Comparative analysis of vehicle turbochargers in energy microgeneration for different compoundings

In this work, possible gas microturbine configurations derived from vehicular turbochargers are evaluated with respect to the number of shafts and electric efficiency-enhancing devices (intercooler, heat recover and reheater). Turbocompounding application is designed for energy microgeneration combining vehicular turbocharger with power turbine (PT). The analysis was performed using Cycle-Tempo software. Ten different configurations of gas microturbines were studied, assessing the parameters of power and isentropic efficiency. For these evaluations, the turbochargers were defined to compose the turbocompounding, using the performance maps from a manufacturer. The main characteristics of seven turbocharger models were identified, which come with different combinations of turbine and compressor rotors. The best configuration found in the simulations was one turbocharger, one turbocompounding, one intercooler, one heat recovery unit and two stages of reheating, with values of power and electric efficiency of 11.98 kW and 5.21%, respectively. The electric efficiency increased from 3.5 to 3.99% adjusting the air mass flow rate and isentropic efficiency of compressors and turbines in the configuration with a turbocharger and with a turbocompounding. In addition, the latter composition was linked to a basic organic Rankine cycle (ORC) operating with R123 refrigerant in order to recover waste heat. Thus, the net total efficiency increased to 8.71%. Moreover, when the same ORC system operating with water combines heat and power generation (CHP), the overall efficiency of the complete system was 70.7%.