Emission control related systems
Due to strict emission legislation, the engines manufacturers must use emission control systems that make exhaust gases and particles more safe to environment.
Most common for that is EGR - Exhaust Gas Recirculation. This recirculates part of exhaust gases back to intake an thus the combustion temperature is lower. The lower the temperature is, the less NOx (nitrogen oxides) the engine produces. EGR system can be internal or external.
Internal system is much cheaper and doesen't require any maintenance. Internal system is just an extra bump on camshaft, that slightly opens intake valve on exhaust stroke and this lets some of exhaust gas back to the intake manifold and this is used to mix with air on next intake stroke.
External EGR has a pipe that connects exhaust and intake and an electrically operated valve. Engine ECU can adjust the gas amount that goes to recirculation depending on drive and load, temperature, throttle pedal position etc. External EGR systems are prone to fail because particles and soot clog the recirculation pipe and valve. Also, external EGR is more expensive to fit in the factory, making tractor price higher.
Another way to control emissions is adding an SCR (Selective Catalytic Reduction) system. This is an aftertreatment system that injects a diesel emissions reducing agent, AdBlue/DEF, into exhaust pipe in order to convert the nitrous oxide (NOx) into a harmless mixture of nitrogen and
water vapour. AdBlue is a colourless fluid containing urea and distilled water. There is 32,5% of urea in AdBlue/DEF. It is not hazardous liquid, as other nitrogen products, such as fertilisers and it can be washed off with water. AdBlue/DEF freezes at -11 degrees celsius. The SCR system includes AdBlue/DEF tank, an injector, a dosing module, sensors and a catalyst. This system is automatically operated by engine control module and driver only needs to fill up the tank when necessary. To avoid freezing of AdBlue/DEF in cold conditions, heating is fitted to the tank and lines. Heating is usually combined of electrical and engine coolant. The AdBlue/DEF consumption can vary depending on engine load, but it is usually less than 10% of fuel consumption. Exhaust gas coming from engine contains NH3 and NOx that is converted to N2 and H20.
Most common for that is EGR - Exhaust Gas Recirculation. This recirculates part of exhaust gases back to intake an thus the combustion temperature is lower. The lower the temperature is, the less NOx (nitrogen oxides) the engine produces. EGR system can be internal or external.
Internal system is much cheaper and doesen't require any maintenance. Internal system is just an extra bump on camshaft, that slightly opens intake valve on exhaust stroke and this lets some of exhaust gas back to the intake manifold and this is used to mix with air on next intake stroke.
External EGR has a pipe that connects exhaust and intake and an electrically operated valve. Engine ECU can adjust the gas amount that goes to recirculation depending on drive and load, temperature, throttle pedal position etc. External EGR systems are prone to fail because particles and soot clog the recirculation pipe and valve. Also, external EGR is more expensive to fit in the factory, making tractor price higher.
Another way to control emissions is adding an SCR (Selective Catalytic Reduction) system. This is an aftertreatment system that injects a diesel emissions reducing agent, AdBlue/DEF, into exhaust pipe in order to convert the nitrous oxide (NOx) into a harmless mixture of nitrogen and
water vapour. AdBlue is a colourless fluid containing urea and distilled water. There is 32,5% of urea in AdBlue/DEF. It is not hazardous liquid, as other nitrogen products, such as fertilisers and it can be washed off with water. AdBlue/DEF freezes at -11 degrees celsius. The SCR system includes AdBlue/DEF tank, an injector, a dosing module, sensors and a catalyst. This system is automatically operated by engine control module and driver only needs to fill up the tank when necessary. To avoid freezing of AdBlue/DEF in cold conditions, heating is fitted to the tank and lines. Heating is usually combined of electrical and engine coolant. The AdBlue/DEF consumption can vary depending on engine load, but it is usually less than 10% of fuel consumption. Exhaust gas coming from engine contains NH3 and NOx that is converted to N2 and H20.