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Multivariable Linearization. Solution of the Dilution Problem with more variables. Problem Description. Consider the following Dilution problem: The inflow concentration c in [kg/m 3 ] of A is time varying The flowrate F [m 3 /s] is NOT constant
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BAE 3023 Multivariable Linearization Solution of the Dilution Problem with more variables
Problem Description BAE 3023 • Consider the following Dilution problem: • The inflow concentration cin [kg/m3] of A is time varying • The flowrate F [m3/s] is NOT constant • The material A in the fluid is not reduced by reaction or other means in the tank • The Tank is well mixed • Find the outflow concentration cout [kg/m3] of A
Equation for multi-variable linearization BAE 3023 A mass balance for component A can be written Inflow rate of A - Outflow rate of A = Accumulation rate of A Note that the product Fc is non-linear, so we must linearize the terms. For the multivariable case, Taylor’s Series truncated to first order terms is: Consider the function: f(F,c)=Fc
Application of multi-variable linearization BAE 3023 The linearized differential equation becomes: Transforming, the equation becomes:
Use of Superposition BAE 3023 The transfer function for cout /cin where F is constant is: The transfer function for cout / F where cin is constant is:
Block Diagram for multi-variable case BAE 3023 Because the system is linear, the effects of Cin and F on Cout can be summed to calculate the total effect on Cout: