The absorbent surface of a passive solar heating system plays an important role in improving its performance. Therefore, in this paper, an experimental comparison was conducted between the thermal performances of modified and classic sample of thermal storage wall (Trombe wall) under Kirkuk city climate in January 2018. The absorbent surface of the modified Trombe Wall was treated by adding a layer of copper chips. In general, the Trombe Wall was made of 10 cm thick vented concrete wall south faced, pained black and covered with a glass layer. The samples’ performances were investigated by computing the thermal efficiency and Nusselt number along with the air channel. The comparative results showed that the absorbent surface type had a significant effect on the Nusselt number and least effect on thermal efficiency. The average Nusselt number of the modified sample increased by about 10% compared to the classic sample, whereas the thermal efficiency of the classic sample was higher at about 5% than the modified sample.
Keywords : Absorbent Surface; Nusselt Number; Thermal Efficiency; Trombe Wall.