The pseudo Stirling cycle, also known as the adiabatic Stirling cycle, is a thermodynamic cycle with an adiabatic working volume and isothermal heater and cooler, in contrast to the ideal Stirling cycle with an isothermal working space.[1] The working fluid has no bearing on the maximum thermal efficiencies of the pseudo Stirling cycle.[2]
Practical Stirling engines usually use a adiabatic Stirling cycle as the ideal Stirling cycle can not be practically implemented.Nomenclature (practical engines and ideal cycle are both named Stirling)[3] and lack in specificity (omitting ideal or adiabatic Stirling cycle) can cause confusion.
The pseudo Stirling cycle was designed to address predictive shortcomings[2] in the ideal isothermal Stirling cycle. Specifically, the ideal cycle does not give usable figures or criteria for judging the performance of real-world Stirling engines.