A controlled EGR cooling system for heavy duty diesel applications using the vehicle engine cooling system simulation

In order to comply with 2002 EPA emissions regulations, cooled exhaust gas recirculation (EGR) will be used by heavy duty (HD) diesel engine manufacturers as the primary means to reduce emissions of nitrogen oxides (NOx). A feedforward controlled EGR cooling system with a secondary electric water pump and proportional-integral-derivative (PID) feedback has been designed to cool the recirculated exhaust gas in order to better realize the benefits of EGR without overcooling the exhaust gas since overcooling leads to the fouling of the EGR cooler with acidic residues. A system without a variable controlled coolant flow rate is not able to achieve these goals because the exhaust temperature and the EGR schedule vary significantly, especially under transient and warm-up operating conditions. Simulation results presented in this paper have been determined using the Vehicle Engine Cooling System Simulation (VECSS) software, which has been developed and validated using actual engine data. Simulation results indicate that a controlled EGR cooling system can maintain the EGR cooler outlet exhaust temperature at 130±8°C, as compared to 110±60°C for an EGR cooling system without coolant flow control. A system with controlled EGR cooling combined with a controlled engine cooling system indicates decreased warmup times for fast warmup of aftertreatment devices, decreased power consumption, and better engine temperature control. The previous version of VECSS did not include the capability to simulate EGR. Therefore, literature related to EGR is reviewed within the paper. Cooling system simulation results at high and low ambient temperature with EGR are also included along with the models created for the EGR cooler, EGR valve, and secondary electric water pump and controller. The engine cycle analysis subroutines were also modified to consider variable mixture compositions, as the thermal properties of the intake air vary significantly with the decreased oxygen concentration present with EGR. Copyright © 2002 Society of Automotive Engineers, Inc

Bioenabled Platform to Access Polyamides with Built-In Target Properties

The diversification of platform chemicals is key to today’s petroleum industry. Likewise, the flourishing of tomorrow’s biorefineries will rely on molecules with next-generation properties from biomass. Herein, we explore this opportunity with a novel approach to monomers with custom property enhancements. Cyclic diacids with alkyl and aromatic decorations were synthesized from muconic acid by Diels–Alder cycloaddition, and copolymerized with hexamethylenediamine and adipic acid to yield polyamides with built-in hydrophobicity and flame retardancy. Testing shows a 70% reduction in water uptake and doubling of char production while largely retaining other key properties of the parent Nylon-6,6. The present approach can be generalized to access a wide range of performance-advantaged polyamides.This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Journal of the American Chemical Society, copyright © 2022 American Chemical Society after peer review. To access the final edited and published work see DOI: 10.1021/jacs.2c01397. Posted with permission

Multifunctional Biobased Comonomers for Flame-Retardant Polyamides with Superior Mechanical Properties

Efforts towards developing biobased chemicals primarily focus on generating molecules chemically analogous to those derived from petroleum. However, the compositional uniqueness of biomass can also be leveraged to reinvigorate the chemical industry with novel multifunctional molecules. We demonstrate the value and potential of these new compounds in the case of Nylon-6,6, a commodity polyamide that suffers from poor flame resistance. The conventional route to inhibit flammability involves blending the polymer with additives, an approach that comes with significant trade-offs on the mechanical properties of the final product compared to the parent polyamide. Herein, we address this limitation through synthesis of a novel multifunctional comonomer derived from renewably sourced trans-3-hexenedioic acid (t3HDA). t3HDA was subjected to a one-pot isomerization and functionalization strategy where the double bond migrates to render this molecule active for phospha-Michael-addition (MA) with 6-oxide6H-dibenz(1,2)oxaphosphorin (DOPO), a prominent halogen-free flame-retardant (FR). This monomer was introduced in the polyamide’s backbone through copolymerization and the obtained polymer was compared to physical mixtures containing proportionate amounts of DOPO and Nylon-6,6. Thermal and mechanical properties of the blends and the FR-grafted polymers were characterized through a suite of techniques that revealed superior crystallinity, thermal, and mechanical properties for the DOPO-tethered bio-advantaged polyamides relative to blends with comparable flame retardance. The synthesis strategy presented herein can be extended for a variety of functional groups for property-modified bio-advantaged polymers.This is a preprint from Carter, Prerana, Ting-Han Lee, Peter M. Meyer, Dhananjay Dileep, Nickolas L. Chalgren, Sohaima Sohaima, Michael J. Forrester, Brent H. Shanks, Jean-Philippe Tessonnier, and Eric W. Cochran. "Multifunctional Biobased Comonomers for Flame-Retardant Polyamides with Superior Mechanical Properties." (2023). doi: https://doi.org/10.26434/chemrxiv-2023-nnww9. Copyright Authors 2023. The content is available under CC BY NC ND 4.0