Lec38_Special_Session_Problems

# Lec38_Special_Session_Problems - Lecture 38 L t ENE801...

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Lecture 38 ENE801: Additional roblems Problems Plus 4 sample final exam roblems from previous problems from previous years (2002-2008)

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Sample Final Exam Problem 1 n ice overed pond used for fish farming An ice-covered pond used for fish farming experiences deoxygenation due to a high rate of oxygen demand within the pond sediments. Prior to the freeze-over date, the dissolved oxygen (DO) concentration in the pond is 12.4 mg/L. Assume that the DO transfer occurs at the sediment-water interface according to a first-order process with a rate of k = 0.1 per day. The DO lower urvival limit is 3 mg/L for cold ater fish Ice DO (a) survival limit is 3 mg/L for cold-water fish. The pond volume is V = 104 m3. (a) Estimate the DO concentration in the pond 30 days after the freeze-over date (b) ow many days can fish survive in the DO Ice (b) How many days can fish survive in the pond? (c) To improve the DO concentration in the pond, water is withdrawn from the pond, aerated with oxygen, and reintroduced below the ice as shown in J 1 J 2 Figure 1 Figure 1(b). The inlet and outlet discharge is 2 L/s and the inlet DO is 13.8 mg/L. Estimate the DO concentration in the pond 30 days after the freeze-over date. (d) How any days can the fish now survive? g many days can the fish now survive?
Sample Final Exam Problem 2 A three segment estuary is shown in the figure below. The concentration of CBOD of the incoming flow is 10 mg/L. Toxic chemicals in the incoming flow create a toxic condition in segments 1 and 2 such that the decay of the CBOD is zero in those segments. The CBOD begins to be oxidized in segment 3 at a rate of k r = 0.1/day. Using backward differences, calculate: (a) The net flux of CBOD from upstream into segment 3 in kg/day? (b) The CBOD concentration in segment 3 in mg/L. The following data is given for the problem. 3 63 83 73 123 53 01 12 3 3 Ocean 10 m , 10 m , 10 m 50 10 m /day, 55 10 m /day 60 10 m /day, 65 10 m /day VV V QQ    23 y, y 10 m /dayfor all interfaces E

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Sample Final Exam Problem 3 or the problem Given: Solution vector in mg/L: For the problem shown what is the exchange E’ 35 in 8 . 0
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Lec38_Special_Session_Problems - Lecture 38 L t ENE801...

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