化工热力学--纯流体的容量性质第-第三章Virial状态方程3.2 - 图文

3-2 The Virial Equation???Principle of virial equaqionIdeal-gas temperature scaleMathematical expression of virial equaqion3-2 The Virial Equation………………………….…….........principle The complexity of Fig.3-2 indicates the difficulty to be expected when one tries to develop an equation that will accurately represent the relationship among P, V, and T for a pure substance. However, for the gas region alone the problem becomes tractable(易处理). 3-2 The Virial Equation………………………….…….........principleFor an isotherm such as T1 we note from Fig.3-2 that as P increases V decreases. Thus, one might expect the PV product for a gas or vapor to be much more nearly constant than either of its .(？) 气体或蒸汽PV乘积,比构成它的任一因子更接近恒值3-2 The Virial Equation………………………….…….........principleThis suggests that PV along an isotherm might be satisfactorily represented by a power series expansion (幂级数) in P:2 PV=a+bP+cP+…If one lets b = a B’, c = a C’, etc, this question becomes 2 PV=a(1+B’P+C’P+…) (3-6)Where a, B’, C’, etc., are constants for a given temperature and a given chemical