Proceeding of 20th National Symposium on Cryogenic held at NIT, Surat, February 2006

Latest Developments in Cryogenics at CERNLaurent Tavian

CERN, Accelerator Technology Department, 1211 Geneva, Switzerland.

The use of cryogenics has started at CERN in the 1960s for cooling high energy physics detectors requiring low temperature technologies to achieve the desired performances. From the 1980s onwards, cryogenics has also been used in CERN accelerators for cooling superconducting accelerating cavities and high field magnets. Today, cryogenics is largely used in the LHC project under construction at CERN for cooling the 27 km magnet ring which requires the largest 1.8 K helium refrigeration and distribution systems in the world as well as its two largest detectors (ATLAS and CMS), which incorporate a variety of cryogenic equipment. In addition,cryogenics is used for cooling specific experiments not related to the LHC complex. After a brief historical review, the present status and latest developments in cryogenics at CERN are reviewed.

Superconducting Cyclotron Project and Related Cryogenic Activities at VECC, Kolkata

Rakesh K. Bhandari (for VECC Staff)Variable Energy Cyclotron Centre, Department of Atomic Energy, Kolkata 700 064

A superconducting cyclotron is under construction at the Variable Energy Cyclotron Centre, Kolkata. This cyclotron will deliver heavy ion beams up to a maximum of 80 MeV/nucleon energy. Fabrication and development of most of the major systems have advanced significantly. The cryostat housing the superconducting coil has been installed in the magnet structure. Installation of the cryogenic delivery line has been completed. Cool down of the main coil has started. The energization of the superconducting coil (stored energy about 22 MJ at full excitation) will start as soon as the coil is cooled to 4.5K temperature in a stable way. The radiofrequency system is under fabrication and will be delivered at site by mid 2005. The design and fabrication work of injection line and the external beam line is in progress.

An overview of Cryogenic Storage & Distribution SystemParag P. Kulkarni

Inox India Limited, ABS Tower, 4th Floor, Old Padra Road Vadodara 390007

Challenges In Cryogenic Propulsion DevelopmentN.K. Gupta

C25 Project,LPSC/ISRO, Valiamala P.O. Trivandrum

Geo-synchronous Satellite Launch Vehicles (GSLV) use Cryogenic Engines for their upper stage due to higher specific impulse. The cryogenic propellants differ from the Earth Storable Propellants in terms of their operating temperatures and storability.Liquid Propulsion Systems Centre is developing Cryogenic stages for its various GSLVs. This paper present the details of the technological challenges faced during the development and also the current status of development.

Space SimulationN.NARASIMHAN

Space Applications Centre, ISRO, Ahmedabad-380015

The spacecraft has to perform its intended function reliably in the hostile space environment during its design lifetime. The thermal design of the spacecraft is validated in the space simulation chamber simulating the effects of hard vacuum, radiative heat sink of space in addition to Sun radiation. The functional performance is tested under thermal vacuum condition. This paper describes the cryogenic engineering aspects of the space simulation chamber. The advances in cryo pumping technology to produce pumping speed of millions of liters /sec, the methods to achieve 100 K on the thermal shroud to simulate radiative heat sink of space, the customized cryo targets to cool the infrared detectors of the remote sensing payloads and the cryo targets in the temperature range of 10 K - 100 K to calibrate sensitive payloads are discussed.

Mixed Refrigerant Cycle Refrigeration and Liquefaction SystemsG. Venkatarathnam and M. Siva Sankar

Refrigeration and Airconditioning Laboratory, Deptt. of Mechanical EngineeringIndian Institute of Technology Madras, Chennai 600036

Mixed refrigerant cycle refrigerators and liquefaction systems are under development in our laboratory. The main advantage of these processes is the requirement of low working pressures, typically less than 20 bar. The cost of the system is quite low since single stage traditional refrigeration (R22) compressors can be used in these systems. In case of nitrogen liquefiers, nitrogen pressures of 5 to 6 bar is adequate in many processes. In this paper, we present some results obtained with our mixed refrigerant refrigerator prototypes.

Cryogenics Applications in Defence V D Abraham, SM

Commanding Officer,Faculty of Instrumentation Technology,EME School, Baroda

Superconducting Linear Accelerator : Analysis of Measured Load at 4.2 K from Total Linac System

T. S. Datta, S. Kar, A. Choudhury, J. Antony, C. Jacob, M. Kumar, S. Babu, R. S. Meena, S. A. Krishnan , A. Roy, Nuclear Science Centre, Aruna Asaf ali Marg. New Delhi – 110067

Cryogenic system for the ongoing project on superconducting linear accelerator at Nuclear Science Centre has been established and is operational for last three years.The main system consists of helium and nitrogen refrigerators, five cryostats to house the superconducting RF cavities and cryogen transfer lines, connecting refrigerators and cryostats. The system has been operated several times to cool down the LINAC and to maintain the temperature at 4. 2 K with present cold mass of approx. 600 kg from partly established LINAC. Individual heat load measurement had been carried out earlier on each subsystem. Recently attempts have been made to measure the total load at 4. 2 K from the integrated cryosystem by balancing the refrigerator operation with an external heater. This paper will be highlighting the procedure followed to measure the total load along with the analysis of heat load from past and present measured parameters.

Development of Helium Refrigeration/Liquefaction System at BARCTrilok Singha, Anindya Chakravartyb, Rajendran Menon, Mukesh Goyal,

Naseem Ahmed and Piyush PrasadCryogenic Technology Division,Bhabha Atomic Research Centre, Mumbai-85 Email : tsingh@magnum.barc.ernet.in, b Email : c_anindya1@rediffmail.com

Turboexpanders constitute the most critical component of most modern cryogenic process plants. All the critical components of this system has been designed and developed. These include expansion turbine, Brake compressor tilting pad bearings,Spiral groove thrust bearings and turboexpander shaft. This system has been in use in an experimental Helium refrigerator capable of producing 1kW at 20K temperature. Stable operation of this plant has been achieved and valuable operational data obtained. The paper throws light on the constituents of a Cryogenic Turboexpander, some fabrication aspects as well as results from some initial experiments of a turboexpander based experimental helium refrigerator.

New Generation of Vortex Tubes - Development and ExperimentsJacob. S.

Centre for Cryogenic Technology, Indian Institute of Science, Bangalore-560 012,

The use of CFD techniques to arrive at optimum design parameters of vortex tubes is described. The optimum cold end diameter (dc), the length to diameter (L/D) ratios and other critical parameters for obtaining the maximum temperature difference between the hot end gas exit and the cold end gas exit are obtained through CFD analysis and validated by experiments. Studies of LOX separation from pre-cooled air flow show that conical vortex tube gives highest LOX purity of ? 96% and higher separation efficiency of ? 61% compared to straight vortex tubes.

Recent Research & Development in the area of Cryogenics and Superconducting Magnets at National Physical Laboratory

R.B. Saxena, M.A. Ansari and Hari KishanNational Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi - 110012

In recent years, many projects involving development of cryogenic infrastructure, accessories & cryostats and R & D on superconducting magnets have been carried out at National Physical Laboratory. These include developments of a) Long hold liquid helium cryostat with a room temperature bore for SC magnet for 100 MHz NMR spectrometer, b) Bucket type 25 litres capacity, 164mm bore liquid helium cryostats, c) Liquid nitrogen transfer pumps and level detectors, d) Rig for testing of cryogenic valves, e) R-T measurements set-up using closed cycle cryo-cooler, f) 7 Tesla 50 mm bore Superconducting magnets, g) A 3.5 Tesla insert type SC magnet with 28 mm working bore, h) A 2.35 Tesla high homogeneity Superconducting magnet using Nb-Ti conductor, suitable for NMR applications, i) An 11 Tesla SC magnet (a hybrid magnet with outer coil of Nb-Ti conductor and inner coil of Nb3Sn conductor) and j)One of the largest size SC magnet based on Nb-Ti technology in the country with a working bore of 255 mm and an overall length of 680 mm.

NIT Rourkela - a New Centre for Education and Research in Cryogenic Engineering

Sunil Kr Sarangi, Director, National Institute of Technology Rourkela - 769 008

Education and research in the field of Cryogenic Engineering has been carried out in our country for nearly three decades. Still, there is significant gap between what we need to sustain a large industrial economy and what we have today. A new facility for education and research in the subject of Cryogenic Engineering has been set up at the Department of Mechanical Engineering, NIT Rourkela. The major activities in the laboratory include research on screw compressors, expansion turbines, cryogenic treatment of cutting tools, low temperature heat transfer and development of heat transfer equipment. The paper presents a review of the ongoing R & D projects, the academic programme and the infrastructure facilities that have been created.

