Review of the systems analysis of interactions between the thermal, lubricant, and combustion processes of diesel engines

Abstract

A review of technologies surrounding the thermal management system of the modern diesel engine with increased attention on fuel consumption is presented. A system-based approach has been adopted, looking at the interaction with other key systems. Previous innovation has aimed at reducing the power consumption of the cooling system or incorporating different cooling strategies and improving the engine warm-up rate for improved fuel consumption by higher operating temperatures. Electrical pumps can operate independently of the engine speed, and precision cooling and nucleate boiling have improved the heat transfer within the engine, reducing coolant flow requirements by 90 per cent. Improved warm-up rates have been demonstrated by using reduced thermal inertia or energy recovery systems either simulated on the test rig or through heat exchangers with exhaust gases. The resultant reduction in the fuel consumption is a result of various effects of the temperature on both the lubricating system and the combustion process. Despite difficulties in accurately measuring the engine friction, studies suggest that an increase in the engine temperature from 50°C to 80°C reduces the engine friction by 44 per cent because of 67 per cent lower oil viscosity. Simultaneous reduction in the emissions of nitogen oxides (NO x) and the fuel consumption of 13.5 per cent and 0.7 per cent respectively have been achieved by including the engine thermal system in the calibration procedure. However, in-cylinder data needs to be studied to understand fully the mechanisms involved. Hotter engine temperatures reduce ignition delay, making combustion occur earlier in the cycle, which has a positive effect on the fuel consumption but a negative effect on the NO x emissions. Engine thermal management requires a system-based approach if the effects are to be fully understood but offers potential as an additional parameter in engine calibration.

Advances in Integrated Vehicle Thermal Management and Numerical Simulation

“…In order to solve the ICEV emission problem, there are more and more heat exchangers, likewise, EGR coolers, charge air coolers (CACs), lubricant coolers and so on are being used, located in the compact underhood [45][46][47]. As for EGR, which can lower the in-cylinder combustion temperature to reduce pollutant emissions, its use emerged in the early 1970s [48][49][50][51].…”

Emission Treatment towards Cold Start and Back Pressure in Internal Combustion Engine against Performance of Catalytic Converter: A Review

“…Hence, for the vehicle that only involve in short distance trips, it needs to improve the fuel consumption especially during the warmup phase because the engine could not reach the optimum temperature for the catalytic converter to be activated which could causes cold start emission. (Roberts et al, 2014) [16] claims that the average of the cars travel in Europe is around 10 km while Burke et al (2010) [17] state that in United State of America, the mean length of travelling distances of vehicles are less than 15km. The data presented in Figure 3 shows the energy thermal balance occurs in the vehicles cylinder during the warm-up stages.…”

Effects of Engine Cooling Water Temperature on Performance and Emission Characteristics of a Compression Ignition Engine Operated with Biofuel Blend

“…Therefore, the temperature of combustion within the engine is directly affected by the cooling system. In addition, the cooling system also has an influence on the lubricating oil temperature and the exhaust recirculation gas temperature [18]. Effects on engine performance due to the changes in the temperature of the engine coolant and intake air have been previously investigated, when operated with fossil diesel [19][20][21][22][23][24][25].…”