Studying effects of storage types on performance of CNG filling stations

At CNG filling station, compressed natural gas must be stored in storage system in order to make the utilization of the station more efficient. There are two systems for storing natural gas namely buffer and cascade storage systems. In buffer storage, CNG is stored at single high-pressure reservoirs. The cascade storage system is usually divided into three reservoirs, generally termed low, medium and high-pressure reservoirs. In current study, based on first and second laws of thermodynamics, conversation of mass and real gas assumptions, a theoretical analysis has been developed to study effects of reservation type on performance of CNG filling stations and filling process. Considering the same final natural gas vehicle cylinder (NGV) on-board in-cylinder pressure for both storage systems, the results show that each storage type has advantages over the other. The best configuration should be selected by balancing these advantages.

► Effects of reservation type on performance of CNG filling stations studied. ► The reservations types are buffer and cascade storage systems. ► The filling time in the buffer system is about 66% less than cascade storage system. ► The charged mass for cascade system is about 80% of buffer system. ► The advantage of cascade system is less required compressor input work.