【摘要】 为了弄清引起基于过剩吸附量的气-固超临界实验吸附等温线表现出极大值后下降现象的原因,在分子动力学原理的基础上,应用分子模拟方法,模拟了超临界甲烷在不同温度下0~50 MPa压力范围的分子密度,并结合单分子吸附理论对"过剩吸附量"和"绝对吸附量"进行了转换,并提出适用于临界前后大压力范围的转化方法。结果表明:分子模拟的密度结果与美国国家标准局(NIST)的数据一致,在甲烷超临界压力以下,"过剩吸附量"与"绝对吸附量"差异不大,但随着压力升高差异逐渐增大,在甲烷储层压力下,两者的差异可达到150%以上。该方法的转化具有较高精度,且突破了现有转化方法的低压条件限制。更多还原

【Abstract】 In order to find out the reason why the adsorption isotherm obtained by gas-solid supercritical adsorption experiment based on the excess adsorption amount shows declining after the maximum value,the density of supercritical methane in the pressure range of 0 ~50 MPa at different temperature is obtained using molecular simulation based on the principle of molecular dynamics,the excess adsorption capacity is transformed into absolute adsorption capacity according to single molecular adsorption theory,and a new method for transforming the excess adsorption capacity into absolute adsorption capacity is put forward. It is shown that,the molecular simulation density results are in accordance with the data in National Institute of Standards and Technology( NIST); when pressure is lower than supercritical pressure,the difference between the excess adsorption capacity and absolute adsorption is not so much,but the difference increases with the increase of pressure,and it reaches to above 150% under reservoir pressure. This method has high precision and breaks through the restriction of low pressure condition of the existing transformation method.更多还原