Liqiang Liu

The BESIII detector magnet

Publisher Summary BESIII (Beijing Spectrometer III) is a detector designed to run in the autumn 2007 at a 1 ╳ 10 33 cm -2 s -1 luminosity @1.89 GeV at BEPCII (Beijing Electron–Positron Collider II) at IHEP Beijing. It has a 1 T superconducting solenoid magnet with the inner winding diameter of 2962 mm, winding length of 3532 mm, and a 600 tonne flux return yoke. The indirectly cooled, pure aluminum stabilized single layer coil is internally wounded with a 4 kA superconductor. The magnet design is described. The NbTi/Cu superconductor has been delivered and the critical current test of a short sample of the superconductor has been performed. An inner winding machine is under construction.

Thermo-hydraulic analysis of cooldown for ITER toroidal field coils from 80 K to 6 K

ITER is the next-step large-scale experiment for magnetically confined fusion. Thermo-hydraulic analysis of the cool-down from 80 K to 6 K for TF coils has been carried out recently. This TF coils cool-down stage should be analyzed by considering the influence of the cryoplants. To carry out the simulation, a time-dependent thermo-hydraulic simulation cool-down from 80 K to 6 K stage has been performed by using FORTRAN code. The code for analyzing coils is based on a 1D helium flow and 3D solid heat conduction model. The cool-down model for the thermal and gas dynamic process of the equipments in cryoplants is also developed, which will be described in detail in this report. The simulation results for cool-down of TF coils to 6 K are also discussed, which indicate that cool-down from 80 K to 6 K stage can be completed in 10 days.

The control system of a 2kW@20K helium refrigerator

The automatic control of a helium refrigerator includes three aspects, that is, one-button start and stop control, safety protection control, and cooling capacity control. The 2kW@20K helium refrigerators control system uses the SIEMENS PLC S7-300 and its related programming and configuration software Step7 and the industrial monitoring software WinCC, to realize the dynamic control of its process, the real-time monitoring of its data, the safety interlock control, and the optimal control of its cooling capacity. At first, this paper describes the control architecture of the whole system in detail, including communication configuration and equipment introduction; and then introduces the sequence control strategy of the dynamic processes, including the start and stop control mode of the machine and the safety interlock control strategy of the machine; finally tells the precise control strategy of the machines cooling capacity. Eventually, the whole system achieves the target of one-button starting and stopping, automatic fault protection and stable running to the target cooling capacity, and help finished the cold helium pressurization test of aerospace products.

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.

Development of a measurement and control system for a 10 kW@20 K refrigerator based on Siemens PLC S7-300

A 10 kW@20 K refrigerator has been established by the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences. A measurement and control system based on Siemens PLC S7-300 for this 10 kW@20 K refrigerator is developed. According to the detailed measurement requirements, proper sensors and transmitters are adopted. Siemens S7-300 PLC CPU315-2 PN/DP operates as a master station. Two sets of ET200M DP remote expand I/O, one power meter, two compressors and one vacuum gauge operate as slave stations. Profibus-DP field communication and Modbus communication are used between the master station and the slave stations in this control system. The upper computer HMI (Human Machine Interface) is compiled using Siemens configuration software WinCC V7.0. The upper computer communicates with PLC by means of industrial Ethernet. After commissioning, this refrigerator has been operating with a 10 kW of cooling power at 20 K for more than 72 hours.

Reliability and availability analysis of a 10 kW@20 K helium refrigerator

A 10 kW@20 K helium refrigerator has been established in the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences. To evaluate and improve this refrigerators reliability and availability, a reliability and availability analysis is performed. According to the mission profile of this refrigerator, a functional analysis is performed. The failure data of the refrigerator components are collected and failure rate distributions are fitted by software Weibull++ V10.0. A Failure Modes, Effects & Criticality Analysis (FMECA) is performed and the critical components with higher risks are pointed out. Software BlockSim V9.0 is used to calculate the reliability and the availability of this refrigerator. The result indicates that compressors, turbine and vacuum pump are the critical components and the key units of this refrigerator. The mitigation actions with respect to design, testing, maintenance and operation are proposed to decrease those major and medium risks.

Process design of helium refrigerators collaborated with the predesign of turbo expander

Turbo expanders are the most critical components in helium refrigerators. However, since the performance of expanders is dependent on a number of operating parameters and the relations between them are quite complex, usually only very simple modeling for expanders is applied during the process design, with which the scale and performance of expanders cannot be rated. Hence the design parameters specified by process design may not match the current turbine technology. As a solution, we employed a collaborated design method with which a predesign for turbo expanders is integrated into the process design. The tip wheel diameter, the tip speed, the rotational speed and the efficiency of turbo expander are preliminarily calculated. Evaluation of these parameters helps us to check if the process design is appropriate or need to be further improved.

Thermal mechanical analysis on the ACB-CP valve box of ITER cryogenic system

ACB-CP is an auxiliary cold box used to distribute and control the cryogenic fluids to cool the cryopumps in ITER cryogenic system. A 3-D structure design is performed as a preliminary design. In order to validate the structure design, the thermal mechanical analysis on the piping must be followed. A 3-D finite element model of ACB-CP is built. The steady state thermal analysis and thermal mechanical coupling analysis of the internal piping are performed. The thermal stress distributions and the maximal thermal stress values are obtained. The results lay the reliable foundation for the design and improvement of ACB-CP.

Conceptual design of ACB-CP for ITER cryogenic system

ACB-CP (Auxiliary Cold Box for Cryopumps) is used to supply the cryopumps system with necessary cryogen in ITER (International Thermonuclear Experimental Reactor) cryogenic distribution system. The conceptual design of ACB-CP contains thermo-hydraulic analysis, 3D structure design and strength checking. Through the thermohydraulic analysis, the main specifications of process valves, pressure safety valves, pipes, heat exchangers can be decided. During the 3D structure design process, vacuum requirement, adiabatic requirement, assembly constraints and maintenance requirement have been considered to arrange the pipes, valves and other components. The strength checking has been performed to crosscheck if the 3D design meets the strength requirements for the ACB-CP.

The cryogenic system of BESIII in preliminary design

Publisher Summary This chapter describes the preliminary design of a cryogenic system of the superconducting (SC) solenoid magnet, including the heat load estimation, the cooling flow scheme, the operation modes, the structural design of the pipes, control dewar, and cryostat of this SC solenoid magnet. The cryogenic system consists of a refrigerator, compressor, buffer tank, recovery tank, liquid nitrogen storage tank, control dewar and SC solenoid magnet, where the refrigerator, compressor, buffer tank, and recovery tank are shared with another superconduting user of Beijing Electron Positron Collider II (BEPC II), a pair of superconducting interaction region quadrupole magnets (SCQ). The solenoid magnet is indirectly cooled by forced, two-phased helium flow during steady state operation and switched to a thermo-syphon mode in case of emergency stop of the refrigerator. The design of the cryogenic system of the superconducting solenoid magnet of BESIII has been done. In this design, the heat load of the whole system has been estimated, the cooling flow scheme and the operation modes determined, and the structural design of the pipes, control dewar and cryostat accomplished.