Advanced Compressor Engine Controls to Enhance Operation, Reliability and Integrity

Bourn, Gary D.

doi:10.2172/825591

Cited by 1 publication

(3 citation statements)

References 8 publications

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“…The structure of the equation is adapted from the semi-empirical equations used for engine control in the natural gas transmission sector. 20,23 The actual control equations used, however, have additional empirical factors to account for operating point and even fuel composition 48 changes. Such equations have to be ''tuned'' for specific engines using air flow and engine emissions measurements across multiple operating points, and only work reliably for the particular engine at the operating points it has been tuned for.…”

Section: Ter Resultsmentioning

confidence: 99%

“…To bypass the challenges associated with direct TER determination, engine control systems use simple mean value scavenging models to estimate the scavenging and trapping efficiencies of two-stroke engines and through those estimates, determine the TER. 20,27,28 Such schemes rely on enginespecific empirical curve fitting parameters to compensate for the inaccuracies in the scavenging model estimated TE and SE, and are not sufficiently flexible and robust to provide the precise emissions control needed for regulatory compliance. Therefore, better (lessempirical and more phenomenological) scavenging models are needed.…”

Section: Gas-exchange In Two-stroke Enginesmentioning

confidence: 99%

“…This paper proposes a method of accurately computing a cylinder compositionbased engine control metric, the trapped equivalence ratio (TER), from high fidelity experimental gas-exchange characterization data of a two-stroke engine at multiple operating conditions. The computed TER and temporal insights gained regarding the flow physics of scavenging will be used to develop improved simple gas-exchange models that are less reliant on engine/operating-condition-specific empirical tuning, as is the case for currently available models, [18][19][20][21][22] and are more phenomenological in nature. Such models will help develop robust and flexible control systems for managing engine operation across an increasingly wide-ranging list of control variables, for example, fuel composition variations, 23 variable valve/ port opening timing, 12,16 variable compression ratio, 8 multiple injections.…”

Section: Introductionmentioning

confidence: 99%

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Trapped equivalence ratio determination in two-stroke engines

Bajwa

Patterson

Jacobs

2022

Proceedings of the Institution of Mechanical Engineers, Part D:

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The chemical composition of the trapped fuel-air-residual gas mixture controls the nature of combustion in internal combustion engines and thus serves as a key determinant of the ensuing emissions and work production processes. A frequently used trapped composition metric for engine control is the trapped equivalence ratio. Unfortunately, in two-stroke engines, it is unfeasible to accurately determine this using traditional intake flow and exhaust emissions measurements because of the simultaneous occurrence of intake and exhaust processes, which causes: (1) exhaust emissions to be diluted by the slippage (short-circuiting) of fresh air through the exhaust ports, i.e., trapping inefficiencies, and (2) high residual combustion product retainment, i.e., scavenging inefficiencies. The current paper supplements scavenging efficiency data obtained in a previous study for a cross-scavenged, natural-gas, two-stroke engine with experimental trapping efficiency data from the same engine, and characterizes the overall gas-exchange (scavenging + trapping) behavior of the engine at two engine loads, three speeds, and three spark timings. The trapping efficiency experiments use natural gas as a tracer for fresh charge and the total gas-exchange data is used to compute the trapped equivalence ratio. The trapping performance of the engine – which improves with speed and load increase, and spark retardation – along with scavenging, volumetric, thermal, and combustion efficiency changes determine the trapped equivalence ratio of the engine. The relationship between trapped equivalence ratio and NOx emissions is presented and the importance of accounting for scavenging and trapping inefficiencies in accurately determining equivalence ratio is discussed.

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Section: Ter Resultsmentioning

confidence: 99%

Section: Gas-exchange In Two-stroke Enginesmentioning

confidence: 99%