HTTA 2020 01 17 Solutions

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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 17/01/2020 Surname: Name: ID number: Signature: (“matricola” or person code) Part A 1. Write the generic (before application of the b.c.s) temperature and heat flux profiles T (x) and ˙Q ′′ (x) for a wall with a heat source, for 1D steady-state conduction. 2. Write the Laplace-Young equation for an interface having a generic shape. 3. Write the general conduction equation for a solid with conductivity variable with temperature. 4. Put the following substances in ascending order of Prandtl number (at atmoshperic pressure and ambient tem- perature): air - water - liquid metal - viscous oil. 5. Sketch a basic capillary heat pipe. 6. Sketch the equivalent electrical network for the system in the picture. 7. Write the espressions of three dimensionless groups used to estimate the convective coefficient and state their physical meaning. Heat T ransfer and Thermal Analysis - A.Y. 2018/19 - Date 17/01/2020 - 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, signature) on part A sheet; • you must answer to part A questions in the spaces provided after the questions themselves; • for part B, you can use only one foolscap for the final copy (additional foolscap will not be collected/corrected); • on top-left of the first page of the foolscap paper for part…