Converter performance parameters

The central part of the synthesis system is the converter, in which the conversion of synthesis gas to ammonia takes place. Converter performance is determined by the reaction rate, which depends on the operating variables. The effect of these parameters is discussed briefly in the following (see also Section 4.5.7). 

Eq. (1) is called Richardson-Dushmann equation. Jr never indicate output current density in itself, although it helps account for the converter performance. Large Jr from Eq. (1) suggests that the converter generates a great deal of output power. Since the work function of the electrodes immersed in Cs vapor can be expressed as a ratio of Tr to T, following three temperatures, Te, Tc, Tr, are important parameters, which will be presented later. 

Barrier index Figure-of-merit parameter for characterizing the performance of a thermionic converter that is given by the sum of the arc drop and the collector work function, thus accounting for the plasma plus the collection losses. The lower this parameter, the higher is the converter performance. 

The barrier index, or Fb, is a eonvenieiit parameter for characterizing thermionic converter development, comparing experimental data, and evaluating converter concepts. It is an inverse figure of merit because the lower the Fb, the higher is the converter performance. The barrier index is defined as... 

Data collection and analysis is critical for monitoring system performance. As a minimum the data must be entered in Table 4.7. Mathematical relations for converting field data to performance data are given in Chapter 2. Normalised data must be plotted to study the performance trends, for example RO membrane rejection vs. time and RO productivity vs. time. The key performance parameters in Tables 4.8 and 4.9 should be used in conjunction with normahsed data to evaluate system output. The data along with RO systems design guidelines provided in Chapter 2, and RO projections given in Table 4.1 should be used to monitor and troubleshoot the performance over time. 

There is a general trend toward structured packings and monoliths, particularly in demanding applications such as automotive catalytic converters. In principle, the steady-state performance of such reactors can be modeled using Equations (9.1) and (9.3). However, the parameter estimates in Figures 9.1 and 9.2 and Equations (9.6)-(9.7) were developed for random packings, and even the boundary condition of Equation (9.4) may be inappropriate for monoliths or structured packings. Also, at least for automotive catalytic converters. 

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