Technical Report 166, c4e-Preprint Series, Cambridge

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

Reference: Technical Report 166, c4e-Preprint Series, Cambridge, 2016

Associated Themes:
 

• 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.

This 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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