Analytical Method for the Prediction of Freezing Time of Irregular Shaped Food Materials

Sanoj Kumar, S.C.Pattanayak and H.DasaCryogenic Engineering Centre, Indian Institute of Technology, Kharagpur, India

Freezing is one of the most suitable methods for the preservation of perishable food products .The determination of freezing time and temperature distribution inside the product dictate the design of the freezing process. Three distinct periods during freezing are noticeable at any location inside the body of a food material. The time period of precooling, phase change and freezing are the important parameters required to be evaluated for adopting proper freezing technique of food items. The knowledge of this complex processes is very important in order to arrive at an optimised condition. A simplified analytical method is worked out in this paper for the prediction of freezing time of the irregular shaped food

materials. A suitable computer program using C language is developed using above analytical approach to determine separately the time period for cooling, phase change and freezing during the freezing process. This technique would be of very much important in the design of food freezing equipments.

Development of Grooved Journal Bearings forCryogenic turbo-expander rotors

Tapas Kumar NandiCryogenic Engineering Centre, Indian Institute of Technology, Kharagpur - 721 302

One of the major problems of developing turbo-expander system for gas liquefaction plants is the instability of the rotor at high rotational speed. Gas lubricated externally pressurized (aerostatic) bearings consume process gas and they are suitable only upto a medium rotational speed. Present work is on the development of herring bonegrooved aerodynamic type journal bearing. Some of the aspects of development, including design, fabrication, and testing are presented. The shallow grooves are cut on the rotor by chemical etching. The journal is rotated by expanding compressed air/Nitrogen through a turbine. Aerostatic gas bearings are used to operate at the start-stop transients while an aerostatic thrust bearing is used to take the axial load of the vertically placed journal.

Mathematical Analysis of Oil Injected Twin Screw CompressorN.Seshaiah, Subrata Kr. Ghosh, R.K. Sahoo, Sunil Kr. Sarangi

Mechanical Engineering Department, National Institute of Technology, Rourkela, OrissaCorresponding author mail ID: seshuet@yahoo.com

Mathematical analysis of oil injected twin screw compressor is carried out on the basis of the laws of perfect gas, and standard thermodynamic relations. Performance of an oil injected twin-screw compressor depends on a large number of design parameters. A computer model for calculating compressor performance and to validate the results with experimental data is developed. The flow coefficients required to calculate leakage flow rates for simulation are obtained from efficiency versus clearance curves. Some numerical examples of P-V diagrams, influences of oil injection on volumetric efficiency etc for a given compressor are presented.

Liquid Nitrogen Powered Prime MoverS.A.Krishnan, S.Maji *, Manoj Kumar, R.S.Meena, Suresh Babu and T.S.Datta

Nuclear Science Centre, New Delhi, Delhi College Of Engineering, Delhi

A heat engine that operates between atmospheric temperature as a heat source and cryogenic temperature as a heat sink called cryogenic heat (C-H) engine. A liquid nitrogen (LN2) powered heat engine is a best alternative zero emission engine concepts compared to battery operated one. The development of this kind of engine has been initiated at NSC to study its possibility as a prime mover for lightweight applications. The preliminary stage of this project has been demonstrated by running a modified single cylinder, four-stroke engine as a two-stroke cycle expander based on open Rankine thermodynamic cycle. The detail of this developmental work is presented in this paper.

Operational Experience of Indigenously DevelopedAutomated Helium Purifier at NSC

A Choudhury, T. S. Datta, M Kumar, R. S. Meena, S Kar, J Chacko, S. A. Krishnan, S BabuNuclear Science Centre, Aruna Asaf Ali Marg , New Delhi - 110067

An indigenously developed medium pressure (225 psi) helium gas purifier of capacity 40M3/hr was commissioned at NSC in 2002. It works on the principle of adsorption of impure gases (N2, O2, etc) from helium by charcoal at 78K. Since its installation, it has undergone 65 cycles of cool down operation till date and has purified almost 5200M3 helium gas with an inlet impurity varying from 8% to 0.1%. The purifier generally runs in the automatic mode to perform two operational cycles, purification and regeneration. This paper will be highlighting the operational experience along with running data for purifier.

A setup for the studies of Freeze Drying ProcessArpita Mondal, Sanoj Kumar and S.C.pattanayak

Cryogenic Engineering Centre, Indian Institute of Technology, Kharagpur - 721302

Freeze-drying, which is also known as lyophilization, is the process of removing moisture from a food product by freezing it and then condensing the sublimated vapor at vacuum. In this work the condensation process of moisture is replaced by adsorption using zeolite. It is estimated that 3.6 kg of zeolite is required for adsorbing total moisture of 1 kg shrimp. A setup is designed and fabricated which consists of a Cu cylinder of ID 10.5 cm and length 64.0 cm insulated by 5 cm thick polyurethane foam. The bottom of the cylinder is closed and the top flange is connected to a vacuum pump. The top flange has the provision for introducing the cabinet of perforated trays loaded alternatively with frozen shrimp and adsorbent. This arrangement gives sufficient exposed surface area to adsorption process, which make the process more efficient. Heat in-leak and the heat of adsorption to the system are sufficient to maintain the heat of sublimation. However a nicrome made coil heater is kept inside for use if necessity arises. This setup has been developed to study the following characteristics; 1.Adsorption rate of zeolite at different operating condition. 2.Sublimation rate of a particular sample at different vacuum level. A detail description of the developed freeze-drying setup is described in the paper.

Different methods for the estimation for freezing time of foodSanoj Kumar, S.C.Pattanayak and H.Dasa

Cryogenic Engineering Centre, Indian Institute of Technology, Kharagpur, India

The preservation of food is one of the most significant applications of refrigeration. In order of preserving operations to be cost-effective, it is necessary to optimally design the refrigeration equipment. This requires estimation of the freezing times of foods under different condition. Numerous methods for predicting food-freezing times have been proposed. The designer is thus faced with the challenge of selecting an appropriate estimation method from the plethora of available information. The present paper deals with the semi-analytical/empirical food freezing time prediction methods that apply to regular and irregular shaped food items. The performance of these various methods is quantitatively evaluated by comparing their numerical results to a comprehensive experimental freezing time data compiled from the literature.

Revolution in Cryogenic-CryotemperingShirish R. Gandhi and Gehlot Rajesh

Department of Mechanical Engineering L.D.C.E. Ahmedabad.

Cryogenic Treatment of metal parts can enhance metallurgical properties, which in turn, improve various strengths of the treated parts. This paper presents the details of cryotempering, its method, importance, application of this process. The test results shows the enhancement in various structural properties due to permanent metallurgical changes that take place in the specimens during the cryogenic treatment. However, no permanent change in the dimensions or surface finish of the specimen occurs. Such treated parts improve the reliability and performances of the whole machine, thereby increasing its MTBF, wear resistance & ductility. Cost factor limits its use in production phase of material industry.

Specific Heat For Metals At low TemperaturePuwar Dhairyapalsinh Narpatsinh (1), R. M. Shah (2), Nisha V. Bora (3)

Mechanical -Cryogenic Engg. , L.D. College of Engg., Ahmedabad-380015 Email: rajani_10_2@yahoo.co.in, Email: nisha_mech@engineer.com

In present section various theories representing specific heat of solids have been discussed briefly such as Dulong and Petit law, Einstein theory, Debye theory and Sommerfeld theory. Then using Debye theory and Sommerfeld theory, lattice specific heat (Cvl), electron specific heat (Cve), and total specific heat (Cvt) are evaluated and plotted versus absolute temperature (T) for aluminum and the same can be followed for other metals. Also (%Cvl) ?T and (%Cve) ? T have been plotted for aluminum. Furthermore method of

obtaining value of electron specific heat co-efficient (re) has been shown by plotting (Cvt /T)? (T2) for aluminum.

