Technical Institute Of Physics And Chemistry Research Articles

Efficiency Improvement of Small Cryogenic Helium Turbo-expanders in TIPC

An experimental helium liquefier/refrigerator, using ultra high speed cryogenic turbo-expanders is designed and developed in Technical Institute of Physics and Chemistry (TIPC), and liquefaction rate of around 42 L/hr and refrigeration capacity of around 130 W @ 4.5 K is achieved. The turbo-expander constitutes the most critical component of a helium liquefier/refrigerator causing that the turbine efficiency has a great influence on the performance of the whole cryogenic process plant. Inlet Flow Radial (IFR) turbine design is dictated by criteria like velocity ratios. For small flow rate plants the size of the turbine impeller needs to be reduced. In order to reach a high efficiency, the rotational speed must be increased to complete a large specific enthalpy drop. The present article describes the latest technical developments at TIPC, including results obtained during field trials with the TIPC helium liquefier and refrigerator. The motivation of these developments is to improve the efficiency of the machines, and also to widen the range of operation.

Development of mobile miniature natural gas liquefiers

With increasing consumption of natural gas (NG), small NG reservoirs, such as coalbed methane and oil field associated gas, have recently drawn significant attention. Owing to their special characteristics (e.g., scattered distribution and small output), small-scale NG liquefiers are highly required. Similarly, the mixed refrigerant cycle (MRC) is suitable for small-scale liquefaction systems due to its moderate complexity and power consumption. In consideration of the above, this paper reviews the development of mobile miniature NG liquefiers in Technical Institute of Physics and Chemistry (TIPC), China. To effectively liquefy the scattered NG and overcome the drawbacks of existing technologies, three main improvements, i.e., low-pressure MRC process driven by oil-lubricated screw compressor, compact cold box with the new designed heat exchangers, and standardized equipment manufacturing and integrated process technology have been made. The development pattern of “rapid cluster application and flexible liquefaction center” has been eventually proposed. The small-scale NG liquefier developed by TIPC has reached a minimum liquefaction power consumption of about 0.35 kW·h/Nm3. It is suitable to exploit small remote gas reserves which can also be used in boil-off gas reliquefaction and distributed peak-shaving of pipe networks.

Resonance frequency measurement with accuracy and stability at the 10−12 level in a copper microwave cavity below 26 K by experimental optimization

Single-pressure refractive index gas thermometry (SPRIGT) is a novel primary thermometry technique, developed jointly by the Technical Institute of Physics and Chemistry (TIPC) of the Chinese Academy of Sciences (CAS) in China and LNE-Cnam in France. To help obtain a competitive uncertainty of 0.25 mK in thermodynamic temperature measurements, high-stability and low-uncertainty of microwave resonance frequency measurements better than 2 ppb have been demonstrated. This article describes how high-stability and low-uncertainty resonance frequency measurements were achieved using a copper microwave cavity. Microwave measurements were carried out under vacuum and isobarically at helium-4 pressures of 30, 60, 90, and 120 kPa over the temperature range of 5–26 K, with good consistency among microwave modes for the thermodynamic temperatures determined. Performance was optimized using an Allan variance analysis. In this way, with an integration time of 3 h, a stability and accuracy at the 10–12 level were obtained, an almost 20-fold improvement upon our previous result (Zhang et al 2019 Sci. Bull. 64 286–8).

Experimental research on the J-T orifice of a space 4.5 K hybrid J-T cooler

Hybrid J-T cryocooler is commonly employed in space detective missions requiring liquid helium temperature. In fact, nearly all the space applications of mechanical cryocoolers working at 4.5 K, having been launched or under development are hybrid J-T cryocoolers. For instance, mechanical cryocoolers used in Planck, JWST, SMILES, SPICA and so on, are all hybrid J-T cryocoolers. However, there is hardly any research on space 4.5 K hybrid J-T cryocooler in China. Key laboratory of space energy conversion technologies in Technical Institute of Physics and Chemistry (TIPC), Chinese Academy of Sciences (CAS) has developed a 4.5 K J-T cooler precooled by two-stage pulse tube cryocooler. Base on this cryocooler, the influence of supply pressure and diameter of the J-T orifice on the cooling capacity of the J-T cooler is analyzed and experimentally studied. First of all, the influence of supply pressure and diameter of the J-T orifice is theoretically calculated. Then, experimental research is carried out. For the purpose of shortening experimental time, a two-stage GM cooler instead of pulse tube cooler is used to precool the J-T cycle. Firstly, open loop experiments are conducted because it’s much easier to adjust the supply pressure precisely. The mass flow rate of the J-T cooler rises monotonously as diameter of the J-T orifice decreases. However, the cooling capacity of the J-T cooler goes through an up and down process because the J-T effect turns to be worse when diameter of the J-T orifice increases. That is to say, performance of the J-T cooler turns to be worse when the diameter of the J-T orifice is larger than 34 μm. Based on the research of this paper, 34 μm J-T orifice may be the best choice of the hybrid J-T cooler. Besides, both mass flow rate and cooling power increase as supply pressure increases when supply pressure is below 2.0 MPa. In addition, the no load temperature of the J-T cooler rises with increasing supply pressure which is attributed to the flow resistance of the counter-flow heat exchangers. Secondly, three-stage oil-free linear J-T compressors are used to drive the J-T cooler, and the suction pressure and supply pressure of the three-stage compression system are 0.12 and 2.0 MPa, respectively. Finally, cooling power of 81.5 mW @4.48 K is achieved when the total power consumption of the J-T compressors is 102.7 W. And the temperature fluctuation at the evaporator is lower than ±0.05 K because the cooling capacity of the J-T cooler is provided by the vaporization of liquid helium.

