Why do we need to reduce the compression ratio for the Atkinson cycle?
In the Otto cycle, after the combustion process, the force exerted on the piston during the power stroke increases so that when the piston reaches BDC, the exhaust valve opens, and useless heat discharges from the combustion chamber.
Therefore, this cycle uses to reduce the compression ratio for more expansion during the expansion stroke so that the entire force generated due to the combustion process can be used on the piston before the piston reaches BDC.
This means that the Atkinson cycle always has a lower/equivalent performance than the Otto cycle. However, the Otto cycle has lower thermal efficiency than the Atkinson cycle.
How to Calculate Thermal Efficiency of Atkinson Cycle?
Thermal Efficiency of Atkinson Cycle calculator uses Thermal Efficiency of Atkinson Cycle = 100*(1-Heat Capacity Ratio*((Expansion Ratio-Compression Ratio)/(Expansion Ratio^(Heat Capacity Ratio)-Compression Ratio^(Heat Capacity Ratio)))) to calculate the Thermal Efficiency of Atkinson Cycle, The Thermal Efficiency of Atkinson Cycle formula is defined as the fraction of heat converted into useful work in an Otto engine following Atkinson cycle. It considers both compression ratio and expansion ratio with the adiabatic index as well. Thermal Efficiency of Atkinson Cycle is denoted by ηatk symbol.
How to calculate Thermal Efficiency of Atkinson Cycle using this online calculator? To use this online calculator for Thermal Efficiency of Atkinson Cycle, enter Heat Capacity Ratio (γ), Expansion Ratio (e) & Compression Ratio (r) and hit the calculate button. Here is how the Thermal Efficiency of Atkinson Cycle calculation can be explained with given input values -> 34.03648 = 100*(1-1.4*((4-1.75)/(4^(1.4)-1.75^(1.4)))).