Cryogenic Supply Research Articles

Preliminary studies of the MINERVA cryogenic supply system

MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) will be composed of a 600 MeV LINear ACcelerator (LINAC) with a large number of cryomodules and a 100 MW thermal power subcritical nuclear reactor cooled by lead-bismuth. The MINERVA MYRRHA Isotopes productioN coupling the linEar acceleRator to the Versatile proton target fAcility) project is the first phase of the MYRRHA project composed of a 100 MeV, 4 mA continuous-wave proton LINAC. The MINERVA LINAC takes advantage of 60 superconducting radiofrequency (RF) cavities cooled at 2 K by saturated superfluid helium (He II). The MINERVA cryoplant will supply the required cryogenic cooling power of the LINAC through cryogenic lines and cryogenic valve boxes. This paper describes the LINAC cryogenic system supply architecture, the different operating modes, the heat loads, the cryoplant main requirements and the strategy to comply with high reliability requirements. The MINERVA cryoplant shall provide helium flows at 40 K for the thermal shielding, at 5 K for the cooling of the RF couplers and at 2 K for the 60 superconducting cavities installed in 30 cryomodules. The total equivalent refrigeration power of the MINERVA cryoplant is about 3.5 kW at 4.5 K. The cryoplant is composed of a warm compression station including sub-atmospheric volumetric compressors, helium gas storages and a refrigeration cold box with cold centrifugal compressors.

Cryogenic Air Supply Feasibility for a Confined Space: Underground Refuge Alternative Case Study.

A breathable air source is required for a confined space such as an underground refuge alternative (RA) when it is occupied. To minimize the risk of suffocation, federal regulations require that mechanisms be provided and procedures be included so that, within the refuge alternative, the oxygen concentration is maintained at levels between 18.5% and 23% for 96 h. The regulation also requires that, during use of the RA, the concentration of carbon dioxide should not exceed 1%, and the concentration of carbon monoxide should not exceed 25 ppm. The National Institute for Occupational Safety and Health (NIOSH) evaluated the cryogenic air supply's ability to provide breathable air for a refuge alternative. A propane smoker was used to simulate human breathing by burning propane gas which will consume O2 and generate CO2 and H2O. The rate of propane burned at the smoker was controlled to represent the O2 consumption rate for the breathing of a certain number of people. Two 96-h tests were conducted in a sealed shipping container, which was used as a surrogate for a refuge alternative. While burning propane gas to simulate human oxygen consumption, cryogenic air was provided to the shipping container to determine if the cryogenic air supply would keep the O2 level above 18.5% and CO2 level below 1% inside the shipping container as required by the federal regulations pertaining to refuge alternatives. Both of the 96-h tests simulated the breathing of 21 persons. The first test used the oxygen consumption rate (1.32 cu ft of pure oxygen per hour per person) specified in federal regulations, while the second test used the oxygen consumption rate specified by (Bernard et al. 2018, "Estimation of Metabolic Heat Input for Refuge Alternative Thermal Testing and Simulation," Min. Eng., 70(8), pp. 50-54) (0.67 cu ft of pure oxygen per hour per person). The test data shows that during both 96-h tests, the oxygen level was maintained within a 21-23% range, and the CO2 level was maintained below 1% (0.2-0.45%). The information in this paper could be useful when applying a cryogenic air supply as a breathable air source for an underground refuge alternative or other confined space. [DOI: 10.1115/1.4064062].

Non-flow cryogenic supply systems for HTS power systems

Operation principles of cryogenic supply systems for power HTS systems have been examined. Two non-flow (autonomous) cryogenic supply systems have been described. Gas circuit of cryorefrigerator uses neon, rather than helium, what makes it possible to decrease several-fold the number of compression stages in compressors and losses of working fluid in the circuit when leakage occurs. The use of turbomachines and gas bearings allows for substantially increasing an overhaul period of cryorefrigerator (over 30 000 h).

Flow cryogenic supply systems for HTS power systems

Operation principles of cryogenic supply systems for power HTS systems have been examined. Two flow cryogenic supply systems have been described. These cryogenic supply systems have been created in MAI and utilized to ensure the operation of HTS power devices (power cables, electric motors, and generators, transformers, etc.).

