Estimation of Entropy Generation in a SCR-DeNOx System with AdBlue Spray Dynamic Using Large Eddy Simulation

Area of Science:

• Thermodynamics
• Fluid Dynamics
• Chemical Engineering

Background:

• Selective Catalytic Reduction (SCR) systems are crucial for reducing emissions in internal combustion (IC) engines.
• Understanding entropy generation is key to optimizing SCR efficiency and minimizing energy losses.
• Multi-phase flow phenomena, including water/AdBlue injection, significantly impact SCR performance.

Purpose of the Study:

• To extend entropy generation analysis to multi-phase fluid flow within a Large Eddy Simulation (LES) framework for SCR systems.
• To quantify the individual contributions of various physical processes (heat transfer, fluid flow, phase change, mixing, chemical reaction) to overall entropy generation.
• To investigate the influence of operating parameters on entropy generation in a generic SCR configuration.

Main Methods:

• Utilized a Large Eddy Simulation (LES) framework to model multi-phase fluid flow.
• Validated numerical modules against experimental data for film thickness and H2O mass fraction/temperature.
• Assessed entropy generation by evaluating viscous dissipation, heat dissipation, species mixing, chemical reactions, and dispersed phase contributions.

Main Results:

• Entropy generation is predominantly driven by heat transfer, chemical reactions, and the dispersed phase, surpassing viscous and mixing processes.
• AdBlue injection introduces significant entropy generation due to heat transfer, chemical reactions, and phase changes.
• Operating parameters like exhaust gas temperature, flow rate, and AdBlue injection strategy critically influence total entropy generation.

Conclusions:

• The study provides a detailed analysis of entropy generation sources in SCR systems with water/AdBlue injection.
• Heat, chemical reactions, and dispersed phases are identified as the primary contributors to irreversibility.
• The findings offer insights for optimizing SCR system design and operation to enhance efficiency and reduce emissions.