Resumen:
The aim of this paper is to develop guidelines for the placing of new coolers in cooling systems
subject to retrofit. The effects of the accumulation of scale on the flow system are considered.
A methodology to assess the interconnected effect of local fluid velocity and fouling deposition is
developed. The local average fluid velocity depends on the water flow rate distribution across the
piping network. The methodology has four main calculation components: a) the determination of
the flow rate distribution across the piping network, b) the prediction of fouling deposition, c)
determination of the hydraulic changes and the effect on fouling brought about by the placing of
new exchangers into an existing structure, and d) the calculation of the total cooling load and
pressure drop of the system. The set of disturbances introduced to the system through fouling
and the incorporation of new coolers, create network responses that eventually influence the
cooling capacity and the pressure drop. In this work, these interactions are analysed using two
case studies. The results indicate that, from the thermal point of view, the incorporation of new
heat exchangers is recommended in series. The limit is the point where the increase of the total
pressure drop causes a reduction in the overall volumetric flow rate. New coolers added in
parallel create a reduction of pressure drop and an increase in the overall water flow rate; however, this increase is not enough to counteract the reduction of fluid velocity and heat
capacity removal.