Self ignition operation of alternative fuel internal combustion engines

A method of switching to operating a self ignition internal combustion engine with a low cetane fuel, the method comprising:

• operating the internal combustion engine with a crude oil based fuel and respective settings for cooling and injection timing;
• switching to and operating the internal combustion engine with a switch over fuel and respective settings for cooling and injection timing, until the internal combustion engine is cleaned from crude oil based fuel residue;
• and then
• switching to and operating the internal combustion engine with the low cetane fuel by:
• providing the internal combustion engine with a compression ratio of at least 17:1;
• loading a combustion chamber of the internal combustion engine with charge air having a minimal temperature in the range of 340 degrees K to 360 degrees K;
• injecting the low cetane fuel at an injection angle of a piston of the internal combustion engine within the range of 20° to 10° before to dead center into the charge air, thereby forming a low cetane fuel-charge air mixture;
• and
• compressing the low cetane fuel-charge air mixture further to reach a compression end temperature of at least 1000 degrees K, thereby allowing self ignition of the low cetane fuel.

A self-ignition internal combustion engine for operation with a low cetane fuel, the self-ignition internal combustion engine comprising:

• a cylinder unit with a piston delimiting a combustion chamber that, during an operation cycle of the piston, is reduced in size by a compression ratio of at least 17:1;
• an air system configured for loading the combustion chamber with charge air having a minimal temperature of at least 350 degrees K;
• and
• an injection system configured for injecting the low cetane fuel at an injection angle of the piston within the range of 20° to 10° before top dead center, thereby forming a low cetane fuel-charge air mixture within the combustion chamber,
• wherein, during operation of the self-ignition internal combustion engine, a self-ignition compression end temperature of at least 1000 degrees K for the low cetane fuel-charge air mixture is provided.

An internal combustion engine system comprising:

• a self-ignition internal combustion engine for operation with a low cetane fuel, the self-ignition internal combustion engine comprising:
• a cylinder unit with a piston delimiting a combustion chamber that, during an operation cycle of the piston, is reduced in size by a compression ratio of at least 17:1;
• an air system configured for loading the combustion chamber with charge air having a minimal temperature of at least 350 degrees K;
• and
• an injection system configured for injecting the low cetane fuel at an injection angle of the piston within the range of 20° to 10° before to dead center, thereby forming a low cetane fuel-charge air mixture within the combustion chamber,
• wherein, during operation of the self-ignition internal combustion engine, a self-ignition compression end temperature of at least 1000 degrees K for the low cetane fuel-charge air mixture is provided;
• and further comprising a low temperature cooling system with a coolant operated in a temperature range between 280 degrees K and 330 degrees K and a low temperature cooler for cooling pre-compressed charge air;
• an external fuel system comprising tanks for crude oil based fuels and alternative fuels and an external fuel system for supplying one or more selected ones of the fuels to the self-ignition internal combustion engine;
• and
• a control system for controlling a switching process between crude oil based fuel operation and alternative fuel operation during continuous operation of the self-ignition internal combustion engine on crude oil based fuels and alternative fuels, the control system comprising a control unit configured to control, during alternative fuel operation, cooling to be performed using a high temperature cooler, thereby cooling compressed charge air to a minimal temperature in the range of 340 degrees K to 360 degrees K, and, during fossil fuel operation, cooling to be performed using the high temperature cooler and the low temperature cooler, thereby cooling the compressed charge air to a minimal temperature in the range of 320 degrees K to 340 degrees K.