An innovative R-744 system goes offshore: fully modulating racks for ships and boats

Following its established adoption in retail refrigeration, the use of R-744 as a natural refrigerant has attracted the interest of other fields of application that require both a low environmental impact and low energy consumption.

Here CAREL will present the use of its top-in-class multiDC rack for marine applications. Two fully-modulating booster racks with transcritical R-744 were installed on a cargo ship to serve its cold rooms.
In this presentation, we will outline the excellent performance achieved in this unique environment, describing the challenges of marine cooling and the reasons why R-744 suits such a wide range of refrigeration applications. In the installation system examined here, the cold rooms are served by two identical multiDC booster racks, with redundancy in the event of problems. The racks serve two pressure levels, cooling a medium temperature cold room at 3 °C and a low temperature cold room at -22 °C.
Oil management in such a wide modulation range (20-100%) is handled using a patented technology developed by CAREL, which ensures the constant presence of oil in each compressor. System commissioning was made possible by CAREL’s extensive network of subsidiaries around the world, providing technical support in the field, combined with the BOSS supervisory system to remotely monitor the system’s performance and behaviour. Natural refrigerants are a viable solution even for the most extreme applications, and as seen with these offshore units, they can be adopted in high-efficiency layouts such as the multiDC, which offers compact dimensions, low noise and low energy consumption.