A study of cooling tower performance analysed on the basis of the film coefficients.

Experiments were carried out in a small forced-draught water cooling tower. The results were analysed by a graphical method duo to Mickley (31), which enabled the estimation of the gas- and liquid-film heat transfer coefficients as well as the gas-film mass transfer coefficient. The group of experiments has a factorial design and it was possible to correlate the results in terms of the three major operating variables Air Rate, Water Rate and Packed Height. Two complete sets of experiments were carried out. The first showed the limitations of the method which severely restrict its range of useful applicability and which are discussed in some detail. The second set, designed to overcome these difficulties, gave highly satisfactory results, showing that the method is extremely useful under suitable conditions of, operation. It is also shown that the liquid-film heat transfer coefficient is far from negligible in the present work and it is felt that it ought to be included in the design of water cooling apparatus. Equations are presented describing the variations of the three film coefficients and the tie-line slope with change in magnitude of the three major operating variables. These are found to agree well with those of other workers whose experiments were carried out in more or less the same range of Air and Water Rate but with much larger Packed-Heights. The Mickley method of analysis is considered to be potentially very important, however a considerable amount of work is needed to try to increase its range of applicability to all cases before it can be used to its fullest advantage