Helium Liquefier Research Articles

CEC Awards

SAMUEL C. COLLINS AWARD 2017Dr. Steven Van SciverIn 1965 the Cryogenic Engineering Conference (CEC) established an award in honor of the late Samuel C. Collins, Professor of Mechanical Engineering at the Massachusetts Institute of Technology. One of Professor Collins’ most notable works is his invention of the modern helium liquefier. The Collins Award is awarded to an individual who has made outstanding contributions to the identification and solution of cryogenic engineering problems and has additionally demonstrated a concern for the cryogenic community through service and leadership to this community. The award is open to persons without regard to national origin.List of THE RUSSELL B. SCOTT MEMORIAL AWARDS, Best Paper for Cryogenic Engineering Research, STUDENT MERITORIOUS PAPER AWARD, DONNA JUNG SCHOLARSHIP AWARD, KLAUS AND JEAN TIMMERHAUS SCHOLARSHIP AWARD are available in this pdf.

SNS Central Helium Liquefier spare Carbon Bed installation and commissioning

The Spallation Neutron Source (SNS) Central Helium Liquefier (CHL) at Oak Ridge National Laboratory (ORNL) has been without major operations downtime since operations were started back in 2006. This system utilizes a vessel filled with activated carbon as the final major component to remove oil vapor from the compressed helium circuit prior to insertion into the system’s cryogenic cold box. The need for a spare carbon bed at SNS due to the variability of carbon media lifetime calculation to adsorption efficiency will be discussed. The fabrication, installation and commissioning of this spare carbon vessel will be presented. The novel plan for connecting the spare carbon vessel piping to the existing infrastructure will be presented.

Experimental helium liquefier with a GM cryocooler.

A helium liquefier has been developed with a Gifford-McMahon cryocooler using the cold enthalpy available at the first stage, the inter-stage, and the second stage of the cryocooler. Most of the enthalpy of the helium gas at 300 K is absorbed in the first stage by a coaxial heat exchanger and inter-stage region of the cryocooler. Pre-cooled helium gas is liquefied at the second stage heat exchanger where the final cooldown and condensation happens. The measured production capacity of the liquefier is 17.4 l/day at atmospheric pressure. The whole setup has been designed to work in a coaxial configuration where the two heat exchangers, the cryostat, and the dewar are symmetrically placed around the central axis.

Capacity enhancement of indigenous expansion engine based helium liquefier

Development of technology and understanding for large capacity helium refrigeration and liquefaction at helium temperature is indispensable for coming-up projects. A new version of helium liquefier designed and built to provide approximately 35 liters of liquid helium per hour. The refrigeration capacity of this reciprocating type expansion engine machine has been increased from its predecessor version with continuous improvement and deficiency debugging. The helium liquefier has been built using components by local industries including cryogenic Aluminum plate fin heat exchangers. Two compressors with nearly identical capacity have been deployed for the operation of system. Together they consume about 110 kW of electric power. The system employs liquid Nitrogen precooling to enhance liquid Helium yield. This paper describes details of the cryogenic expander design improvements, reconfiguration of heat exchangers, performance simulation and their experimental validation.

Multi-objective Optimization on Helium Liquefier Using Genetic Algorithm

Research on optimization of helium liquefier is limited at home and abroad, and most of the optimization is single-objective based on Collins cycle. In this paper, a multi-objective optimization is conducted using genetic algorithm (GA) on the 40 L/h helium liquefier developed by Technical Institute of Physics and Chemistry of the Chinese Academy of Science (TIPC, CAS), steady solutions are obtained in the end. In addition, the exergy loss of the optimized system is studied in the case of with and without liquid nitrogen pre-cooling. The results have guiding significance for the future design of large helium liquefier.

Study of a multi-strategy controller on a helium liquefier

Helium liquefier is widely used in the fields of superconducting, nuclear fusion energy and high-energy physics. However, the present PID controlling system of the liquefier is not able to keep the compressor suction pressure, outlet pressure and turbine inlet pressure all in the expected range at the same time. Thus, a multi-strategy controller for a helium liquefier is proposed in this paper. A dynamic simulation model of this liquefier is also developed and shown. To study the control effect, an operation process including cool-down, steady-state and pulse of heat is described. The simulation result of this process is presented and compared with the result of the present PID controlling system.

