High efficiency, low carbon supermarket refrigeration

This paper was presented at the IIR Gustav Lorentzen Conference in Glasgow (Sep. 2004). A new but simple high efficiency refrigeration system design suitable for use in supermarkets has been developed based on standard components so that reliability is not adversely affected and maintenance should be reduced. The vapour compression system takes advantage of lower condensing temperature, sub-cooling of liquid refrigerant, raised evaporator temperature, reduced amount of refrigerant circulating, circulating velocities reduced to the minimum required for oil return and suppression of vapour formation in the liquid lines. A variant of the floating head system has been conceived based on existing standardized components in order to allow a significant decrease in refrigerant inventory and energy consumption while running on traditional refrigerants. The system takes full advantage from any ambient temperature, hence minimizing the temperature lift and possibly returning the highest performance. At lower ambient temperatures the system can operate as a single stage but at higher temperatures a second stage can provide the necessary liquid sub-cooling to achieve the maximum cycle energy efficiency. A simple variant of the system allows the adoption of natural refrigerants. Such as system is predicted to save up to 14% of the energy consumption when compared with the best existing technology. When running on traditional refrigerants, the two stages can be linked with an open intercooler reducing energy consumption by up to 26% when the inefficiency of the indirect heat exchanger is eliminated. Source: 6th IIR Gustav Lorentzen Natural Working Fluids Conference, Conference papers from Day 3 Sessions 5, 6&7, 6/C/12.20. Author: O.Caretta. You can order the proceeding CD-ROM of the Glasgow conference by clicking here.