Steady Simulation Research Of Dual-phase Change Heat Exchanger And Air-cooled Condenser

Based on research production of correlated fields at home and abroad and a new indirect air cooling system using refrigerant ammonia in which the steam power cycle was coupled with the positive and negative sequence refrigerating cycle, this research believes that the principle is credible, the technology is feasible and effects are outstanding for the new cooling system according to the result of static mathematic model and calculation procedure, especially accomplish the equipment simulation of the special dual-phase change heat exchanger through the way of computational fluid dynamics.First of all, program calculation of ammonia's thermodynamic process with regard to the whole circulation system is carried out, according to Martin-hou's state equation. The caculation results show that the pressure ratio varies to suit the variation of ambient temperature and wind velocity, the p-T diagram change when the calculation process consider pipeline pressure loss. In the next place, one-dimensional countercurrent static distributed simplified geometric model of air cooled condenser and the dual-phase change heat exchanger are established according to principle of heat transfer balance on the assumption that the author neglects the influence of flow pressure drop, wall resistance, axial heat conduction and heat leak on a heat transfer pipe. Based on the available model and theory of two-phase flow and heat and mass transfer, and the way of heat exchanger modeling, one-dimensional cross flow basic uniform flow model and shunting model of the dual-phase change heat exchanger are established according to continuity equation, momentum equation and energy equation. Finally, suitable correlation of flow boiling with pure refrigerants in horizontal tubes, condensation heat exchange factor of steam containing non condensable gases and air-side thermal performance of condenser are selected by means of programming calculation. On the basis of the 1D simplified countercurrent models, this research discretizes the computational field by enthalpy drop and get difference equations. Iteration method is used to solve the algebraic equations by using program computation. Then applying data visualization technique to process the calculation results. These flow parameter distribution curves are used to predict the detailed performance and to show ways to develop suitable remedies in the concept phase of the heat exchanger module development. The simulation results can provide some insight and experience for heat exchanger design engineers.