Zhongjun Hu

Cryogenic adsorber design in a helium refrigeration system

The cryogenic adsorber is specially designed to eliminate impurities in gaseous helium such as O2, and N2 which is normally difficult to remove, based on the reversible cryotrapping of impurities on an activated carbon bed. The coconut shell activated carbon is adopted because of its developed micropore structure and specific surface area. This activated carbon adsorption is mostly determined by the micropore structure, and the adsorption rate of impurities is inversely proportional to the square of the particle sizes. The active carbon absorbers maximum permissible flow velocity is 0.25 m/s. When the gas flow velocity increases, the adsorption diffusion rate of the adsorbent is reduced, because an increase in the magnitude of the velocity resulted in a reduced amount of heat transfer to a unit volume of impure gas. According to the numerical simulation of N2 adsorption dynamics, the appropriate void tower link speed and the saturated adsorption capacity are determined. Then the diameter and height of th...

Analysis of Pressure Control for CSNS Cryogenic Hydrogen Circulation

Brief introduction of cryogenic helium and hydrogen circulation system of Chinese Spallation Neutron Source (CSNS) is given. According to heat load change of pulsed-proton-beam injection, the temperature and pressure of supercritical hydrogen are calculated. Based on the calculation results, profiles of temperature and pressure with the change of heat load are given. Accordingly, controlling optimization strategy of hydrogen circulation is preliminarily concluded. The results may provide guidelines for design and operation of other under-constructed SNS pressure controlling system.

Real-time measure system of linear alternator efficiency in Thermoacoustic electricity generator

Thermoacoustic electricity generator could convert heat to electric power. It is composed of thermoacoustic engine and linear alternator. In TIPC, a traveling wave thermoacoustic electricity generator had been built and tested. Long resonator was replaced by linear generator in the thermoacoustic electricity generator. There were mechanical impedance, acoustic impedance and electric impedance. Only adjustment parameter was electric load when the generator ran. Electric load could affect the acoustic impedance of linear alternator, which was close related with efficiency from acoustic power to electric power. In order to optimize the electric load in real time, a kind of on-line measure method was supposed and tested. Volume flow rate and pressure were measured by resistance strain gauge and piezo-electric pressure sensor respectively. Correlation arithmetic was used to evaluate the acoustic power. On-line analysis of acoustic power and electric power made it possible to measure efficiency. Some tests were...

Coupling of regenerator and end load in a standing wave thermoacoustic engine

In the thermoacoustic system, the performance of regenerator strongly depends on the acoustic field. To study the thermoacoustic characteristics of regenerator in different acoustic field, a model of loudspeaker-driven thermoacoustic system with a RC load is built and simulated based on linear thermoacoustic theory. The thermoacoustic conversion efficiency of regenerator is calculated by changing three parameters: the resistance R, the regenerators position and the hydraulic radius. The results show that the acoustic fields in the system vary with the RC load in a wide range and the performance of the regenerator is also influenced by the RC load. The further analyses reveal that the efficiency of the regenerator can be improved by optimizing the hydraulic radius and the position of regenerator in the resonance tube. The research is useful for us to understand the thermoacoustic characteristic of the regenerator in different acoustic fields.