Simulation Analysis of the Impact of Exhaust Backpressure on a Variable Compression Ratio Diesel Engine Performance

Abstract

This study investigates the impact of exhaust backpressure (EBP) on the performance of a single-cylinder, four-stroke, variable compression ratio (VCR) diesel engine using Gamma Technologies (GT)-POWER software. The simulation of this engine varied EBP by adjusting an orifice diameter at the exhaust pipe's end and compression ratio (CR) incrementally from 12 to 18. The study found that, contrary to expectations, increasing CR significantly increased brake specific fuel consumption (BSFC), primarily due to increased EBP. While higher CRs generally improve thermal efficiency and increase brake power, the presence of high EBP reduced brake power, especially at lower CRs. Increased EBP also significantly reduced brake torque at higher CRs. Additionally, the impact of CR on hydrocarbon (HC) emissions was non-linear, with EBP significantly influencing HC and carbon monoxide (CO) emissions. The results highlight a trade-off between CR and EBP levels in optimizing engine performance and emissions. The study emphasizes the necessity of considering EBP and CR to optimize the performance and reduce emissions of VCR diesel engines