Generalised Balance of Internal Energy for an Open System

The paper presents the definition of mass density of generalised enthalpy and the balance equation of generalised enthalpy for intensive quantities (IQs). The functions of generalised enthalpy have been defined for homogenous fields of intensive quantities and the balance equation of generalised enthalpy - for extensive quantities (EQs). In this respect, the generalised balance of internal energy has been defined for an open system which, in case of the absence of the exterior impact on the system, has been reduced to the balance of internal energy for an open system. In the case of a reversible transformation, the generalised balance of internal energy has been reduced to the balance called the first generalised principle of thermodynamics for an open system and the balance of internal energy has been reduced to the balance called the first principle of thermodynamics for an open system.