Solar Air Colectors for Space Heating and Ventilation Applications – Performance and Case Studies in Romania Climatic Conditions

In the context of extending the use of renewable energy, solar air collectors have various applications: on the one hand they can be used for air heating in winter, on the other hand in summer to evacuate the warm and polluted air from the residential or offices, industrial and commercial buildings.The paper presents experimental results of testing a solar collector air heater type SH 1500 G, used in climatic conditions in South Eastern Europe – Romania. There are highlighted the relationships between the direct solar irradiation specific to the region, the heat flow resulted, the air velocity at the outlet, the air flow rate, the time of input in nominal regime of the collector and efficiency of conversion of solar energy into thermal energy. Thus, it was shown that after maximum 50 minutes, solar air mentioned collectors, with baffles and double pass of air can reach 55% efficiency for solar radiation of 900-1000 W/m2.The article also presents a mathematical model and the results of a computational program that allows sizing solar panels for the transfer of the air, in their use to improve the natural ventilation of buildings. The article is completed with useful case study, sizing the area needed to be covered with solar collectors for different values of the solar radiation and various speeds of the air flow inside the collector, to ensure ventilation of a house with two floors or of an office building.