The formation and behavior of fog in a tube bundle condenser

Abstract

The formation and behavior of fog during partial condensation of humid air in a vertical tube bundle condenser has been investigated. For this purpose a special glass condenser has been constructed which allows to measure the aerosol parameters everywhere along the cooling tubes using an optical aerosol measurement system. At the operation conditions adjusted in the present work fog occurs only in the presence of foreign nuclei by heterogeneous nucleation. It is shown, that the total mass of fog being formed was not influenced by the number concentration of foreign nuclei. The formation of fog occurs immediately after the first contact of the humid air with the cooling wall due to local supersaturation. After the fog has been formed in the entry of the condenser, a strong decrease of fog particles has been observed further down with the total amount of fog being constant. The effect of various process settings on the resulting aerosol parameters has been investigated. Both simple and rigorous one-dimensional calculations and complex multi-dimensional simulations using CFD were carried out for the interpretation of experimental data. Although the multi-dimensional simulations showed strong local effects the one-dimensional models were suitable to predict the conditions for fog formation.