A study setup for a GM cooler based helium liquefier

A helium liquefier study setup has been developed at IUAC using a 1.5 watt at 4.2K Gifford Mac Mahon (GM) cryocooler, for understanding the heat transfer mechanism between the gas and the cryocooler surface at all the four stages of cooling. A thermo-siphon loop is added to the liquefier bottom with a heater to know the precise liquefaction rate under various study conditions. Inclusion of thermo-siphon loop reduces the consumption of helium gas by utilising the evaporated gas in a controlled manner. The study setup has other capabilities to measure the liquefaction rate under various conditions such as varied pressure, with or without heat exchanger at both cooling stages, and with or without nylon shroud in the regenerator regions etc. The experimental setup is successfully put in place and preliminary experimental results have started coming in. A liquefaction rate of 18.4 liters per day (lpd) has been measured at STP condition with the basic configuration.