No abstract

Fouling of heat transfer surfaces introduces a major uncertainty into the design and operation of heat transfer equipment. After a brief discussion on impact of fouling, we present and discuss a stochastic approach to the analysis of fouling models. In view of the performance indicator (U/Uc) of the heat exchangers, a maintenance strategy for planned maintenance schedules is presented. Various scenarios of reliability based maintenance strategy are introduced. The strategy is explained in terms of the scatter parameter (α) of the time-to-fouling distribution corresponding to a critical level of fouling, and the risk factor (p) representing the probability of tubes being fouled to a critical level after which a cleaning cycle is needed. In addition, the cost implications of the above mentioned strategy are explained and their impact on heat exchanger maintenance is highlighted.

No abstract

Calcium carbonate fouling is typically encountered in a cooling-water circulating system. An experimental program is initiated to study fouling growth law (s) as well as the basic mechanism of calcium carbonate (CaCO3) scaling. After a brief description of the experimental apparatus and procedure for calculating fouling resistance, we present the deposition data in terms of fouling resistance as a function of time taken at different sections of the tube. In addition, the randomness of fouling growth is illustrated by repeating the experiments several times under the same thermal-hydraulic conditions. The results are presented in terms of a set of sample functions and their associated probability density functions at various levels of fouling. In addition, basic mechanism of CaCO3 scale formation is also explained through Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX).

No abstract