Heat Transfer Rate Analysis of Hydrogen-Enriched Internal Combustion Engine Under Different Load Conditions

Abstract A series of experiments were conducted on a compressed natural gas internal combustion engine across varying load conditions with 1200rpm, 20% hydrogen, different exhaust gas recirculation (EGR) and spark timing to capture in-cylinder pressure data and heat transfer rate. The authors compared six distinct models for heat transfer. These models systematically incorporated into a quasi-dimensional combustion model (QDCM) for hydrogen-compressed natural gas engine, accounting for diverse load conditions by using MATLAB code. Convective heat transfer models, including Woschni, Nusselt, Hohenberg, Han, Eichelberg, and Assanis correlations, were employed. Comparative analyses were undertaken to identify the most precise correlation for predicting engine in-cylinder pressure and heat transfer rates with experimental results across a broad spectrum of operational conditions. The Woschni model, as presented, is most suitable for the QDCM of the hydrogen-compressed natural gas fuel blend, particularly when exhaust gas recirculation is used in, as indicated by the proximity of Taylor length and turbulent intensity coefficients to 1, and the minimal absolute percentage error for indicated mean effective pressure. It’s also observed that the heat transfer rate increases by 13.29% by increasing from 75% to 100% load conditions. Heat transfer rate is increased by increasing the engine load 25%, 50%, 75% and 100% as 49.57 J/deg, 129.26 J/deg, 245.35 J/deg and 250.62 J/deg respectively with woschni model as depicted in figure 13. Heat transfer rate is different for different models with 100% load as 250.62 J/deg, 36.85 J/deg, 16.11 J/deg, 29.46 J/deg, 27.71 J/deg and 15.52 J/deg with Woschni, Nusselt, Hohenberg, han, Eichelberg and Assanis respectively.