Off-design operation of ORC and CO2 power production cycles for low temperature surplus heat recovery

In process industry, large amounts of surplus heat are available. Electricity production is an interesting method to recover this energy. This paper focuses on the off-design operation of the Rankine cycles and compares the behaviour of transcritical CO2 cycles and an organic Rankine cycle (ORC) with R-123 as the working fluid. The simulations show that the ORC is more sensitive than the CO2 cycle to reduction in available heat, and will with only small changes get droplets in the inlet of the expander. With small increments in the available heat source, the CO2 cycle also seem to have a marginally better response without control of the process.