The high costs of the heliostat field, as well as the issues related with the receiver operation in solar power towers are some of the main reasons to study different tube geometry shapes for the receiver. The new geometries intend to improve its thermal efficiency and increase its lifetime, such as the elliptical tubes presented in this research. A thermal model considering circumferential and longitudinal divisions of the tubes has been used to study the thermal efficiency of elliptical tubes receiver. For this analysis, the tube's geometry varies according to three different considerations when its major axis increases, and the resulting efficiencies are compared with the ones obtained for circular tubes of a fixed diameter. The results show that there is an improvement in the efficiency with the new tubes, because of the radiative exchange with the environment using the elliptical tubes, resulting in lesser radiative heat losses.