Question

1. Water flows over a cylinder perpendicular to its axis (in cross flow) at 3 m/s. The water is at 300 K and the cylinder surface is at 350 K. The cylinder diameter is 50 mm. 1. Identify the characteristic length 2. The temperature at which properties must be evaluated 3. Calculate the Reynolds number 4. Identify the Nusselt correlations for this problem 5. Calculate the average convective heat transfer coefficient

Answer 1

Answer: omm water - Given water relocity v = 3 m/s water temperature - To = 300k Cylinder surface temperature Ts = 350k Cylinder diameter = somm. 0 Characteristic length is external pipe flow of when flow direction is perpendicular to cylinder axis = diameter of Cylinder = somm. - of flow • 2 Properties evaluated at mean temperature cylinder surface temperature and external fled temperature. Tm= 300+350 - 325k Se properties evaluated at 375k temperature. Reynold ruumber Rezero Properties of water at 325k :- P = density = 987.09 kg/m3 u= dynamic riscosity = 0.000529 Kg/m-s o 09x 3 x 0.05 = 279893. 1947 987.09X 3 X 0.05. 0.000529 Re = 27989 3.1947

4/5) Nusselt number is exprimently determined. Average heat transfer coefficient Ex = 1 1 6 hx dx and Nuxe = txx hoc Nuxkf and i { where Kra Conductivity of a third flowing . - 0 2 Equation hoc = 4 * Nux Kf dx xox x Norte

In equation ( Nesselt numbers is unknown, Hesselt number relationship is exprimently determined and put in equation .