An environmental control system utilizing solar energy would generally be more cost-effective if it were used to provide both heating and cooling requirements in the building it serves. Various solar powered heating systems have been tested extensively, but solar powered air-conditioners have received little more than short-term demonstration attention.
This paper reviews past efforts in the field of solar powered air-conditioning systems with the absorption pair of lithium bromide and water. A number of attempts have been made by researchers to improve the performance of the solar applied air-conditioning (chiller) subsystems.
It is seen that the generator inlet temperature of the chiller is the most important parameter in the design and fabrication of a solar powered air-conditioning system. While collector choice, system design and arrangement are other impacting factors for the system operation.
As a result of the projected world energy shortage, the use of solar energy for environmental control is receiving much attention in the engineering sciences literature. Air-conditioning is a particularly attractive application for solar energy because of the near coincidence of peak cooling loads with the available solar power.
Of the air-conditioning alternatives, the absorption system appears to be one of the most promising methods. Many arrangements or cycles are possible: solar collectors can be used to provide energy for absorption cooling, desiccant cooling, and Rankine-vapour compression cycles. Solar hybrid cooling systems are also possible.
Although a large potential market exists for this technology, existing solar cooling systems are not competitive with electricity-driven or gas-fired air-conditioning systems because of their high first costs. Lowering the cost of components and improving their performance could reduce the cost of solar cooling systems.
Improvements such as reduced collector area, because of improved system performance, and reduced collector cost will lower the cost of solar components. Several solar driven refrigeration systems have been proposed and are under development such absorption systems including liquid/vapor, solid/vapor absorption, adsorption, vapor compression and photovoltaic±vapor compression systems. Most of the above mentioned systems have not been economically justified.
Source: National Technical University of Athens
Author: Z.F. Li, K. Sumathy