Методика расчета длины участка течения ненасыщенного влажного воздуха в канале оросителя вентиляторной градирни

Abstract

In the channels of mechanical-draft cooling tower sprinklers, a saturated air flow section may appear under certain initial conditions, the mass transfer intensity in which is limited by the steam content in the saturated air. For correctly calculating the heat and mass transfer processes in the cooling tower channel, it is necessary to have a method for determining the unsaturated air flow section length. Publications devoted to studying water cooling processes in the channels of mechanical-draft cooling tower sprinklers do not contain an assessment of the unsaturated air flow section length. A method for determining the unsaturated humid air flow section length in the mechanical-draft cooling tower sprinkler channels is proposed, which is based on the well-known criterion equations for calculating the heat transfer and mass transfer coefficients. The effect the initial air parameters have on the unsaturated air section length is studied, and graphic dependences of the unsaturated air section length are drawn up for each of the analyzed parameters. It is shown that the unsaturated humid air flow section length increases with increasing the initial air temperature. It is also found that the unsaturated air flow section length decreases with a growth in the relative air humidity. An increase in the air flow rate with a constant water flow rate leads to an increase in the unsaturated air flow section length. For the considered sprinkler channel, the saturated air region exists at an air temperature of 15°C and below, and for air temperatures above 25°C there is no saturated air flow section. It is shown that the conclusions drawn about the effect the initial air parameters have on the relative change in the unsaturated air flow section length are valid for channels of various shapes and geometric sizes. The proposed methodology and the results obtained can be used in designing mechanical-draft cooling towers and estimating their efficiency.