Transient Conduction

Question 1

When can lumped capacity method be used?

Answer 1

When Bi < 0,1

Question 2

How do you find the convection coefficient of a small sphere in an airstream given the temperature time history?

Answer 2

1. Assume Bi < 0.1
2. Use Transient Temperature formula to find b.
3. Use b to find h
4. Validate assumption 1 using h

Question 3

How do you solve transient electric wire heater in fluid system?

Answer 3

1. Use Energy Balance: q_el - q_convec = rho V c dT/dt
2. Integrate the equation: You will have to use substitutions until you are able to use separation of variables

Question 4

Given a transient sphere system in a stream, how do you use One-term approximation to solve the system?

Answer 4

1. Calculate Biot Number
2. Assume F_0 > 0,2
3. Use one-term approximation formula for sphere
4. Get the constants for the formula from the table
5. Verify assumption 2

Question 5

In what case can one term approximation be used?

Answer 5

Fo > 0,2

Question 6

Given a transient sphere system in a stream, how do you use Heisler Charts to solve the system?

Answer 6

1. Find Bi^-1
2. Find theta^*
3. Find Fourier number from chart
4. Use Graph to find required values