The behavior of physical and chemical systems depends on values of the parameters that characterize the system. The analysis of how a system responds to changes in the parameters is called parametric sensitivity. For the purposes of reliable design and control, this analysis is important in virtually all areas of science and engineering. While similar concepts and techniques can be applied in different types of systems, we focus on chemical systems where chemical reactions occur.

In many cases, when one or more parameters are varied slightly, while holding the remaining parameters fixed, the response of a chemical system also changes slightly. However, under other sets of parameter combinations, the chemical system may respond with an enormous change, even if one or more parameters are varied only slightly. In this case, we say that the system behaves in a parametrically sensitive manner. Clearly, it becomes difficult to control the chemical system when it operates in a parametrically sensitive region, and sometimes this leads to so-called runaway behavior that ends up with catastrophic results. This book is concerned with parametric sensitivity and parametrically sensitive behavior of chemical systems, analyzed with a unified conceptual and theoretical framework.

In Chapter 2, we define various sensitivity indices and illustrate numerical techniques that are commonly used for their evaluation. Then, in Chapters 3 to 4, sensitivity analysis is used to identify the parametrically sensitive regions in various types of reactors, such as batch, tubular, continuous-flow stirred tank, and fixed-bed, where either a single or complex reactions occur. In Chapter 7, we use explosions in hydrogen-oxygen mixtures as an example to show that the same analysis can be used to quantify critical ignition conditions in combustion systems.