Conversion of exhaust gases from the internal combustion engine to electrical power at small scale

Concept of a small scale waste heat recovery system using exhaust gases from the internal combustion engine is presented in the paper. The system is based on the Clausius-Rankine steam cycle as recommended for this purpose due to its simplicity and relatively lower investment costs if compared to the organic Rankine cycle systems. The source of the waste heat were exhaust gases from the internal combustion engine fueled with a biogas (60% methane and 40% carbon dioxide). The engine power was assumed of 700 kW. On the basis of thermodynamic analysis the following results were obtained: the waste heat recovery boiler produced steam at amounts of 158 kg/h at 350°C and 12 bar. The turbine generates power of 24 kW and overall heat-to-electricity efficiency of this power system was approximately 17%. Furthermore, impacts of several parameters on cycle efficiency and turbine power were investigated with aim to provide the system optimization. Summing up, waste heat recovery systems, as presented in the paper, can be proposed as promising solutions for increasing overall efficiency of fuel-to-power conversion systems based on combustion technologies.