Assessment of corrosion and performance characteristics of secondary working fluids

Abstract

Consulta en la Biblioteca ETSI Industriales (8123)

[EN] The main goal of this project was the assessment of the corrosion asociated with some wide know secondary fluids. A family of coolants based in potassium formate salts has shown a very promising properties for low temperatures, such a high volumetric heat capacity, good heat transfer performance and a relative low density which give it a low pressure drop and thus the pumping requirements are not excessive. The problem with those coolants is the compatibility with metals, alloys and sealants. Some of them shown corrosion problems while they were being tried in UCD test facility, even producing refrigerant leakage in some joints and in the heat exchangers. The crux of matter of this project is to assess how much those coolants are more corrosive than the traditional secondary working fluids used. It is difficult to asure the time that a system can last working with a corrosive coolant, but those traditional secondary fluids, like HFEs, are being used for a long time in seocondary systems and corrosion have not become a problem there. Thus a method to compare their corrosion rates with the ones of the potassium formate based coolants would be enough a priori. The results of the corrosion test carried out have shown that one of the potassium formate based coolants, called Zitrec S, is completely valid for refrigerant systems since its corrosion rates in metals used in the most of the cooling applications are almost zero. It can not be said the same for the coolant called Hycool, another seondary fluid based in potassium formate. Its rates for metals as copper, brass and aluminium, all of them widely used in cooling systems, are not negligible at all and that should be taken into account. Finally, an attempt to correlate the theoretical performance characteristics of the secodary fluids with their performance characteristics in the UCD test facility was tried, showing that a priori it does not exist an only expression which can correlate both data, since each fluid vary its behavior in a different way from the theoretical to the experimental approach.