Suppose we are interested in improving the yield of a
chemical process. Let’s say that we know from the results of a
characterization experiment that the two most important
process variables that influence yield are operating temperature
and reaction time. The process currently runs at l55°F and 1.7 h
of reaction time, producing yields around 75%. Figure 13.2
shows a view of the time-temperature region from above. In this
graph the lines of constant yield are connected to form
response contours, and we have shown the contour lines for
60%, 70%, 80%, 90%, and 95% yield.