R290 concentrations arising from leaks in commercial refrigeration cabinets.

Currently R290 is used widely in small commercial refrigeration cabinets. In the majority of products refrigerant charge sizes are up to 150 g per refrigerant circuit, which is the limit implied by the product standard IEC 60335-2-89. Some larger cabinets that are constructed to EN 378 or ISO 5149 use up to 1.5 kg of R290. Work is underway to extend the range of charge sizes within the product standard. As a contribution to this process, some of the parameters that affect the development of concentrations within the room in the event of a leak have been examined in order to identify important boundaries and considerations when applying larger charge sizes. Several of these parameters have been investigated by carrying out simulated leaks of R290. These include charge size, leak mass flow rate, leak orientation, height of refrigerant-containing parts, cabinet doors, condensing unit enclosures, airflow and room congestion. R290 concentrations are measured at various locations such as the room floor, within and at the rear of the cabinet, and within the condensing unit enclosure and the adjacent cabinets. These measurements are used to understand the implication of leaks in installations and possible construction features that could help limit the development of high concentrations and thus limit the risk associated with using larger refrigerant charges.