Indigenous Development of Helium Liquefier and Cyclic Refrigerators P K Kush Head, Cryo Engineering and Cryo Module Development Section Raja Ramanna Centre for Advanced Technology, Indore, INDIA Web:

India’s First Indigenously Developed Helium Liquefier

Components of a Helium Liquefier  Expansion Devices  Heat Exchangers  Thermal Insulation system (Cold Box)  Process Control Components  Thermally Insulated Transfer Lines  Main Dewar (To collect Liquid)  Cyclic Compressor

Schematic of a Helium Liquefier

Cryogenic Expansion Engine Expansion Engine : A Critical part in Claude/ Collins cycle based cryogenic refrigerators and liquefiers Types of Expansion Engines Reciprocating Type Turbine Type Reciprocating Type Expansion Engine  High Expansion Ratio  Low Flow Rate  Constant Efficiency Over Wide Range of Operating Conditions.  Less Sensitive to Contamination and Power Fluctuation Problems  Control of Speed/ Flow Rate is Easier

Expansion Engines 3D Model of expansion engine developed at RRCAT Photograph showing expansion engine along with heat exchangers and auxiliary components. 1. Cryogenic Expander, 2. Work extraction mechanism, 3. 1 st heat exchanger, 4. Flywheel

Expansion Engines Expansion Cycle Actual P-V Diagram, near Room Temperature Actual P-V Diagram, at low Temperature

Expansion Engines Distorted P-V Diagram due to valve leakage Graph showing condition when both Inlet and exhaust valves are leaking Graph showing condition better leak tightness of valves

Valves to seal at Cryogenic Temperature

Parameters for 1 st Expansion Engine Diameter: 75 mm, Stroke: 50 mm, Engine speed: 120 rpm Inlet cam opening angle: 50 deg Inlet gas pressure: bara, Inlet Temp., KExpander Eff., %Mass flow rate, g/s Parameters for 2 nd Expansion Engine Diameter: 50 mm, Stroke: 50 mm, Engine speed: 120 rpm Inlet cam opening angle: 45 deg, Inlet gas pressure: bara, Inlet Temp., KExpander Eff., %Mass flow rate, g/s Expansion Engines

Stress analysis of expander liner Temperature profile Temperature profile using 80K anchoring Expansion Engines

Heat Exchangers 300 K 80 K  Low losses of use full refrigeration through  Heat Conduction through solid material – long length  Through radiation – lower surface area  Very low pressure drops – critical pressure for helium: 2.2 bar absolute  Heat Transfer – One side high pressure helium (about 230 psig) – Other side Very low pressure Helium (about 2 psig)

Heat Exchangers Heat Transfer area/ Volume (m 2 / m 3 )700

Specifications of heat exchangers HX- #Efficiency, (%)Fin Tube Heat transfer area (m 2 ) HX HX HX HX HX HX Heat Exchangers Photograph of heat exchanger HX-6 before final welding

Make: Sulzer India, Four Stage, air cooled, oil Lubricated, Reciprocating type (Suitably modified for using it with above expansion engine) Oil Removal System : Designed, Processed and commissioned by us. (Fabricated by local fabricator) Cyclic Compressor

Process Integration of Components  Cyclic Compressor – Suitable compressor lubricating oil – Efficient oil removal system  Quality welding and brazing – problem of “cold leaks”  Processing of components  Pressure Control and Helium Gas management system – 740 liters (NTP) produces 1 liter liquid

Helium gas recovery compressor and Gas recovery bags

Helium Liquefier Developed at RRCAT

Liquefaction Temperature reading of the sensor put inside the liquid helium collection container after J-T valve, when liquefaction was approached for the first time.

Present Status Helium Liquefier developed at RRCAT has been operated more than 6 times so far Each time it was operated till the main Dewar was filled to safe limit liter Nearing 1,000 hours of operation – no breakdown

Team Members Samir Ranjan Sardar, Om Prakash, Krishna Kant Mahawar, Ravindra S. More, Pawan Kumar, Radha Krishan Pathak, Nakka Sathi Babu, S K Joshi, Ashok Kumar Dewangan, M S Ansari, Ravi Sharma, Chetan Singh Sunil Kamthre.