Design and Analysis of Psa Based Nitrogen Separation System for a Liquid Nitrogen, Plant

Rohit Kumar.N.Mehta1 , R.M.Shah2Mechanical Engineering department, L.D.College of Engineering Ahmedabad - 380015

Distillation has been the process for separation of gases and producing liquefied gases. Atmospheric air contains about 76% nitrogen and the rest being oxygen, argon and rare gases. One of the major draw back of distillation process being high energy consumption for the separation of particular species of gas, as the complete mixture has to be liquefied and the liquefied gases are separated based on difference in boiling points. Thus if 76% nitrogen is to be separated the rest 24% part of the air also needs to be liquefied. The energy spent on this un- used mass of gas could only be saved by providing additional heat exchangers, which would make the system cost prohibitive or the system will utilize higher quantum of energy. Adsorption process is the solution, which would provide energy efficient separation for small scale plants, by separating out first the species of gas to be liquefied at room temperature utilizing only a fraction of work consumed by a cryo cooler for separation. In this paper Design of Adsorption based air separation plant using carbon molecular sieves as the adsorbent working at room temperature was done for product recoveries of 30% and 40% . Analysis was carried out on a proto type and results were tabulated for purity of the product (gaseous nitrogen) at different flow rates. The cycle of Adsorption was a 6 valved process based Barbau-Forschung cycle and capable of producing 30 L/ Hr of liquefied nitrogen.

Some Aspects of Pinch Technology Applied to CryogenicHeat Exchangers

H. V. Panchasara* and R.M.Shah**Mechanical Engineering Department, L.D. College of Engineering, Ahmedabad-380015

The paper aims to explain the fundamentals of the Pinch Technology for the analysis of the heat exchanger network synthesis. It is a well-established synthesis and analysis-tool for the exchange of heat within the network of heat exchangers. This paper presents a simple methodology for systematically analyzing the process utility streams with the help of first and second law of thermodynamics. The concept of the theory is basically dependant on the 'Pinch Point' or 'Pinch Condition' or 'Closest Approach' which is the temperature level at which the ?Tmin is observed which in turn defines the minimum driving force allowed in the exchanger unit. The points to be discussed are the analysis of the Pinch point or Pinch region for the cryogenic heat exchangers, the benefits, objectives and applications of the Pinch analysis or Pinch Technology.

Development of Cryogenic Adsorber Based Helium Purifier at VECC, Kolkata

Trijit Kumar Maiti, S. Banerjee, Abanindra Mukherjee, U. Panda,Nirmalya Datta, Jagdishkumar Parate, Ananda Das, R. Dey

V.E.C.C, Deptt of Atomic Energy, 1/AF Bidhannagar, Kolkata 700064, India

For ongoing project of Superconducting Cyclotron at VECC, Kolkata, liquid helium plant constitutes an essential component of cryogenic system. This plant is equipped with an integral internal purifier working at impurity level of 2%. During simultaneous operation of liquefier as well as purifier, liquefaction rate reduces considerably and may become insufficient for Super-conducting Cyclotron operating at full swing. For experimental purpose, we designed and fabricated one module of cryogenic adsorber based helium purifier, tested and result was encouraging. Also conducted rigorous cryoshocking of insulated tape heater meant for regeneration. Now we are developing a fully integrated helium purifier to meet Grade 'A' helium requirement of Superconducting Cyclotron.

Operation , Instrumentation and Control of Psa Based Adsorption System

Rohit Kumar.N.Mehta1 , R.M.Shah2Mechanical Engineering department, L.D.College of Engineering Ahmedabad -15

All modern day air separation industry and users of compressed air for pneumatic actuation of controls use Adsorption process. They can be classified as purification process if the impurity to be adsorbed in the fluid is about 3 to 5% as in the case of moisture and carbon di oxide removal and separation if the fluid to be removed is of the order of 20 to 80% as in the case of separation of oxygen and nitrogen. The sequence of cycle and the quantum of purging for reactivation varies . These variations are due to continuous development in Adsorbents and in improvement in the cycle of operation. In this paper we have discussed unitary, unmanned operation of an adsorption system, the instrumentation required, the controls and interlocking arrangement for full proof operation of air separation plant for separation of nitrogen has been discussed has been discussed.

Innovative Techniques for recycling the recovered CFC'sS.S. Verma

National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi - 110012

The utilization of large quantities of CFC's in Industries as well as in Refrigeration and Airconditioning has rendered the environment more susceptible to mankind due to its ozone depleting characteristics. A decision was already made at the Montreal protocol's 4th meeting to phase out the production and consumption of CFC's. The mechanism to recover and recycle the CFC's are established in the developed countries and in India, there is hardly any awareness on large scale, to recover, recycle the flons. A system has been established to collect flon from refrigerated warehouses and large air-conditioners, walk-in-coolers etc. After refining by distillation, it is returned to the users. Flon is collected at the gas stations and repair workshops. Small devices are employed to refine the collected flon by filtration, moisture adsorption by zeolite and oil water separation have been developed and are functional. Some other devices are employed to cool and liquefy and collect the flon at low temperatures. The decomposition of CFC's are still at an experimental stage to make the end product environmentally friendly or reusable. A device is under development to decompose the CFC's by plasma decomposition method using radio frequency inductively coupled plasma reaction system achieving a temperature of 5000? C -10000? C to decompose the CFC's.

Design of Turboexpander For Cryogenic ApplicationsSubrata Kr. Ghosh *, N. Seshaiah, R. K. Sahoo, S. K. Sarangi

Department Of Mechanical Engineering, NIT, Rourkela, Orissa.Corresponding author mail ID: subratarec@yahoo.co.in

The indigenous design and development of turboexpander have been started at NIT, Rourkela. This paper briefly discuses the design methodology and the fabrication drawings for the whole system, which includes the turbine wheel, nozzle, diffuser, shaft, brake compressor, two types of bearing, and appropriate housing. With this method, it is possible to design a turboexpander for any other fluid since the fluid properties are properly taken care of in the relevant equations of the design procedure.Nomenclatureb blade heightC absolute velocityCr mean radial clearanceCn chord length of nozzleds specific diameterD diameterd0 feed hole or orifice diameter of bearingh enthalpy (J / kg)hbg bearing clearanceKbg bearing radial stiffness

L axial length of the journal bearing.mmass flow ratens specific speedN rotational speed (rev/ min)nh number of holes in the bearingp pressureP power producedQ volumetric flow rate (m3 / s)Rj radius of journalrt0 feed hole pitch circle radius of thrustbearingrt1 outer radius of thrust bearingrt2 inner radius of thrust bearingT0,in turbine inlet temperaturet thickness of bladesU circumferential velocityWL load capacity of bearingw width of flow passagez number of bladesGreek symbols? rotational speed (rad/s)e ratio of tip diameter to turbine wheeldiametere eccentricity ratio of the bearing? ratio of hub diameter to tip diameter? isentropic efficiencyf power input factor? slip factor? relative velocity angle? specific heat ratio of bearing gas? density of gasSubscripts0 stagnation condition1 inlet to nozzle1 inlet to brake compressor2 inlet to turbine wheel2 outlet to brake compressor3 inlet to the diffuser (exit to wheel)ex discharge from diffuserhub hub of turbine wheeltip tip of turbine wheelm meridional components isentropic conditions supplytr turbine wheelb brake compressorn nozzlet throatbg bearingc chokingd dischargeFigure 1 Longitudinal section of the expansionturbine displaying the layout of the components.This turbine is comparable in characteristics tothat developed earlier at IIT Kharagpur [1,2] and

drawn heavily from that experience.Design Methodology

Design of a Cryotreatment Chamber and Studies on Cryogenic Treatment on Metals

Nadig D. S., Jacob. S., Kasthurirengan. S., Karunanithi R. and Geetha Sen*Centre for Cryogenic Technology, Indian Institute of Science, Bangalore - 560 012, India

* Liquid Propulsion Science Centre, ISRO, Bangalore.

Studies in the thermal, mechanical and electrical properties of metals at cryogenic temperatures are important for many scientific and technical applications. To study the changes in properties, a cryotreatment test unit has been designed and developed. This unit incorporates a PUF insulated cryotreatment chamber made of SS 304. The controlled liquid Nitrogen supply to the chamber is carried out by using a solenoid valve activated by a PID controller. To gradually cool the test specimens to cryogenic temperature with out a direct contact with the liquid nitrogen droplets, a concept of cold nitrogen gas forced convection has been employed. The system has the capability of cooling the test specimens to ~ 98 K and holding at that temperature for desired durations. Experiments have been carried out to study the effect of cryogenic treatment on wear resistance properties of molybdenum based HSS tools (M42). There has been significant improvement in the properties after cryogenic treatment.

