Scaling Law for Dry Cooling Towers with Combined Mechanical and Natural Draft,

摘要

The gasdynamic performance equation for large-scale dry cooling towers is generalized to include mechanical draft as well as natural draft. A sequence of four elements;heat-exchanger,fan,heat-exchanger,fan,are contemplated in the final result which thus includes both induced-draft and forced-draft towers as special cases. The result consists of a zero-order formula suitable for scaling tower configurations,together with a set of correction terms of first order in temperature rise. These serve both to evaluate the accuracy of the zero-order formula,and to compare systems which are nearly equivalent gasdynamically. In particular,it was found that a forced-draft system requires slightly less power than the corresponding induced-draft tower. That is,the effect of a heat exchanger on a downstream fan is much greater than that of a fan on a downstream heat exchanger. (Modified author abstract)