Question

A flat plate maintained at a temperature of 80°C experiences a flow of atmospheric air at 0°C. If the temperature gradient at the plate’s surface at a given downstream-stream location is 43°C/mm, what is the local heat transfer coefficient?

Answer 1

Answer:

h =12.9 w/m2 k

Explanation:

we know that thermal conductivity of air K at 0 degree celcius = 0.024 w/mk

T_S = 80 Degree celcius

temperature gradient = -43 degree C/mm = - 43*1000 / m$\frac{dT}{dx} = - 43*1000 / m$

by fourier law

$Q = -k_{air} A * \frac{dT}{dx}$

$\frac{Q}{A} = -0.024 *1*(-43000)$

q = 1032 watt/m2

we know that from newton's law

q = h (T_s - T_∞)

1032 = h*(80 - 0)

h =12.9 w/m2 k