Determining Hydraulic Resistance and Volumetric Heat and Mass Transfer Coefficients during Cooling of Circulating Water in a Multistage Vortex Chamber

To improve the thermal performance of evaporative cooling process and reduce hydraulic resistance, a new vortex chamber has been designed with several stages of phase contact whose distinguishing feature is the arrangement of contact zones of swirling liquid and gas flows in the annular space of the chamber. The designed vortex chamber can operate stably in a wide range of loads, both high and low loads with respect to liquid and gas phases. Process design calculations of new contact elements are based on the criterion of energy efficiency. The best way for its estimation is by the Merkel and Kirpichev method. The hydraulic resistance and thermal power of the vortex chamber are determined under various operating conditions. The obtained dependence of hydraulic resistance on the spray rate in the vortex chamber makes it possible to estimate the energy efficiency of the chamber and select the best operating conditions according to the Kirpichev criterion. Expressions for calculation of heat and mass transfer coefficients are presented. The criterion equation enables us to determine whether the efficiency of the proposed device corresponds to the design value. The volumetric mass transfer coefficients encountered in the developed vortex chamber with known type of sprinklers are compared with experimental data. The developed vortex chamber has an enhanced mass transfer coefficient at the gas-to-liquid mass flowrate ratio of G/L > 0.5. The vortex chamber cooling capacity is maximized at low mass spray rates, i.e., at low hydraulic loads with respect to the liquid phase. To increase the energy efficiency of the used contact devices, the circulating water should be cooled at low average gas flow velocities.