Susceptibility to corrosion of aluminium alloy components in ethanol adsorption chiller

Methanol, and more recently ethanol, have been deeply employed as adsorbate phase (refrigerant) inadsorption chiller and heat pump applications (e.g. refrigerator adsorption ice maker). The use ofanhydrous alcohols however can cause several problems related to the corrosiveness of such moleculestowards light alloys (from titanium to aluminium). The problem was already highlighted in bio-fueltechnology where bio-ethanol was considered as a promise alternative to fossil hydrocarbons. Watercontent was observed as one of the main factors influencing corrosion rate. In the present works severalaccelerated corrosion tests on 6061 Aluminium alloy have been carried out in autoclave in a temperaturerange from 110 to 135 C with different ethanol to aluminium mass ratio. Highly exothermic reactionsrelated to aluminium oxidation, coupled to hydrogen evolution, have been recorded. The main drawbackof hydrogen evolution is the formation of a stagnant layer over the heat exchangers surface, which canlimit the ethanol vapour diffusion, thus reducing adsorption/condensation rate.