7<1000K,气体为量热完全气体( calorically perfect gas), 为常数 已=C T (7.6a) h=c t (7.6b) 注意:e和h均为热状态变量( thermodynamic state variables) 它们只依赖与气体的状态而与过程无关.( they depend only on the state of the gas and are independent of any process)T<1000Ｋ，气体为量热完全气体（calorically perfect gas ), cv 、 c p 为常数 (7.6b) (7.6a) h c T e c T p v = = 注意：e和h均为热状态变量（thermodynamic state variables ), 它们只依赖与气体的状态而与过程无关．（they depend only on the state of the gas and are independent of any process)