Geyser phenomenon

Geyser phenomenon refers to the eruption phenomenon caused by the cryogenic liquid being transported down the vertical long pipe (referring to the length-diameter ratio reaching a certain value) due to the bubbles produced by the vaporization of the liquid, and the polymerization between the bubbles will occur with the increase of bubbles, and finally the cryogenic liquid will be reversed out of the pipe entrance.

Geysers may occur when the flow rate in the pipeline is low, but they need to be noticed only when the flow stops.

When cryogenic liquid flows down in the vertical pipeline, it is similar to the precooling process. Cryogenic liquid will boil and vaporize due to heat, which is different from the precooling process! However, the heat mainly comes from the small ambient heat invasion, rather than the larger system heat capacity in the pre-cooling process. Therefore, the liquid boundary layer with relatively high temperature is formed near the tube wall, rather than the vapor film. When the liquid flows in the vertical pipe, due to the environmental heat invasion, the thermal density of the fluid boundary layer near the pipe wall decreases. Under the action of buoyancy, the fluid will reverse upward flow, forming the hot fluid boundary layer, while the cold fluid in the center flows downward, forming the convection effect between the two. The boundary layer of the hot fluid thickens gradually along the direction of the mainstream until it completely blocks the central fluid and stops the convection. After that, because there is no convection to take away heat, the temperature of the liquid in the hot area rises quickly. After the temperature of the liquid reaches the saturation temperature, it begins to boil and produce bubbles The zingle gas bomb slows the rise of bubbles.

Due to the presence of bubbles in the vertical pipe, the reaction of the bubble’s viscous shear force will reduce the static pressure at the bottom of the bubble, which in turn will make the remaining liquid overheated, thus producing more vapor, which in turn will make the static pressure lower, so mutual promotion, to a certain extent, will produce a lot of vapor. The phenomenon of a geyser, which is somewhat similar to an explosion, occurs when a liquid, carrying a flash of steam, ejects back into the pipeline. A certain amount of vapor ensued with liquid ejected to the upper space of the tank will cause dramatic changes in the overall temperature of the tank space, resulting in dramatic changes in pressure. When the pressure fluctuation is in the peak and valley of pressure, it is possible to make the tank in a state of negative pressure. The effect of pressure difference will lead to structural damage of the system.

After the vapor eruption, the pressure in the pipe drops rapidly, and the cryogenic liquid is re-injected into the vertical pipe due to the effect of gravity. The high speed liquid will produce a pressure shock similar to the water hammer, which has a great impact on the system, especially on the space equipment.

In order to eliminate or reduce the harm caused by the geyser phenomenon, in the application, on the one hand, we should pay attention to the insulation of the pipeline system, because the heat invasion is the root cause of the geyser phenomenon; On the other hand, several schemes can be studied: injection of inert non-condensing gas, supplementary injection of cryogenic liquid and circulation pipeline. The essence of these schemes is to transfer the excess heat of cryogenic liquid, avoid the accumulation of excessive heat, so as to prevent the occurrence of geyser phenomenon.

For the inert gas injection scheme, helium is usually used as the inert gas, and helium is injected into the bottom of the pipeline. The vapor pressure difference between liquid and helium can be used to make mass transfer of product vapor from liquid to helium mass, so as to vaporize part of cryogenic liquid, absorb heat from cryogenic liquid, and produce overcooling effect, thus preventing the accumulation of excessive heat. This scheme is used in some space propellant filling systems. Supplementary filling is to reduce the temperature of cryogenic liquid by adding supercooled cryogenic liquid, while the scheme of adding circulation pipeline is to establish a natural circulation condition between pipeline and tank by adding pipeline, so as to transfer excess heat in local areas and destroy the conditions for the generation of geysers. 

Tuned to the next article for other questions！

HL Cryogenic Equipment 

HL Cryogenic Equipment which was founded in 1992 is a brand affiliated to HL Cryogenic Equipment Company Cryogenic Equipment Co.,Ltd. HL Cryogenic Equipment is committed to the design and manufacture of the High Vacuum Insulated Cryogenic Piping System and related Support Equipment to meet the various needs of customers. The Vacuum Insulated Pipe and Flexible Hose are constructed in a high vacuum and multi-layer multi-screen special insulated materials, and passes through a series of extremely strict technical treatments and high vacuum treatment, which is used for transferring of liquid oxygen, liquid nitrogen, liquid argon, liquid hydrogen, liquid helium, liquefied ethylene gas LEG and liquefied nature gas LNG.

The product series of Vacuum Jacketed Pipe, Vacuum Jacketed Hose, Vacuum Jacketed Valve, and Phase Separator in HL Cryogenic Equipment Company, which passed through a series of extremely strict technical treatments, are used for transferring of liquid oxygen, liquid nitrogen, liquid argon, liquid hydrogen, liquid helium, LEG and LNG, and these products are serviced for cryogenic equipment (e.g. cryogenic tanks, dewars and coldboxes etc.) in industries of air separation, gases, aviation, electronics, superconductor, chips, automation assembly, food & beverage, pharmacy, hospital, biobank, rubber, new material manufacturing chemical engineering, iron & steel, and scientific research etc.