Experimental and Numerical Investigation of a Turbocharger Turbine Using Exergy Analysis at Non-Adiabatic Conditions

Lim, Shyang Maw; Bakhshmand, Sina Kazemi; Biet, Clemens; Mihăescu, Mihai

doi:10.4271/2020-01-2225

Cited by 5 publications

(6 citation statements)

References 16 publications

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“…The use of the concept of exergy as a post-processing tool is rapidly growing in turbocharger applications [9,30,31,[40][41][42]. However, in the present work, exergy assumes an important role in the pre-processing phase, since it represents a constraint for the design of the pulses.…”

Section: Validation Studymentioning

confidence: 92%

“…To replicate the experimental setup, the computational domain is modified by substituting the exhaust manifold with a straight pipe 310 mm long. Adiabatic boundary conditions are imposed at the walls since, under gas-stand conditions, the expansion ratio has been demonstrated to not vary with respect to the type of boundary condition imposed [30]. Two different operating points are also studied through the DES model: the first is characterized by a similar rotational speed as for the pulsating flow cases, while the second represents an off-design point to assess the generality of the model.…”

Section: Validation Studymentioning

confidence: 99%

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Turbocharger Radial Turbine Response to Pulse Amplitude

Mosca

Lim

Mihăescu

2022

Journal of Energy Resources Technology

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Under on-engine operating conditions, a turbocharger turbine is subject to a pulsating flow and, consequently, experiences deviations from the performance measured in gas-stand flow conditions. Furthermore, due to the high exhaust gases temperatures, heat transfer further deteriorates the turbine performance. The complex interaction of the aerothermodynamic mechanisms occurring inside the hot-side, and consequently the turbine behavior, is largely affected by the shape of the pulse, which can be parameterized through three parameters: pulse amplitude, frequency, and temporal gradient. This paper investigates the hot-side system response to the pulse amplitude via Detached Eddy Simulations (DES) of a turbocharger radial turbine system including exhaust manifold. Firstly, the computational model is validated against experimental data obtained in gas-stand flow conditions. Then, two different mass flow pulses, characterized by a pulse amplitude difference of 5%, are compared. An exergy-based post-processing approach shows the beneficial effects of increasing the pulse amplitude. An improvement of the turbine power by 1.3%, despite the increment of the heat transfer and total internal irreversibilities by 5.8% and 3.4\%, respectively, is reported. As a result of the higher maximum speeds, internal losses by viscous friction are responsible for the growth of the total internal irreversibilities as pulse amplitude increases.

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Section: Validation Studymentioning

confidence: 92%

Section: Validation Studymentioning

confidence: 99%

Turbocharger Radial Turbine Response to Pulse Amplitude

Mosca

Lim

Mihăescu

2022

Journal of Energy Resources Technology

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“…Then, a steady-state simulation is performed through the use of a multireference frame method. The walls are treated as adiabatic since, under continuous flow conditions, the expansion ratio has been demonstrated to not vary with respect to the type of boundary condition imposed [28].…”

Section: Validation Under Steady Flowmentioning

confidence: 99%

Influence of Pulse Characteristics on Turbocharger Radial Turbine

Mosca

Lim

Mihăescu

2021

Journal of Engineering for Gas Turbines and Power

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Due to the reciprocating engine, a pulsating flow occurs in the turbine turbocharger, which experiences conditions far from the continuous flow scenario. In this work, the effects of the characteristics of the mass flow pulse, parameterized through amplitude, frequency and temporal gradient, are decoupled and studied via unsteady Computational Fluid Dynamics calculations under on-engine operating conditions. Firstly, the model is validated based on comparisons with experimental data in steady flow conditions. Then, the effect of each parameter on exergy budget is assessed by considering a +/-10% variation with respect to a baseline pulse. The other factors defining the operating conditions (e.g. mass flow, shaft speed and inflow exergy) are kept the same as the baseline. The adopted approach enables to completely isolate the effects of each parameter in contrast with previous literature studies. Based on the results observed, pulse amplitude is identified as the primary parameter affecting the hot-side system response in terms of turbine performance, heat transfer and entropy generation, while frequency and temporal gradient show a smaller influence compared to it. As the pulse amplitude increases, the turbine work is reported to improve up to 9.4%. Smaller variations are observed for the frequency and temporal gradient analysis. With a 10% increase of the pulse frequency the turbine work is registered to improve by 5.0%, while the same percentage reduction of the temporal gradient leads to an increase of turbine work equal to 3.6%.

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“…On the other hand, the first law of thermodynamics is not sufficient on its own to understand the aerothermodynamic behavior of the turbocharger, such as the losses caused by heat transfer and internal irreversibilities. S. M. Lim et al have performed a numerical CFD-based exergy analysis, in which the CFD results have also been validated with the experimental data, and suggested that the aerothermodynamic performance cannot be fully depicted when based on an energetic consideration alone [1]. Furthermore, S. M. Lim et al concluded that the amount of losses caused by heat transfer and internal irreversibilities occurs during the expansion process and fluctuates between factors of 8 and 15 for different operating points.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the traditional approach via the first law of thermodynamics does not provide adequate insight into the prevalent aerothermodynamic losses. By introducing the entropy term to quantify the irreversibility The diabatic (i.e., non-adiabatic) behavior and heat transfer within the turbocharger is significant, especially at low operating speeds, as the effects of the heat transfer dominate the aerodynamic turbine expansion work, leading to overestimation of the turbine power and isentropic efficiency [1]. Therefore, the characterization of heat flows in turbochargers is of great interest beyond the state of the art.…”

Section: Introductionmentioning

confidence: 99%

Experimental Energy and Exergy Analysis of an Automotive Turbocharger Using a Novel Power-Based Approach

2021

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The performance of turbochargers is heavily influenced by heat transfer. Conventional investigations are commonly performed under adiabatic assumptions and are based on the first law of thermodynamics, which is insufficient for perceiving the aerothermodynamic performance of turbochargers. This study aims to experimentally investigate the non-adiabatic performance of an automotive turbocharger turbine through energy and exergy analysis, considering heat transfer impacts. It is achieved based on experimental measurements and by implementing a novel innovative power-based approach to extract the amount of heat transfer. The turbocharger is measured on a hot gas test bench in both diabatic and adiabatic conditions. Consequently, by carrying out energy and exergy balances, the amount of lost available work due to heat transfer and internal irreversibilities within the turbine is quantified. The study allows researchers to achieve a deep understanding of the impacts of heat transfer on the aerothermodynamic performance of turbochargers, considering both the first and second laws of thermodynamics.

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Experimental and Numerical Investigation of a Turbocharger Turbine Using Exergy Analysis at Non-Adiabatic Conditions

Cited by 5 publications

References 16 publications

Turbocharger Radial Turbine Response to Pulse Amplitude

Turbocharger Radial Turbine Response to Pulse Amplitude

Influence of Pulse Characteristics on Turbocharger Radial Turbine

Experimental Energy and Exergy Analysis of an Automotive Turbocharger Using a Novel Power-Based Approach

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