ABSTRACT

Solar thermal energy has been used for centuries by ancient people’s harnessing solar energy for heating and drying. More recently, in a wide variety of thermal processes solar energy has been developed for power generation, water heating, mechanical crop drying, and water purication, among others. Given the range of working temperatures of solar thermal processes, the most important applications are

for less than 100°C: water heating for domestic use and swimming pools, heating of build-• ings, and evaporative systems such as distillation and dryers; for less than 150°C: air conditioning, cooling, and heating of water, oil, or air for industrial • use; for temperatures between 200 and 2000°C: generation of electrical and mechanical power; • and for less than 5000°C: solar furnaces for the treatment of materials.•

For processes where more than 100°C are required, the solar energy ux is not enough to elevate the working uid temperature to such a high level; instead, some type of concentration of the energy ux using mirrors or lenses must be used. Then the ratio of the energy ux received for the energy absorber to that captured by the collector must be greater than one, and designs often easily achieve a concentration of hundreds of suns.