Plume rise from multiple sources: a new model

In 1974 and 1975, Briggs presented two semiempirical models for computing plume rise from multiple sources for stacks with the same height and emission. Since in our country there are many power plants with more than one stack and generally of different heights and emissions, we developed a new model based on "virtual" stack concept, able to provide estimates of maximum plume height for this problem. Firstly we compared a simplified expression, derived from our model for the case of chimneys of equal heights and emissions, with the above mentioned Brigg's' models and with a series of data quoted by Briggs in his 1974 paper. Then we tested our model with a few experimental data relative to stacks of different heights and obtained during the La Spezia field experiments. All the comparisons made showed a satisfactory agreement. Finally a comparison among an empirical expression due to Montgomery et al. giving the correction factor for ground level concentrations in the multiple sources case and the analogue ones derived from our and Briggs' models is presented.