From the study at the University of Warwick, it is noticed
that the energy efficiency of scroll expanders drops with the
compressed air supply pressure decreases in the relatively
low supply air pressure situations, which will definitely
affect the expander operation and performance especially in
exhaust energy recycling applications. Through the initial
study at Warwick, it is found that the main reasons resulting
to such phenomenon are the friction from the movement of
scroll mechanisms and the air leakage between different
pneumatic scroll expander chambers. To solve this issue,
one method is to modify/redesign the scroll expander which
can provide the driving force not only from compressed air
energy when the low compressed air supply pressure is in
use. The method can overcome or reduce the negative effect
of scroll expanders from the air leakage and the friction.