ESTIMATION OF FOULING RATE AT ADVERSE AIR QUALITY IN AIR COOLED CONDENSER

Abstract

Fouling is a very common problem of a heat exchanger which may cause serious deterioration of the air-side performance heat exchangers like condenser and evaporator. The main aim of this study is to investigate the mechanism of air side deposition of dust particles and its effect on the performance of heat exchanger. For this a FEM-LPP based numerical model is developed to simulate the dynamics of dust particle movement and their deposition on the heat exchanger walls. Here the continuous phase, air is resolved using Finite element solver and discrete phase i.e., particulates is modelled using Lagrangian point particle approach. Different mechanism of dust deposition like inertial impaction and gravitational settling across the plate fin type heat exchangers are studied in this effort. The effect of geometrical parameters like fin pitch and fin shape are investigated for a range of in-flow conditions. Further, the effect of dust particle loading on fouling rate is evaluated. The size of dust particles considered in this study are based on the proportions of particle sizes present in four major cities of India. The results conclude that both decrease in fin pitch and increase in dust loading ratio are having adverse effect on the performance of the heat exchanger. Further, the leading edge of the fins and the front face of condenser tubes are the critical locations where majority of the particle deposition is observed. Based on these trends of particle deposition and the growth of deposition layer thickness, approximate timelines for removal/cleaning of condenser are proposed.