Use of computational fluid dynamics for modelling passive downdraught evaporative cooling.

The air flow in a Passive Downdraught Evaporative Cooling (PDEC) tower has been modelled using a Computational Fluid Dynamics (CFD) code. Water is injected into dry warm air and the interaction between the water and the air is represented using a particle transport model. This models the transfer of mass, momentum and heat between the water particles and the air in addition to predicting individual particle trajectories. The CFD code successfully produced predictions for the air flow in such a cooling system and the results are comparable with those obtained from a one dimensional finite difference model. The CFD results however, provide much more spatial information, in particular, individual particle trajectories. CFD also offers far greater potential for modelling full PDEC systems in which the evaporatively cooled air is delivered to occupied spaces.