Modelling nonstationary thermohydrodynamic processes in heat-exchange circuits with a two-phase coolant

This paper presents a mathematical model and a "fast" computer program for analyzing nonstationary thermohydrodynamic processes in distributed multielement circuits containing a two-phase coolant. The author's approach is based on representing the distributed multielement circuits with the two-phase coolant (such as cooling circuits of the reactor of an atomic power station) in the form of equivalent thermohydrodynamic chains composed of idealized elements with the intrinsic properties of the structure elements of real systems. The author has developed the nomenclature of such conceptual elements for objects which can be modelled; the nomenclature encompasses the control volumes (with a single-phase or two-phase coolant or a moving boundary of boiling/condensation) and the branch lines (type of tube and connections in dependence on the inertia of the coolant being taken into account) for a hydrodynamic submodel and the thermal components and lines for a thermal submodel. The notation and the subscripts used in the equations below correspond to Fig. 1. A finite control volume is described by the equations of mass and energy conservation: