Comparative study of heat and mass exchanging materials for indirect evaporative cooling systems

This paper investigated several types of materials, namely metals, fibres, ceramics, zeolite and carbon, which have potential to be used as heat and mass transfer medium in the indirect evaporative cooling systems, and from the investigation, the most adequate material and structure were identified. Magnitude of heat/mass transfer rates in relation to an air-conditioning application was analysed, and the results showed that thermal properties of the materials, i.e., thermal conductivity and water-retaining capacity (porosity), have little impact on system heat/mass transfer, and therefore, these two parameters play low keys in terms of material selection. Instead, shape formation/holding ability, durability, compatibility with water-proof coating, contamination risk as well as cost, are more important concerns in this regard. Each material type was then analysed based on the above criteria and the preferable structure and configuration of this type was illustrated. A comparative analysis into different material types was carried out, and the results showed that the wick (sintered, meshes, groves and whiskers) attained metals (cooper or aluminium) are the most adequate structure/material over the others. Wick-attained aluminium sheet is much cheaper than cooper with the same structure and therefore more suitable for this application.