Abstract
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.
Highlights
In the light of growing awareness of the environmental impacts of CO2 -intensive processes on global warming, the need for the optimization of energy conversion systems has gained significant importance in recent decades
Are shown in the form of a power-based diagram in Figure 5 The investigated operating points are indicated by a circle and correspond to the highest isentropic power (ICP) of every speed line, starting from 37 k RPM and increasing in increments of 13 k RPM, up to 87 k RPM for 400 ◦ C and 800 ◦ C turbine inlet temperatures (TIT), and 100 k RPM for 600 ◦ C
Based on the ordinate intercept for each TIT scenario, the heat loss can be quantified to calculate the corrected turbine aerodynamic power PT,corr according to Equation (2) and, the turbine isentropic efficiency ηT,is,corr
Summary
In the light of growing awareness of the environmental impacts of CO2 -intensive processes on global warming, the need for the optimization of energy conversion systems has gained significant importance in recent decades. In the past few years, engine downsizing has been seen as one of the key technologies to reduce fuel consumption and emissions. This is achieved by reducing the size of the internal combustion engine (IC engine) while using the turbocharger to compensate for the power loss due to the engine size reduction. A turbocharger is composed of a turbine, using the thermal energy from the hot exhaust gas from the combustion process of the IC engine and a compressor that is mechanically connected to the turbine via a rotating shaft. Recovering the mostly wasted thermal energy of the exhaust gas of the IC engine via driving the turbocharger turbine and delivering the demanded compressor power gives the required engine boost pressure
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