Novel industrial gas filling station with an internal cooling system dedicated for speeding up cylinder charging process - Energy and exergy analysis

In the paper, a novel patented system which meets the demand to shorten gas cylinder charging times is described and investigated. It has been analytically proven that the charging time of a 50-L gas cylinder can be reduced to 15 min (twice as fast as in conventional systems) and keep its temperature within safe limits when the cylinders are cooled. The second advantage of the introduced novel system is the cold exergy recovery from the evaporation process of the liquefied gas. The recycled cold fully covers the demand for cooling power, making the system self-sufficient. A very useful and common method to evaluate the thermal performance of any recovery system is energy and exergy analyzes, which are also applied to the presented system. The paper provides numerical simulations based on linear thermodynamic analysis, supported by CFD simulations. To optimize the cold exergy recovery and cylinder cooling process, three different cooling intensities are compared: ΔT = 10, 20, 30 K. These are defined by the assumed growth of the gas temperature during the filling process. A smaller temperature increase means a higher cooling airflow rate, which results in a more intense cooling process. Analyses were carried out for three selected gases: argon, nitrogen, and oxygen, all compressed to the same final pressure of 30 MPa. In total, it gives nine different cases, which are analyzed and compared. Analysis brings a deeper insight into the system and provides indications for designing a real installation.