A Comparative Study of the Thermal Evaluation of the PTC System in Saharan Areas

Abstract

     Tamanrasset and Adrar regions were chosen to study the water heating performance using a parabolic cylindrical solar concentrator, and calculations were used for this. But before that, we examined the evolution of the total daily intensities of direct solar radiation, as well as its relationship to the duration of insolation and the maximum air temperature during the year, with the aim of choosing the days when the values of these amounts are the lowest in each region. We found that smaller quantities occur over several days, and due to the great similarity of these quantities, we settled for two days, the first being the winter solstice and the second being the seventh day of the year. During which the evolution of the intensity of direct solar radiation, the air temperature, the water temperature at the outlet of the solar center, the flow of absorbed thermal energy, instantaneous or total, were monitored, and finally the total thermal efficiency.

We noticed that the shape of the evolution of the first four is generally parabola-shaped, while the evolution of the last two differs from it and is similar, regardless of the school day and its region. Comparing the two regions, the values of most quantities are the highest in the Adrar region, with a close deviation at maximum values and a significant deviation at sunset. This difference is of the order of 200 W/m², 3-5 °C, 8-9 °C, 1-1.5 kW, 30-40 MW, and 50-60%, depending on the previous arrangement of the quantities studied. The intensity of direct solar radiation is excluded from the maximum value because it is the highest in the Tamanrasset region, with a slight difference estimated at 8 W/m². Comparing the two days of the study, the values of the seventh day of January are the highest, both for the intensity of direct solar radiation (2-18 W/m²), and for the thermal energy flow absorbed, whether instantaneous (0.15-0.01 kW) or total (4 MW). While it is lower for all air temperatures (2-3°C), outlet temperature (0.5-1.5°C) and efficiency (15%).