Techno-economic assessment of blue and green ammonia as energy carriers in a low-carbon future

Ammonia is an industrial chemical and the basic building block for the fertilizer industry. Lately, attention has shifted towards using ammonia as a carbon-free energy vector, due to the ease of transportation and storage in liquid state at −33 °C and atmospheric pressure. This study evaluates the prospects of blue and green ammonia as future energy carriers; specifically, the gas switching reforming (GSR) concept for H2 and N2 co-production from natural gas with inherent CO2 capture (blue), and H2 generation through an optimized value chain of wind and solar power, electrolysers, cryogenic N2 supply, and various options for energy storage (green). These longer-term concepts are benchmarked against conventional technologies integrating CO2 capture: the Kellogg Braun & Root (KBR) Purifier process and the Linde Ammonia Concept (LAC). All modelled plants utilize the same ammonia synthesis loop for a consistent comparison. A cash flow analysis showed that the GSR concept achieved an attractive levelized cost of ammonia (LCOA) of 332.1 €/ton relative to 385.1–385.9 €/ton for the conventional plants at European energy prices (6.5 €/GJ natural gas and 60 €/MWh electricity). Optimal technology integration for green ammonia using technology costs representative of 2050 was considerably more expensive: 484.7–772.1 €/ton when varying the location from Saudi Arabia to Germany. Furthermore, the LCOA of the GSR technology drops to 192.7 €/ton when benefitting from low Saudi Arabian energy costs (2 €/GJ natural gas and 40 €/MWh electricity). This cost difference between green and blue ammonia remained robust in sensitivity analyses, where input energy cost (natural gas or wind/solar power) was the most influential parameter. Given its low production costs and the techno-economic feasibility of international ammonia trade, advanced blue ammonia production from GSR offers an attractive pathway for natural gas exporting regions to contribute to global decarbonization.

Electromagnetic analyses of the CFETR TF coil terminal

To develop and validate the manufacturing technologies of the key components for the CFETR, a comprehensive research facility for fusion technology (CRAFT) project has been approved by the Chinese government in 2019. As part of this project, a full size toroidal field (TF) prototype coil is being constructed by the Institute of Plasma Physics Chinese Academy of Sciences. In this paper, our main concern is the TF coil terminal, which is quite complex as it integrates many sub-systems and interfaces in a very limited space and connects the TF coil to the cryogenic supply, the power supply and other systems. In order to provide the design basis for the TF coil terminal, electromagnetic analyses are performed. First the structures of the TF coil winding packs (WPs) and the coil terminal are presented. Then, electromagnetic analyses are conducted for the condition of 16 TF energized, and for the condition of a single TF energized, namely the cryogenic test condition for a single TF prototype coil. Finally, the magnetic field and Lorentz force on the external joints, leads and jumpers are calculated, visualized and discussed. Our results indicate that the single TF energized load condition is more important for the design of the TF coil terminal, than the 16 TF energized condition.

Study on Prediction and Influencing Factors of Cryogenic Compressed Hydrogen Storage and Supply Process

Study on Prediction and Influencing Factors of Cryogenic Compressed Hydrogen Storage and Supply Process

Система кріогенного забезпечення кріомагнітного комплексу КМК–1000 на базі мікрокріогенних систем замкнутого циклу

Система кріогенного забезпечення кріомагнітного комплексу КМК–1000 на базі мікрокріогенних систем замкнутого циклу

Cryogenic Performance Test Platform for the Gas Bearings of Helium Turbine Expanders

The turbo-expander is the core part of the helium refrigerator, and the gas bearing is the critical component influences the stability of the machine. There is 300 K operating temperature difference between the turbine wheel and the gas bearing regions in the helium turbo-expander. Therefore, it is necessary to consider the heat transfer between the bearing surfaces, nominally at room temperature, and the rest of the machine when studying bearing dynamic stability. This paper describes a cryogenic test platform that is being developed to analyze the dynamic performance of gas bearings with cryogenic gas supply. The system flow loop has been designed for bearing and small turbine testing at 80 K and above. The experimental method has been determined. All of the components are ready for the cold box assembly. The commissioning of the platform will be carried out in the near future.