Development of helium refrigeration/ liquefaction system at BARC, India

An experimental helium refrigerator/liquefier, using ultra high speed cryogenic turboexpanders, is designed and developed at Cryo-Technology Division, BARC. The developed system is based on the modified Claude cycle. The developed system is presently fully functional consisting of process compressor with gas management system, coldbox, helium receiver Dewar, tri-axial transfer line and helium recovery system. Extended trial runs are conducted to evaluate the performance of the developed system. During these trials, liquefaction rate of around 32 l/hr and refrigeration capacity of around 190W is achieved. The paper addresses design, development and commissioning aspects of the developed helium liquefier along with results of performance evaluation trial runs.

Cryogenic system for the 43 T Hybrid Magnet at LNCMI Grenoble: from the needs to the commissioning

LNCMI is one of the unique worldwide laboratories offering the scientific community access to various experimental conditions with continuous magnetic fields well above 20 T. LNCMI is currently developing a large field flexible experimental platform. One configuration will produce a continuous magnetic field of 43 T in a 34 mm warm bore aperture from the combination of homemade resistive electromagnet inserts and a large bore outer superconducting magnet (1.1 m internal cold dia.), the latter being built in close collaboration with CEA-IRFU Saclay. The superconducting magnet with its mechanical structure and its helium vessel will represent a mass of 22 tons to cool down to 1.8 K and maintain at this temperature 10 months per year. An overview of the project will be given focusing on the cryogenics and particularly on the helium liquefier designed and manufactured by Air Liquide Advanced Technologies. This system - the most powerful even produced in the Helial ML range - and its ancillaries has been integrated and commissioned as a turnkey system in the existing site of LNCMI.

Process Control Migration of 50 LPH Helium Liquefier

Two helium liquefier/refrigerators are operational at VECC while one is dedicated for the Superconducting Cyclotron. The first helium liquefier of 50 LPH capacity from Air Liquide has already completed fifteen years of operation without any major trouble. This liquefier is being controlled by Eurotherm PC3000 make PLC. This PLC has become obsolete since last seven years or so. Though we can still manage to run the PLC system with existing spares, risk of discontinuation of the operation is always there due to unavailability of spare. In order to eliminate the risk, an equivalent PLC control system based on Siemens S7-300 was thought of. For smooth migration, total programming was done keeping the same field input and output interface, nomenclature and graphset. New program is a mix of S7-300 Graph, STL and LAD languages. One to one program verification of the entire process graph was done manually. The total program was run in simulation mode. Matlab mathematical model was also used for plant control simulations. EPICS based SCADA was used for process monitoring. As of now the entire hardware and software is ready for direct replacement with minimum required set up time.

Theoretical study on the efficacy of the cold compressor based cryogenic cycles

Cold compressor based cycles have emerged as practical necessity for sub 4.5K (sub atmospheric) large scale cryogenic systems as used in most modern high energy accelerators and tokamaks. The concept of cold compressor can be applied in a generalized way for even atmospheric (high pressure) cycles, if justified. A rise in temperature is exhibited at the exit of the cold compressor due to pressurization and the inefficiency involved in the process. This rise in temperature results in gain of sensible heat, and acts like a refrigeration load at that temperature. This loss can only be acceptable if other advantages of cold compressors are substantial. In the present work, it is tried to explore the possibility of using the emerged cold compressor technology for medium scale cryogenics. One of the objectives of the study is to develop a cold compressor based refrigeration cycle which can be implemented using the present infrastructure at Cryo-Technology Division, Bhabha Atomic Research Centre (BARC). In this endeavour, a cryogenic cycle analysis tool is developed and is validated against the process data available for 2K cryogenic plant at LHC. Three cold compressor based modifications are proposed to the presently installed modified Claude cycle based helium liquefier. These three cases are analysed and compared.

Experimental and analytical studies on a foam insulated rigid type transfer line for use with liquid nitrogen

The transfer line is one of the important components of any cryogenic system needed to transport the cryogenic fluid from one location to another. Towards our efforts to develop a long rigid-type transfer line for liquid nitrogen (LN2) to transfer this fluid from a 5000 litre capacity vertical storage tank to the Helium liquefier (Linde Model 1610) located at a distance of nearly 50 m, we designed and fabricated several units of straight section transfer lines of length ≈ 6.5 m and they were integrated to make the long length transfer line. Each unit was fabricated with 0.5 inch dia. copper inner tube supported by spacers within 2 inch dia. PVC outer tube. Each section was foam insulated after the necessary instrumentation for temperature measurements. The individual sub units were integrated together with a small bellow section in between to take care of thermal contraction during use. We present here the analytical and experimental studies of the cool down and mass flow characteristics of a single foam insulated unit. These experimental studies are representative results of the performances of the long length rigid foam insulated transfer line.

