Introduction to Fuel Systems Aims and Objectives Aim

Introduction to Fuel Systems Aims and Objectives Aim • To be able to recognize the main components within a basic engine fueling system and its function within an internal combustion engine Objectives • • Recognize the main components within an engine’s fueling system Be able to identify the correct air and fuel ratio for an internal combustion engine Be able to list the main components within an engine’s fueling system To list the main differences between diesel and petrol fueling systems

Introduction to Fuel Systems Introduction to fuels Petrol and Diesel are fuels that are particularly suitable for use in internal combustion engines Fuel is mixed with air and introduced into the engines cylinder in order to be burnt within the engines Otto cycle

Introduction to Fuel Systems Mixture strength “The mixture strength is the proportion of air that is mixed with the fuel required to produced the engine’s power” Hiller’s Fundamentals of Motor Vehicle Technology 5 th ed. V. A. W Hiller and Peter Coombes The ideal mixture for a petrol internal combustion engine is 14. 7: 1 (14. 7 air to 1 g fuel)

Introduction to Fuel Systems Ideal, rich and lean 14. 7: 1 (14. 7 air to 1 g fuel) =ideal (stoichmetric ratio) 10: 1 = rich mixture (more fuel than air) 20: 1 = lean mixture (more air than fuel)

Introduction to Fuel Systems Question What is stoichmetric ratio ? And what is the ideal fuel to air mixture for a petrol engine ?

Introduction to Fuel Systems Exhaust gas emissions If the engine burns the chemical correct mixture the following gases are produced: CO 2 H 2 O N 2 As an engine will never be 100% efficient harmful gases are produced CO, HC. O 2 and NOx A richer mixture produces more CO which is harmful for the environment ( produces a sooty black exhaust gas ) A technician can analyse the vehicles exhaust gases using an exhaust gas analyser

Introduction to Fuel Systems Vaporization and Atomization Vaporization It is important to remember that petrol burns in vapour form so it must be like this before it enters the cylinder Diesel, however must be subjected to heat and compression for it to burn Atomization Helps brake the fuel into vapour form before it goes into the cylinder This is achieved by either subjecting it to turbulent airflow or by pumping the fuel through holes in an injector before it goes into the main air stream of the cylinder

Introduction to Fuel Systems The main fuelling components Carburettor or injectors Fuel tank Fuel lines Fuel gauge Fuel filter

Introduction to Fuel Systems The difference between Petrol and Diesel Petrol is lighter Diesel oil is heavier More volatile Less volatile Contains hydrocarbons with around 8 carbon atoms per molecule Greater lubrication qualities, contains hydrocarbons with around 10 carbon atoms per molecule A petrol engine is a spark-ignition engine Utilises a spark to ignite the volatile petrol/air mixture A diesel engine is a compression-ignition engine Utilises high compression to create the high temperatures in which diesel oil will burn

Introduction to Fuel Systems Question Can you list the main differences between diesel and petrol ?

Introduction to Fuel Systems Summary – Have we ? Recognized the main components within an engine’s fueling system ? Been able to identify the correct air and fuel ratio for an internal combustion engine ? Been able to list the main components within an engine’s fueling system ? Listed the main differences between diesel and petrol fueling systems ?

Introduction to Fuel Systems Any questions ?