HFC-245fa and HFO-1234zeE have been selected in a research project for applying Organic Rankine Cycle (ORC) technology to recovering heat in a galvanizing steel cooling system.
HFC-245fa has a better energy efficiency than HFO-1234ze(E) and is non flammable, while HFO-1234ze(E) is mildly flammable but has a lower expansion rate (favourable for cost reasons).
In the galvanizing process, thin (0.3 2.5 mm) steel sheets are coated with zinc in a bath at around 460 C. Steel sheets heat treated at 600 C for mechanical properties have to be cooled precisely down to the zinc pot temperature by jet cooling with high speed jets of a hydrogen-nitrogen mixture at 50-100 C.
The gas mixture leaves the system at 150-250 C. The ORC system will be able to recover power from the hot gas to run the large gas recirculation fan.
Source : CMI Industry Greenline