This work investigates the optimal working fluids for Organic Rankine Cycles ORC with focus on thermo-physical, environmental and safety aspects. The choice of the working fluid is of key importance for the cycle efficiency and the Net Work Out. In this study more than 100 pure fluids are investigated from many different perspectives.
REFPROP 9 was used as the main source for the thermo-physical data of working fluids. The data in REFPROP 9 were connected to MatLab and different dynamical models were built for simulations and numerical analysis.
To determine what is the optimal working fluid for Organic Rankine Cycle is not easy process, there are many different criteria to deal with. These criteria mainly has to do with working fluids thermodynamic and heat transfer properties from a side and safety and environmental aspects from other side. To study the working fluids thermodynamically, the process needs building accurate thermodynamic models and running numerical calculations in MatlLab.
In this work several simulation scenarios with different boundary conditions are done. For every heat source and heat sink there is a series of working fluid candidates. The temperature profile in evaporator and condenser is of key importance for energy losses and best energy utilization.
Sometimes the condenser and evaporator pressure limits the using of some working fluids. A very high evaporator pressure needs more advanced equipment and stronger materials and subsequently increase costs. A very low condenser pressure involves air infiltration problems and needs expensive and special vacuum equipment to reject air from the cycle.
It is hard to find all the needed information about environmental and safety data for some working fluids and it is harder to find the prices. Appendix 1 shows the pure working fluids which exist in NIST REFPROP 9. The environmental and safety data for some working fluids are completed with help of “Physical, Safety and Environmental data” by J. M. Calm.
Author: Nouman, Jamal