Pressure variation in a natural circulation loop with end heat exchangers

The pressure variation in a natural circulation loop has been investigated for both steady state and transient operating conditions. The loop exchanges heat with hot and cold external fluid streams through counterflow concentric tube heat exchangers. Considering spatial changes only in the direction of the loop length, closed form expressions have been obtained for pressure difference under steady state condition. An iterative scheme based on finite element method (FEM) has been formulated to solve the conservation equations in the transient state. The variation of dynamic pressure and its relationship with the variation of temperature field and circulation rate has been described.