Doehlert Design for Wet Pelletization

x

1

0

x

2

0

x

3

0

fixed

x

1

x

2

x

3

Consider the experimental design problem in which there are three factors: (1) impeller speed (in rpm) with associated variable

x

1

, such that the lower and upper levels are 250 and 400, respectively, (2) amount of binding solution (in %) with associated variable

x

2

, such that the lower and upper levels are 60 and 70, respectively, (3) pelletization time (in min) with associated variable

x

3

, such that the lower and upper levels are 5 and 20, respectively.

Pelletization experiments using Doehlert design scheme determine one parameter: the mean pellet size (in mm).

This Demonstration computes the quadratic model by multilinear regression; the response

y

versus

x

1

,

x

2

, and

x

3

is given by:

y=1594-97.5

x

1

+117.6

x

2

+16.7

x

3

-20.0

2

x

1

-379.0

2

x

2

-70.8

2

x

3

-223.4

x

1

x

2

+120.1

x

1

x

3

+83.0

x

2

x

3

You can set the value of one of the variables (say

x

1

) and the Demonstration will display the contour plot of the response

y

versus the other two variables (

x

2

and

x

3

).