HTTA 2019 09 10 Solutions

Pagina 1

VER Y IMPOR T ANT Please read with great attention the instructions written at the beginning of the text of Part B. Not complying with them will result in a penalty . Heat T ransfer and Thermal Analysis - A.Y. 2018/19 - Date 10/09/2019 Surname: Name: ID number: Signature: (“matricola” or person code) Part A 1. Write the conduction equation for a medium having constant conductivity in steady-state conditions. see p. 18 slides Part 1 2. Draw the temperature profile in the system sketched in the figure (including both the solid and the fluid parts): 3. Write the equation to calculate the net energy transfer between two gray diffuse planes facing each other. see p. 32 slides Part 5 4. Write the finite difference approximation of the 2D Fourier law in a Cartesian coordinate system. Fourier law: see p. 10 slides Part 1; FD approximation of the 1st derivatives: centered (also forward accepted), see p. 52/53 slides Part 1. Also FD approximation of the Fourier equation as been accepted (for this time only). 5. State the difference between homogeneous and heterogeneous boiling. see p. 7 slides Part 3B 6. State the difference between an active and a passive device for thermal control. see p. 22 slides Part 6 7. Sketch the convective coefficient profile as a function of the height over the Earth surface during atmospheric re-entry. see p. 12 slides Part 6 Heat T ransfer and Thermal Analysis - A.Y. 2018/19 - Date 10/09/2019 - Part B INSTRUCTIONS Read them very carefully - Not complying with them will result in a penalty from -1 point to not having some parts of the test corrected. • test duration is 1 h 45’. The text of both exam parts is given at the beginning. The suggestion is to devote to part A no more than 35’. • you must fill in all the fields (surname, name, student ID number,…