The Influence of Friction Factor on the Convective and Radiative Heat Transfer in Inclined Cylindrical Annulus

作     者：Manal Hadi Al-Hafidh Lina Senan Safwat 

作者机构：Department of Mechanical Engineering Faculty of Engineering Baghdad University Baghdad 964 Iraq College of Engineering University of Baghdad Baghdad 964 Iraq 

出 版 物：《Journal of Energy and Power Engineering》 (能源与动力工程（美国大卫英文）)

年 卷 期：2013年第7卷第11期

页      面：2027-2036页

学科分类：080701[工学-工程热物理] 08[工学] 0807[工学-动力工程及工程热物理] 080203[工学-机械设计及理论] 0802[工学-机械工程] 

主　　题：Laminar flow mixed convection radiation inclined annulus friction factor. 

摘      要：The effect of friction factor on the unsteady state mixed convective-radiative heat transfer in an inclined cylindrical annulus is investigated from continuity, momentum and energy equations. The outer cylinder is kept at a constant temperature while the inner cylinder is heated with constant heat flux. The governing equations are normalized and solved using the vorticity-stream function and the BFC （body fitted coordinates） methods. The two heat transfer mechanisms of convection and radiation are treated independently and simultaneously. A computer program （Fortran 90） was built to calculate Nusselt number （Nu） and friction factorffor unsteady state condition for fluid Prandtl number fixed at （Pr = 0.7） （for air as working fluid） with radius ratio （/~ = 2.6）, Rayleigh number （0 〈 Ra 〈 103）, Reynolds number （50 〈 Re 〈 2,000）, conduction-radiation parameter （0 〈 N 〈 10）, optical thickness （0 〈 l＂ 〈 10） and different annulus inclination with horizontal plane （0~ _〈 d 〈 90~） for concentric cylindrical annulus. For the range of parameters considered, results show that radiation enhance heat transfer. It is also indicated in the results that as 3 increasefwill be decrease and also when Re increasefwill be decrease for any value of Ra causing increase in heat transfer. The maximum value off can be recognized at ~ = 90~ and the minimum value at 6 = 0~ for low Re. There is an optimum value of annulus inclination that gives maximum value of Nu, this maximum value appears at 90~ of annulus inclination comparison of the result with the previous work shows a good agreement.