Cold start for high-octane fuels in a diesel engine architecture

Abstract

Embodiments disclosed herein relate generally to systems and methods of operating internal combustion (IC) engines, and more specifically to systems and methods of starting compression ignition (CI) engines when the surrounding environment is significantly colder than the normal operating temperature of the engine (i.e., “cold-starting”). In some embodiments, the CI engine can include an ignition-assist device. In some embodiments, a method of operating a CI engine during cold-start can include opening an intake valve to draw a volume of air into the combustion chamber, moving a piston from a bottom-dead-center position to a top-dead-center position in a combustion chamber at a compression ratio of between about 15 and about 25, injecting a volume of fuel, the fuel having a cetane number of less than about 30, closing the intake valve, and combusting substantially all of the volume of fuel.

1 - 43 . (canceled) 
     
     
         44 . A method of operating a compression ignition engine, the compression ignition engine including an engine cylinder having an inner surface, a head surface, a piston disposed and configured to move in the engine cylinder, an intake valve, an exhaust valve, and an ignition-assist device, the inner surface of the engine cylinder, the piston, the head surface, the intake valve, and the exhaust valve defining a combustion chamber, the piston and the head surface defining a bowl region of the combustion chamber, the method comprising the steps of:
 opening the intake valve to draw a volume of air into the combustion chamber, the volume of air having a mass-average temperature of less than about 150° C. at the moment the volume of air passes through the intake valve;   moving the piston from a bottom-dead-center (BDC) position to a top-dead-center (TDC) position in the combustion chamber at a compression ratio of between about 15 and about 25;   injecting a volume of fuel at an engine crank angle between 0 and 360 degrees, the fuel having a cetane number of less than about 30, the volume of fuel and the volume of air forming an air-fuel mix;   closing the intake valve; and   combusting substantially all of the volume of fuel.   
     
     
         45 . The method of  claim 44 , wherein the ignition-assist device includes a glow plug, a spark plug, and/or a plasma-ignition device. 
     
     
         46 . The method of  claim 44 , wherein closing the intake valve is at a first engine crank angle during a first engine cycle, the method further comprising:
 closing the intake valve at a second engine crank angle during a second engine cycle, the second engine crank angle more than 40 engine crank angle degrees earlier or more than 40 engine crank angle degrees later than the first engine crank angle, the second engine cycle occurring later than the first engine cycle.   
     
     
         47 . The method of  claim 46 , further comprising:
 operating the compression ignition engine for a time period such that the air-fuel mix has a mass-average temperature of greater than about 400° C. at an engine crank angle of 330 degrees.   
     
     
         48 . The method of  claim 47 , wherein closing the exhaust valve is at a first engine crank angle during a first engine cycle, the method further comprising:
 closing the exhaust valve at a second engine crank angle during a second engine cycle, the second engine crank angle more than 40 engine crank angle degrees earlier or more than 40 engine crank angle degrees later than the first engine crank angle, the second engine cycle occurring later than the first engine cycle.   
     
     
         49 . The method of  claim 48 , further comprising:
 operating the internal combustion engine for a time period such that the air-fuel mix has a mass-average temperature of greater than about 500° C. at an engine crank angle of 330 degrees.   
     
     
         50 . The method of  claim 49 , further comprising:
 closing the intake valve at an engine crank angle between 175 and 255 degrees.   
     
     
         51 . The method of  claim 44 , further comprising:
 recirculating a portion of exhaust from the exhaust valve to the combustion chamber via the intake valve.   
     
     
         52 . The method of  claim 44 , wherein the ignition-assist device is located in the bowl region of the combustion chamber. 
     
     
         53 . The method of  claim 44 , wherein injecting the volume of fuel is at an injection pressure of at least about 1,000 bar, and wherein the compression ignition engine further comprises a turbocharger, a supercharger and/or a turbo-compounding device, the method further comprising:
 passing the volume of air through the turbocharger, the supercharger, and/or the turbo-compounding device prior to drawing the volume of air into the combustion chamber.   
     
     
         54 . The method of  claim 44 , further comprising:
 operating the internal combustion engine for a time period such that the air-fuel mix has a mass-average temperature of greater than about 500° C. at an engine crank angle of 330 degrees.   
     
     
         55 . The method of  claim 54 , further comprising:
 closing the intake valve at an engine crank angle between 175 and 255 degrees.   
     
