★Specialized Examination in Chemical Engineering ★ — One question per day (2015-12-2) — Increased participation
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This post was last edited by zshiwei2008 on 2015-12-3 at 13:08. Points system for the daily question: Participation – 1~3 points; Correct answer – 5 points; In-depth analysis – 5~10 points. The answer is provided the next day. Due to limited capabilities, I am unable to provide more in-depth explanations for each question; therefore, on the second day, in addition to offering reference options, I will also remove the restriction on reading responses. I hope that all candidates can learn from one another and improve together! Daily Question (2015-12-2): 1. When a fluid flows in a circular straight pipe under forced turbulence, what is the exponent that represents the influence of the fluid properties on the convective heat transfer coefficient? A. Nusselt number Nu B. Prandtl number Pr C. Reynolds number Re D. Grashof number Gr 2. If an object can be considered a gray body, then ( ) equals 1. A. Absorptance A B. Reflectance R C. Transmittance D D. The sum of absorptance A and reflectance R Answer: Question 1: B Question 2: D
1. B Pr = Cpμ/λ 2. D
B D suggests that moderators create more questions related to the standards and regulations that will be covered in the exams
B and D. Nu is the convective heat transfer coefficient; Re, the Reynolds number, indicates the influence of the flow conditions; Pr = μcp/k represents the influence of material properties such as heat capacity, viscosity, and heat transfer coefficient; Gr denotes the influence of natural convection ； Definition and characteristics of a gray body: The absorptivity does not vary with the wavelength of the radiation, and it is a heat impermeable body, i.e., A + R = 1
1. B. Plant’s criterion Pr 2. D. The sum of absorptance A and reflectance R
1. When a fluid undergoes forced turbulence in a circular straight pipe, the exponent governing the effect of the reactive fluid properties on the convective heat transfer coefficient is (B). A. Nusselt number Nu B. Prandtl number Pr C. Reynolds number Re D. Grashof number Gr 2. If an object can be considered a gray body, then (D) is equal to 1. A. Absorptance A B. Reflectance R C. Transmittance D D. The sum of absorptance A and reflectance R