ABSTRACT
Air-operated solar systems are comparable with solar systems in which the heat transfer medium is a liquid. However, air as the heat transfer medium in solar systems has very different physical properties from those of water (see Table 8.1), which has marked effects on solar air systems:
■ Air heats up faster than water, owing to its much lower heat capacity. This means that in solar air collectors useful temperatures can be reached even at low irradiation levels.
