Heat transfer in a staggered bare-tube bank immersed in a vast water pool

The heat transfer in a rarefied staggered bank composed of serpentine bare thick-walled tubes was studied by numerical simulation. Calculations are performed for two problems: the main and auxiliary ones. Data were obtained on the conjugate heat transfer for the main problem within the framework of a coupled three-dimensional (3D) formulation; the 3D forced flow of the cooled gas in the tubes, the thermal conductivity in the tube walls, and the mixed unsteady convection of water in the intertubular space were taken into account. In the simplified auxiliary problem, only the flow of water is simulated, while the constant temperature of the outer walls of the tubes is given by the solution of the main problem. The solution of the conjugate problem showed a significant effect of the change in the difference between the temperature of the external surface of the wall and the surrounding water temperature on the local heat transfer due to the gradual cooling of the gas. It is concluded that a simplified nonconjugate formulation of the problem becomes practically meaningful when the data from parametric calculations of the problem in the conjugate formulation are accumulated.