摘要
超临界CO2流体声速随压力和温度变化规律,对超声技术强化超临界流体萃取应用具有理论指导作用。为研究超临界CO2流体的超声速特性,设计了单探头脉冲回波法的声速测量探头,频率2.5MHz。采用汕头超声研究所生产的CTS-3600数字式超声探伤仪与声速测量探头连接。以温度每5℃和压力每1MPa为间隔,测量了温度为25℃～55℃,压力为7MPa～26MPa的CO2流体声速,根据不同温度下声速随压力变化的一组等温线,采用多项式拟合得到超临界CO2流体声速随压力和温度变化关系模型,在T=300K时计算模型计算值和文献参考值的相对误差。结果表明:超临界CO2流体声速随压力增加而增大,随温度升高而降低,在T=300K时模型计算值和文献参考值的相对误差在7%以内。
The laws of ultrasonic velocity with respect to pressure and temperature in supercritical fluid CO2 can provide a theoretical guide in ultrasonic enhancing supercritical fluid extraction. To study the characterization of ultrasonic velocity in supercritical fluid CO2, a measuring detector of ultrasonic velocity based on a pulse-echo method with a single transducer operating at 2.5 MHz has been designed. The transducer is connected with a CTS-3600 digital ultrasonic flaw detector. Ultrasound velocity was measured at 5℃ intervals from 25℃ to 55℃, and 1 MPa step from 7 MPa up to 26 MPa. Based on seven isotherms, ultrasound velocity in supercritical fluid CO2 as a function of pressure and temperature was obtained by polynomial fitting. The results show that sound speed in supercritical fluid CO2 increases with pressure, and decreases with increasing temperature. Deviations in the calculated values of model on the isothern at T=300K from the values obtained from the literatures were within 7%.
出处
《声学技术》
CSCD
北大核心
2006年第5期431-435,共5页
Technical Acoustics
关键词
超临界CO2流体
声速
压力
温度
supercritical fluid CO2
ultrasonic velocity
pressure
temperature
