中文摘要：

研制了一套高精度的流体压力-密度-温度（p,ρ,T）测量系统,其适用温度、压力和密度范围分别为90—290 K,0—3 MPa,0—2 000 kg/m3。该系统基于阿基米德原理,采用单浮子磁选耦合力传递方法,实现密度的高精度测量。该系统的温度、压力测量标准不确定度分别为5 mK、250 Pa（1.5 MPa量程）/390 Pa（3 MPa量程）,密度测量最大相对标准不确定度为0.1%。用新研制的密度测量系统,对190—276 K温度区间和0—3 MPa压力区间的甲烷气体密度进行了测量,实验结果与REFPROP密度值有较好的一致性,验证了该系统的可靠性。

英文摘要：

An accurate fluid pressure-density-temperature measurement system was developed. The temperature, pressure and density range is 90 K to 290 K, 0 to 3 MPa, 0 to 2 000 kg/m^3 respectively. The density measurement system is based on Archimedes＇ buoyancy principle and is a single-sinker system incorporating a magnetic suspension coupling. The standard uncertainty in temperature is 5 mK, and that in pressure is 250 Pa for 1.5 MPa and 390 Pa for 3 MPa full scale range respectively. The maximum relative standard uncertainty is 0.1% in density. In order to verify the new apparatus, comprehensive pressure-den- sity-temperature measurements on pure methane were carried out in the temperature range （190 K to 276 K） and pressure range （0 to 3 MPa）. The experimental data were compared with the value calculated by REFPROP and good agreements were found.