Steady-state performance of a two-phase natural circulation loop

Using both HEM and TEDFM the steady-state behaviour of a rectangular uniform cross section two-phase closed NCL has been studied through one-dimensional approach. Uniform heat flux for heating as well as cooling has been considered along with the constant physical properties, uniform pressure inside the loop and water-steam as the working fluid. For the given operating range and loop geometry, the circulation velocity lies in the turbulent regime. The flow rate monotonically increases with the loop height. However, with heat flux it initially increases, reaches maximum and then falls. This implies that the surface heat flux should match the loop geometry and other operating parameters to produce the maximum flow rate. It has also been observed that the cooling and heating lengths and the temperature of the liquid at the entry of the heating section have to be selected optimally to generate the maximum mass flow rate.