Open Dual Cycle with Composition Change and Limited Pressure for Prediction of Miller Engines Performance and Its Turbine Temperature

Antonio Lecuona,Antonio Famiglietti,José I Nogueira

doi:10.3390/en14102870

Antonio Lecuona, Antonio Famiglietti + Show 1 more

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https://doi.org/10.3390/en14102870

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Abstract

An improved thermodynamic open Dual cycle is proposed to simulate the working of internal combustion engines. It covers both spark ignition and Diesel types through a sequential heat release. This study proposes a procedure that includes (i) the composition change caused by internal combustion, (ii) the temperature excursions, (iii) the combustion efficiency, (iv) heat and pressure losses, and (v) the intake valve timing, following well-established methodologies. The result leads to simple analytical expressions, valid for portable models, optimization studies, engine transformations, and teaching. The proposed simplified model also provides the working gas properties and the amount of trapped mass in the cylinder resulting from the exhaust and intake processes. This allows us to yield explicit equations for cycle work and efficiency, as well as exhaust temperature for turbocharging. The model covers Atkinson and Miller cycles as particular cases and can include irreversibilities in compression, expansion, intake, and exhaust. Results are consistent with the real influence of the fuel-air ratio, overcoming limitations of standard air cycles without the complex calculation of fuel-air cycles. It includes Exhaust Gas Recirculation, EGR, external irreversibilities, and contemporary high-efficiency and low-polluting technologies. Correlations for heat ratio γ are given, including renewable fuels.

Highlights

Modeling thermal engines with simplified processes in a closed layout is at the roots of Thermodynamics
The isentropic compression starts from maximum volume (Bottom Dead Center or BDC) and ends at the
This paper reveals that the results of such a model are explicit formulae, but not exclusively for work and efficiency of reciprocating Internal Combustion Engines (ICE)

Summary

Introduction

Modeling thermal engines with simplified processes in a closed layout (control mass) is at the roots of Thermodynamics This is so due to the importance of prime movers for our society, science, and technology, being these models named thermodynamic cycles (e.g., see Moran et al [1]). The air-standard Otto cycle tries to idealize the processes in external or Internal Combustion Engines (ICE) of the reciprocating type. It pursues obtaining both the fluid state at key points in the cycle and the figures for power and efficiency. A non-reacting perfect gas constitutes the constant mass working substance In this cycle, the isentropic compression starts from maximum volume (Bottom Dead Center or BDC) and ends at the

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