REVIEW ON  TECHNOLOGY ADVANCEMENT OF HELIUM REFRIGERATOR / LIQUEFIER : INDIA & WORLD

Dr Tripti Sekhar Datta

 

Head, Cryogenics & Applied Superconductivity Group, Inter- University Accelerator Centre.

New Delhi. India

&

 President, Indian Cryogenic Council

 

 

The humble Collins helium liquefier with a liquefaction capacity of 4 litres/hr (12-15 W at 4.2 K) has undergone metamorphosis to giant machines producing cold to the tune of 18 kW and still bigger machines with 25-30 kW capacity are in sight.  India, though in its infancy compared to western world, nevertheless has made great stride since 1995, on installing high capacity helium liquefiers at some selected places. Power required having 1 W refrigeration at 4.2 reduced from 1000 W in earlier small capacity refrigerator to 225 W for large refrigerator. This is contributed mainly with optimization on thermodynamic cycle and improvement on efficiency of expander, compressor and heat exchanger. Overall efficiency also improved as heat leak to cold surface/ per unit watt of refrigeration is reduced. Similarly low pressure drop across plate-fin heat exchanger compared to earlier Collins or GH heat exchanger reduces the compressor power.

 

In India starting with first Collins machine (ADL - 52) in 1952 at National Physical Laboratory we now have about 40 He-liquefiers/ refrigerator in the country. Prior to 1995 most of the research laboratories used to have liquefiers with 10-20 l/hr capacity. Today there are dozens of helium liquefier with capacity more than 100 litres/ hr.  Total available capacity jumped from mere 150 litres/ hr in 1995 to 2500 litres/ hr in 2016.  This growth can be attributed to our national  projects on accelerators and fusion programme which are using superconducting technology.  Majority of the earlier machines in India were based on the reciprocating expansion engine and the reciprocating compressor. Later few reciprocating compressor was replaced with screw compressor to upgrade the capacity. Considering upgraded technology on turbine and also higher capacity refrigerator is available only with turbine, percentage of turbine based plant has improved significantly after 1995. Scientific laboratories under Department of Atomic Energy demonstrated the successful development of helium liquefier based on turbine and piston based reciprocating expander. Efforts are on to upgrade the capacity and efficiency of each individual components of helium liquefier

 

 The talk will review on technology up-gradation of helium refrigerator since the first production of liquid helium in 1908 by Kamerlingh Onnes along with the growth of helium liquefier and their development effort in India.