Experimental and numerical assessment of methods to reduce warm up time of engine lubricant oil

Carbon dioxide emission reduction is the most important challenge concerning on the road transportation. Stringent quantitative commitments have been set, both for automotive and for light and heavy duty vehicles. Future engine (and vehicle) technologies will consider a portfolio of new components, engine layouts, control strategies, integrated functions which will match also new comfort standards and fun to drive options, and complying fuel consumption savings.Engine thermal management is an area of intervention aimed at reducing the warm up time: in most part of the homologation cycle, both in passenger cars and in light duty vehicles, engines do not reach a stabilized thermal state. This produces a significant pollutants and fuel consumption increase. Engine thermal management can match also more effective cabin heating requirements, improving comfort, which is an important market advantage.Basic idea of engine thermal management is to reduce or make nil the cooling fluid circulation inside the engine.In this paper, the oil warm up is considered as the main focus: a faster temperature grow up decreases oil viscosity and improves mechanical efficiency and organic efficiency, during engine cold state. An experimental activity has been conducted on a dynamic test bench, testing the cooling fluid and oil dynamics of a widely known commercial engine, in fixed engine points and during the New European Driving Cycle (NEDC).A comprehensive mathematical model reproducing both the integrated circuits has been developed and validated: this required an overall engine and vehicle modeling whose input data was determined by the vehicle mission profile. By means of such model, three new technologies have been proposed and verified in terms of warm up time. They are: (a) by pass of the oil cooling, (b) oil heating using exhaust gases, and (c) a partial reduction of the oil quantity inside the sump.All of them were applied during transients, which revealed they are able to reduce warm up time of about 65-70% with a significant benefit in terms of CO2 reduction.