Numerical study of solid-gas two phase flow in air-side of a compact heat exchanger using Lagrangian approach

In this paper, the effect of particle size on deposition in a compact heat exchanger was investigated numerically. The effect of flow velocity and particle mass on the deposition was also studied and discussed. Flow simulation was performed using Eulerian approach and particle motions were simulated using Lagrangian approach and discrete particle model (DPM) by ANSYS-FLUENT package. Turbulence was modeled with the k-ωSST model. Five fin channels of a compact heat exchanger were chosen as a 3D computational domain. The air flow was entered with velocity over a range from 1 m/s to 5 m/s and particles having various diameter sizes, were introduced to the computational domain from inlet boundary condition. The results showed that the pressure drop was increased with increase of particle size and particle mass. Besides, deposition ratio was grown with the increase of particle size. The results also demonstrated that most of the particles were settle down on the front of the channels and on the first and the second fins of channels. The effect of simultaneous injection of big and small particles was investigated and the results showed that small particles had more chance to deposit in the presence of the big particles.