气体PVT热物性实验台测量绝对零度

Experimental Determination of Absolute Zero Using Gas PVT Thermal Physical Properties

基于理想气体状态方程,即在体积一定的条件下定量气体的压力与热力学温度成正比,利用气体PVT热物性实验台对高纯氦气（99.995%）在等体积条件下的p-t（t为摄氏温度）关系特性进行了实验测量。实验中保持He的体积不变,充气压力分别为1,2,2.5和3 MPa,在每一充气压力下改变实验温度（5-85℃）,每隔10℃记录实验温度及该温度下对应的压力。通过线性拟合得到不同充气压力下He的p-t拟合直线,利用外推法获得绝对压力为零时对应的温度,即热力学绝对零度。外推得到的结果与现行的标准值-273.15℃相比,最大和最小相对误差分别为1.36%和1.14%,平均值为-276.58℃,可作为工程热力学实验教学内容的拓展与补充。

Absolute zero is one of the significant concepts in thermodynamics,which has experienced a long history of discovery and development. In order to have a deeper understanding of the concept of absolute zero and the establishment of the Kelvin scale, experiments were conducted to determine absolute zero utilizing fundamental thermodynamic knowledge. Based on the ideal gas equation of state,there is a linear relationship between the pressure and temperature of a constant volume of ideal gas. In this research,the PVT measuring system was utilized to determine the relationship between the pressure and centigrade temperature of pure He（ 99. 995%）. The volume of He was kept constant during experiments,and the inflation pressures were 1 MPa,2 MPa,2. 5 MPa and 3 MPa respectively. Under each inflation pressure,the temperatures were altered in the range of 5 - 85 ℃. Experimental temperatures and the corresponding pressures were recorded every 10 ℃. By linear fitting,the method of extrapolation was applied to determine the corresponding centigrade temperature when pressure became zero. This temperature was what we called the absolute zero. The extrapolated results have a maximum relative error 1. 36% and a minimum relative error 1. 14%compared with the standard value- 273. 15 ℃,with an average value of- 276. 58 ℃,which can serve as an extension and complement of experimental teaching practice of the engineering thermodynamics.