Analise of selected systems cng supply of city buses engine

This paper presents analyze of selected solutions of compressed natural gas (CNG) supply systems in powering the bus. They are shown solutions of supply with normal inhaust pressure and with turbocharger using. Modern CNG supply systems are equip by computer systems for bus and engine process control. The major reason of CNG usage is an environmental aspect of the engine operation, since the CNG powered engines are much more environment friendly than the Diesel ones, which are widely used at the moment in such application as bus communication. The CNG combustion produces much less NOx and CO emissions and enables to comply EURO II and EURO III requirements. The major benefit of the CNG application in the city transportation is a reduction of air contamination within the city borders (and outside). Another advantage is the fact that natural gas is less expensive than diesel oil, which makes its application more economical.