Densities in the homogeneous liquid phase of (mono-)ethanolamine (MEA) and diethanolamine (DEA) were investigated using a commercially available high-pressure vibrating-tube densimeter (VTD). Due to the melting point of the experimental materials, the setup of the VTD had to be modified by an insulated housing of the entire piping including the pressure pump. The insulated housing could be heated up by a temperature-controlled heating fan. The liquid samples with a purity of (0.9994 or 0.9950) mole fraction, respectively, were decanted within an inert protective argon atmosphere and further degassed by several freeze–pump–thaw cycles. Density measurements were carried out at temperatures between (293, respectively, 313 and 423) K and at pressures between (5 and 90) MPa. The resulting 140, respectively, 120 (p, ρ, T) data points, explicitly extend the published database for MEA and DEA, with regards to pressure. A comparison with the currently used equations of state for MEA and DEA revealed a maximum relative deviation of – 0.18 % for MEA and – 0.41 % for DEA, each at the highest investigated temperature and pressure. Considering the measurement uncertainties in temperature, pressure, and oscillation period, as well as uncertainties resulting from the calibration and from the impurities of the sample, the combined expanded relative uncertainty (k = 2) in density varied from (0.1027 to 0.1038) % and from (0.1104 to 0.1130) %, respectively. The VTD was previously calibrated by comprehensive measurements of water and helium and had been further validated by measurements with pure propane.

使用可商购的高压振动管密度计（VTD）研究了（单）乙醇胺（MEA）和二乙醇胺（DEA）在均相液相中的密度。由于实验材料的熔点，VTD的设置必须通过包括压力泵在内的整个管道的绝缘外壳进行修改。绝缘的外壳可以由温度控制的加热风扇加热。将纯度分别为（0.9994或0.9950）摩尔分数的液体样品在惰性保护性氩气气氛中can析，并通过几个冷冻-泵-融化循环进一步脱气。在（293分别为313和423）K之间的温度和（5到90）MPa之间的压力下进行密度测量。所得的140分别为120（p，ρ，T）数据点，明确扩展了有关MEA和DEA的压力数据库。与目前使用的MEA和DEA状态方程的比较表明，在最高的研究温度和压力下，MEA的最大相对偏差为– 0.18％，DEA的最大相对偏差为– 0.41％。考虑到温度，压力和振荡周期的测量不确定度，以及校准和样品杂质带来的不确定度，组合的扩展相对不确定度（k = 2）的密度分别从（0.1027至0.1038）％和（0.1104至0.1130）％变化。VTD之前已通过对水和氦的全面测量进行了校准，并已通过使用纯丙烷的测量进行了进一步验证。