Engine Encapsulation for Increased Fuel Efficiency of Road Vehicles

Transcription

1 Engine Encapsulation for Increased Fuel Efficiency of Road Vehicles A project within the program: Energy and Environment Start: July 2013 End: June 2017 Blago Minovski Department of Mechanics and Maritime Sciences Chalmers University of Technology Total state funding: 4699 ksek Supervisors: Professor Lennart Löfdahl Dr. Peter Gullberg 1

2 Content Introduction Why do we want to encapsulate the engine? How does engine encapsulation work? Aims of this work Methods to test and predict the results from encapsulating the engine on the overall fuel consumption Experimental and computational methods A coupled 1D-3D method to predict the effects of engine encapsulation on fuel consumption Engine encapsulation for passenger vehicle Volvo S80 Presentation of features Results from complete vehicle simulations for extended drive-cycles Conclusions 2

3 Noise limit db(a) Environmental aspect CO 2 emissions A strict penalty system for regulation of emissions charges the carmaker 95 Euro for every exceeded gram of CO 2 /km Permitted limits for CO 2 emissions have been continuously reduced Figure 1.1: Global CO2 regulations for passenger cars in terms of NEDC g CO2/km. Noise Limits for vehicle-generated noise have been progressively decreased It is expected that the maximum noise limit for most passenger cars by 2026 will be 68 db Year Figure 1.2: European noise regulations for passenger vehicles. 3

4 Engine encapsulation Figure 2.1: Engine encapsulation designed for Volvo S80. Encapsulation retains heat in the engine the engine is not fully efficient until it has warmed up lubricants/fluids perform best at operating temperature Increases the probability for high initial oil temperature at next engine start Reduces airborne noise Figure 2.2 Standard engine, Volvo S80. 4

5 Aims To build knowledge within thermal engine encapsulation as a technical solution with focus on fuel consumption. How does engine encapsulation influence fuel consumption? How can the effects of thermal engine encapsulation be estimated using numerical simulations and what are important factors to consider? 5

6 A combined simulation environment Figure 4.2: An illustration of the interaction between different vehicle subsystems relevant to engine encapsulation analysis. Figure 5.1: Simulation architecture. 6

7 1D model of powertrain cooling systems Figure 9.2: Chematic of 1D discretization, staggered grid approach.. Figure 9.1: Block diagram of powertrain cooling system. 7

8 3D model of heat transfer in the engine bay Figure 10.1: Discretized surface of complete vehicle model located in a virtual laboratory. Figure 10.2: Section cut through the computational grid in the underhood. (5) (6) (7) Figure 10.3: 3D CFD engine wall boundaries with imposed temperature specification coordinated with 1D engine thermal model.. 8

9 Thermal engine encapsulation concept for Volvo S80 (a) Front view (b) Side view (c) Back view Figure 12. Thermal engine encapsulation concept. 9

10 Drive-cycle simulations Figure 13.1: Simulated drive-cycle consisting of sequences of WLTC with different periods of inactivity. (a) Ambient temperature 5 C. Table 1: Overview of simulated combinations. (a) Ambient temperature 20 C. Figure 13.2: Variation in engine oil temperature during a sequence of simulated WLTC drivecycles with 16 hours of inactivity. 10

11 Drive-cycle simulations Figure 14.1: Increase in temperature of engine parts as a result of encapsulation after key-off in ambient temperature 5C. Figure 14.3:Fuel savings expressed as percentage of the burned fuel mass with non-encapsulated engine during WLTC drive cycle, 5 and 20 C ambient temperature. Figure 14.2: Variation in oil temperature after engine start preceeded by 4 hours of inactivity at 5C ambient temperature. 11

12 Conclusions Integrated simulation platform for predicting the effects of engine encapsulation on fuel consumption Longitudinal vehicle dynamic model Mapped engine model Temperature-dependent engine friction 1D model of PCS Coupled 1D-3D approach for predicting buoyancy-driven heat transfer in the engine bay Simulations of WLTC with periods of inactivity 2,5% fuel saved from 2 to 8 hours after engine shut-off at 5 C 12