1. INTRODUCTION Since the petrol crisis, attention is drawn to the various sources of alternative energy, including: renewable energy geothermal energy [1], solar energy, wind energy etc. Solar system is the energy which the sun provides by its radiation directly or diffusely through the atmosphere. Solar energy transformed into heat is usually reorganized as one of the most effective ways to exploit solar energy. It has found many applications in the field of heating, drying, cold production, etc. [2-5]. Several types of air collectors were constructed and tested throughout the world. The main objective is to collect the maximum amount of solar energy at minimum use materials and cost [6, 7]. To increase the efficiency of solar air collectors, the heat transfer coefficient between the absorber plate and air stream should be improved, one of the most common methods to increase the heat transfer coefficient using the turbulence promoters in the form of artificial roughness on the absorber plate. In order to improve the performance of solar air heaters, different methods have been suggested to increase the rate of heat transfer between air stream and absorber plate. According to many researches, the performance of solar air collectors can be improved by utilizing corrugated surfaces [8, 9], employed artificial roughness in the air duct [10-12], attaching fins [13-18] and fins and baffles [19-22]. These ways mentioned are usually introduced as some of most promising kinds of the performance enhancement techniques. They play double aspect role in promoting heat transfer to the air flow: i) they make the turbulent flow near the hot plate [23, 24]; ii) they extend the path of the air flow [25, 26]. A number of studies have investigated theoretically for different air heaters designs by applying the heat balance equations in order to compute the temperature distributions in each of their components [27-31]. Mohammadi and Sobzpooshani[29] investigated the influence of fins and baffles attached over the absorber plate on the performance of the upward type single pass solar air collector the problem was treated and solved theoretically under steady state conditions. Yeh [32] investigated theoretically the effect of internal re cycle on the collector efficiency in upward-type flat-plate solar air collectors with fins attached. The results of their work illustrated that the improvement in solar air collector efficiency increase with increasing reflux ratio, especially for operating at lower flow rate of air with higher inlet air temperature. Moreover, the performance in the device operated with internal recycle overcomes that in the same-size device operated with external recycle. However, the study did not take into consideration the effect on fins number height and fin arrangement. Bahrehmand et al.[33]developed a mathematical model for simulating the thermal behavior of single and two glass cover solar air heater systems worked in forced convection flow. Results of their work showed that, the systems with fin and thin metal sheet are more efficient than other studied systems from the INTERNATIONAL JOURNAL OF HEAT AND TECHNOLOGY ISSN: 0392-8764 Vol. 35, No. 2, June 2017, pp. 289-296 DOI: 10.18280/ijht.350209 Licensed under CC BY-NC 4.0 A publication of IIETA http://www.iieta.org/Journals/IJHT Numerical study on thermal performance of a solar air collector with fins and baffles attached over the absorber plate Faris Aissaoui 1* , Abdelmoumene H. Benmachiche 2 , Abdelhafid Brima 1 , Yousef Belloufi 1 , Moussa Belkhiri 1 1 Laboratoire de Génie Mécanique, Université de Biskra, B.P.145 R.P. Biskra 07000, Algeria 2 Department of Mechanics, University of Biskra, B.P.145 R.P. Biskra 07000, Algeria Email: techno_fares@yahoo.fr ABSTRACT In this study, a mathematical model is developed for simulating the influence of fins and baffles on the thermal performance behavior of single pass solar air collector system working in forced convection. Due to the lack of theoretical work in the case of single pass solar air heaters having artificial roughness, we have proposed a theoretical model which consists of dividing the collector into several differential elements along the panel. This model is based on a numerical solution of energy equations in each component of collector. The results obtained from the present work and results of others researches are in good agreement. Using energy analysis, influence of parameters such as width of baffles, distance between baffles, length of air heater and number of fins are presented. The obtained results would be useful to select the most efficient and design parameters. Keywords: Baffles, Efficiency, Fins, Solar Air Collector. 289