Exergy analysis for high - PowerPoint Presentation

Slide1

Exergy analysis for high efficiency ICE gases exchange system

Beichuan Hong

beichuan@kth.se

KTH CCGEx

This study aims to provide insight on the energy availability (exergy) of ICE gas exchange system architecture with respect to design parameters and engine performances. Efficiency improvement and exergy optimization of ICE gases exchange system are studied utilizing 1D engine modelling with experimental validation. This study focuses on applied exergy observation, modelling, and optimization concerning ICE systematic performance, especially for its relation with devices (e.g. valve motion, gas path geometry, turbocharger behaviors, EGR, waste heat recovery, etc.) of the overall gas exchange system.

Introduction and Motivation

Objective

Research activities (

2018-19)Detailed 1D model describing exergy destruction in ICE exhaust systemExergy-based approach for improving the design parameter & architecture of the gas exchange system.Research questions (2018-19)How to model and observe the exergy destruction in the gases exchange system? The weakness of 1D model? How to improve system exergetic efficiency based on exergy model (associated with exhaust flow manners)? [Comparison of various system architectures and operating strategies.]

Traditional approaches using the 1st-law of thermodynamics have been wildly used for describing energetic efficiency within gas exchange systems. However, relevant researches based on the 2nd-law still remain at the macroscopic analysis without exploiting the utilization of the exergy flow in term of detailed inlet and exhaust flow manners. In this study, we investigate the thermal details of ICE gases exchange system associated with the exergy dissipation and utilization as functions of engine parameters. An novel exergy-based approach is proposed to identify irreversibility of processes detrimental to overall ICE performance, and to further optimize the systemic architecture and operating strategy by reducing the irreversibility and increasing exergy extraction.

Exergy destroyed

can be measured using entropy generation:Chemical reaction, i.e. combustion process (including fuel oxidization and internal energy exchange); Flow restrictions occurring at the inlet and exhaust paths (e.g. throttling effects, expansion, turbulence and vorticity, friction, flow loss) ;Dissipative effects such as: mixing process (for example, fresh charge and burned gas), heat transfer.

Schematic diagram of exergy analyses framework for

an example diesel engine with dual-loop EGR system

Stages of exergy project and relevant research areas

Macroscopic view:

exergy analyses of ICEs system for reducing system irreversibility and improving the

exergetic

utilization

.

To

establish a 1D model-based framework for modelling exergy flow in overall engine system;

To

identify the ICEs components or processes that affect the major

exergetic

destruction.

To optimize the cooperating strategy integrating

multiple gases-path devices

for maximizing

exergetic

utilization.

Microscopic view:

understanding the ICEs exhaust pulse flow

and its relations with the behavior of gases-path devices from

exergetic

perspective.

To improve understanding of the character of the

irreversibilities

of gas exchange processes associated with different engine performances & design parameters.

To develop an applicable exergy-based methodology to optimize the design parameters & architecture of gases-path devices.