Life Cycle Cost Analysis for Industrial Refrigeration Systems: a comparison between R-744 and R-717

Since several years carbon dioxide (CO2 - R-744) has been identified as one of the best alternatives to high GWP refrigerants in a number of market sectors, such as supermarkets and sanitary hot water heat pumps.
However, experts are sometime concerned about its use in larger industrial systems, with lower energy efficiency and lack of large scale R-744 trans-critical components being considered as main limiters in this sense, thus leaving anhydrous ammonia (NH3, R-717) as the preferred choice for larger duty applications.
And while ammonia is an excellent refrigerant from a thermodynamic standpoint, its application can be hampered by local government regulation and, sometimes, by its associated energy efficiency drawback. For instance, local safety regulation may lead to the installation of smaller R-717 charges thus making it difficult to implement flooded configurations and thus negatively impacting the overall system energy efficiency. In recent years, however, significant technological advances, such as large-displacement
6 cylinders R-744 trans-critical compressors are enabling cost effective carbon dioxide solutions for industrial refrigeration.
This work describes a life cycle cost comparison between various R-744 and R-717 technologies applied to an industrial R-744 system featuring 3 MW refrigeration capacity.