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Simulation and analysis of two phase flow that crosses over tube bundles is crucial in safety analysis and design of kettle reboilers and steam generators. The geometry complexity of the tube bundle flow field increases the difficulty of the conventional numerical analysis. One of the methods to reduce the numerical calculations cost, is to use the porous media theory instead of the complete tube bundle modeling. Drag and tube bundle resistance force equations have been used in the porous media analysis. Based on available experimental results, two tube bundle arrangements have been considered. Due to existence of symmetric geometry and uniform energy source over the tube bundle, the two dimensional symmetric models has been used as well. It was observed that the predicted pressure drop in this research has acceptable adaptation with the experimental results. Meanwhile, by considering different outlet boundary conditions, calculated void fraction is compared to the experimental results and showed better accuracy than similar CFD research. It was observed that the enhancement of the tube bundle thermal power increases the void fraction in the heating area of the reboiler.

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Steam generators as an interface between first and second loop of light water nuclear power plants is very important in design and safety analysis. Thermo hydraulic analysis can affect the design and operation of a horizontal steam generator using prediction of vapor distribution. In this kind of thermo hydraulic analysis, simulation and study of the tube bundles is crucial in design and safety study of the steam generator two phase flow field. In this research, due to high complexity of the numerical simulation, the tube bundles have been assumed as the porous media. Two phase flow field correlations such as interfacial drag force and tube bundle resistance force have obtained by the equations that have been reported in the similar computational fluid dynamic researches. The heat transfer from primary side fluid to the secondary is calculated three-dimensionally each iteration and is supplied as a heat source on the secondary flow field calculation. Besides porous media flow field validation, decrease of computational domain has been studied using appropriate boundary conditions. It was observed that the computed void fraction compared to the experimental results show better accuracy than similar computational fluid dynamic investigations