A blackened plate is exposed to the sun so that a constant heat flux of 800 W/m^2 is absorbed. the back side of the plate is insulated so that all the energy absorbed is dissipated to an airstream that blows across the plate at conditions of 2ْC , 1 atm , and 3 m/s . the plate is 25 cm square. Estimate the average temperature of the plate . What is the plate temperature trailing edge?
Answers
Answer:
The back side of the plate is insulated so that all the energy absorbed is dissipated to an airstream that blows across the plate at conditions of 25°C, 1 atm, and 3 m/s. The plate is 25 cm square. Estimate the average temperature of the plate. What is the plate temperature at the trailing edge?
Step-by-step solution:
Step 1 of 5
This solution must be solved using trial and error approach.
Unless the wall temperature is initially assumed, the properties cannot be obtained.
First Iteration:
Let us assume the wall temperature to be .
Convert the temperature into kelvin.
Approximate the wall temperature to 300K for the ease of obtaining properties.
From the TableA-5 (properties of air), obtain the following properties at .
Kinematic viscosity of air, ,
Prandtl Number,
Thermal conductivity of the air,
Determine the Reynolds’s number from the following equation:
…… (1)
Here, the velocity of the air is v, distance of the leading edge from initial point is L and kinematic viscosity of the air is .
Substitute for v, for and for L in equation (1).