Establishment of air-cooled condenser unit structural model Physical model The radiator of a domestic 1000MW direct air-cooled unit is composed of 80 air-cooled units. Each air-cooling unit includes a sub-radiator and a fan. Each of the partial radiators is composed of several bundles of rectangular aluminum fins of an oval aluminum tube and is arranged in a single row. The air flow and heat exchange outside the finned tube have periodic characteristics along the length of the tube. The geometry unit containing the fins can be selected as the calculation area for geometric modeling. Since the finned tube is an axisymmetric pattern with the major axis as the axis of symmetry, the simplified model is designed to eliminate the effect of inlet and outlet boundary recirculation on the calculation results, and to extend the inlet and outlet regions, respectively. The overall model mathematical model assumes that the mathematical model of the elliptical tube condenser is simplified as follows: the heat transfer and flow in the calculation area are steady; the air in the calculation area is incompressible; the elliptical base tube is not considered Contact resistance and radiation heat transfer between the fins; the top of the flow path is insulated.
The physical parameters of the fins in the boundary condition: the density is 2719kg/m, which is the velocity inlet boundary condition and the outlet is the free outlet boundary condition. The base pipe and the fins adopt their own heat conduction and surface convection heat transfer. Coupling heat transfer method; assuming that the steam in the base pipe is saturated steam, the wall surface of the base pipe is a fixed wall temperature boundary condition: numerical simulation of the heat transfer characteristics of the 1000MW direct air cooling unit heat dissipation unit; the top section of the model is adiabatic boundary conditions; the rest The geometric surface is set as a symmetry boundary condition. Computation method The mesh of the heat sink calculation model is divided using Gambit software. The structural non-uniform multi-block structured mesh is used. The mesh adopts the hexahedron structure, and the fluid mesh at the entrance and exit is locally encrypted. About 1 million. By using different grid numbers, the independence of the grid is checked, and the number of grid cells divided can eliminate the influence of the grid density.
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