Cryogenic Air Supply for Cooling Built-in-Place Refuge Alternatives in Hot Mine

Built-in-place (BIP) refuge alternatives (RAs) are designed to provide a secure space for miners who cannot escape during a mine emergency. Heat and humidity buildup within RAs may expose miners to physiological hazards such as heat stress. To minimize the risk of heat stress, Title 30 Code of Federal Regulations (CFR), or 30 CFR, mandates a maximum allowable apparent temperature (AT) for an occupied RA of 35 °C (95 °F) (MSHA 2008 [1]). The National Institute for Occupational Safety and Health (NIOSH) has conducted extensive research on the thermal environment of occupied RAs intended for use in underground coal mines. NIOSH research has demonstrated that a fully occupied BIP RA can exceed the AT limit by > 5.6 °C (10 °F) in mines with elevated mine strata and air temperatures (Bissert et al. 2017 [2]). In this circumstance, an RA cooling system could provide a solution. This paper provides an overview of test methodology and findings as well as guidance on improving the performance of a cryogenic air system prototype by optimizing the flow rate, increasing the tank storage capacity, and improving the efficiency of the heat exchanger of the cryogenic system. This may enable BIP RAs to meet the 35 °C (95 °F) AT limit in mines with elevated temperatures. The information in this paper is useful for RA manufacturers and mines that may choose to implement a cryogenic air system as a heat mitigation strategy.

System Cryogenic Supply Cryomagnetic Complex KMK–1000 on the Basis of Micro-Cryogenic Systems of Closed Cicle

System Cryogenic Supply Cryomagnetic Complex KMK–1000 on the Basis of Micro-Cryogenic Systems of Closed Cicle

Numerical and experimental study of end-milling process of titanium alloy with a cryogenic internal coolant supply

Cryogenic machining is an environmentally friendly process; liquid nitrogen (LN2) is sprayed onto cutting tool to reduce cutting temperature, increasing tool life. Cutting temperature and force were numerically predicted during cryogenic assisted milling with an internal coolant-assisted tool holder (internal cryogenic milling) for Ti-6Al-4V alloy. The influence of LN2 on the material temperature throughout the machining was estimated; a numerical model to simulate the initial temperature of work material was discussed by consideration of LN2 injective mechanism. A modified Johnson-Cook model including the cryogenic temperature range was adopted to model material plasticity. The predictive models were validated based on side-milling test. The predicted values captured the trend of experimental result; the minimum and maximum temperature errors were 0.1% and 8.6%, and those for the cutting force were 0.2% and 34.4%. Moreover, comprehensive experimental studies for the cutting temperature, cutting force, chip morphology, and chip composition were performed to understand the effect of cryogenic cooling condition. In internal cryogenic milling, the cutting temperature and force tended to be lower than dry machining. Based on the morphological analysis of the generated chip, the coefficient of sliding friction at tool-chip interface under the internal cooling was reduced by 21.4% as compared to the dry condition.

Underground Mine Refuge Alternatives Heat Mitigation.

In case of an emergency in an underground coal mine, miners who fail to escape from the mine can enter a refuge alternative (RA) for protection from adverse conditions, such as high carbon monoxide levels. One of the main concerns with the use of both portable and built-in-place (BIP) RAs, especially for hot or deep mines, is the interior temperature rise due to the occupants' metabolic heat and the heat released by devices such as the carbon dioxide (CO2) scrubbing system. The humidity within the RA will also increase through occupants' respiration and perspiration and from the chemical reaction within the CO2 scrubbing system. Heat and humidity buildup can subject the occupants to hazardous thermal conditions. To protect RA occupants, Mine Safety and Health Administration regulations mandate a maximum apparent temperature of 95 °F within an occupied RA. The National Institute for Occupational Safety and Health (NIOSH) tested both an air-conditioned borehole air supply (BAS) and a cryogenic air supply for RAs in the NIOSH Experimental Mine in Bruceton, PA. The BAS was tested on a 60-person BIP RA, while the cryogenic air supply was tested on a 30-person BIP RA and a portable 23-person tent-type RA. Multiple tests were conducted with both air supplies to assess their ability to cool RAs. The test results show that the BAS and the cryogenic air supply were able to maintain the apparent temperature within the tested RAs under the 95 °F limit. The BAS and the cryogenic air supply are potential RA heat mitigation strategies that mines could use to prevent heat/humidity buildup within RAs.

Options for a reliable cryogenic supply for the FAIR facility

FAIR, which is currently being built at GSI, will provide particle beams with unprecedented intensity and quality. The facility's diversity makes it unique: ions of all natural elements of the periodic table as well as antiprotons can be accelerated. Hence the accelerators and the experimental infrastructure have to be extremely flexible in the adaptation to various operating schemes. The main accelerator, that will be realized within the starting phase of FAIR, is the SIS100 (SchwerIonenSychrotron 100 Tm). The superconducting magnets of SIS100 will to be hardly not to fast-ramped for several hours, which causes variations in the 4.5K heat load by factor 4. The larger cold mass and the higher liquid helium inventory is necessary for the Super-FRS (Superconducting FRagment Seperator), which will be supplied from the same cryo plant as SIS100.

Momentum-preserved node for fusion magnet cryogenic network analysis and its implications

Cryogen supply is one of decisive factors for the analysis of fusion magnet. In order to analyze cryogenic networks, numerical node joining each component together is required. In SUPERMAGNET code, such joint called as ‘volume’ node, behaves like a small reservoir, cryogen completely loses its momentum. However, when there is severe AC loss, especially at inlet, transient massive backward flow can occur and the assumption on total momentum loss is a bit dubious. Here, we discuss plausible momentum-preserved node concepts suitable for thermo-hydraulic analysis of fusion magnet. Based on requirements of cryogenic network solver, two types of node, namely ‘plenum’ and ‘manifold’ are proposed and compared. Plenum node is an extension of volume node including velocity and manifold is a quasi-0D node calculating velocity similar to finite volume method (FVM). Interestingly, the ‘volume’ node does not behave like a reservoir. Instead, it is more like a frictionless pass-through. Therefore, we argue that we need to introduce additional pressure drop at both inlets and outlets, somewhat like bending loss. Furthermore, if there is a severe backflow at inlet then it is also possible heat generated by AC loss can detour to another path, to other magnet. A case study has been carried out and it is shown that AC loss estimation error can be quite substantial as high as over 10%.

A half-bridge HTS transformer–rectifier flux pump with two AC field-controlled switches

Flux pumping provides a method of inductively magnetizing superconducting coils and can provide thermal, electrical and mechanical isolation between cryogenic environment and power supply. This offers the possibility of lower cryogenic loading and more flexible arrangements for superconducting magnet systems. This paper reports on the performance and analysis of a high-temperature superconducting (HTS) half-bridge transformer–rectifier type flux pump using two switching elements formed by applying AC magnetic field to sections of HTS. Theory of operation is presented followed by results from an experimental prototype which are compared with SPICE simulation. There is good qualitative agreement between simulation and experiment and all current, voltage and power waveforms from experiment are presented. This work represents a step forward in the understanding of the operation of HTS transformer–rectifier flux pumps and shows that SPICE simulation can provide designers of future HTS flux pumping systems with a useful tool for making design decisions.

Nitrogen Cryogenic System for the NICA Accelerator Complex at JINR

The Nuclotron-based Ion Collider fAcility (NICA) accelerator complex is scheduled to be put into operation in full configuration in 2023 at JINR. This facility comprising the existing Nuclotron together with two newly created superconducting accelerators-booster and collider-will require additional refrigerating capacity at 4.5 and 77 K. The helium cryogenic system of the NICA complex will be constructed as a result of the modernization of the existing equipment for cryogenic supply of the Nuclotron, but the liquid nitrogen plant will be completely new. It will be based on a 1300 kg/h nitrogen liquefier and two 500 kg/h recondensers of nitrogen vapors. This report describes the schematic diagram of the system of liquid nitrogen that will be used for refrigerating the thermally insulating shields of the cryostats at 77 K and at the first stage of cooling down three accelerator rings with the total length of about 1 km and the “cold” mass of 290 t. We demonstrate the status and recent development of the nitrogen cryogenic system: location, basic parameters, and design of major components and discuss their phased commissioning.

