Aerothermodynamics and Exergy Analysis in Radial Turbine With Heat Transfer

Lim, Shyang Maw; Dahlkild, Anders; Mihăescu, Mihai

doi:10.1115/1.4040852

Cited by 16 publications

(13 citation statements)

References 21 publications

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“…Based on the flow thermal energy conversion ratios, the design of a heat exchanger was improved for better waste heat recovery [3]. In particular, many turbocharger studies focused on the utilization of energy carried by ICE pulsating flows, such as the impacts of different unsteady inlet conditions [4][5][6] along with reducing the thermal dissipation of exhaust pulses upstream of the turbine [7][8][9] and optimizing the configurations of turbocharging systems [10,11], to name a few.…”

Section: Literature Reviewmentioning

confidence: 99%

“…Additionally, the energy quantities inside the ICE system can be discussed in specific (i.e., the unit mass basis) and mass flow rate based forms. The specific energy quantity as an intensive property is commonly used to compare the energy transport by unit mass under different operating conditions [7,14]. For instance, the specific exhaust gas enthalpy and exergy in a gasoline compression ignition engine were compared to indicate the input energy change of the turbocharger and waste heat recovery efficiency under different combustion strategies [14].…”

Section: Literature Reviewmentioning

confidence: 99%

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Numerical Analysis of Engine Exhaust Flow Parameters for Resolving Pre-Turbine Pulsating Flow Enthalpy and Exergy

2021

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Energy carried by engine exhaust pulses is critical to the performance of a turbine or any other exhaust energy recovery system. Enthalpy and exergy are commonly used concepts to describe the energy transport by the flow based on the first and second laws of thermodynamics. However, in order to investigate the crank-angle-resolved exhaust flow enthalpy and exergy, the significance of the flow parameters (pressure, velocity, and temperature) and their demand for high resolution need to be ascertained. In this study, local and global sensitivity analyses were performed on a one-dimensional (1D) heavy-duty diesel engine model to quantify the significance of each flow parameter in the determination of exhaust enthalpy and exergy. The effects of parameter sweeps were analyzed by local sensitivity, and Sobol indices from the global sensitivity showed the correlations between each flow parameter and the computed enthalpy and exergy. The analysis indicated that when considering the specific enthalpy and exergy, flow temperature is the dominant parameter and requires high resolution of the temperature pulse. It was found that a 5% sweep over the temperature pulse leads to maximum deviations of 31% and 27% when resolving the crank angle-based specific enthalpy and specific exergy, respectively. However, when considering the total enthalpy and exergy rates, flow velocity is the most significant parameter, requiring high resolution with a maximum deviation of 23% for the enthalpy rate and 12% for the exergy rate over a 5% sweep of the flow velocity pulse. This study will help to quantify and prioritize fast measurements of pulsating flow parameters in the context of turbocharger turbine inlet flow enthalpy and exergy analysis.

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Section: Literature Reviewmentioning

confidence: 99%

Section: Literature Reviewmentioning

confidence: 99%

Numerical Analysis of Engine Exhaust Flow Parameters for Resolving Pre-Turbine Pulsating Flow Enthalpy and Exergy

2021

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“…Usually, a time step corresponding to a degree of rotation of 1 deg is recommended. Some cases might however allow for a larger time step size (e.g., Lim et al (2018) [16]). Depending on the application, the benefit of rotating the blades using the RBM approach and therefore obtaining a physically accurate solution can outweigh the high computational effort.…”

Section: Fan Modellingmentioning

confidence: 99%

Evaluation of the Multiple Reference Frame Approach for the Modelling of an Axial Cooling Fan

et al. 2019

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The modelling of rotating parts, such as axial fans, is one of the main challenges of current CFD simulations of industrial applications. Different methods are available, but the most commonly used is the multiple reference frame (MRF) method. This paper investigates how different flow properties, such as temperature, pressure and velocity, develop when passing through the MRF domain. The results are compared to the more physical rigid body motion (RBM) approach. It is found that the MRF method transports the upstream properties with the streamlines of the relative velocity from the upstream to the downstream interface. This leads to a non-physical rotation by an angle that is dependent on the length of the domain and the ratio between axial and tangential velocity in the MRF region. The temperature field is more affected than the flow field, since wake structures from upstream obstacles are destroyed due to the wake of the blades. Downstream structures affect the flow in the upstream region by an increase in static pressure, which causes the streamlines in the MRF zone to slow down. Depending on the size of the obstacle, this can cause substantial distortions in the upstream and downstream flow field.

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“…In an experimental campaign, Shaaban and Seume [8] registered a 55% turbine power decrease compared to adiabatic conditions, demonstrating the effectiveness of thermal insulation to increase the turbine power. On the numerical side, Lim et al [9] reported a decrease of the turbine power up to 10%, for increasing levels of heat transfer, compared to adiabatic conditions.…”

Section: Introductionmentioning

confidence: 99%

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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Aerothermodynamics and Exergy Analysis in Radial Turbine With Heat Transfer

Cited by 16 publications

References 21 publications

Numerical Analysis of Engine Exhaust Flow Parameters for Resolving Pre-Turbine Pulsating Flow Enthalpy and Exergy

Numerical Analysis of Engine Exhaust Flow Parameters for Resolving Pre-Turbine Pulsating Flow Enthalpy and Exergy

Evaluation of the Multiple Reference Frame Approach for the Modelling of an Axial Cooling Fan

Turbocharger Radial Turbine Response to Pulse Amplitude

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