Thermal Analysis of Antistokes Fluorescent Cryocooler Using Finite Difference Methods

Biju T. Kuzhiveli *, Subhash JacobIndian Institute of Science, Bangalore, India - 560 012

Department of Mechanical Engineering, VJCET, Kerala, India - 686 670, Email: btkuzhiveli@yahoo.com

A new type of solid state cryocooler based on laser induced anti stokes fluorescence is being developed. Design studies indicate that the fluorescent cryocooler could operate for years with efficiencies and cooling powers comparable to current low capacity cryocoolers. The most important attributes of such a cryocooler is that it has no moving parts, no vibrations, electrically isolated and hence not susceptible to EMI, rugged and reliable that would not adversely affect the electronic or mechanical component components with which they are used, cools to 77 K, weighs less than 2 kg/W of useful refrigeration, life time of 10 years of continuous operation. The cryocooler can be deployed to cool detectors and electronics to cryogenic temperatures for space based missions and ground applications. In order to develop laser induced anti stokes fluorescent cryocooler, it was required to develop numerical tools that support the thermal design. It is expected that, with improved materials and optical and thermal designs, future cryocoolers could be over twice as efficient as present day optical coolers to cool to cryogenic temperature. The improvements in materials along with a better thermal design as a result of the developed computer program could make the efficiency and temperature range of optical cryocooler superior to those of small mechanical cryocoolers in near future. This paper presents the details of development of a mathematical model and the subsequent development of a computer program for the application of thermal design of components and the system as a whole in an antistokes fluorescent Cryocooler.

Performance Prediction and Experimental Investigations to Study the Effect of Hot End Heat Exchanger Volume on Orifice Pulse Tube Cryocooler

Gawali B. S.1 and Narayankhedkar K.G.21 Mechanical Engineering Department,Walchand College of Engineering, Sangli-416415,

2 Mechanical Engineering Department, I.I.T, Bombay, Powai, Mumbai-400076

A theoretical model based on cyclic analysis has been developed for the analysis of the Pulse Tube cryocooler to calculate the ideal refrigerating effect and ideal power requirements. Based on Martini's second order analysis, different losses have been considered to analyze the actual behavior of the orifice pulse tube cryocooler, to predict the actual refrigerating effect and power required. Theoretical model is applied to predict the performance of the cryocooler. The model is also applied to predict the effect of hot end heat exchanger volume. A linear Pulse Tube cryocooler was designed and developed. Experimental investigations were carried out. To study the effect of hot end volume, the hot end heat exchanger volume

was varied using spacers. A comparison of the theoretical and experimental results for this cryocooler is also presented in the paper.

Determination Of Apparent Thermal Conductivity Of Perlite PowderPankaj I. Jagad, Prof. M.B. Jain

Institute of Technology, Nirma University, Ahmedabad - 382 481

At very low temperatures it becomes economical to conserve the cold using insulating material rather than to produce it because of the requirement of very large amount of energy to produce very low temperature. Therefore the cryogenic storage vessels, transport vessels and transfer lines are insulated. Perlite powder at atmospheric pressure and under vacuum is a common insulating material used for these purposes. For estimation of heat transfer, thermal conductivity must be known. A double guarded cylindrical boil off calorimeter, an absolute method of determining thermal conductivity, is discussed. The apparatus consists of a main vessel in the middle and two guard vessels located at top and bottom. These vessels are housed in a cylindrical vessel. For determining the thermal conductivity of perlite powder under vacuum, the powder is filled in the annular space and pressure is reduced to 1X 10-2 Pa. The test and guard vessels are filled with liquid nitrogen. The heat transferred to the main vessel results in formation of nitrogen vapour. From the amount of vapour formed the heat transfer rate and subsequently the apparent thermal conductivity of perlite powder is estimated. The set up is helpful in determination of the thermal conductivity of different sizes of perlite as well as vermiculite powders.

Some studies on a LN2 FreezerS.Kumar, R.M.Khadatkar*, S.C.Pattanayak and H.Dasa

Cryogenic Engineering Centre, Indian Institute of Technology, Kharagpur, India *Mechanical Engg Department, HCST, Agra, India

A batch type top loading LN2 freezer is developed, with the provision of precooling by exit GN2 and forced air-cooling. The two chambers can change alternately either as precooler or freezer by set point temperature. A set of studies are carried out to optimize the performance of cryofreezer and to predict the freezing time as follows; (1) cooldown characteristics of cryofreezer at different flow rates of LN2 (2) cooldown time for different setpoint temperatures and flow rate. (3) LN2 consumption for different set point temperature and flow rates. (4) temperature history of the surfaces of the sample holder (tray) and its enclosed chambers (5) study on two-phase flow in helical-tube heat exchangers (6) uniformity of airflow in freezing chamber The present paper deals with the results obtained from the above experiments.

Design & Development of LN2 Batch FreezerSanoj Kumar, R.M.Khadatkar*, S.C.Pattanayak and H.Dasa

Cryogenic Engineering Centre, Indian Institute of Technology, Kharagpur, India*Mechanical Engg. Department, HCST, Agra, India,

An improved batch type, LN2 freezer has been designed, developed and commissioned with the following features:(1) Top loading and convenient door system.(2) No handling of food during the process.(3) Arrangement of alternate use of chambers as freezer and precooler.(4) Arrangement for air stirring system with variable Reynold number(5) Temperature controlled automatic fluid distribution system.(6) Simplified design of freezer and cooler.Experimental data on different characterization and optimization of energy and LN2 consumption are reported in another paper. The paper deals with the different aspects of fabrication, fluid circuit and temperature control arrangement for achievinga particular condition.

Additional energy requirement for an O2-N2 distillation column using pinch analysis and its comparison with Ponchon-Sovarit graphical method

Bhavsar Hardik Prakashchandra(1), Aditi Oza(2) and R M Shah(3)L.D. College of Engg, Ahmedabad-380015 E-mail: hardik_bhavsar@rediffmail.com

In cryogenic air separation, distillation column is the most energy consuming part. The pinch technology is used for generating column composite curve and column analysis of distillation column. This paper presents the use of column composite curve and column grand composite curve for minimization of additional energy required in condenser and reboiler of distillation column by changing parameters such as reflux ratio, feed conditioning and number of plates. Ponchon-Sovarit graphical method is used in the construction of column composite curve and column grand composite curve. Results obtained using the graphical approach is compared with the analytical approach.

Theoretical Optimization Of Claude Liquefaction CycleBhavsar Hardik Prakashchandra(1), Aditi Oza(2) and R M Shah(3)Mech-Cryogenic Engg, L.D. College of Engg, Ahmedabad-380015

E-mail: hardik_bhavsar@rediffmail.com

To liquefy gas, enormous amount of energy is required. To have minimum operating and maximum yield, parameters affecting the liquefaction system should be optimum. This paper presents theoretical optimization of Claude liquefaction system. The parameters like presents work required per unit mass of gas liquefied as function of (i) pressure (ii) expander inlet temperature of fluid and (iii) expander mass flow rate ratio.

Magnetic Refrigeration, its Developments and it's Utility in Magnetic Hydrogen Liquefier.

Aditi Oza (1) Hardik Bhavsar (2) R.M.Shah (3)Mech-Cryogenic Engineering, L.D.College of Engineering, email:aditioza@yahoo.com

Low-temperature refrigeration and the quest to attain absolute zero have paved the path for the system of magnetic refrigeration producing temperatures from room temperature down to milli-kelvin temperature. The basic idea of magnetic refrigeration, magneto-caloric effect, and magnetic materials and till date developments taken place around the globe for low temperature magnetic refrigeration to that of room temperatures and also magnetic refrigeration for aiding gas liquefiers is described. Liquid hydrogen is a promising medium as an alternative fuel source. This paper presents the merits of magnetic liquefiers and the basic design of 100ton/day magnetic hydrogen liquefier.

Design of Low Capacity Vertical LOX Storage VesselBhargav Hitesh A.

Mechanical Department, Charotar Institute of Technology, Changa-388421(Gujarat).

An increasing use of low temperatures in the various fields of science and technology has been necessitated, the development of effective system for storage of liquid cryogen. Vertical DEWAR vessel is ideal for stationary application vertical design ensures minimum floor space for installation, in comparison to horizontal vessel of the same capacity. Also it gives higher natural head. Low capacity LOX vessel is more suitable for laboratory purposes, hospitals, electronics industries and automobile industries. For better mechanical strength and easy fabrication, suggested design length = diameter. By providing elliptical head, it reduces the discontinuity stress at the joint.

