Waterside fouling performance in brazed-plate-type condensers for cooling tower applications

Abstract

This article presents a new experimental methodology and results of the waterside thermal hydraulic performance of brazed-type condensers under fouling operating conditions. High water fouling potential was developed in to create conditions that cause severe precipitation and particulate fouling during the experiments; corrosion and biological fouling were intentionally prevented by chemical inhibitors. Among other advantages, this new methodology is independent from the geographical location of the laboratory and from the local water supply source. Using this technique, a Langelier saturation index of the water of about 3–3.5 was achieved, which represents very severe fouling conditions. Four brazed-plate heat exchangers were tested, and a maximum reduction in heat flux of 28% and a maximum increase in pressure drop of 250% illustrate the potentially critical impairment of the heat exchanger thermal hydraulic performance. The asymptotic fouling resistance had a strong dependence on the internal geometry of the plates and weak dependence on the aspect ratio of the plates. A soft corrugation angle of 30° gives low pressure drop in clean conditions but significantly increases the propensity of fouling deposition on the heat transfer surfaces. The measured fouling resistance for the soft corrugation angle brazed-plate heat exchanger was about ten times higher than those for similar geometries but with hard corrugation angles.