**Nomenclature**

The fouling resistance increases over time, which leads to a decrease in the flow of heat exchanged between the phosphoric acid and the steam, and subsequently the decrease in the overall heat transfer coefficient. As it appears clearly on **Figures 5** and **6**, when the fouling resistance increases with the time, the overall heat transfer coefficient decreases until reaching a minimum value varied from 1821

One of the earliest correlative models for the characterization of the asymptotic kinetics of fouling, we distinguish Kern and Seaton [17], whose general expression

*τ*

(14)

h i � �

*Rf t*ðÞ¼ *Rf* <sup>∗</sup> <sup>∗</sup> <sup>1</sup> � *exp* � *<sup>t</sup>*

This model gives rather satisfactory results, provided that the asymptotic value of the thermal resistance *Rf*\* as well as the time constant τ are evaluated, which

The analysis of the experimental data which makes it possible to carry out the plots of **Figure 7** gives us the results of the two greatness *Rf*\* and *τ* for the stainless steel tubular heat exchanger. The asymptotic model is fairly faithful to the experi-

**] τ [h] R2**

1.72\*10�<sup>4</sup> 40.32 0.975

*Values of the asymptotic fouling resistance, the time constant and the determination coefficient for the*

mental data with determination coefficient *R*<sup>2</sup> close to 1 (**Table 1**).

**8.3 Temporal evolution of the fouling resistance obtained from both**

**measurement and the Kern and Seaton model**

*Kinetics of fouling of the stainless-steel-tubular heat exchanger.*

*Inverse Heat Conduction and Heat Exchangers*

strongly conditions the accuracy of the model.

to 2078 W.m�<sup>2</sup>

**Figure 7.**

is as follows:

**Rf\* [m<sup>2</sup>**

**Table 1.**

**58**

**.K.W**�**<sup>1</sup>**

*stainless-steel tubular heat exchanger.*

.K�<sup>1</sup> .


*Inverse Heat Conduction and Heat Exchangers*

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