Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Paper format. National Exam 04-Chem-A2 Mechanical and Thermal Operations, May 2013 — open-book, 3 hours. Two sections: Section A (Mechanical Operations, A1–A3) and Section B (Thermal Operations, B1–B3); all problems 25 marks. The rubric asks candidates to attempt two problems per section; all six are solved in full below.
Reference texts: McCabe, Smith & Harriott, Unit Operations of Chemical Engineering (7th ed., McGraw-Hill) — pipe-flow friction, loss coefficients, sphericity and the Ergun equation (Tables 7.1, 5.1); de Nevers, Fluid Mechanics for Chemical Engineers (3rd ed.) and Brodkey & Hershey, Transport Phenomena — mechanical-energy balance and sudden expansion/contraction losses; Incropera & DeWitt, Fundamentals of Heat and Mass Transfer (7th ed., Wiley) — composite-wall resistance networks, LMTD/ε–NTU cross-flow exchangers and lumped radiative cooling; Lienhard, A Heat Transfer Textbook and Özişik, Radiative Transfer for the appended correction-factor and emissivity charts.
Compressible-flow note. Water properties at 180 °F are taken as $\rho=60.55\ \mathrm{lb/ft^3}=970\ \mathrm{kg/m^3}$ and $\mu=2.32\times10^{-4}\ \mathrm{lb/(ft\cdot s)}=3.45\times10^{-4}\ \mathrm{Pa\cdot s}$; commercial-steel roughness $\varepsilon=0.0457$ mm (Table A2).
