Learn more about working fluids refrigerants for organic Rankine cycle and high-temperature heat pumps
The critical temperature firstly limits working fluids in ORC and HTHP. Traditionally, HTHP and ORC work in subcritical conditions. Consequently, working fluids critical temperature must be above evaporation/condensation temperatures.
In this sense, refrigerants used in conventional heat pumps and refrigeration applications are unsuitable. Thus, at this time, standard ORC and HTHP are not designed considering R32, R134a, propane or R1234yf, among other fluids.
Secondly, after this filter, many other aspects must be considered, such as thermodynamic and transport properties, chemical and thermal stability, material and lubricating oil compatibility, availability, cost, and last but not least, environmental and safety characteristics.
Environmental characteristics comprise ozone depletion potential (ODP) and global warming potential (GWP) parameters, but also the energy performance of the resulting cycle. Besides, safety characteristics involve flammability and toxicity, classified by the ASHRAE 34 Standard. This causes some other working fluids not to accomplish these restrictions, including pentane, R245fa, or benzene, among others.
Rank® is a company committed to the environment. Therefore, we only consider environmentally friendly and safer fluids such as HFO and HCFO. The working fluid of each Rank® ORC or HTHP model is carefully selected to optimize the energy or heating production and minimize costs.