Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Paper format. Eight problems, three hours, open book. Problem 1 carries 30 marks, Problem 2 carries 10 marks and Problems 3 to 8 carry 20 marks each; candidates answer any five, and indicate their choice on the cover of the first workbook. Psychrometric charts (SI and inch-pound) and an R-134a pressure–enthalpy diagram are appended to the paper. All eight problems are solved below, because the set as a whole is the study resource.
Reference texts.
Check: two readings taken from the printed paper.
(1) The length label on the Problem 6 duct sketch is printed as “L1 = =100 ft == 6ft”. The equation editor has dropped the symbols after each equals sign; the pattern “something = something = 100 ft” and “something = something = 6 ft” means four named lengths in two equal pairs, and the sketch shows exactly four duct runs. The solution therefore takes L1 = L2 = 100 ft (plenum to tee, and tee to elbow) and L3 = L4 = 6 ft (the two drops to the ceiling diffusers), and states the reading as an assumption under cover-page instruction 1. Only the pressure totals in parts (c) and (d) depend on it; the duct diameters in part (a) do not.
(2) Problem 1 gives the outdoor air as “percentage saturation 50 %” but the room as “RH 50 %”. These are different quantities and the difference is deliberate: percentage saturation is $\mu = W/W_{s}$, relative humidity is $\phi = p_{w}/p_{ws}$. At 26 °C the 50 % saturation state is 50.8 % RH, so treating them as interchangeable shifts the outdoor humidity ratio by about 0.2 g/kg.