     
         56 . A method of operating a compression ignition engine during cold-start, the compression ignition engine including an engine cylinder having an inner surface, a head surface, a piston disposed and configured to move in the engine cylinder, an intake valve, an exhaust valve, and an ignition-assist device, the inner surface of the engine cylinder, the piston, the head surface, the intake valve, and the exhaust valve defining a combustion chamber, the compression ignition engine further comprising a turbocharger, a supercharger and/or a turbo-compounding device, the method comprising the steps of:
 passing a volume of air through the turbocharger, the supercharger and/or the turbo-compounding device;   opening the intake valve to draw the volume of air into the combustion chamber;   moving the piston from a bottom-dead-center (BDC) position to a top-dead-center (TDC) position in the combustion chamber at a compression ratio of between about 15 and about 25;   injecting no more than about 25% of a volume of fuel into the combustion chamber while the intake valve is open, the fuel having a cetane number of less than about 30;   closing the intake valve;   injecting at least about 75% of the volume of fuel into the combustion chamber at an injection pressure of at least about 1,000 bar while the intake valve is closed, the volume of fuel and the volume of air forming a fuel-air mix;   igniting a portion of the volume of fuel; and   combusting substantially all of the volume of fuel.   
     
     
         57 . The method of  claim 56 , wherein the volume of air has a mass-average temperature of less than about 150° C. at the moment the volume of air passes through the intake valve. 
     
     
         58 . The method of  claim 56 , wherein the ignition-assist device includes a glow plug, and/or a cartridge heater. 
     
     
         59 . The method of  claim 56 , wherein the ignition-assist device contacts a portion of the volume of fuel. 
     
     
         60 . The method of  claim 56 , wherein the ignition-assist device includes a glow plug, a spark plug, and/or a plasma-ignition device. 
     
     
         61 . The method of  claim 60 , wherein the ignition-assist device is located in the combustion chamber. 
     
     
         62 . The method of  claim 61 , wherein the ignition-assist device is located in the combustion chamber bowl region 
     
     
         63 . The method of  claim 56 , wherein the fuel has a cetane number of less than about 10. 
     
     
         64 . The method of  claim 56 , further comprising:
 restricting at least a portion of a volume of exhaust from exiting the combustion chamber.   
     
     
         65 . A method of operating a compression ignition engine, the compression ignition engine including an engine cylinder having an inner surface, a head surface, a piston disposed and configured to move in the engine cylinder, an intake valve, an exhaust valve, and an ignition-assist device, the inner surface of the engine cylinder, the piston, the head surface, the intake valve, and the exhaust valve defining a combustion chamber, the method comprising the steps of:
 opening the intake valve during a first time period to draw a volume of air into the combustion chamber, the volume of air having a mass-average temperature of less than about 150° C. at the moment the volume of air passes through the intake valve;   moving the piston from a bottom-dead-center (BDC) position to a top-dead-center (TDC) position in the combustion chamber at a compression ratio of between about 15 and about 25;   injecting a volume of fuel into the combustion chamber, the fuel having a cetane number of less than about 20, the volume of fuel and the volume of air forming an air-fuel mix;   closing the intake valve; and   combusting substantially all of the volume of fuel,   wherein at least about 20% of the volume of fuel is pre-mixed with the volume of air immediately prior to ignition.   
     
     
         66 . The method of  claim 65 , wherein the ignition-assist device is located in a bowl region of the combustion chamber. 
     
     
         67 . The method of  claim 65 , wherein the ignition-assist device includes a glow plug, a spark plug, a plasma ignition device, and/or a cartridge heater. 
     
     
         68 . The method of  claim 65 , wherein at least about 50% of the volume of fuel is pre-mixed with the volume of air immediately prior to ignition. 
     
     
         69 . The method of  claim 65 , wherein closing the intake valve during the first time period is at an engine crank angle between 175 and 255 degrees, further comprising:
 closing the intake valve at an engine crank angle less than 175 or greater than 255 degrees during a second time period to draw air into the combustion chamber.   
     
     
         70 . The method of  claim 69 , further comprising:
 closing the intake valve at an engine crank angle between about 175 and about 255 degrees during a third time period.   
     
     
         71 . The method of  claim 65 , wherein the fuel has a cetane number of less than about  10 . 
     
     
         72 . The method of  claim 65 , wherein injecting the volume of fuel is at an injection pressure of at least about 1,000 bar, and wherein the compression ignition engine further comprises a turbocharger, a supercharger, and/or a turbo-compounding device , the method further comprising:
 passing the volume of air through the turbocharger, the supercharger, and/or turbo-compounding device prior to drawing the volume of air into the combustion chamber.   
     
     
         73 . The method of  claim 72 , further comprising:
 restricting at least a portion of a volume of exhaust from exiting the combustion chamber.