LNG filling equipment technology can be divided into emission filling and no emission filling. Emission filling is to use the manual vent valve on the vehicle LNG cylinder to discharge the gas in the vehicle LNG cylinder, so as to reduce the pressure in the vehicle LNG cylinder and accelerate the filling speed.

In view of various unfavorable factors of emission refueling, no-emission refueling technology has been more and more favored by the market. Emissions-free filling is to point to in the process of filling only charging line connected to the low temperature storage tank, the filling process of other line has no connection with the outside world [. No emissions axis of LNG filling equipment adopts has a better effect of direct injection at the top of the single pipe structure, reduce the filling resistance, can make the cylinder inner part of the gas phase by LNG liquefaction, to keep the israelites that pressure in the filling process of relative stability. When a large number of saturated liquid LNG from low temperature storage tank into the vehicle LNG cylinders, added the direct absorption of LNG vehicle LNG cylinders gas heat, reduce the pressure in the bottle, reduce vehicle LNG cylinders at the top of the gas phase space, Thus, the air filling speed is improved.

LNG is used as vehicle fuel. During the storage process, due to the input of external heat, the pressure in the vehicle LNG cylinder continues to rise, which will eventually lead to excessive LNG emissions and the composition of LNG in the cylinder will gradually become heavier, thus affecting the performance and life of the engine. In order to solve the problems of pressure control and fuel transportation, undercooling process and saturation process are usually used in vehicle air supply systems [14].

Super-cooling technology for gas supply system, automobile cylinders are stored in low saturation pressure cold LNG (pressure is 0.345 MPa), carried by the same volume of large amount of fuel, LNG vehicles travel distance of the far, but in order to achieve the engine required delivery pressure system (0.4 ~ 1.0 MPa), usually need to add supercharging system to achieve the required working pressure, make the system more complicated and economy.