Role of Vacuum Technology in CryogenicsP. Gopi Kishore

Bharat Heavy Plate and Vessels Limited Visakhapatnam - 530012gopikishore_bhpv@sify.com

Advances in Vacuum Technology are one of the reasons for the wide spread applications of Cryogenics whether in the field of Gas Separation, cryogenic fluid transfer, Simulation Chambers etc. Whereas the Cryogenic techniques are relied upon for obtaining the Ultra High Vacuum, Vacuum Technology is utilised for effective thermal insulation which is an essential condition to be able to retain the cryogenic temperatures obtained through various techniques. At Cryogenic temperatures, the predominant mode of heat leak is through Radiation. Heat Leak through radiation can be controlled to a very little extent by selection of materials with effective properties viz. emmissivity etc. However, substantial measures to tackle the heat loss through radiation can be obtained through vacuum technology. The annular space between the inner and outer vessels of a typical cryogenic container is evacuated to calculated limits by means of appropriate vacuum pumping methods. After these vacuum limits are obtained, suitable insulating materials and techniques are employed to retain it.

Design Approach And Constructional Features Of Cryorefrigerator For Cryopumping Applications

C. R. Sonawane*, M. C. A. Naidu** and Dr. L. N. Patel**** Mechanical Engg. Dept., Sankalchand Patel College of Engineering, Visnagar

** Space Application Center, ISRO, Ahmedabad, *** Sankalchand Patel College of Engineering, Visnagar

A cryopump operates over a wide range of pressure varying from 760 torr to 10-10 torr. It captures gases by freezing them out. Thus, it does not return unwanted gases to the vacuum system. A typical cryopump consists of a cryogenic refrigerator that provides refrigeration at two temperature stages, which are used to cool two extended surfaces of cryopanels on which the gas can freeze out. The first stage of the refrigerator usually operates in the range of 50 K - 70 K. It is used to cool the outer cryopanel that provides radiation-shielding for the colder panel and cools the louvers across the inlet of the pump on which water vapor freezes out when it hits the pump, very much as liquid nitrogen cooled cold trap freezes out water vapor. The second, or the cold stage of the refrigerator, which usually operates between10 K - 20 K is used to cool the inner cryopanel that is used to freeze out nitrogen, oxygen and argon, which pass through the louvers. The gases that would not freeze out at this temperature are cryosorbed by charcoal, which is inside of the cold panel. This cooling at both stages is achieved by cryorefrigerator. As we are operating at 20 K, it is necessary to use helium, as it is the only working medium available in gaseous form used in Gifford – McMahon cryorefrigerator. In this paper design aspects of cryorefrigerator for cryopumping applications are discussed. Design considerations of the regenerator, which is a critical component of this type of refrigerator and the vacuum system used in cryopumping are explained.

Design of An Energy Efficient Large Cryogenic Liquid Storage CewarM. I. VYAS*, R. M. SHAH**

* Mech. Engg. Dept., L. D. College of Engineering, Ahmedabad - 380 015.

This paper aims to discuss some of the design aspect of energy efficient storage vessels for cryogenic fluid. Basic areas, such as material selection, insulationselection, vessel and support system design and piping design etc. have been considered. Total heat in leak is made up of three major components viz. - heat in leak through vessels walls, support system and piping. An effort has been made to analyze percent contribution of each of the above factors in total heat in leak rate. Cost of boil of loss has been shown to arrive at cost effective storage of cryogenic liquid.

Insulation Performance Study by Low Temperature CalorimeterR.S. Meena, S.A. Krishnan, A.Choudhury, Manoj Kumar, S .Kar, S. Babu,

J Chacko, R.G Sharma and T.S. Datta, Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi-110067

To reduce the static heat load at 4.2 K, an efficient thermal insulation like the multilayer insulation (MLI) is widely used. This insulation is, however, not suitable for our LINAC cryostat as it's superconducting resonators need very clean and high vacuum environment. We have evaluated the performance of an aluminum tape as an alternate cryogenic insulation using a double guard calorimeter technique. Number of experiments have been carried out in the temperature range of 300 -78 K and 78 -4.2 K with different configurations of MLI and a single layer of Al -tape on a bare SS-304 surface to measure the total heat load. It is observed that in vacuum better than 10-5 Torr, the performance of a single aluminum tape is comparable with that of the MLI. Experimental details with results will be presented in the paper.

Design and Development of Vortex TubeM.V. Suresh Babu. and T.S.Datta

IUAC, New Delhi

The Vortex Tube is a device, which is capable of producing low temperature from a high-pressure gas. At present a few companies abroad are manufacturing these devices and are available commercially in various

capacities. There may be further scope to improve this device's dimensional and other parameters to produce maximum temperature difference. An attempt has been made to develop similar device and study the main features, which determine its performance. This paper explains in detail about the various designs of devices and the analysis of experimental data generated from the indigenous device. Achieved minimum temperature is - 40oC with a drop of 60 oC from inlet temperature of air 20 oC at a pressure of 7-bar. Performance of these devices with respect to dimensions, pressure, flow and inlet temperature will be discussed.

Two-Stage Stirling Cycle Cryocooler Development for Space Applications: Preliminary Test Results

A.Ramasamy, Padmanabhan, C.S.Gurudath, P.P.Gupta, D.R.Bhandari and H.NarayanamurthyThermal Systems Group, ISRO Satellite Centre, Vimanapura, Bangalore - 560017

A two-stage stirling cycle cryocooler for cooling IR detector to 30K is being developed for space applications at ISRO Satellite Centre, Bangalore under advanced R&D activities. This paper outlines the preliminary test results of the two-stage split stirling cycle cryocooler (Lab.Model). The present laboratory model provides 250mW of heat lift at 30K at the second stage and no load at the first stage for the total input power of 70W. This unit has achieved a base temperature of 22.2K for the input power of 76.5W.

Loss Analysis of Stirling Cryorefrigerator with Two-Component Two-Phase Working Fluid

N.G. Pandya*, N.V. Bora**, L.N. Patel**** Mechanical Engg. Department, L.D.C.E.,Ahmedabad

Stirling cryorefrigerator operates on a closed regenerative thermodynamic cycle with compression and expansion of the working fluid occurring at different temperature levels. Generally hydrogen or helium is used as a (single component) working fluid in such cryorefrigerators. Analytical / experimental investigations show that the use of "two-component two phase working fluid" improves the performance of the Stirling cryorefrigerator. In this novel approach the pressure range is wide relatively. This increases the available refrigerating effect, of course, with a correspondingly higher input power. Thus, a given cryorefrigerator can provide higher liquefaction capacity while working with a two-component two-phase working fluid. Alternately, for a fixed liquefaction capacity the maximum cycle pressure can be kept lower than the maximum cycle pressure with a single component working fluid. The change over from single component to a two -component working fluid does not involve any change in the cryorefrigerator configuration. In this paper a computer simulation of two-component two-phase working fluid using second order cyclic analysis has been carried out for PLN-106 cryorefrigerator. The results obtained for a two-component two-phase working fluid are compared with a single component working fluid with the same maximum cycle pressure for a given cryorefrigerator.

Experimental Investigations on a Linear, Inertance Pulse Tube RefrigeratorPingale L. B., Naik J. M., Mulani B. S., Pandav R. S., Awasare S. S., Gawali B. S.

Mechanical Engineering Department, Walchand College of Engineering, Sangli-416415

Affordable, minimal vibration, long life and more capable active refrigerators must be developed to meet many current and future commercial and military needs. Modern Pulse Tube refrigerators can potentially satisfy these combined advanced requirements better than other types of known refrigerators. Different configurations are reported in literature to improve the performance of the Pulse Tube refrigerators like Orifice Pulse Tube Refrigerator (OPTR), Double Inlet Pulse Tube Refrigerator (DIPTR), and Inertance Pulse Tube Refrigerator (IPTR). Theoretical model is developed for the analysis of counter flow linear integral inertance Pulse Tube Refrigerator. Theoretical model is used to design the refrigerator. Experimental model is developed to demonstrate the concept of counter flow linear inertance Pulse Tube refrigerator. Preliminary results obtained using air as working media are presented. Lowest temperature of -2.5? C is measured using 3.5 Kg/Cm2 charge pressure.

