Thermodynamic Model for Cold-Phase Influence on Light Vehicles’ Fuel Consumption

Abstract

The present and appropriate concern regarding climate changes resulting from the combustion of fossil fuels in light passenger vehicles raises the necessity to develop appropriate instruments to investigate probable and feasible solutions for fleet decarbonization. Given the direct relationship between fossil fuel consumption and greenhouse gas emissions have historically been determined through experimental tests in the laboratory following standard cycles, to enhance the vehicle’s energy efficiency these should be complemented by numerical simulation tools, as they demonstrate fast response and adequate correlation to experimentation. In this aspect, one of the biggest challenges of numerical simulation is quantifying the impact of the various phenomena that affect the vehicle operation during the cold phase, in which the internal combustion engine loses efficiency. This study proposes a thermodynamic model for simulating the fuel consumption of light vehicles during the cold phase of operation. Measured lubricant temperature, ignition spark retardation, exhaust valve timing, and coolant temperature in the vehicles along the drive cycle are the required input data for the model. This thermodynamic procedure makes it possible to quantify the impact on fuel consumption while driving the vehicle in cold operation. The cold phase, with a 505 s duration, is responsible for approximately a 21% increase in fuel consumption in a standard urban drive cycle. It is considered that the shorter the route, the more pronounced and significant the cold phenomena are, and the impact of vehicles frequently driven on short urban routes can be accurately estimated for future analyses.