Cold Tests and Magnetic Characterization of a Superconducting Magnet for a Compact Cyclotron for Radioisotope Production

A superconducting magnet able to provide the required field of 4 T has been developed for a compact cyclotron to produce radioisotopes for medical imaging, in the framework of the AMIT project. It consists of two coils in Helmholtz confi-guration, embedded in a stainless steel casing to hold the Lorentz forces. The cooling scheme is based on a low pressure forced internal flow of two-phase liquid-vapour helium through a narrow channel machined in that casing. This paper reports on the cooling tests and the preliminary magnetic measurements of the magnet. Regarding cooling tests, liquid Helium from a Dewar has been used first to train the magnet and to estimate the thermal losses. Later, refrigeration will be accomplished from a stand-alone cryogenic supply system that would allow a user-friendly operation of the cyclotron, without external supply of cryogens. Regarding magnetic measurements, a custom magnetic measurement bench developed in collaboration with ALBA/CELLS, has been used to map the magnetic field and first results are presented and discussed in this paper.

Effect of Cryogenic Machining for Titanium Alloy Based on Indirect, Internal and External Spray System

Due to the excellent properties of Ti-6Al-4V titanium alloy such as lightweight, high wear and corrosion resistance and able to maintain high strength at high elevated temperature, this material has been used mostly in aerospace and biomedical industries. However, titanium alloy being considered as a hard-to-cut material with poor machinability due to its low thermal conductivity which leads to the excessive tool wear during machining and requires high machining cost. To overcome these problems, cryogenic machining has been taken place as a promising method for machinability improvement in terms of tool wear reduction, lower energy consumption and low machining cost. Even though this method has been implemented for titanium alloy machining, it is difficult to handle the excessive extremely low-temperature coolant (up to -150 ℃) that exposed directly to the workpiece. As a result, the workpiece hardness will be increased, hence will increase the required cutting force for the machining process. In concern with the problem, this paper presents a novel cryogenic cooling mechanism (indirect cryogenic cooling) that will be used as one of the cooling and lubrication strategy. The performance of the indirect cryogenic cooling will be compared with flood cooling, Minimum Quantity Lubrication (MQL) and conventional cryogenic cooling method by using the external and internal spray system. Liquid nitrogen (LN2) being selected as the cooling medium in this work since its temperature can reach lower -196 ℃, odorless and more environmentally friendly. A specially designed tooling kit that able to supply the liquid nitrogen to the cutting tool internally is used in this method. The developed indirect cryogenic supply method able to improve the machinability of Ti-6Al-4V. The cutting force is reduced by 54% and the tool life is improved by 90% compared to the conventional flood coolant strategy.

Evaluation of Losses Of Cold Energy of Cryogen Products in The Transport Systems

At present, there are problems of energy saving in various areas of human life and in power complexes of industrial plants. One possible solution to the problem of increasing energy efficiency is the use of liquefied natural gas and its cold energy. Pipelines for fuel or gas supply in cryogen supply systems have different length depending on the mutual position of storage and cryogen consumption devices relatively to a start construction. Cryogen supply and transport systems include a lot of fittings of different assortment. Reservoirs can be installed on different elevation points. To reduce heat inleak and decrease cold energy of cryogen product different kinds of thermal insulation are used. Cryogen pipelines provide required operation conditions of storage and gasifying systems. The aim of the thermal calculation of cryogen transport and supply systems is to define the value of cryogen heat. In this paper it is shown values of cryogen temperature rise due to heat inleaks at cryogen’s transfer along transport systems for ethane, methane, oxygen and nitrogen were calculated. Heat inleaks also due to hydraulic losses were calculated. Specific losses of cold energy of cryogen product for laminar and turbulent flow were calculated. Correspondences of temperature rise, critical pipeline’s length and Reynolds number were defined for nitrogen, argon, methane and oxygen.