Experimental Determination of the Performances during the Cold Start-Up of an Air Compressor Unit for Electric and Electrified Heavy-Duty Vehicles

Compressed air is crucial on an electric or electrified heavy-duty vehicle. The objective of this work is to determine experimentally the performance parameters of the first prototype of an electric-driven sliding-vane air compressor, specifically designed for electric and electrified heavy-duty vehicles, during the transient conditions of cold start-ups. The transient is analyzed for different thermostatic temperatures: 0 °C, −10 °C, −20 °C, and −30 °C. The air compressor unit is placed in a climatic chamber and connected to the electric grid, the water cooling loop as well as the compressed air measuring and controlling rig. The required start-up time is greater the lower the thermostatic temperature, ranging from 30 min at 0 °C to 221 min at −30 °C and depending largely on the volume of the lubricant oil filled initially. The volume flow rate of the compressed air is lower than nominal at the beginning, but it shows a step increase well beyond nominal when the oil reaches 50 °C and then decreases gently towards nominal, while the input power keeps steady at nominal after a short initial peak. These facts must be considered when estimating the time and the energy required by the air compressor unit to fill up the compressed air tanks of the vehicles.