Open AccessCritical Design Issues of Heavy Fuel APUs Derived from Automotive Turbochargers. Part 1: Nominal Ambient Conditions
Author(s) -
Luca Piancastelli,
Patrich Ferretti,
Gian Maria Santi,
Alessandro Scaltrini,
Stefano Cassani,
Federico Calzini
Publication year - 2021
Publication title -
tecnica italiana
Language(s) - English
Resource type - Journals
ISSN - 0040-1846
DOI - 10.18280/ti-ijes.650108
Subject(s) - automotive engineering , recuperator , turbocharger , turbine , auxiliary power unit , automotive industry , environmental science , nuclear engineering , engineering , electrical engineering , mechanical engineering , voltage , heat exchanger , aerospace engineering
Small, turbine-powered eAPUs (electric Auxiliary Power Unit) have poor off-design performance and efficiency. Turbo eAPUs remain competitive where efficiency is sacrificed to lightness and compactness. The first part of this paper summarizes the transformation of a very efficient, very large automotive turbocharger into an eAPU. A satisfactory solution for the design of the heavy fuel combustor has been found on the Giandomenico’s site. The performance of the APU is evaluated at the Garrett nominal air conditions (T0=302.6 K, p0=0.962 bar, dry air). The turbogas has an approximately linear braking torque from 50% to 100% load at nearly maximum efficiency. Below 50% load, it is more convenient to vary the maximum temperature of the cycle and adjust the generator torque. However, a better compromise can be obtained by coupling the APU with a battery that would supply the electric power under 50% load. The use of a recuperator is not convenient due to the increase in volume and the additional complication. The problem of the intake air filtering is particularly serious in dirty/sandy ground applications. Regarding efficiency, the turbogas is no match for the diesel eAPUs.