INVESTIGATION THE EFFECT OF ASPECT RATIO ON THE FREE HEAT CONVECTIVE INSIDE A HORIZONTAL HEATED TUBE. J. eng. sustain. dev. [Internet]. 2017 May 1 [cited 2024 Apr. 29];21(3):119-35. Available from: https://jeasd.uomustansiriyah.edu.iq/index.php/jeasd/article/view/539