Parameterisation of a biodiesel plant process flow sheet model

Authors: Janusz Sikorski, George Brownbridge, Sushant S. Garud, Sebastian Mosbach, Iftekar A. Karimi, and Markus Kraft*

  • A process flow sheet of a biodiesel plant is described with two types of surrogate models: polynomial and High-Dimensional Model Representation (HDMR).
  • Third order polynomial and HDMR surrogates achieve best and similar degree of accuracy.
  • Polynomials of order higher than 3 suffer from overfitting, especially in high-dimensional scenarios.
  • Global sensitivity analysis indicates that interaction terms have negligible effect on heat duties of the biodiesel plant.

abstractThis paper presents results of parameterisation of typical input–output relations within process flow sheet of a biodiesel plant and assesses parameterisation accuracy. A variety of scenarios were considered: 1, 2, 6 and 11 input variables (such as feed flow rate or a heater's operating temperature) were changed simultaneously, 3 domain sizes of the input variables were considered and 2 different surrogates (polynomial and high dimensional model representation (HDMR) fitting) were used. All considered outputs were heat duties of equipment within the plant. All surrogate models achieved at least a reasonable fit regardless of the domain size and number of dimensions. Global sensitivity analysis with respect to 11 inputs indicated that only 4 or fewer inputs had significant influence on any one output. Interaction terms showed only minor effects in all of the cases.

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Keywords: Biodiesel, model, parameter estimation, process flow sheet model, sensitivity, sensitivity analysis,

Associated Project: Numerics

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