Answer:
263.69 W.
(None of the option).
Explanation:
So, from the question above we are given the following parameters or data or information which is going to allow us to solve this question and they are;
(1). diameter of 25 cm.
(2). Initial temperature of 300°C.
(3).temperature drops to 200°C = final temperature.
Step one: Calculate the Reynolds number.
Reynolds number = 3 × 0.25/1.562 × 10^-5 = 48015.365.
Step two: Calculate average heat transfer coefficient.
The average heat transfer coefficient = k/D { 2 + (0.4Re^1/2 + 0.06Re^2/3} px^0.4 × (u/uz)^1/4.
The average heat transfer coefficient = 0.10204 × [ 2 + (87.65 + 79.26) (0.8719) × 0.8909.
average heat transfer coefficient = 0.20204 ( 2 + 129.652).
average heat transfer coefficient = 13.43/m^2.k.
Step three: The rate of heat transfer loss due to convection = (average heat transfer coefficient ) × πD^2 × ( T1 - T2).
The rate of heat transfer loss due to convection= 13.43 × π(0.25)^2 × (300 - 200).
=>The rate of heat transfer loss due to convection = 263.69 W.
