Liquid helium may show superfluidity. Helium we quickly can establish that ideal gas laws are sufficient to calculate a process above an entropy of 13 j g k and below a pressure of 2 0 mpa covering a large part of any helium cycle.

Liquid Helium Wikipedia

Linde is the popular in industry for providing helium liquefaction solutions.

How to liquefy helium. Its boiling point and critical point depend on which isotope of helium is present. This means that as temperature decreases the pressure and or volume decrease and vice versa. Most of the helium liquefiers are claude cycle based.

1 1 helium liquefaction process helium liquefies at 4 4 k 268 75 c. At standard pressure the chemical element helium exists in a liquid form only at the extremely low temperature of 269 c about 4 k or 452 2 f. The first is cooled in the heat exchanger labeled he1 with the help of helium vapours while the other part passes through the heat exchanger he2 to be cooled with hydrogen vapours.

Liquid helium is a physical state of helium at very low temperatures if it is at standard atmospheric pressures. According to this you can either cool the helium to liquid or decrease the volume. Linde helium liquefiers are based on claude cycle.

Decreasing the volume most of the time means applying pressure. Close to the two phase area and below 2 2 k helium becomes anything but ideal 2 detailed calculation of any process needs to relate of the real gas data. Pressure required to liquefy a gas at its critical temperature.

Both these streams combine to be passed through the liquid hydrogen heat exchanger he3 before finally again getting cooled in he4 by helium vapours.