Thermodynamic comparative analyses between (organic) Rankine cycle and Kalina cycle

This paper presents the thermodynamic comparative analyses among the organic Rankine cycle (ORC), Rankine cycle (RC) and Kalina cycle system 11 (KCS 11) with low-grade heat. R245fa is selected as the working fluid for the ORC, and NH3-H2O mixture is selected as the working fluid for RC and KCS 11, respectively. Water is chosen as the heating fluid of the low-grade heat, and the same temperature and mass flow rate of water are as the standard conditions for the comparative analyses among the ORC, RC and KCS 11. The thermodynamic analyses and the comparisons among these different cycles are conducted. Results show that the maximum net power output (W-net_max) of the cycles can be ranked from high to low: RC_NH3-H2O>ORC_R245fa>KCS 11. In the KCS 11, there exist two kinds of turning points of the NH3 mass fraction to yield the Wnet max with the water temperature. (C) 2015 Published by Elsevier Ltd.