Pumping work in the organic Rankine cycle

Calculation results for the pumping work in the ORC systems are presented. Analysis has been carried out for 18 different organic fluids that can be used as working media in the subcritical ORC power plants. An attempt was made to find correlations between various thermo-physical properties of working fluids, specific work and power of the cycle. The simulation results allow a statement that the working substances with relatively low critical temperature have a greater cycle pressure range for the specified cycle temperature range than those with higher critical temperatures. The greater cycle pressure range contributes to a higher pumping power demand. Due to the fact that the specific pumping work does not result in explicit statement on the suitability of some working fluid to a specified ORC power plant, a definition of the power decrease factor κ is introduced.