Performance of Natural-Gas-Fueled Engines with Variable Intake-Manifold Temperatures 922364
The possiblity of using an elevated intake-manifold temperature for lean-burn, turbocharged spark-ignition engines fueled by natural gas has been investigated. Experiments have shown that the power capacity, shaft efficiency and NOx emissions could be maintained at the rated level if an increase in intake-manifold temperature was accompanied by an increase in air-to-fuel ratio. A higher air-to-fuel ratio is allowed with hotter mixtures since both the lean misfire limit and the volumetric efficiency appear to increase with increasing mixture temperature. An intake-manifold temperature at the level of the jacket-water temperature of the engine has the advantages of an easier control of the mixture temperature, a better energy utilisation in cogeneration systems and a better part-load efficiency of the engine.