Effects of injection temperature and pressure on combustion in an existing otto engine using CNG fuel

Changes in temperature and pressure influence the operational conditions of motor vehicles using Compressed Natural Gas (CNG) fuel. Therefore, engine torque and exhaust emissions (CO, CO₂, NO_x and hydrocarbons) were tested to determine the effects of altering initial temperature and pressure of CNG prior to entering the combustion chamber of an Otto engine. It was found that variations in initial temperature and pressure do not affect torque. Increased gas temperature leads to decreased contents of CO, HC (hydrocarbons) and NO_x but increased C02 in exhaust gas. Meanwhile, increase in gas pressure is associated with decreased C02, HC and NO_x but increased CO in exhaust gas. Based on experimental results, it is clear that fuel gas temperature and pressure do not affect the engine torque but affect the exhaust gas composition.