Analysis of a possible application of a small power plant in the Organic Rankine Cycle, which apply waste heat from a combustion engine

Some considerations on the waste heat treatment, heat and power combined generation and principles of the Organic Rankine Cycle and its application are produced. A thermodynamic screening of eight working fluids for Organic Rankine Cycle (ORC) was carried out. All investigated agents were single component fluids. The considered ORC systems operated at the upper temperature in the range Tmax=146-185°C and the lower one Tmin=27-37°C. The highest pressure in the cycles equalled pmax=3500 kPa and pmin=85 kPa. The cycles were run at subcritical pressures and the saturated vapour line was of the overhanging type in all cases. Heat regeneration was not considered in this paper. The heat source for the ORC system was heated air exhausted from the cooling system of an opposed-piston engine. The temperature of this heat at the inlet to ORC was equal to Th,in=230°C. Air was also the heat sink for the ORC with the inlet temperature Tcold,in=20°C. The power output of the ORC, neglecting electric generator efficiency, was kept in the range N=10-11 kW. Calculated thermal efficiencies h held values between 0.121 and 0.164.