The demand for cooling may be driven by different aspects, comfort and refrigeration being the most common uses. In fact, the cooling demand is growing worldwide, even in colder climates, as comfort demand rises. This results in an increase in air conditioning mainly for tertiary buildings but also for residential applications. Refrigeration is increasing as well with a wider variety of use, mainly within the food industry.
Air conditioning is the main process used for comfort cooling. It involves changing air properties, such as lowering temperature
and humidity levels. Refrigeration implies bringing temperature to low levels, even below freezing point.
Cooling is basically achieved by retrieving heat from a fluid or gas and transferring it to the environment, which is usually called heat rejection. This transfer can be done mechanically or chemically.
One of the technologies used for cooling purposes are thermally driven chillers. These use thermal energy to cool down gases or fluids. This thermal energy can be provided by different technologies, including solarthermal energy.