Solar collectors are of particular kind of heat exchangers which absorbs the incoming solar radiation and convert it into thermal energy. The collected solar thermal energy is carried through a working fluid (liquid/gas) which could be used for hot water or space conditioning or may be for thermal storage to use during cloudy days/night times.
In the conventional solar thermal collectors water, glycol and organic/ synthetic oils were used as working fluid. However, these fluids have relatively low thermal conductivity and thus cannot reach high heat exchange rates in thermal engineering devices. A way to overcome this barrier is using ultra fine solid particles suspended in common fluids to improve their thermal Conductivity.