsorber (2) to slow the temperature rise rate of the HC adsorber (2), so as to keep the adsorption temperature and the adsorption process for a long enough time.
10. A method of controlling the temperature of exhaust gases in an exhaust system at cold start of an engine according to claim 6, where Φ z2<Ф2After the exhaust heat enters the heat collector (5), the larger phi is2The rate of rise of the temperature of the exhaust gas entering the three-way catalyst (3) is increased, and the light-off time of the three-way catalyst (3) is shortened.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1031708A1 (en) * 1999-02-25 2000-08-30 HEINRICH GILLET GMBH &amp; CO. KG Module for an exhaust gas system
JP2004162626A (en) * 2002-11-14 2004-06-10 Hitachi Ltd Exhaust emission control device
CN101737131A (en) * 2008-11-11 2010-06-16 通用汽车环球科技运作公司 Catalytic combustor strategy using hc adsorber
CN102322319A (en) * 2011-07-13 2012-01-18 湖南大学 HC (hydrocarbon compound) emission purifying system used for cold boot working condition of gasoline engine
CN105443202A (en) * 2014-09-23 2016-03-30 福特环球技术公司 Method of controlling NOx by PNA

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1031708A1 (en) * 1999-02-25 2000-08-30 HEINRICH GILLET GMBH &amp; CO. KG Module for an exhaust gas system
JP2004162626A (en) * 2002-11-14 2004-06-10 Hitachi Ltd Exhaust emission control device
CN101737131A (en) * 2008-11-11 2010-06-16 通用汽车环球科技运作公司 Catalytic combustor strategy using hc adsorber
CN102322319A (en) * 2011-07-13 2012-01-18 湖南大学 HC (hydrocarbon compound) emission purifying system used for cold boot working condition of gasoline engine
CN105443202A (en) * 2014-09-23 2016-03-30 福特环球技术公司 Method of controlling NOx by PNA

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