Development of Cyclic Refrigerators –30 K Cryocoolers –10 K Cryocoolers –Cryopump with pumping speed of 1,200 liters/sec for air

Cryocoolers like domestic refrigerator require only electricity to produce low temperature. The Cryocoolers developed at RRCAT are based on Gifford McMahon Cycle. They produce 30K in a single-stage system and 10K in a two-stage system. The entire cryocooler is made of indigenously available components. The Cryocooler consist of two parts, an expander module and a compressor module. The Cryocooler uses Helium gas as working fluid.

30 K Cryocooler 10 K Cryocooler Development of Cyclic Refrigerators

3D Design Model Product Photograph

Reference: “Low-power cryocooler survey”,H.J.M. ter Brake, G.F.M. Wiegerinck, Cryogenics 42 (2002) 705–718. (Data of 235 cryocoolers made world wide) Cryocooler developed by RRCAT: Compressor power 2.19 kW. Cooling power w at 80 K

30 K CCR supplied to user Labs. 06 Numbers of 30 K systems are supplied to different labs + One Compressor Module matched with imported unit and supplied to BARC, Mumbai, Year 2002.

(1) One 30 K Cryocooler supplied during first half of year 2004 (Laser Physics Applications Division, RRCAT), It is being used for study of “Temperature Dependent Transient Photoconductivity & Photoluminescence of Organic Semiconductors” Sample Holder

(2) Another 30 K Cryocooler was supplied to Semiconductor Laser Section, RRCAT during year It is being used to study “Temperature Dependent Electrical Transport measurements a)Hall Mobility, Carrier Concentration, Resistivity b)Study of J – V and e – V characteristics at low Temperature On semiconductors thin films and optoelectronic structures like lasers, detectors – Regularly grown using MOVPE system at RRCAT

(3) Another 30 K Cryocooler was supplied to Laser Physics Applications Division, RRCAT. It is being used to study “Temperature Dependent Carrier Dynamics measurements by Ultra Fast Pump Probe Spectroscopy”

(4) One 30 K Cryocooler is coupled to a specrofluorometer of Jobin-Vyon (Model no- Fluoromax-3) suitable for experiments in Temperature range of 40 to 300K. This is being used in a Photoluminescence setup at BARC Spectroscopy Lab RRCAT Indore.

(5) Another 30 K Cryocooler was supplied to Materials, Advanced Accelerator Science Div.:, RRCAT. On this Cryocooler a cryogen free ac-susceptometer working over a wide temperature range (30-400K) is developed. Which amongst other things is capable of precision measurements of phase transition phenomenon in magnetic materials and superconductors.

(6) Materials, Advanced Accelerator Science Div.: Resistivity versus Temperature Measurements.

10K Cryocooler Lowest Temperature – < 8 K Temperature Stability - ± 0.5 deg

One cryocooler producing a minimum temperature of 7K is installed in Photophysics beamline at Indus-1 for Matrix Isolation Spectroscopy setup being developed by BARC and IGCAR. 3D Model during DesigningProduct Photograph Cryocoolers Developed at RRCAT

Cryopump Using Our 10K G-M Cryocooler Ultimate Vacuum: 4 x 10E-8 mbar Pumping Speed – Nitrogen: 1200 Liter/sec – Argon: 900 Liter/sec Max. Throughput: 2 mbar. Liter/sec Impulsive gas load (Cross over) Tolerance: 60 mbar-Liter Gas Capacity for Nitrogen: 300 Std. liters

Compressor Modules Developed at RRCAT Problems Related with Helium Compressor : Helium gas compressors of suitable size are not available in open market. High heat of compression for Helium Gas Suitable Lubricating Oil for clean operation On line Oil removal system for ultra clean high pressure Helium gas All the above problems solved by modifying Commercially available Air- Conditioner Compressor for helium gas. Completed more than 3,000 hours of operation.

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