A comparison between a microturbine and a scroll-type expander for a small scale orc energy recovery system for vehicular application

This paper deals with the comparison between an IFR microturbine and a scroll-type expander for the exploitation of an on board ORC energy recovery system. The sensible heat recovered from a common bus engine (typically 8000cc) feeds the energy recovery system that can generate sufficient extra power to sustain the air-conditioning system and part of the auxiliaries. The concept is suitable for all kind of thermally propelled vehicles, but the application considered here is specific for an urban bus. The ORC cycle performance is calculated by a Process Simulator (CAMEL Pro) and the results are discussed. A preliminary design of the considered expanders is proposed using ad-hoc made models implemented in MATLAB, the technical constraints inherent to each machine are listed and the expected performance is presented in order to perform the optimal choice of the expander.