Experimental investigation on the extreme cold start-up of an air compressor for electric heavy vehicles

Engine-driven reciprocating air compressors are employed on fuel-powered heavy vehicles to actuate a number of auxiliary systems, like brakes and suspensions. Electrically-driven sliding-vane air compressors turn particularly suited for electric heavy vehicles. Unlike in fuel-powered vehicles, the compressor is not heated up in the case of electric mobility, a situation that may lead to potential issues in extreme cold weathers. This paper investigates experimentally the start-up of a sliding-vane air compressor designed specifically for electric heavy vehicles. The compressors, equipped with instruments, is positioned in a climatic chamber. During the tests, the chamber is set to a desired ambient temperature, 0, -10, -20, -30 °C or 20 °C taken as reference following ISO 1217, and the compressor is started-up when a steady-state initial condition is achieved. The delivery pressure is controlled at 10 bar(g) and all measurements are recorded until a temperature of 80 °C is reached in the air-lube oil separator. No issues are encountered during the tests, such as sudden damage due to improper lubrication. Moreover, the curves of the measured temperature within the air-lube oil separator show similar trends but higher initial plateaus and lower slopes at lower ambient temperatures resulting into lower oil flow rates, higher energy spent for heating up the system as well as higher warm-up times, from 15 minutes at 20 °C up to 69 minutes at -30 °C.