关键词: 位形积分, 初始条件, 可解偏微分方程, 齐次常微分方程

Abstract: A simple formula for calculating the pressure and temperature in a high pressure tank is worked out not by making concrete calculation of configuration integral, but by using the basic formulas for the canonical ensemble. And the difference between the result worked out by this formula and that made by tests is very small. Applying this formula to engineering thermophysics can reduce the time of tests.

Key words: configuration integral, soluble partial differential equation, initial condition, homogeneous ordinary differential equation