Tests of the Stability of Chinese RhFe Resistance Thermometers at Low Temperatures

Rhodium–iron resistance thermometers are recommended as precise thermometers at temperatures below 25 K. The thermometers were developed at the National Physical Laboratory and produced by H. Tinsley and Co Ltd almost 50 years ago. Later, they were made by other companies and institutes as well, but despite this, the availability of the thermometers decreased and a new source of supply was needed. Several years ago, the Technical Institute of Physics and Chemistry (TIPC), Chinese Academy of Sciences, developed its own technology for making wire of Rh-0.5 at% Fe alloy which was used in the production of new thermometers. These devices have been tested previously at INRIM (Italy) and later at INTiBS (Poland). INTiBS has carried out an investigation focused on the thermometers’ stability after thermal cycling treatment. This paper presents the results of stability tests of about 30 thermometers produced by TIPC in two batches. The resistance of each thermometer was measured at temperatures of about 4.6 K and 7.2 K before and after 10, 30 and 50 thermal cycles from room temperature. The methods of measurement and the design of the cryostat used for the research are also presented.

Research Development on Solid Buoyancy Material for Deep-sea Application

The solid buoyancy material and research status at home and abroad were briefly introduced in this paper, then related research on solid buoyancy material by Technical Institute of Physics and Chemistry(TIPC)of CAS in detail. The high-performance hollow glass microspheres obtained independently through methods of soft chemistry by TIPC. By loading this kind of high-performance hollow glass microspheres into high-strength epoxy resin matrix, solid buoyancy materials of a variety of specification were prepared by pouring in vacuum.Then we obtained samples with densities of 0.40—0.60 g/cm³, hydrostatic compression strength of 20—100 MPa.After submersible buoy test of solid buoyancy material of 0.54 g/cm³ at 4000 m for 155 days, we found that the rate of water absorption is less than 2%. In addition, we also conducted the preliminary research on the solid buoyancy material for full ocean depth; samples can meet the full ocean depth pressure with density of 0.64 g/cm³ and 0.68 g/cm³.

4 K high frequency pulse tube cryocooler used for terahertz space application

Terahertz (THz) frequency region, defined from 0.1 to 10 THz, is an important frequency band for radio astronomy and atmospheric science. As NbN Superconductor-Insulator-Superconductor (SIS) mixers used for terahertz detection, which are studied by the Purple Mountain Observatory (PMO), Chinese Academy of Sciences (CAS), work at 8-10 K, and require condition of micro vibrations, its astronomical observation in aerospace is limited by suitable refrigeration method. 4 K high frequency pulse tube cryocooler developed by Key Laboratory of Space Energy Conversion Technologies (SECT), Technical Institute of Physics and Chemistry (TIPC), CAS, offers an opportunity for the application of SIS mixers. This article introduces the progress of the two-stage high frequency pulse tube cryocooler researched by TIPC. The cryocooler has reached a no load temperature of 4.5 K which is the lowest temperature for this kind of cryocooler reported so far. The successful coupling between the THz component and the high frequency pulse tube cryocooler lays a solid foundation for space detection in the terahertz band.

Design of a Test Cryomodule for a 1.3 GHz Single 9-cell Superconducting Cavity at IHEP

In order to obtain the design, manufacture and operation experiences on the Superconducting Radio Frequency (SRF) cryomodule for the International Linear Collider (ILC), a test cryomodule for 1.3 GHz single 9-cell SC cavity was designed by IHEP (Institute of High Energy Physics) and TIPC (Technical Institute of Physics and Chemistry) jointly. This cryomodule will be used as a horizontal test facility for a 1.3 GHz 9-cell SC cavity. The cryogenic system for the cryomodule was also designed, which will be operated at 2.0 K with saturated superfluid helium. The major requirements, design, simulation results of the cryomodule are reported in the paper. This key component of a superconducting accelerator test unit will be built in the near future at IHEP.

Recent Activities of TIPC on Cryogenic Systems Used for Superconducting Accelerators in China

With the requirement of higher beam energy and luminosity, the cryogenic technologies are applied more and more widely in accelerator facilities. As a main research entity on cryogenics in China, Technical Institute of Physics and Chemistry (TIPC) makes significant contributions to the construction of cryogenic systems for several superconducting accelerators in China, i.e. the upgrade of the Beijing Electron-Positron Collider (BEPCII), the Shanghai Synchrotron Radiation Facility (SSRF) and the Peking University Free-Electron Laser Facility (PKU-FEL). In this paper the cryogenic systems for BEPCII, SSRF and PKU-FEL are introduced briefly, and our recent activities for these accelerators are described.

