Abstract: A pressure vessel refueling system enables fast refueling of Compressed Natural Gas (CNG) fuel tanks. The system includes a pressure vessel having a gas inlet/outlet port and a liquid inlet/outlet port; a first liquid at least partially filling the pressure vessel; a liquid layer of a second liquid floating on top of the first liquid, wherein the second liquid is immiscible with the first liquid; a gas at least partially filling the pressure vessel above the liquid layer of the second liquid, the gas in fluid communication with the gas inlet/outlet; and a pump in fluid communication with the liquid inlet/outlet of the pressure vessel, whereby the first liquid can be pumped or returned to/from storage into or out of the pressure vessel.

Abstract: A pressure vessel refuelling system enables consistent mass flow rates and reduces the in-tank temperature rise caused by the heat of compression as gas is added to a vessel. The system includes a pressure vessel having a first gas inlet/outlet port and an interior cavity, and a nozzle is in fluid communication with the first gas inlet/outlet port. The nozzle and the pressure vessel are thermally coupled such that Joule-Thomson expansion of a gas flowing through the nozzle cools the interior cavity and contents of the pressure vessel.

Abstract: A compressed gas transfer system comprising at least one first pressure vessel able to hold a volume of gas; and a first gas line to allow gas to pass out of the at least one first pressure vessel wherein the volume of the first pressure vessel is able to be varied to maintain the gas within the pressure vessel at a constant pressure.