Analysis and design of two-stage miniature Stirling cryocooler for space applications

V.K. Bhojwani, S.L. Bapat and K.G. NarayankhedkarIndian Institute of Technology, Bombay, Powai, Mumbai - 76

Small capacity Stirling cryocoolers are used in space applications for cooling of IR detectors. These coolers are compact which utilize compressor with opposed piston configuration. Both the compressor and displacer are driven by linear drive. Since the direct linear motion is obtained, the components required to convert rotary to linear motion are absent. This increases the life, reduces the wear and maintenance, which are necessary requirements of space applications for life durations of 3 to 5 yrs of continuous operation. The current work reports analysis and design of a two-stage Stirling cycle cryocooler with a cooling capacity of 2W at 100 K (Stage - I) and 0.5 W at 50 K (Stage - II). The performance predicted by the analysis is presented in this paper.

Design and development of Stirling Cycle CryocoolerLele M. M., Bapat S. L and Narayankhedkar K.G

Indian Institute of Technology Bombay, Powai, Mumbai-400076.

The cyclic analysis is the most important tool for designing Stirling Cycle cryocooler. Based on this analysis the Stirling Cycle Cryocooler was designed, developed and tested. The above analysis takes care of all possible losses like temperature swing loss, loss due to regenerator ineffectiveness, loss due to shuttle conduction, loss due to pumping action, loss due to conduction, P-V loss etc. The particular application discussed here is, to meet the specification of 3W at 80 K. The experimental results of initial trials are reported.

Theoritical Analysis of GM Type Orifice Pulse Tube RefrigeratorK. P. Desai *, H. B. Naik* and K. G. Narayankhedkar **

* Mechanical Engineering Department, S. V. National Institute of Technology, Surat 395 007** Mechanical Engineering Department, Indian Institute of Technology, Mumbai 400076

Cryogenics is mainly concerned with design and development of cryocoolers. The pulse tube refrigerator consists of a thin-walled tube, with heat exchangers at both ends, connected to a pressure oscillator via regenerator. The heat exchange may be attributed to the surface heat pumping and/or enthalpy flow. The absence of moving parts in the cold region, high reliability, better temperature stability, economy of manufacturing and quiet vibration free operation have given promising future to the pulse tube refrigerators. The performance of a pulse tube refrigerator is sensitive to many operating parameters and using a suitable model performance prediction can be carried out. Various researchers [4-12] have attempted to develop analytical and numerical models for better understanding for the physical process. In the present work an analytical model for cyclic simulation of G-M type orifice pulse tube refrigerator is developed assuming ideal gas behavior, sinusoidal pressure variation, isothermal heat exchange and adiabatic compression and expansion of working gas. Frictional and viscous effects, convective heat loss to the atmosphere and losses due to oscillating flow are neglected. The parametric investigations were carried out.

Experimental Investigations on G-M Type Orifice Pulse Tube RefrigeratorK. P. Desai *, H. B. Naik* and K. G. Narayankhedkar **

* Mechanical Engineering Department, S. V. National Institute of Technology, Surat 395 007

The prospect of inexpensive and reliable cooling with very little magnetic and mechanical interference has stimulated research and development of pulse tube refrigerators. In orifice pulse tube refrigerator, the warm end of the pulse tube is connected via an orifice (usually realized by a needle valve) to a buffer reservoir [1]. The orifice pulse tube refrigerator has a higher efficiency than the basic pulse tube refrigerator. An experimental setup has been designed and fabricated for experimental investigations on G-M type orifice pulse tube refrigerator. It also includes the development of a distribution valve to generate the necessary pulse. The necessary instrumentation for measurement of cold end temperature, refrigeration power and

recording of pressure waveform is provided. Experiments were carried out to investigate the effect of pressure, frequency, and opening of orifice valve, on the performance of orifice pulse tube refrigerator. The results obtained are reported. The lowest no-load temperature of 72.1 K was obtained. The refrigeration power of 3.73 W at 100 K was obtained.

Double Inlet Pulse Tube Refrigerator capable of reaching 48 KK. P. Desai *, H. B. Naik* and K. G. Narayankhedkar **

* Mechanical Engineering Department, S. V. National Institute of Technology, Surat 395 007** Mechanical Engineering Department, Indian Institute of Technology, Mumbai 400076

The prospect of inexpensive and reliable cooling with very little magnetic and mechanical interference has stimulated research and development of pulse tube refrigerators. Double-inlet pulse tube refrigerator (DIPTR), introduced in 1990 by Zhuet al. [1], can achieve higher efficiency than orifice pulse tube refrigerator. An experimental setup has been designed and fabricated for experimental investigations on double inlet pulse tube refrigerator. The experimental investigations for double-inlet pulse tube refrigerator were carried out. The performance of doubleinlet pulse tube refrigerator was evaluated in terms of no-load temperature and refrigeration power. The lowest no-load temperature of 47.9 K was obtained. The refrigeration power of 4.35 W at 80 K and 7.35 W at 100 K was obtained. The results obtained are in qualitative agreement with those available in the literature.

Design Methodology for Free Piston Free Displacer Stirling CryocoolerBiju T. Kuzhiveli *, S. L. Bapat and K. G. Narayankhedkar

Department of Mechanical Engineering, Indian Institute of Technology-Bombay, Mumbai, India - 400 076, * Department of Mechanical Engineering,VJCET Kerala, India - 686 670, Email: btkuzhiveli@yahoo.com

Many applications such as IR detector cooling in Satellites, imaging cameras in battle tanks and laboratory spot cooler require cryogenic cooling in the range of 60-80 K with a cooling power varying from mW to a few Watts. This paper deals with the analysis of Free Piston Free Displacer (FPFD) system and the development of a design methodology for miniature Stirling cycle cryocooler. The major modules involved in the program are design of magnet, linear motor, regenerator, dynamic components and heat dissipation system. However the focus of the description shall be on linear motor design and magnet design. This methodology has been applied to existing cryocoolers and it found that the predicted values were in a reasonably good agreement with the actual results.

Validation of Design Methodology and Experimental Investigation of Stirling, Cryocooler

Biju T. Kuzhiveli *, S.L. Bapat and K.G. NarayankhedkarDepartment of Mechanical Engineering, Indian Institute of Technology-Bombay, Mumbai, India - 400 076, * Department of Mechanical Engineering, VJCET, Kerala, India - 686 670, Email: btkuzhiveli@yahoo.com

Some of the modern scientific applications including space applications have a demand for cryogenic cooling in the range of 60-80K with a cooling power varying from fraction of a watt to few watts of refrigeration, low weight, compact size, trouble free operation, no usage of oil, high reliability and high endurance limit. Cryocooler working on Stirling cycle with free piston free displacer (FPFD) concept is one candidate for such an application that meets the above requirements. This paper deals with the experimental investigations conducted on two miniature FPFD Stirling cryocoolers. The endurance limit, cool down characteristics, cooling power with varying pressure, cooling power with varying input power and the measurement of cooling power from no load temperature below 60 K to 200 K are experimentally found out and the results discussed.

Quench Results of 1/5th Scale of K-500 Superconducting Cyclotron Main Magnet

J. Pradhan, Md. Z. A. Naser, U. Bhunia, T. K. Bhattacharrjee, A. Sarkar, A. Sur, S. Saha, R. Ranganathan* and R. K. Bhandari, V.E.C.C,1/AF Bidhan Nagar, Calcutta 700 064,

Email: jpradhan@veccal.ernet.in, *Saha Institute of Nuclear Physics, Kolkata

The super-conducting cyclotron having K value of 500 is in commissioning state at VECC, Kolkata [1]. The main magnet coil is made up of multi filamentary composite superconducting wire of Nb-Ti having copper to superconductor ratio of 20:1. A 1/5th scale of this main superconducting magnet coil made in-house is tested in liquid helium. The stability of coil is verified by energizing the coil beyond the operating current of K-500 cyclotron. The magnet is forced to quench by means of heater placed close to the magnet coil and studied the quench propagation. The test has also been carried out to verify dump circuit along with quench detection circuit made in-house this paper describes the test set-up along with the test results obtained.

Thermal analysis for temperature transients during VEC K-500 Superconducting magnet cool down

C Nandi, T K Bhattacharyya, G Pal, J Chaudhuri and R K BhandariVariable Energy Cyclotron Center, 1/AF Bidhan Nagar, Kolkata 700064

AbstractA superconducting cyclotron is being constructed at VEC Centre, Kolkata. The cyclotron magnet has a superconducting NbTi coil. The iron core is, however, at room temperature. Liquid helium cools the NbTi coil. The coil is surrounded by liquid nitrogen cooled thermal radiation shield to reduce heat in leak to liquid helium system. A Helium refrigerator, Helial 50, supplied by M/s Air Liquide, France will deliver liquid helium to magnet coil through an efficient cryogen delivery system. During cool down from room temperature, the refrigerator will directly deliver cold gas to magnet coil. After attaining a temperature of about 20K, liquid helium will be supplied to magnet coil from liquid helium dewar. This paper presents detailed cool down procedure, the thermal model and results of transient behavior of superconducting magnet coil during cool down.

