Analysis of Boosting Architectures for Hydrogen Internal Combustion Engines

The application of turbocharging is still a crucial aspect, especially in hydrogen engines where ultra-lean combustion is required, to mitigate abnormal combustion and NOx formation. The adoption of advanced turbocharging systems results in an increased complexity of the engine intake and exhaust circuits and requires a proper design to optimize unsteady flow phenomena. Therefore, it is essential to understand the performance of the single elements of the turbocharging circuit and their interactions when coupled. A specific test rig for components of propulsion system is operating at the University of Genoa, where investigations under steady, transient and pulsating flow conditions can be performed. This study presents the results of experimental investigations conducted under unsteady flow conditions on the exhaust manifold of an internal combustion engine, specifically examining unsteady phenomena in the turbine inlet circuit. The pulsating flow is generated by a motor-driven cylinder head. Pressure signals recorded in different sections of the exhaust circuit located in the inlet and outlet turbine circuit are analysed in detail, quantifying also the effects of flow unsteadiness using parameters proposed in the open literature. In particular in the following article, the degree of instability, the Strouhal number and the reduced frequency are considered to quantify the impact of unsteady phenomena within the system for the considered lengths. Understanding the unsteadiness within engine circuits is crucial for determining the appropriate modeling approach for system simulation. This work highlights that a quasi-steady flow model is appropriate for modeling individual branches for the exhaust manifold, while a wave action model is necessary for the entire exhaust circuit.

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Experimental analysis of the performance of a turbocharger compressor under pulsating flow condition

Nannetti,

Usai,

Cordalonga

et al. 2024

J. Phys.: Conf. Ser.

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To achieve zero CO2 emissions in the transport sector, hydrogen internal combustion engines (H2 ICE) appear to be one of the most promising solutions, particularly for heavy-duty applications. Achieving low NOx emissions requires ultra-lean combustion, which necessitates the use of high air-to-fuel ratios. To obtain this result, suitable boosting systems are required. This study aims to understand the behaviour of a turbocharger compressor. The performance of the compressor is strongly influenced by the unsteady flow generated by the motion of the engine’s intake valves. Achieving a more accurate prediction of engine performance in simulation models requires a deeper understanding of the pulsating flow performance. This understanding can be obtained through measurements conducted in specialized test facilities using appropriate measuring equipment. All the analyses reported in this paper take place at the Test Bench for Components of Propulsion System of the Department of Mechanical, Energy, Management and Transportation Engineering (DIME) of the University of Genoa. Following a short description of the instrumentations adopted, the actual experimental layout, the results obtained from the investigations on the compressor, operating under both steady and unsteady flow conditions, are outlined. The tested turbocharger compressor is coupled to the automotive engine intake circuit, where pulsating flow is generated by a motor-driven cylinder head. Different levels of turbocharger and camshaft rotational speeds are analyzed. For each operating condition, the unsteady performance of the compressor is assessed by measuring several instantaneous parameters, including inlet and outlet static pressure, mass flow rate, and turbocharger rotational speed. Furthermore, the effects of the intake circuit and its interaction with the compressor is deeply analyzed. In particular, the energy content associated with the pulses generated by the intake valves motion is taken into account, considering the hysteresis loops on the compressor map.

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Analysis of Boosting Architectures for Hydrogen Internal Combustion Engines

Cited by 7 publications

References 4 publications

Experimental investigation of the matching boundary and optimization strategy of a variable geometry turbocharged direct-injected hydrogen engine

Experimental investigation of the matching boundary and optimization strategy of a variable geometry turbocharged direct-injected hydrogen engine

Unsteady phenomena in the exhaust circuit of turbocharged automotive engines

Experimental analysis of the performance of a turbocharger compressor under pulsating flow condition

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