Chemical Engineering Engineer 2016 Case, Question 22 in the morning
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Chemical Engineering Engineer 2016 Case, Question 22 in the morning
The Reynolds number Re = duρ/μ = 0.02×u×980/0.66e-3 = 29696.97/u. The Darcy friction factor f can be calculated using the Brashausen formula (since the roughness value is not given, the calculation is done assuming a smooth pipe). Thus, f = 0.3164/Re^0.25 = 0.3164/(13.127u^0.25). By substituting this into the pressure drop formula Δp = f×(l/d)×ρu^2, the value of u is determined to be 0.943 m/s. Using the energy balance equation Q = ρ×n×πd^2/4×u×cp×Δt, it can be calculated that n = 103.55 ≈ 104. This solution was provided by an expert; although I was able to arrive at the same answer as well, I noticed that the Reynolds number is a range of values, so I first assumed a value for it and then used iteration, also applying these formulas. By looking at the expert’s approach, I realized that it’s possible to solve the problem without iteration!