Group, CHETAH program

In summary, we would like to emphasize the two current capabilities of the CHETAH program. The first is the estimation of gas phase thermodynamic data over the range of 25-1200°C, using Benson s second order group contribution method. The second capability of CHETAH is a hazard appraisal. This uses thermodynamic data to... 

Batch reactor, typical, DACSL kinetic and reactor modeling, 94 Benefits, HAZOP study, 37 Benson s second-order group additivity method, CHETAH program, 82 Benzoyl peroxide (BPO), effect of dilution with xylene, CHETAH program, 87... 

Copies of the TNO peroxide test databases have been provided to E27.07 and the new versions of CHETAH are expected to contain an extensive database as well as pattern-recognition techniques for estimating the hazard of new materials. The CHETAH software will continue to rely on bond energy data and group contribution calculations to estimate energy release potential. Hopefully, the new versions will also incorporate natural language expert system-type front ends so that the CHETAH program(s) will see expanded use in both analytical and tutorial modes. Copies of the LEILA (8) dissertation have also been provided to E27.07 as an example of an expert system approach to selection and use of appropriate theories and computational methods for the solution of problems in chemical kinetics. 

Two standard estimation methods for heat of reaction and CART are Chetah 7.2 and NASA CET 89. Chetah Version 7.2 is a computer program capable of predicting both thermochemical properties and certain reactive chemical hazards of pure chemicals, mixtures or reactions. Available from ASTM, Chetah 7.2 uses Benson s method of group additivity to estimate ideal gas heat of formation and heat of decomposition. NASA CET 89 is a computer program that calculates the adiabatic decomposition temperature (maximum attainable temperature in a chemical system) and the equilibrium decomposition products formed at that temperature. It is capable of calculating CART values for any combination of materials, including reactants, products, solvents, etc. Melhem and Shanley (1997) describe the use of CART values in thermal hazard analysis. 

References Benson, S. W, et al., Chem. Rev., 69 (1969) 279 CHETAH Version 8.0 The ASTM Computer Program for Chemical Thermodynamic and Ener Release EoaluaUon (NIST Special Database 16). Classification Group contributions. 

The CHETAH data bank contains data for about 500 group contributions and about 400 chemical compounds. The data stored for the current program is heavily oriented toward organic materials. Data for chemical compounds is stored for 1) common, frequently used molecules, 2) molecules which are too small to be estimated by second order groups, 3) common decomposition products, and 4) molecules which can be used as building blocks to create other molecules. The results for a typical heat of reaction calculation are shown in Table II. 

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