Individual Film Coefficients in Cooling Towers

Abstract

Water-cooling data obtained by London et al.⁹⁾ with Ovate-type slats (shown in Table 1 and Fig. 1) and by Simpson and Sherwood¹²⁾ with Redwood slats and Masonite sheets (shown in Table 2 and Fig. 2), were analysed by means of the new methods previously proposed by the author, ⁴⁾ according to which the individual coefficients may be determined by reading the air condition curves on a humidity chart. Experimental formulas on individual film coefficients for each packing were derived; eqs. (1) and (6) for Ovate-type slats, eqs. (2), (3), (7) and (8) for Redwood slats; eqs. (4), (5). (9)and (10) for masonite sheets, respectively.
Moreover, taking into consideration the representation of air rates and water rates, and the area of transfer surface, generalized eqs. (23) and (26) were derived, which may be applicable to over the range of the experimental conditions for R-1, R-2, M-1 and M-2 packings. The relations between the over-all coefficients and individual film coefficients are shown by eqs. (28)a and (28)b and the comparison of the observed and calculated over-all coefficients for R-1, R-2, M-1 and M-2 packings is shown in Fig. 10. Fig. 5 and 6 show the comparison of the performances of Ovatetype slats, Redwood slats, masonite sheets and Raschig rings.