Thermal Analysis of a Superconducting Magnet Stabilization Using a 3D Simulative Finite Element Model

Quench behavior is an important issue in stability of superconducting magnets for practical applications. A 3D FEM model was developed to study the cryogenic stabilization of a solenoid magnet. The magnet is a ‘notched’ superconducting solenoid of 170 mm in inner diameter, 223.8 mm in outer diameter and 504 mm in length which has been designed, and manufactured by a group comprising the members from Technical Institute of Physics and Chemistry (TIPC) and Institute of Modern Physics (IMP) Chinese Academy of Sciences (CAS). Quench behaviors, such as minimum quench energies and current decay, are also studied by this model. The calculated results based on this model are in good agreement with the experimental data presented by Martin N. Wilson.

Development of a China test cryomodule for ILC

Research and development of a 1.3 GHz 9-cell cavity test cryomodule were carried out by a collaboration group between IHEP (Institute of High Energy Physics) and TIPC (Technical Institute of Physics and Chemistry) in China. The cryomodule is a ‘test model’ for the ILC cryomodule, and a key component of a superconducting accelerator test unit which will be built in the near future, also can be used as a horizontal test facility for 1.3 GHz 9-cell cavities. This paper presents the development status of the cryomodule, including structure design, cryogenic flow diagram, thermal and mechanical simulations, heat load estimation and etc.

Recent progress on thermoacoustic heat engines and refrigerators

In this talk, recent progress on thermoacoustic heat engines and refrigerators developed at the Technical Institute of Physics and Chemistry (TIPC), Chinese Academy of Sciences (CAS), is covered, which mainly includes three aspects: (i) Energy-focused thermoacoustic-Stirling heat engines (EF-TASHE) by using tapered resonators are highlighted for both low-frequency (̃50Hz) and medium-frequency (̃300Hz) operation; (ii) A thermoacoustically driven two-stage pulse tube cryocoolers capable of achieving liquid hydrogen temperature (̃20K) is described. In addition, a 300 Hz compact thermoacoustically driven pulse tube cryocooler operating below 80K is also covered. In this part, an acoustical pressure amplifier is highlighted; (iii) A heat-driven thermoacoustic refrigeration system with double thermoacoustic-Stirling configuration for room temperature cooling is reported. This system is able to provide a cooling power of more than 300 W at -20°C, showing good prospect as an alternative of CFC refrigeration. Finally, consideration and prospect for future development are forecasted.

Investigation of the effects of three key parameters on the heat transfer capability of a CLHP

A cryogenic loop heat pipe (CLHP) has been developed for future aerospace applications at the TIPC (Technical Institute of Physics and Chemistry). The device has been tested in different situations with constant heat sink temperature of about 78 K. The effects of the reservoir volume and the pore size of the primary wick on the performance of CLHP were investigated. With a wick pore size of 2 μm, the CLHP can transfer a heat load of 26 W under horizontal orientation no matter what size of the reservoir volume being used. On the contrary, when the pore size was large (10 μm), the heat transfer capability of the CLHP can be up to 26 W only when a smaller reservoir (60 cc) was used, and its ability to operate against gravity was greatly weakened. Moreover, when the working fluid was oxygen instead of nitrogen, the heat transfer capability can be up to 50 W under horizontal orientation with the other experimental conditions remaining the same.

Operational performance of a cryogenic loop heat pipe with insufficient working fluid inventory

A cryogenic loop heat pipe (CLHP) has been developed for future aerospace applications at the Technical Institute of Physics and Chemistry (TIPC). It has been demonstrated that this CLHP, when placed horizontally, can operate in liquid-nitrogen temperature range and have a heat transfer capability of up to 12 W with proper working fluid inventory. This paper presents some particular characteristics of the CLHP when the compensation chamber is half-filled with liquid-phase working fluid before startup. The device has been tested at different orientations using nitrogen as the working fluid in order to compare its thermal behavior, specially related to the heat transfer capability, the operation temperature and the thermal resistance, as well as to investigate its operational characteristics under power level as low as 1 W. Tests were performed for the CLHP at horizontal position and with the liquid line 3.4 and 6.4 cm below the vapor line, respectively. The experimental results show the operationability of the CLHP tested at three orientations and tests with the liquid line 6.4 cm below the vapor line show lower operation temperatures and higher heat transfer capability.

A novel design and experimental study of a cryogenic loop heat pipe with high heat transfer capability

A cryogenic loop heat pipe (CLHP) has been developed for future aerospace applications at TIPC (Technical Institute of Physics and Chemistry). This article presents a novel design of a cryogenic loop heat pipe and corresponding test system. The CLHP studied in this work has demonstrated to be able to operate in liquid-nitrogen temperature range using nitrogen as working fluid and to transfer large amount of heat over long distance with very small temperature difference. This device has been tested at three different orientations with respect to the relative position of the liquid line and the vapor line. The experimental results show that the CLHP can have a heat transfer capability of up to 12 W under horizontal and adverse gravity orientations and up to 20 W in liquid-nitrogen temperature range under gravity-assisted orientation.