Active hydrocarbon trap for reduction of emissions from internal combustion engines using an electrically-heated catalyst
A device for reducing emissions from an internal combustion engine having a close-coupled catalyst including an electrically-heated catalyst and a hydrocarbon trap disposed downstream of the close-coupled catalyst. The device includes a heat exchanger and a liquid water knockout disposed downstream of the close-coupled catalyst. The device includes a valve-less system configured to dynamically adjust a flow path of exhaust from the internal combustion engine through the electrically-heated catalyst and the hydrocarbon trap to reduce emissions. A method for reducing emissions including feeding an exhaust gas from the internal combustion engine to the close-coupled catalyst, producing a catalyzed exhaust gas. The method includes flowing the catalyzed exhaust gas from the close-coupled catalyst to the valve-less system.
1. A device for reducing emissions from an internal combustion engine including a close-coupled catalyst, the device comprising:
a hydrocarbon trap disposed downstream of the close-coupled catalyst;
an electrically-heated catalyst disposed downstream of the hydrocarbon trap, the electrically-heated catalyst including at least one electrical heating element which is controlled so as to reduce emissions in conjunction with the hydrocarbon trap;
a heat exchanger disposed downstream of the close-coupled catalyst, the heat exchanger configured to heat exhaust gas of the internal combustion engine via an ambient air stream; and
a liquid water knockout disposed downstream of the close-coupled catalyst.
2. The device of claim 1 , further comprising:
a first flow line extending from the close-coupled catalyst to the hydrocarbon trap;
a second flow line extending from the hydrocarbon trap to the electrically-heated catalyst; and
a third flow line extending from the electrically-heated catalyst to an ambient environment.
3. The device of claim 1 , wherein the at least one electrical heating element is activated via a power source during a first period of time corresponding to a cold engine condition.
4. The device of claim 3 , wherein the at least one electrical heating element is deactivated during a second period of time corresponding to a warm engine condition.
5. The device of claim 1 , wherein the electrically-heated catalyst is separate from the hydrocarbon trap.
6. The device of claim 1 , wherein the heat exchanger is configured to alternately operate in a heating mode and a cooling mode.
7. The device of claim 1 , wherein the hydrocarbon trap contains a sorbent material, further comprising a zeolite or activated carbon.
8. The device of claim 7 , wherein the sorbent material is pelletized or wash-coated onto a honeycomb-like structure of the hydrocarbon trap.
9. A method for reducing emissions from an internal combustion engine including a close-coupled catalyst and the device of claim 2 , the method comprising:
feeding the exhaust gas from the internal combustion engine through the close-coupled catalyst so as to produce a catalyzed exhaust gas;
flowing the catalyzed exhaust gas from the close-coupled catalyst through the hydrocarbon trap so as to produce a hydrocarbon trap effluent; and
heating the hydrocarbon trap effluent in the heat exchanger via the ambient air stream so as to produce a heated hydrocarbon trap effluent.
10. The method of claim 9 , further comprising:
during a first period of time corresponding to a cold engine condition:
activating the electrically-heated catalyst;
flowing the heated hydrocarbon trap effluent through the activated electrically-heated catalyst so as to produce an activated electrically-heated catalyst effluent; and
ejecting the activated electrically-heated catalyst effluent from the activated electrically-heated catalyst to the ambient environment.
11. The method of claim 10 , wherein the cold engine condition corresponds to an exhaust gas temperature less than 350° C.
12. The method of claim 10 , wherein a temperature of the exhaust gas has is less than 350° C. during the first period of time.
13. The method of claim 10 , wherein a temperature of the hydrocarbon trap effluent received by the heat exchanger during the first period of time is less than 350° C.
14. The method of claim 9 , further comprising:
during a second period of time corresponding to a warm engine condition:
deactivating the electrically-heated catalyst;
flowing the heated hydrocarbon trap effluent through the deactivated electrically-heated catalyst so as to produce a deactivated electrically-heated catalyst effluent; and
ejecting the deactivated electrically-heated catalyst effluent from the deactivated electrically-heated catalyst to the ambient environment.
15. The method of claim 14 , wherein the warm engine condition corresponds to an exhaust gas temperature greater than 350° C.
16. The method of claim 14 , wherein a temperature of the exhaust gas is greater than 350° C. during the second period of time.
17. The method of claim 14 , wherein a temperature of the hydrocarbon trap effluent received by the heat exchanger during the second period of time is greater than 350° C.