The Cryogenic System For The TIFR-BARC Superconducting Linac BoosterP. B. Patil, K. S. Parab, J. N. Karande, S. S. Jangam, P. B. Thakkar and R. G. Pillay

Tata Institute of Fundamental Research, Colaba, Mumbai-05

The first phase of LINAC Booster was inaugurated in September 2002 and is operational since March 2003. An energy gain of 49 MeV for Si13i has been achieved with one superbuncher and three cryostats comprising twelve cavities operating at 149.105 MHz. A LINDE TCF-50S refrigerator of 300 W rated capacity (without LN2 precooling) provides liquid He at 4.5 K. Actual total heat load of 134 W is observed for the first phase. This paper presents the details of the refrigerator, indigenously developed cryogenic distribution system, related instrumentation and the control system.

Development of Multilayer Insulation Blanket for Spacecraft ApplicationS.C.Rastogi, R. Rathnakar, V.Sasidara Rao, Suresh Babu, Idikulla Vergheese.

H.Bhojraj, P.P.Gupta, D.R.BhandariThermal Systems Group, ISRO Satellite Centre, Bangalore 560017, India

Multi Layer Insulation Blanket is a passive thermal control element used to control the geosynchronous and polar spacecraft temperatures. The multilayer insulation blanket consists of number of layers of low emissivity radiation shields interspaced by low conductivity spacer. Top and bottom layers are aluminized kapton selected to achieve desired optical characteristics of the surface. MLI blankets were developed for APPLE spacecraft. The technologies for fabrication of blankets, mounting technique on spacecraft were developed and qualification tests were conducted to demonstrate the suitability of system for space use. Electrostatic discharge grounding technique was developed and implemented on spacecraft blankets. The thermal performances of the blanket for different configurations and at different hot and cold boundary conditions were measured and the same was used in design of spacecraft thermal control system. Using the developed technology MLI blankets were fabricated for structure/thermal model, electrical model of APPLE spacecraft and subsequently on flight models of APPLE, SROSS and other spacecrafts of ISRO.

Thermal Performance of 20 K Cryotarget Simulators for Space Environ- ment Simulation of Metsat VHRR Radiant Cooler Thermal Balance Testing

N.k. Mishra1, D.P. Karnik1, P. Govindan1, S.C. Rastogi2, Madhu prasad2, Basavaraj S.A.2, Sant ram2, T. Selvan2, Subramanya2, A.K. Shrivastava2, Satish wani2, D.W. Tijare2, P.P. Gupta2 & D.R. Bhandari2

1 Environmental Test Facility, ISRO Satellite Centre, Bangalore 560017, India

Thermal Balance Test on METSAT Cooler Assembly was conducted in space simulation chamber simulating space condition of vacuum and space sink by achieving vacuum better than 10-6 mbar and shroud of 100K. To simulate deep cold space and to achieve low temperature on cooler cold stage, a cryotarget simulator is utilized achieving a temperature of 20K. It consists of cryotarget plate, closed cycle helium refrigerator, temperature indicator. The refrigerator system consists of three scroll compressor, oil removal and gas control unit, three refrigerators (cold heads) and interconnecting hoses. The solar heat input and incident IR heat input to cooler is simulated by supplying the precalculated power supply through on-board heaters mounted on cooler assembly. Thermal Balance Tests were conducted for winter solstice, summer solstice for Beginning of Life (BoL) and End of Life (EoL) conditions. The thermal performance of 20K cryotarget simulator was evaluated for different test cases. The performance of 20K cryotarget simulator was found satisfactory and met all the specifications and requirement of METSAT VHRR radiant cooler thermal balance testing.

Non-metal Liquid Helium Cryostat for SQUID operationR. Karunanithi*, S. Jacob*, S. Kasthurirengan*, K. Tamizhanban* and K. Gireesan#

*Centre for Cryogenic Technology, Indian Institute of Science, Bangalore,#Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam

Design, development and performance evaluation of a non-metal cryostat for use with liquid helium for operation of SQUIDs for NDT studies are reported in this paper. The cryostat is made of Fibre-glass Reinforced Plastic (FRP) except the top flanges, which are stainless steel. The distance between the pick-up coil at 4.2K and the outer vessel bottom flange is about 6mm (including the flange thickness) and the radiation shields are made of carbon fabric. The capacity is about 5 liters for liquid helium with a neck and tail inner diameter of about 50mm. The steady state evaporation rate without the dipstick is about 175ml/hour of liquid helium.

Application of Cryogenics in Nuclear Power Plants operations and Nuclear Science

R C Khandelwal, Head HWMG & R G Pathak, SCE, KAPSKakarapar Atomic power station, NPCIL

In a nuclear power plant operation especially PHWR type cryogenics has a very important role to play in tritium activity reduction, positive isolation of process equipments, operation of HPGe detector for gamma ray spectroscopy and for heavy water vapour recovery operation.

Cryo Technology For Space ApplicationsVinod Kumar Manglik

Deptt. of Mech.Engg.ADIT, New Vallabh Vidyanagar,Anand

The cryo technology has good potential for space applications and remarkable progress is made in last decade or so. The use of cryogenic cooled detectors have brought un-precedent advantages over the competitive technology. Continuous improvements in reliability, simplicity of operation and long life have covered large range of instruments which are using cryogenic system to meet their goal easily and accurately. Several technologies need to be improved for further enhancement of their applications and that include improving COP for active cryo coolers, thermal insulations, high heat transfer at cryo temperatures.

Cryogenic applications of compositesRS Praveen#, G Ayyappan#, Asha S Kumar*

# LS, gsLVM3 Project, VSSC-ISRO, Trivandrum, Lecturer in Chemistry, SN College, Kollam

Composite materials find place in strategic cryogenic applications, both in thermal as well as structural areas. This paper deals with some of the specific applications in space research including its limitations and

complexities in addition to its specific advantages to metals. Only limited work has been carried out elsewhere in this area and this paper consolidates the efforts of eminent scientists worldwide in this field to give an insight into what is already known. Further investigations in this area are required to understand the behavior of these materials for various service conditions.

Studies on Regeneration of Cryopanel in K-500 Superconducting Cyclotron in VECC

U. Bhunia*, Md.Z.A.Naser, J. Pradhan, A. Sur, R. K. Bhandari Variable Energy Cyclotron Centre, Department of Atomic Energy, 1/AF, Bidhan Nagar, Kolkata-700 064, India.

*ubhunia@veccal.ernet.in

Ultra high vacuum in the median plane of K-500 superconducting cyclotron is achieved by three cryopanels placed in the valley regions of the median plane. The cryopanel gets saturated after certain period of operation and needs to be regenerated. This paper describes two regeneration possibilities such as by temperature controlled resistive heating and convective heating by dry gas. The heater wattage required for first kind of regeneration for liquid helium cooled cryopanel and it's transient temperature response during regeneration is studied. The effect of the central screw material for liquid helium cooled panel on its conduction cooling is found. Possibility of regeneration by convective heating by dry nitrogen and helium gas for nitrogen panel and helium panel respectively is also studied.

Electrical transport properties of K-doped La1-XKXMnO3 (x=0.05,0.1,0.15)Prepared by pyrophoric method

S. Das and T. K. DeyCryogenic Engineering Centre, Indian Institute of Technology, Kharagpur - 721 302

The effect of monovalent alkali metal substitution into the La-sites in La1-xKxMnO3 with =0.05,0.1,0.15 on the electrical transport behavior from room temperature to 10K is reported. All the samples show the broad metal-insulator transition which increases with increasing the K-doping and resistivity decreases correspondingly. Below 50K, all the samples show a field-dependent shallow minimum, which is explained by intergrain tunneling model. The conduction mechanism in the insulating region (T>TMI) is explained by means of adiabatic small polaron hopping model, whereas in metallic region, below ~120K, resistivity is explained by small polaron coherent motion involving a relaxation due to a soft optical phonon mode along with twomagnon scattering. These hase separated conduction models at different temperature regions are combined by using a henomenological model considering the energy required to form the two phases and corresponding temperature dependence of the volume fraction is supposed to follow the Boltzmann distribution of a two energy-level system.

