PROBLEM OF RECONDENSATION IN EVAPORATIVE COOLERS OF GASES AND LIQUIDS

The problem of gases and liquids evaporative coolers practical use area widening is associated with the reduction of the evaporative cooling limit from wet-bulb temperature to the dew point temperature of the outside air. This entails a risk of water vapor recondensation when approaching the equilibrium curve. The application of the "enthalpy potential" method to the availability of the water film thermal resistance, which is neglected in traditional calculations of the evaporative coolers is considered in the paper. The developed method allows to analyze the change of air flow state when it is in the directly contact with the liquid film, which is essential for deep cooling of a liquid (when the limit is the dew point temperature and the line of air state changes is coming directly to φ = 100 %). An equation expressing the additive phase resistance was received, and it is shown that the value of the thermal resistance of the liquid is up to 50 % of the total thermal resistance, that is nonnegligible, as assumed in the traditional evaporative coolers calculations. On the basis of experimental data the authors analyzed the influence of the contacting gas and liquid flows ratio and their initial parameters (temperature and moisture) on the danger of recondensation and recommendations to mitigate such threats were made.