Thermodynamic Modeling of an Atkinson Cycle with respect to Relative Air-Fuel Ratio, Fuel Mass Flow Rate and Residual Gases

The performance of an air standard Atkinson cycle is analyzed using finite-time thermodynamics. The results show that if the compression ratio is less than a certain value, the power output increases with increasing relative air-fuel ratio, while if the compression ratio exceeds a certain value, the power output first increases and then starts to decrease with increase of relative air-fuel ratio. With a further increase in compression ratio, the increase in relative air-fuel ratio results in decrease of the power output. Throughout the compression ratio range, the power output increases with increase of fuel mass flow rate. The results also show that if the compression ratio is less than a certain value, the power output increases with increase of residual gases, on the contrast, if the compression ratio exceeds a certain value, the power output decreases with increase of residual gases. The results obtained herein can provide guidance for the design of practical Atkinson engines.