Experimentally validated numerical modeling of heat transfer in crossflow air-to-water fin-and-tube heat exchanger

Abstract

• Crossflow air-to-water FTHEX has been numerically modeled. • Different tube-side inlet boundary conditions have been analyzed. • Numerical results have been compared with experimental measurements. • Water-side thermal resistance has influence on overall thermal performance of FTHEX. • Fully developed inlet boundary condition shows best agreement with measurements. The aim of this work is to analyze different tube-side inlet boundary conditions in order to properly model heat transfer mechanism in a crossflow air-to-water fin-and-tube heat exchanger (FTHEX). For accurately describing conjugated heat transfer, the entire flow length on both fluid sides should be considered. For problem simplifying, domain that include a segment inside the heat exchanger in the water flow direction, is used. This paper studies the effect of fully conjugated heat transfer, including air-side and water-side thermal resistances. Three different numerical models are analyzed by varying the tube-side inlet boundary conditions. In one of these models the water-side thermal resistance is neglected and other two models consider the water-side thermal resistance, but with different velocity and temperature boundary conditions at the water inlets: uniform and fully developed. To validate the proposed numerical models, measurements have been performed on a crossflow air-to-water plain FTHEX. The results show that the numerical model with the fully developed water inlet boundary condition coincides best with the experimental data. It can be concluded that the water-side thermal resistance cannot be neglected, especially when evaluating the air outlet temperature and the overall heat transfer coefficient of heat exchanger.