Numerical studies on sizing/ rating of plate fin heat exchangers for a modified Claude cycle based helium liquefier/ refrigerator

Performance of modern helium refrigeration/ liquefaction systems depends significantly on the effectiveness of heat exchangers. Generally, compact plate fin heat exchangers (PFHE) having very high effectiveness (>0.95) are used in such systems. Apart from basic fluid film resistances, various secondary parameters influence the sizing/ rating of these heat exchangers. In the present paper, sizing calculations are performed, using in-house developed numerical models/ codes, for a set of high effectiveness PFHE for a modified Claude cycle based helium liquefier/ refrigerator operating in the refrigeration mode without liquid nitrogen (LN2) pre-cooling. The combined effects of secondary parameters like axial heat conduction through the heat exchanger metal matrix, parasitic heat in-leak from surroundings and variation in the fluid/ metal properties are taken care of in the sizing calculation. Numerical studies are carried out to predict the off-design performance of the PFHEs in the refrigeration mode with LN2 pre-cooling. Iterative process cycle calculations are also carried out to obtain the inlet/ exit state points of the heat exchangers.

Flow field analysis of high-speed helium turboexpander for cryogenic refrigeration and liquefaction cycles

Turboexpander constitutes one of the vital components of Claude cycle based helium refrigerators and liquefiers that are gaining increasing technological importance. These turboexpanders which are of radial inflow in configuration are generally high-speed micro turbines, due to the low molecular weight and density of helium. Any improvement in efficiency of these machines requires a detailed understanding of the flow field. Computational Fluid Dynamics analysis (CFD) has emerged as a necessary tool for the determination of the flow fields in cryogenic turboexpanders, which is often not possible through experiments.In the present work three-dimensional transient flow analysis of a cryogenic turboexpander for helium refrigeration and liquefaction cycles were performed using Ansys CFX®, to understand the flow field of a high-speed helium turboexpander, which in turn will help in taking appropriate decisions regarding modifications of established design methodology for improved efficiency of these machines. The turboexpander is designed based on Balje's nsds diagram and the inverse design blade profile generation formalism prescribed by Hasselgruber and Balje. The analyses include the study of several losses, their origins, the increase in entropy due to these losses, quantification of losses and the effects of various geometrical parameters on these losses. Through the flow field analysis it was observed that in the nozzle, flow separation at the nozzle blade suction side and trailing edge vortices resulted in loss generation, which calls for better nozzle blade profile. The turbine wheel flow field analysis revealed that the significant geometrical parameters of the turbine wheel blade like blade inlet angle, blade profile, tip clearance height and trailing edge thickness need to be optimised for improved performance of the turboexpander. The detailed flow field analysis in this paper can be used to improve the mean line design methodology for turboexpanders used in helium refrigeration and liquefaction cycles.

The optimization on flow scheme of helium liquefier with genetic algorithm

There are several ways to organize the flow scheme of the helium liquefiers, such as arranging the expanders in parallel (reverse Brayton stage) or in series (modified Brayton stages). In this paper, the inlet mass flow and temperatures of expanders in Collins cycle are optimized using genetic algorithm (GA). Results show that maximum liquefaction rate can be obtained when the system is working at the optimal parameters. However, the reliability of the system is not well due to high wheel speed of the first turbine. Study shows that the scheme in which expanders are arranged in series with heat exchangers between them has higher operation reliability but lower plant efficiency when working at the same situation. Considering both liquefaction rate and system stability, another flow scheme is put forward hoping to solve the dilemma. The three configurations are compared from different aspects, they are respectively economic cost, heat exchanger size, system reliability and exergy efficiency. In addition, the effect of heat capacity ratio on heat transfer efficiency is discussed. A conclusion of choosing liquefier configuration is given in the end, which is meaningful for the optimal design of helium liquefier.

85-ЛЕТИЕ «НПО ГЕЛИЙМАШ»: ИСТОРИЯ И СОВРЕМЕННОСТЬ ОБЪЕДИНЕНИЯ

JSС «SPA «Geliymash» stood at the onset of oxygen engineering. The company's activities positively affected the development of the national foundation of manufacturing effective systems of cryogenic equipment. Currently, the association is a major research and production center for the development and manufacture of all kinds of cryogenic equipment: helium refrigerators and liquefiers, air separation plants, oxygen generators, hydrogen and natural gas liquefiers, cryogenic tanks and cisterns, turbo expanders, etc. It is used in Russia and in over 40 countries all over the world. The company has the capacity and experience to carry out the complete work cycle on the development and production of up to date cryogenic engineering equipment.

