Challenges and opportunities to design chillers using low and medium GWP fluids.

Among the possible refrigerants, low pressure fluids offer the best theoretical cycle efficiency. But because of high volumetric flow, current chiller designs must be completely revisited with such fluids; otherwise, the footprint of units can be huge, or (and) the potential fluid benefits can be wasted in penalties like high internal pressure losses etc. Low pressure fluids like R-11 and R-123 were used in the past, but new technologies were introduced since then like the extensive use of direct drive variable speed motors and falling film evaporators. It is not enough to just “recycle” platforms formerly used for low pressure fluids, or to change fluid in state of the art products using higher pressure fluids. This paper presents challenges, opportunities and trade-offs in the choice between various categories of fluids for chillers.