【Test Your Knowledge】Basic Chemical Engineering Knowledge (159) Please hide your replies

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This post was last edited by zhangyong6404 on 2009-8-14 at 16:50. In accordance with the forum’s uniform requirements, the maximum score for this activity is 15 Wealth points; giving scores based on charm is prohibited. Friendships and duplicate ratings are also declined. To encourage active participation from members, the top 5 correct answers receive a full score; for the remaining answers, 10–15 wealth points are awarded for every correct answer, while 8–12 wealth points are given for each incorrect answer. 2 mistakes result in a loss of 6–10 wealth points; the remaining mistakes earn bonus points of 2–6 wealth points as an incentive for participation. In a single-pass shell and tube heat exchanger, which of the following fluids should flow through the shell side? A. Unclean or scale-prone fluids B. Corrosive fluids C. Fluids at high pressure D. Fluids that are cooled 2. In multi-layer parallel flat-wall steady heat conduction, the heat conduction rate of each flat wall is ( ). A. Not equal ； B. It cannot be determined ； C. Equal ； D. Decline. 3 The reason why electric fans can reduce heat in summer is ( ). A. It lowers the ambient temperature ； B. Forced convection is generated, carrying away the heat from the human body’s surface ； C. Enhanced natural convection ； D. Heat conduction occurred. 4 The thermal conductivity coefficients of air, water, and metal solids are λ1, λ2, and λ3 respectively; the correct order of their values is ( ). A、λ1>λ2>λ3 ； B、λ1λ1 ； D, λ2λc; therefore, the order of the coatings from the inside out is ( ) A, a, b, c ； B, b, a, c ； C, c, a, b ； D, c, b, a 6: Normal-temperature air is heated using saturated water vapor at 120°C. The film coefficient for steam is approximately 2000 W/(m2×K), while that for air is about 60 W/(m2×K). The heat transfer coefficient K and the wall temperature of the heat transfer surface in this process are relatively close to these values. A、2000W/(m2×K), 120℃ ； B, 2000W/(m2×K), 40℃ ； C, 60W/(m2×K), 120℃ ； D、60 W/(m2×K), 40°C. Steam is used to heat a certain salt solution in a shell-and-tube heat exchanger, with the steam flowing through the shell side. To enhance heat transfer, the most cost-effective measure among the following is ( ). A. Increase the size of the heat exchanger to increase the heat transfer area ； B. Install baffle plates in the shell side ； C. Change the single-pipeline to a dual-pipeline ； D. Reduce the thickness of the heat transfer wall surface. When water flows in a circular tube under conditions without phase change, the convective heat transfer coefficient ai is 1000 W/(m2·℃). If the flow rate of water is doubled while all other conditions remain unchanged, then ai will be ( ). A、 2000 ； B, 1741 ； C, unchanged ； D. 500 9 Which of the following cannot increase the convective heat transfer coefficient? A. Utilize a multi-pipe structure B. Increase the pipe diameter ； C. Install baffle plates in the shell side ； D. When condensing, make some longitudinal grooves on the tube walls. In a 10-tube row heat exchanger, during shutdown, it is necessary to stop ( ) first, and then stop ( ). A. Hot fluid, cold fluid ； B. Cold fluid, hot fluid ； C、Cannot be determined ； D. Stop simultaneously – all members now have the permission to use hidden replies, so please cooperate actively. Starting from this issue, no scoring will be given in principle without hiding it. Thank you all! Also, be careful when posting; edits are invalid! To hide the method, click here: Hide Method. Answers for Issue 159: dcbbd ccbba