中文摘要：

基于圆柱声学共鸣法原理，开展了303．10～303．18K，压力从3．855MPa至7．534MPa的近临界区CO2测量研究。二氧化碳声速测量的相对标准不确定度结果为：当压力低于7．1MPa时为0．035％，当压力高于7．3MPa时为0．15％。与CO2国际标准状态方程计算得到的声速相对偏差分布在0．005％～-0．4％范围。所获得的测量结果可为CO2国际标准状态方程的改进提供重要数据来源，建立的实验系统和方法可用于更宽广温区CO2及其他工质的声速精密测量研究。

英文摘要：

Using a cylindrical acoustic resonator, the speed of sound in CO2 at the temperature from 303.10 - 303.18 K and pressure from 3. 855 - 7. 534 MPa is measured. The relative uncertainty of the speed of sound in CO2 is 0. 035% at pressure lower than 7. 1 MPa and 0. 15% at pressure higher than 7. 3 MPa. The relative deviation between present data and the calculation from the equation of state is 0. 005% - - 0.4%. The measurement results can be used to improve the equation of the state of CO2. The experimental system and method can be used in the measurement of CO2 and other working fluids in a wider temperature range in the next future.