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Two tanks are connected together in the following unusual
Chapter 2, Problem 2.3(choose chapter or problem)
Two tanks are connected together in the following unusual way in Fig. E2.3.
(a) Develop a model for this system that can be used to find \(h_{1}\), \(h_{2}\), \(w_{2}\), and \(w_{3}\) as functions of time for any given variations in inputs.
(b) Perform a degrees of freedom analysis. Identify all input and output variables.
Notes:
The density of the incoming liquid, \(\rho\), is constant.
The cross-sectional areas of the two tanks are \(A_{1}\) and \(A_{2}\).
\(w_{2}\) is positive for flow from Tank 1 to Tank 2.
The two valves are linear with resistances \(R_{2}\) and \(R_{3}\).
Questions & Answers
QUESTION:
Two tanks are connected together in the following unusual way in Fig. E2.3.
(a) Develop a model for this system that can be used to find \(h_{1}\), \(h_{2}\), \(w_{2}\), and \(w_{3}\) as functions of time for any given variations in inputs.
(b) Perform a degrees of freedom analysis. Identify all input and output variables.
Notes:
The density of the incoming liquid, \(\rho\), is constant.
The cross-sectional areas of the two tanks are \(A_{1}\) and \(A_{2}\).
\(w_{2}\) is positive for flow from Tank 1 to Tank 2.
The two valves are linear with resistances \(R_{2}\) and \(R_{3}\).
ANSWER:Step 1 of 4
Refer to figure E2.3 in the text book for the two tank system.
(a)
Write the mass balance equation for the tank system.
\(\rho A_{1} \frac{d h_{1}}{d t}=w_{1}-w_{2}-w_{3}\)
Here,
\(A_{1}\) is the area of cross section of tank 1
\(h_{1}\) is the height of water in tank 1
\(w_{1}\), \(w_{2}\) and \(w_{3}\) are the mass flow rates
Write the mass equation for the mass variation of the tank 2.
\(\rho A_{2} \frac{d h_{2}}{d t}=w_{2}\)
Here,
\(A_{2}\) is the area across section of tank 2
\(h_{2}\) is the height of water in tank 2
Thus, the model equations of the system are
\(\begin{array}{l}
\rho A_{1} \frac{d h_{1}}{d t}=w_{1}-w_{2}-w_{3} \\
\rho A_{2} \frac{d h_{2}}{d t}=w_{2} \\
w_{2}=\frac{\rho g}{g_{c} R_{2}}\left(h_{1}-h_{2}\right) \\
w_{3}=\frac{\rho g h_{1}}{g_{c} R_{3}}
\end{array}\)