Question

Air at 10 atm and 25°C flows with free stream velocity of 6 m/s over a flat plate at 75°C. Deter- mine the heat flux at 0.05 m intervals upto a distance where the Reynolds number is 5 x 10^5.

Answer 1

`q=11.37 (KW)/(m^2)`

Step-by-step explanation:

Given that velocity=6 m/s

Temperature of surface=75 °C

Temperature of air=25 °C

Reynolds number =
`5* 10^5`

It means that this is laminar flow.So Nusselt equation given as follows

`Nu=0.644Re^{(1)/(2)}Pr^{(1)/(3)}`

Now properties of air at mean temperature of 75 °C and 25 °C (50 °C) is taken from standard table

K=0.028 W/m-K,Pr=0.71

And we also know that

`Nu=(hL_c)/(K)`

Now by putting the values

`Nu=0.644* (5* 10^5)^{(1)/(2)}* 0.71^{(1)/(3)}`

Nu=406.24

`406.24=(h* 0.05)/(0.028)`

`h=227.49 (W)/(m^2K)`

So heat flux q= hΔT

q=227.49 x (75-25)

`q=11.37 (KW)/(m^2)`