Conversion rate density temperature dependence

The shift factor is philosophically based on the concept that the viscoelastic response is a result of the ability of the polymer chains to respond to stress or deformation. Largely this response is temperature or conversely rate dependent. However, one of the factors often overlooked is that the ability of a polymer to respond is also a function of the volume available for the polymer chain to deform, which is ultimately related to density. This results in an additional vertical shift of the raw experimental data. This shift is often overlooked for two reasons. The first reason is that many practitioners are unaware that it exists and the more valid reason is that the time-temperature transformation (TTT) of the raw data is at best often only an order of magnitude predictor of the response over long times. 

In a variable-density reactor the residence time depends on the conversion (and on the selectivity in a multiple-reaction system). Also, in ary reactor involving gases, the density is also a function of reactor pressure and temperature, even if there is no change in number of moles in the reaction. Therefore, we frequently base reactor performance on the number of moles or mass of reactants processed per unit time, based on the molar or mass flow rates of the feed into the reactor. These feed variables can be kept constant as reactor parameters such as conversion, T, and P are varied. 

The modeling of ECR systems involves, as that of any other reaction system, the development of a suitable reaction model for subsequent use in reactor modeling. The reaction model for an ECR is an expression for the dependence of current density on reaction parameters such as reactant concentration, electrode potential, rate constants, pH, temperature, etc. The reactor model relates the reactor parameters to performance criteria. The objective is to evolve suitable expressions for the computation of the electrode area required for a desired conversion, batch time, etc. We devote the next section to developing reaction models for simple electrochemical systems and proceed to reactor modeling in the following section. 

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