INTAKE TEMPERATURE MANAGEMENT SYSTEMS FOR COMPRESSION IGNITION OF SMALL MOLECULE FUELS
Embodiments described herein relate to systems and methods of managing intake temperature of intake gases in internal combustion engines to enable autoignition of small-molecule low-cetane fuels. In some aspects, a method of operating a compression ignition engine can include moving a volume of air through a first flow path, closing a first valve to prevent the volume of air from entering a charge air cooler (CAC), opening a second valve to guide the volume of air to a second flow path, the second flow path including a heating unit, and moving the volume of air to an intake manifold. In some embodiments, the method can further include applying heat via the heating unit to the volume of air while the volume of air moves through the second flow path.
1 . A method of operating a compression ignition engine on small-molecule fuels, the method comprising:
moving a volume of air through a first flow path;
closing a first valve to restrict the volume air from entering a charge air cooler;
opening a second valve to guide all or part of the volume of air to a second flow path, the first flow path and/or the second flow path including a heating unit; and
moving the volume of air to an intake manifold.
2 . The method of claim 1 , further comprising:
applying heat via the heating unit to the volume of air while the volume of air moves through the second flow path.
3 . The method of claim 1 , further comprising:
merging the volume of air in the first flow path and the volume of air in the second flow path in a common flow path;
applying heat via the heating unit to the common flow path.
4 . The method of claim 1 , further comprising:
moving the exhaust gas through a turbocharger turbine to compress the volume of air.
5 . The method of claim 1 , further comprising:
moving the volume of air into a plurality of cylinders via the intake manifold; and
combusting a small-molecule fuel in the plurality of cylinders while the volume of air is inside the plurality of cylinders to form a volume of combustion product.
6 . The method of claim 5 , further comprising:
retaining the combustion product in the plurality of cylinders for a time period sufficient to raise a temperature of the combustion product to a temperature of at least about 300° C.
7 . The method of claim 5 , further comprising: recirculating exhaust gas from one or more cylinders from the plurality of cylinders back to at least one of the first flow path or the second flow path without flowing the exhaust gas through an exhaust gas recirculation (EGR) cooler based on threshold temperatures for exhaust gas and intake valve closing.
8 . The method of claim 5 , further comprising:
deactivating at least one cylinder of the plurality of cylinders, the deactivating including closing an intake valve, an exhaust valve, and discontinuing injection of fuel into the at least one cylinder.
9 . The method of claim 5 , further comprising:
increasing a load on the plurality of cylinders to increase a temperature within each of the cylinders.
10 . The method of claim 9 , wherein increasing the load on the plurality of cylinders increases the temperature within each of the cylinders at intake valve closing.
11 . The method of claim 5 , further comprising:
measuring a temperature of the volume of air as the volume of air enters the plurality of cylinders.
12 . The method of claim 5 , further comprising:
measuring a temperature of the volume of air at intake valve closing.
13 . The method of claim 11 , further comprising:
directing exhaust gas from the hottest cylinder from the plurality of cylinders to the intake manifold via an exhaust manifold.
14 . The method of claim 1 , further comprising:
moving the volume of air into a first cylinder from a plurality of cylinders while keeping the remaining cylinders from the plurality of cylinders in a deactivated state.
15 . The method of claim 14 , further comprising:
after the exhaust gas has reached a threshold temperature, activating the remaining cylinders from the plurality of cylinders.
16 . The method of claim 1 , further comprising:
opening an EGR valve;
substantially closing or restricting an exhaust passage; and
recirculating the volume of air without injecting fuel until the volume of air has reached a threshold temperature.
17 . An engine, comprising
a first flow path;
a charge air cooler;
a first valve configured to allow, block, or restrict flow through a passage between the first flow path and an inlet of the charge air cooler;
a second flow path;
a second valve configured to allow, block, or restrict flow through a passage between the first flow path and the second flow path;
a third flow path configured to route flow from at least one of the first flow path or the second flow path to an intake manifold;
a plurality of cylinders;
an EGR valve configured to allow, block, or restrict flow through an exhaust path between the exhaust of the cylinders and the third flow path;
an intake manifold fluidically coupling the plurality of cylinders and the third flow path; and
a heating unit disposed at a location along at least one of the second flow path or the third flow path.
18 . The engine of claim 17 , further comprising:
a first EGR path including an EGR cooler, a second EGR path absent of an EGR cooler, and one or more valves configured to adjust the total amount of exhaust routed to the third flow path and the fraction of EGR that is cooled or uncooled.
19 . The engine of claim 18 , further comprising:
a temperature measurement device.
20 . The engine of claim 19 , wherein the temperature measurement device measures at least one of an intake manifold temperature in one or more of the cylinders, a temperature in a cylinder from the plurality of cylinders at intake valve closing, the first valve, the second valve, or the EGR valve to modulate cooling of air and/or exhaust to achieve a target temperature.
21 .- 25 . (canceled)