Experimental study on the sticking probability and deposit bond strength of fouling in enhanced tubes

Abstract

Sticking probability (P) and deposit bond strength (ξ) are two of the most important factors that determine the fouling process, but no calculation correlations for both P and ξ could be found in current models. Thus, the fouling process could not be described by specific formulas. This paper analyzed each parameter in the Kern-Seaton fouling model, and a correlation of dry matter concentration (Cb′) was developed, depending on the water quality test. Test data suggested that the sticking probability (P) in such combined fouling ranged from 0.96445×10−3 to 6.20781×10−3. The deposit bond strength (ξ) of fouling ranged from 0.99953×107 N·s/m2 to 3.51186×107 N·s/m2. Furthermore, the calculation correlations of P and ξ in types of f(Re,Ns,α,e/Di) and f(f,j) for two-dimensional enhanced tubes were developed, respectively, based on long-term fouling data. Results indicated that the sticking probability (P) was consistently decreasing in both the j-factor and frictional factor (f), but it was consistently increasing in the temperature of heat transfer surface (T). Both the sticking probability (P) and deposit bond strength (ξ) were more affected by frictional drag performance of the tubes than the heat transfer performance. The sticking probability (P) was negatively related to the specific geometric parameters (Ns, α, e/Di) of the tubes, but positively related to the Reynolds number, Re, which was completely opposite to the deposit bond strength (ξ). The parameters of e/Di and α affected both the sticking probability (P) and the deposit bond strength (ξ) more than the starting number of Ns.