Development and Validation of a Submodel for Thermal Exchanges in the Hydraulic Circuits of a Global Engine Model

Abstract

To face the current challenges of the automotive industry, there is a need for computational models capable to simulate the engine behavior under low-temperature and low-pressure conditions. Internal combustion engines are complex and have interconnected systems where many processes take place and influence each other. Thus, a global approach to engine simulation is suitable to study the entire engine performance. The circuits that distribute the hydraulic fluids-liquid fuels, coolants and lubricants-are critical subsystems of the engine. This work presents a 0D model which was developed and set up to make possible the simulation of hydraulic circuits in a global engine model. The model is capable of simulating flow and pressure distributions as well as heat transfer processes in a circuit. After its development, the thermo-hydraulic model was implemented in a physical based engine model called Virtual Engine Model (VEMOD), which takes into account all the relevant relations among subsystems. In the present paper, the thermo-hydraulic model is described and then it is used to simulate oil and coolant circuits of a diesel engine. The objective of the work is to validate the model under steady-state and transient operation, with focus on the thermal evolution of oil and coolant. For validation under steady-state conditions, 22 operating points were measured and simulated, some of them in cold environment. In general, good agreement was obtained between simulation and experiments. Next, the WLTP driving cycle was simulated starting from warmed-up conditions and from ambient temperature. Results were compared with the experiment, showing that modeled trends were close to those experimentally measured. Thermal evolutions of oil and coolant were predicted with mean errors between 0.7ºC and 2.1ºC. In particular, the warm-up phase was satisfactorily modeled.

Diesel engine optimization and exhaust thermal management by means of variable valve train strategies

“…Hydraulic circuit elements like thermostats, operable valves, pumps and heat exchangers have been modeled and simulated. Further details regarding the hydraulics sub-models are collected in the study by Broatch et al 23…”

Development of a Variable Valve Actuation Control to Improve Diesel Oxidation Catalyst Efficiency and Emissions in a Light Duty Diesel Engine

“…Simultaneously, the heat exchanger sub-model updates the temperatures. Further details regarding the hydraulics sub-models are collected in [30].…”

Effect of the exhaust thermal insulation on the engine efficiency and the exhaust temperature under transient conditions

“…Further details regarding the hydraulics sub-models are collected in. 27 Figure 6 shows the flow-chart of the virtual engine model. The blue boxes represent the thermo and fluid dynamics sub-models described above, while the red boxes represent the different control sub-models, which have been developed in Matlab/Simulink.…”