In this paper, we report the investigation of various curved solar air heater designs that shows significant enhancement of heat transfer. We have taken the initial design proposed in the reference: Mahboub, C., Moummi, N., Brima, A., Moummi, A., 2015. Experimental study of new solar air heater design. International Journal of Green Energy 13,521-529, and incorporated promising design modifications to further look for the avenues for thermal efficiency enhancement features. The Computational Fluid Dynamic (CFD) model was first validated by the results reported by Mahboub et al. It was observed that secondary vortex formation near the absorber wall increases the Nusselt number significantly. New correlations for friction factor and Nusselt number has been developed as a function of Reynolds number and various geometric parameters such as relative groove height and pitch ratios for different design of air heaters. It is hoped that data of parameters i.e. Nusselt number (Nu), outlet air temperature (T-o), thermal efficiency (eta(th)) and friction factor (f) presented in this paper would help researchers and industry in developing efficient designs of solar collectors.