Abstract: Based on the fluid continuity equation and Bernoulli's equation，the online density and compression factor(gas phase) of hydrocarbon fuel can be achieved by measuring the mass flow under cold state and the differential pressure of orifice plates. The uncertainty of the method is ± 2.84% through analyzing the deviation of each measuring instrument，and the measured deviation is within -1%～4% by comparing the experimental densities of benzene with those from Supertrapp software. The precision of this method is ± 0.7% through three parallel experiments for benzene under 5MPa. The density of benzene was measured in the temperature range of 338～982K and pressure range of 1～5MPa，at the same time，the compression factor of gas phase was calculated. It is indicated that this measurement method can achieve the online density of the fuel with a high accuracy and repeatability under high temperature and pressure.

Key words: Benzene；Density；Online measurement；High temperature and pressure；Compression factor

摘要： 根据流动连续性方程和伯努利方程，建立了一种流体高温密度和气相压缩因子测量新方法。通过测量流体冷态质量流量和节流孔板前后压差，实现了流体密度的在线测量。根据仪器精度，得出密度测量不确定度为±2.84%，苯的测量值与Supertrapp软件获得的参考密度之间的偏差为-1%～4%。通过压力5MPa下的三次平行实验，得出该方法测量苯密度的最大偏差为±0.7%；实验测量了不同温度(338～982K)和不同压力(1～5MPa)下苯的密度，同时计算得到气相压缩因子。实验结果表明:本方法可实现高温高压下流体密度在线测量，具有很好的准确性和重复性。

关键词: 苯；密度；在线测量；高温高压；压缩因子