Problems and Development of Methods of Dynamic Simulation of Cryogenic Systems

The problems of designing and employing cryogenic systems operating in transient modes over a considerable operating time as well as various methods of simulating transient operation of these systems are discussed. The advantages of application of dynamic simulation of cryogenic systems over classical methods of calculation of steady-state mode are shown. The available information on dynamic simulation of large helium cryogenic systems is reviewed. To validate the dynamic simulation method, the transient mode of operation of a large helium liquefier is analyzed applying universal software tool for dynamic simulation modeling of chemical systems, the results of which are compared with the experimental data.

ВИХРЕВЫЕ МАЛОМАСШТАБНЫЕ ТРУБЫ ДЛЯ КРИОГЕНИКИ

Vortex coolers have been manufactured for different areas for many years. Despite a number of advantages inherent in this method of energy conversion, there are few examples of their effective use in cryogenic systems. The problems accompanying the use of vortex coolers in cryogenics are considered in the paper. The examples of application of the cold sources without moving parts in the technologies of rare gases production are given. For example, during the purification of Ne-He-concentrate from nitrogen, the reduction of the mixture phase equilibrium temperature allows reducing in half the content of secondary component (N2) at the output of the phase separator. Wherein this positive effect is achieved by using the existing pressure drop and does not require additional costs. Promising applications of vortex coolers are small rate helium liquefiers and centrifugal separators of gas mixtures, which can operate in the conditions of weightlessness and oscillating motion.

Operational analysis and update on modifications to a helium liquefier under development at BARC

An experimental helium refrigerator/liquefier is being designed and developed by Cryo-Technology Division to be installed at Bhabha Atomic Research Centre, Mumbai. During first trial runs, certain limitations of the process were observed and some other fabrication/development issues came to light. After detailed steady state cycle simulation studies, it was decided to undertake some major modifications to achieve the target of about 200W refrigeration capacity at around 4.7K. The most significant modification involved changing the basic thermodynamic cycle from Collins to a modified Claude cycle which is more suited to turboexpanders. To this effect, simulation studies on the new cycle, with two turboexpanders in series interspaced with a multi stream heat exchanger, was taken up and the process computed. The present paper aims to describe in details different studies taken up on the helium refrigerator. It also aims to provide an update on the present status of development of the helium refrigerator/liquefier.

ARIEL E-linac Cryogenic System: Commissioning and First Operational Experience

The Advanced Rare IsotopE Laboratory (ARIEL) is a major expansion of the Isotope Separator and Accelerator (ISAC) facility at TRIUMF. A key part of the ARIEL project is a 10 mA 50 MeV continuous-wave superconducting radiofrequency (SRF) electron linear accelerator (e-linac). The 1.3 GHz SRF cavities are operated at 2 K. HELIAL LL helium liquefier by Air Liquide Advanced Technologies (ALAT) with a tuneable liquid helium (LHe) production was installed and commissioned in Q4’2013 [1]. It provides 4 K liquid helium to one injector and one accelerator cryomodules that were installed and tested in 2014. The 4 K to 2 K liquid helium transition is achieved on-board of each cryomodule. The cryoplant, LHe and LN2 distributions, sub-atmospheric (S/A) system and cryomodules were successfully commissioned and integrated into the e-linac cryogenic system. Required pressure regulation for both 4 K cryoplant in the Dewar and 2 K with the S/A system was achieved under simulated load. Final integration tests confirmed overall stable performance of the cryogenic system with two cryomodules installed. The paper presents details of the cryogenic system commissioning tests as well as highlights of the initial operational experience.

Liquid nitrogen historical and current usage of the central helium liquefier at SNS

The main cryogenic system for the Spallation Neutron Source (SNS) is comprised of a 4-K cold box, a 2-K cold box, six warm compressors, and ancillary support equipment. This system has been cold and operating with little disruption since 2005. Design and operation of liquid nitrogen (LN2) supplied from a single 20,000-gallon supply Dewar will be discussed. LN2 used to precool the 4-K cold box heat exchanger started to increase around 2011. LN2 Consumption during 2012 and 2013 was almost double the nominal usage rate. Studies of this data, plant parameter changes to respond to this information, and current interpretations are detailed in this paper. The usage rate of LN2 returned to normal in late 2013 and remained there until recent additional changes. Future study plans to understand potential causes of this including contamination migration within the 4-K cold box will also be addressed.