★Specialized Examination for Chemical Engineering ★ — One question per day (2015-11-24) — Points are awarded for participation
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This post was last edited by zshiwei2008 on 2015-11-25 08:19. 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 replying, hoping that all candidates can learn from one another and improve together! Daily Question (2015-11-24): 1. What is the certain effect of increasing the vacuum level in an evaporation unit? A will increase the heat transfer temperature difference of the heater. B will increase the heat transfer temperature difference of the condenser. C will raise the overall heat transfer coefficient of the heater. D will reduce the resistance loss in the flow of secondary steam. 2. What is the purpose of using multi-effect evaporation? A Increase the concentration of the concentrated solution. B Increase the production capacity of the evaporator. C Improve the utilization rate of water vapor. D Increase the output of the concentrated solution. Answer key: Question 1: A; Question 2: C. Detailed explanations are provided in the textbook
1、A； This will reduce the temperature of the secondary steam, thereby decreasing the heat transfer temperature difference in the condenser ； It has nothing to do with the overall heat transfer coefficient ； The flow resistance of secondary steam is related to the flow conditions and the piping at the rear end; increasing the vacuum level raises the flow velocity, thereby increasing the flow resistance. 2、C
This post was last edited by f9kx on 2015-11-24 09:41 due to network latency; multiple clicks were made
What is the certain effect of increasing the vacuum level in the evaporation apparatus? A will increase the heat transfer temperature difference of the heater; C will raise the overall heat transfer coefficient of the heater
What is the purpose of using multi-effect evaporation? C Improve the utilization rate of water vapor