This paper presents an innovative permanent magnetic
scroll expander which has potential to improve the
performance and the energy efficiency of scroll expanders,
especially for the applications in low compressed air supply
pressure situations. The paper starts from the study of the
scroll geometry and the thermodynamic process of standard
scroll expanders. The methodology to determine and to
install the magnetic materials into scrolls for generating the
extra useful force is then described. The magnetic field
between magnetized scrolls and the resultant driving torque
to the expander are analysed. The simulated result is
discussed at the end.