Systems and methods for ultra-low NOx cold start warmup control and fault diagnosis
Systems and apparatuses include an aftertreatment system including a catalyst, and a controller coupled to the aftertreatment system. During a warmup period for an engine coupled to the catalyst, the controller is configured to determine a value of a catalyst heating metric indicative of an amount of emissions produced per unit of exhaust energy based on information received from the engine and the aftertreatment system, and control at least one of a turbocharger, a fuel injection system, or an Exhaust Gas Recirculation (EGR) system to reach a target value of the catalyst heating metric.
1. A system, comprising:
an aftertreatment system including a catalyst; and
a controller coupled to the aftertreatment system, wherein during a warmup period for an engine coupled to the catalyst, the controller is configured to:
determine a value of a catalyst heating metric indicative of an amount of emissions produced per unit of exhaust energy based on information received from the engine and the aftertreatment system;
receive a target value of the catalyst heating metric;
compare the value of the catalyst heating metric to the target value of the catalyst heating metric; and
control at least one of a turbocharger, a fuel injection system, or an Exhaust Gas Recirculation (EGR) system to reach the target value of the catalyst heating metric based on the comparison.
2. The system of claim 1 , wherein the warmup period is defined as a period of time from a start of the engine for the catalyst to reach a predefined operating efficiency.
3. The system of claim 1 , wherein the catalyst is at least one of a selective catalytic reduction (SCR) catalyst, a diesel oxidation catalyst (DOC), or a three-way catalyst.
4. The system of claim 2 , wherein the predefined operating efficiency includes an emission conversion efficiency for the catalyst that is at or above a predefined threshold.
5. The system of claim 2 , wherein the predefined operating efficiency is based on at least one of a temperature of the catalyst, a drive cycle of the engine, a load on the engine, and an age of the catalyst.
6. The system of claim 1 , wherein the catalyst heating metric is calculated using the following formula:
∫
0
t
*
K
*
EOE
*
m
.
E
x
h
dt
∫
0
t
*
m
.
E
x
h
*
C
p
*
T
Exh
dt
where the amount of emission is associated with f 0 t* K * E 0 E * m Exh dt and the exhaust energy is associated with f 0 t* m Exh * C p * T Exh dt, where t* is a period of time, K is a physical constant, EOE is an amount of emissions being produced by the engine, m Exh is a mass flow rate of exhaust being produced by the engine, C p is a constant denoting a heat capacity of exhaust at a certain pressure and T Exh is a temperature of exhaust entering the aftertreatment system.
7. The system of claim 6 , wherein the target value of the catalyst heating metric is based on at least one of a minimum possible value at a particular instant in time during the warmup period for the engine, a minimum possible value over the warmup period for the engine, or on achieving a desired conversion efficiency of the catalyst.
8. A system comprising:
an aftertreatment system, the aftertreatment system including a catalyst; and
a controller coupled to the aftertreatment system, wherein during a warmup period for an engine coupled to the catalyst, the controller is configured to:
determine a value of a catalyst heating metric indicative of an amount of emissions produced per unit of exhaust energy based on information received from the engine and the aftertreatment system;
determine a reference value based on information regarding a current status of the engine and the aftertreatment system;
compare the value of the catalyst heating metric to the reference value; and
diagnose a malfunction in the aftertreatment system in response to determining that the catalyst heating metric exceeds the reference value.
9. The system of claim 8 , wherein the catalyst is at least one of a selective catalytic reduction (SCR) catalyst, a diesel oxidation catalyst (DOC), or a three-way catalyst.
10. The system of claim 8 , wherein the warmup period is defined as a period of time from a start of the engine for the catalyst to reach a predefined operating efficiency.
11. The system of claim 8 , wherein the current status of the engine and the aftertreatment system is based on at least one of a drive cycle of the engine, a load of the engine, and an age of the catalyst.
12. The system of claim 8 , wherein the controller is further configured to take a corrective action in response to the diagnosis of the malfunction, the corrective action comprising at least one of initiating a de-rate of the engine, notifying an operator of the malfunction, and activating an electric heater in the aftertreatment system.
13. The system of claim 8 , wherein the catalyst heating metric is calculated using the following formula:
∫
0
t
*
K
*
EOE
*
m
.
E
x
h
dt
∫
0
t
*
m
.
E
x
h
*
C
p
*
T
Exh
dt
where the amount of emission is associated with f 0 t* K * E 0 E * m Exh dt and the exhaust energy is associated with f 0 t* m Exh * C p * T Exh dt, where t* is a period of time, K is a physical constant, EOE is an amount of emissions being produced by the engine, m Exh is a mass flow rate of exhaust being produced by the engine, C p is a constant denoting a heat capacity of exhaust at a certain pressure and T Exh is a temperature of exhaust entering the aftertreatment system.
14. A method for balancing emissions from an engine and heating a catalyst in an aftertreatment system, the method comprising:
during a warmup period for the engine, determining a value of a catalyst heating metric indicative of an amount of emissions produced per unit of exhaust energy based on information received from the engine and the aftertreatment system;
receiving a target value of the catalyst heating metric;
comparing the value of the catalyst heating metric to the target value of the catalyst heating metric; and
controlling at least one of a turbocharger, a fuel injection system, or an Exhaust Gas Recirculation (EGR) system to affect combustion within the engine in order to reach the target value of the catalyst heating metric based on the comparison.
15. The method of claim 14 , wherein the catalyst is at least one of a selective catalytic reduction (SCR) catalyst, a diesel oxidation catalyst (DOC), or a three-way catalyst.
16. The method of claim 14 , wherein the warmup period is defined as a period of time from a start of the engine for the catalyst to reach a predefined operating efficiency, wherein the predefined operating efficiency is based on a temperature of the catalyst.
17. The method of claim 16 , wherein the predefined operating efficiency includes an emissions conversion efficiency for the catalyst that is at or above a predefined threshold.
18. The method of claim 14 , wherein the catalyst heating metric is calculated using the following formula:
∫
0
t
*
K
*
EOE
*
m
.
E
x
h
dt
∫
0
t
*
m
.
E
x
h
*
C
p
*
T
Exh
dt
where the amount of emission is associated with f 0 t* K * E 0 E * m Exh dt and the exhaust energy is associated with f 0 t* m Exh * C p * T Exh dt, where t* is a period of time, K is a physical constant, EOE is an amount of emissions being produced by the engine, m Exh is a mass flow rate of exhaust being produced by the engine, C p is a constant denoting a heat capacity of exhaust at a certain pressure and T Exh is a temperature of exhaust entering the aftertreatment system.
19. The method of claim 18 , wherein the target value of the catalyst heating metric is based on at least one of a minimum possible value at an instant in time during a warmup period for the engine, a minimum possible value over an entire warmup period, or achieving a desired temperature of a catalyst in the aftertreatment system.
20. The method of claim 14 , further comprising:
determining a reference value based on information regarding a current status of the engine and the aftertreatment system;
comparing the value of the catalyst heating metric to the reference value; and
diagnosing a malfunction in the aftertreatment system in response in response to determining that the catalyst heating metric exceeds the reference value.