Natural circulation precooling experiment of cryogenic pump system

To cool down a cryogenic pump system effectively from room temperature to cryogenic temperature, the natural circulation system is introduced. In this system, the liquid nitrogen is discharged from a liquid nitrogen vessel and goes through the cryogenic pump, then flows in a circle by the reflux pipe back to the vessel. The experimental apparatus is illustrated and test process is described. Heat transfer and pressure drop during the cool-down process is portrayed in the figures. The experimental results demonstrate that the natural circulation is an efficient way to precool the pump system and maintain it at cryogenic temperatures.