Numerical comparison of removal and deposition for fully-distributed particles in central- and split-type air-conditioning rooms

In this study, the removal and deposition of fully-distributed particles in a three-dimensional room equipped by two different air-conditioning systems, i.e. central-type air conditioner and split-type conditioner, were investigated numerically by an Euler-Lagrangian approach. The numerical model for predicting the particle motion was validated by the experimental data found in the previous literature. Special focus was given to the particle removal efficiency, particle deposition and risk assessment of particle exposure in the two air-conditioning rooms. The simulation results showed that the central-type air conditioner had a higher efficiency to remove indoor particles and therefore reduced the airborne pollution more efficiently in comparison with split-type one. The further analysis indicated that the accumulation mode particles (0.1-1 μm) would be more difficult to remove than other size particles in the investigated rooms. On the other hand, the numerical results revealed that the central-type air conditioner settled more suspended particles on the floor while the split-type air conditioner carried particles to the surrounding walls more easily. Finally, the analysis for the fates and necessary ventilation time of 0.5 μm and 10 μm particles concluded that increasing the air supply velocity indoors was a feasible and efficient measure to improve the IAQ faster but it could not reduce the ultimate contamination level.