Quantum Hall Resistance Measurement using Direct Current Comparator and Cryogenic Current Comparator

N D Kataria and H.K. SinghNational Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi-110012

We report on the progress towards the establishment of a quantized Hall resistance (QHR) measurement system for calibrating a reference resistor maintained at a fixed temperature. The system consists of a quantum Hall device, a 9 T superconducting magnet installed in a LHe cryostat, a room temperature direct current comparator bridge (DCC) and a temperature controlled oil bath. We discuss the measurements required to transfer the quantized Hall resistance to the reference resistor by DCC and the cryogenic current comparator (CCC) being developed for future use.

Microwave Characterization of Superconducting and Dielectric Materials at Cryogenic Temperatures

N D Kataria and H.K. SinghNational Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi-110012

Microwave characterization of superconducting bulk and thin films is reported using sapphire loaded dielectric resonator at microwave frequencies and temperature ranging from 10 K to the transition temperature Tc. The Q-value of the resonator depends on the conduction losses of the enclosure besides loss tangent of the dielectric material. Using High temperature superconducting thin films decreases the conduction loss thereby increasing the Q-value of the resonator. Dielectric resonators are also used to characterize dielectric ceramics.

Design and Development of Cryogenic Test Facility for Evaluating hts Current Leads

L PRADEEP KUMAR BHAVANAM, SWAMINATHAN.G*Heat Power- R&Ac, J.N.T.U College of Engineering - Anantapur

* Ceramic Technological Institute, BHEL-EPD - Bangalore

A cryogenic test facility for evaluating critical current characteristics of HTS current leads as a function of temperature is described. The system was constructed by designing a multi purpose cryostat to work as liquid Nitrogen as well as Helium Dewar. An optimum vapor cooled current lead assembly to power the HTS leads at cryogenic environment from ambient temperature with low heat leak was designed using a C-program keeping in view of above process.

Development of Three-Stage Passive Radiant Cooler for Cryogenic Cooling of Infrared Detectors of Imager Meteorological Payload, of INSAT 3D Spacecraft of

ISROS.C. Rastogi*, Madhu Prasad, Basavaraj S Akkimaradi, Sant Ram, T. Selvan, Subramanya,

A.K. Shrivastava, D.W.Tijare, Satish Wani, P.P. Gupta & D. R. BhandariThermal Systems Group, ISRO Satellite Centre, Bangalore - 560017

INSAT-3D IMAGER will provide imaging capability of the earth disk from geostationary altitude in one visible in 0.55 to 0.75 ? m range and five infrared channels viz., Short Wave IR (SWIR) in 1.55 to 1.70 ? m, Mid IR (MIR) in 3.8 to 4 ? m, Water Vapour IR (WV) in 6.5 ? m, Thermal IR-1 (TIR-1) in 10.5 to 11.5 ? m range and Thermal IR-2 (TIR-2) in 11.5 to 12.5 ? m range. The MIR, WV, TIR-1 and TIR-2 are maintained at cryogenic temperature of 95 to 100 K through three-stage passive radiant cooler and close loop heater control. Passive radiant cooler utilizes the deepcold space sink to cool IR detectors. A passive radiant cooler is developed and qualified for this application. The critical areas of development, (1) low conductance FRP support assembly (2) High emittance cold stage, (3) Sun Shield with low emissivity and high specular reflectance and (4) Cryogenic Electrical Wiring processes are highlighted. Thermal mathematical model is developed considering specular/diffuse thermal control surfaces and complete spacecraft surrounding. The on-orbit performance is predicted for different stages of cooler for all seasons in space at Beginning of Life (BoL) and End of Life (EoL) cases. The cooler assembly, as part of acceptance/qualification program will be subjected to various tests like (1) Sine and Random Vibration Test, (2) Optical Alignment Test, (3) Thermal Balance Test etc. On the basis of Thermal Balance Test, Cooler Mathematical Model will be updated to predict on-orbit temperatures.

Application of Cryogenic Systems in Space SimulationP. Gopi Kishore

Bharat Heavy Plate and Vessels Limited Visakhapatnam - 530012gopikishore_bhpv@sify.com

In order to produce a vacuum that approaches that of outer space, best method involves low temperatures. In Space Simulation, the pressure of space is produced by Cryopumps cooled by gaseous helium - backed by Diffusion pumps to remove the non condensibles. Cryopumping or Freezing out the residual gases will result in Ultra High Vacuum.. Temperature of free space is simulated by cooling a shroud with integral

cryo fluid paths within the chamber to liquid nitrogen temperatures. Dense gaseous helium at cryogenic temperatures or liquid helium is used to cool the Cryo Panels which freeze out the residual gases.

Cryogenic PropulsionShirish R. Gandhi, and Nisha V. Bora

Department of Mechanical Engineering, L.D.College of Engineering, Ahmedabad

Cryogenic propulsion utilizing cryogens has dominated over the orthodox methods of propulsion. Cryogenic propulsion for space exploration was investigated very early with initial development work on space activities and rocket propulsion system using liquid oxygen and hydrogen. Use of slush hydrogen in cryogenic propulsion system has solved many problems of using cryogenic propellants such as heat in-leak, storage of low temperature liquid, thermal stratification etc.

Future Thermal Design Prospects of NiH2 Batteries for Indian Space Applications

Alok Shrivastava, Dr. R.A.Katti*, Prof. K.G.Narayankhedkar***Thermal Systems Group, ISRO Satellite Centre, Bangalore - 560017,** Mechanical Engineering Department, IIT Bombay, Mumbai-400076

With the growing demand of communication needs, electrical power of spacecrafts is continuously increasing from 2 kW to 6 kW. During sun-lit part of the orbit, solar cells generate power, while in eclipse power is supplied by NiH2 Batteries. The working temperature regime for these batteries is comparatively lower (-10 to +10 oC), and have a stringent requirement that the maximum temperature gradient within a single battery is 5 oC. For earlier batteries, Passive Thermal Control Techniques were adequate; however Active Thermal Technique is necessary for such high power batteries. Loop Heat Pipes (LHPs) and Capillary Pumped Loop (CPLs) are chosen for low heat fluxes and preferably for diffusing the heat at larger area. For thermal management of high heat flux electronic packages Mechanical Pumped Loop (MPL) system is essential. The conceptual configuration and functioning of a MPL, under development phase in ISRO, have been discussed in this paper.

Transient Heat Transfer -Two Dimensional Mathematical Model for Cryogenic Rocket Engine Thrust Chamber

Biju T. Kuzhiveli* and V. Gnana GandhiLiquid Propulsion Systems Centre, I.S.R.O, Valiamala, Trivandrum, India - 695 547

* Department of Mechanical Engineering, VJCET, Kerala, India - 686 670, Email: btkuzhiveli@yahoo.com

This paper presents two-dimensional transient thermal computational model for a cryogenic rocket engine thrust chamber. Modern cryogenic rocket engine thrust chambers are exposed to high pressure and high heat flux environments due to high energy combustion and has presented some of the most challenging engineering problems in the rocketry and space engineering. A commonly employed method to overcome the problem due to high temperature arising out of high-energy combustion is to provide regenerative cooling by passing liquid hydrogen through coolant channel passages through the thrust chamber. However cooling the thrust chamber by passing cryogenic fluid results in wide range of temperature distribution across the cross section and along the axis of the thrust chamber during transient and steady state conditions and poses serious structural strength concerns. In order to have a thermal prediction that leads to optimal, stable and economical structural design, an accurate accounting of heat transfer characteristics for the complete spectrum of the thrust chamber is necessary. Hence it is essential to develop a tool which can accurately predict the transient thermal characteristics of the thrust chamber. In order to meet the goal, a computational model has been developed which takes into account of flow involved in the operation of cryo engine and various boundary conditions. The flow involved in the operation is a complicated phenomenon as it is turbulent, reactive and undergoes both subsonic and supersonic flow regimes. The mathematical model presented here takes care of the transient temperature distribution along the axis and across the cross section during transient and steady state conditions during chill down and hot test. First phase of computer implementation is currently underway which gives promising results. The computer program is capable of providing two dimensional , transient temperature distribution on the thrust chamber,

hot side and coolant side heat transfer coefficients, coolant temperature rise, coolant pressure drop and heat flux etc.