Abstract
Keywords
Gaseous Fuel, HCCI, Internal Combustion Engine, Turbocharger, Natural Gas, Premixed Combustion
Abstract
The possibility of turbocharging into a natural gas homogeneous charge compression ignition (HCCI) engine is investigated experimentally and by simulation. Experiments are performed using a four-cylinder naturally aspirated engine fitted with an external supercharger and a butterfly valve for back pressure control to simulate a turbocharger with efficiency of 0.64. Based on the test results, the performance and emission characteristics are studied in detail through numerical one-dimensional cycle simulations. The results indicate that the thermal efficiency can be improved by raising the engine compression ratio and lowering the turbocharging pressure. At an engine compression ratio of 21 and turbocharging pressure of 1.9 bar, the brake thermal efficiency reaches 0.43, with NO, emissions of only 10 ppm or less. The cycle simulations demonstrate that performance comparable to that achieved in the external supercharging test can be obtained by optimizing engine and turbocharger specifications.