Characterization of open-cycle coal-fired MHD generators. Quarterly technical summary report No. 6, October 1--December 31, 1977. [PACKAGE code]
DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. EXECUTIVE SUMMARY This sixth quarterly technical summary report documents the conclusion of the initial phase of Aerodyne Research, Inc. 's research program on the ••Characterization of Open-Cycle, Coal-Fired MHD Generators". This effort has included theoretical modeling of important plasma chemical effects such as: conductivity reductions due to
... ductions due to condensed slag/electron interactions; conductivity and generator efficiency reductions due to the formation of slag-related negative ion species; and the loss of alkali seed due to chemical combination with condensed slag. A summary of the major conclusions in each of these areas is presented in this report, along with references to more detailed presentations. A major output of our modeling effort has been the development of an MHD plasma chemistry core flow model. This model has been formulated into a computer program designated the PACKAGE code (Plasma Analysis, Chemical Kinetics, And Generator Efficiency). The PACKAGE code is designed to calculate the effect of coal rank, ash percentage, ash composition, air preheat temperatures, equivalence ratio, and various generator channel parameters on the overall efficiency of open-cycle, coal-fired MHD generators. A complete description of the PACKAGE code and a preliminary version of the PACKAGE user's manual are included in this report. A laboratory measurements program involving direct, mass spectrometric sampling of the positive and negative ions formed in a one atmosphere coal combustion plasma was also completed during the contract's initial phase. This report summarizes the relative ion concentrations formed in a plasma due to the methane augmented combustion of pulverized Montana Rosebud coal with potassium carbonate seed and preheated air. Positive ions measured include K , KO , Na , Rb , Cs , andCsO^, while negative ions identified include PO~, PO^, BO~, OH~, SH", and probably HCrO" vill 1-2 Results from the modeling efforts have been compared with mass spectrometric measurements of positive and negative ion species sampled from a one-atmosphere pulverized coal burner constructed in our laboratory. This burner was designed to simulate, as closely as possible, temperatures, pressures and seed concentrations expected in prototype, direct-fired MHD channels. Relative concentrations of positive and negative plasma ions due to methane augmented combustion of Montana Rosebud coal with potassium carbonate seed and preheated air have been obtained and compared with PACKAGE code predictions. This experimental data is now being used to modify and validate the code, thus adding confidence to code predictions of full scale generator properties. A final phase of the effort has been the preliminary design of a mass spectrometric Ion and neutral probe which can gather data from MHD channels fired by prototype MHD combustors. Final validation of the negative ion, alkali, and slag models will come from a comparison of model predictions with these prototype measurements. 1-3 TECHNICAL PROGRESS SUMMARY During the sixth quarter of effort, the final three technical tasks of the contract's initial phase were completed, as indicated on the Contract Milestone Chart shown in Figure 2 .1. The final status of each of these three tasks is summarized below. Model Validation and Modification (Task 3) Major emphases during the past quarter have included the effects of solution models on the level of slag derived negative ions, the modeling of seed/slag interactions coupled with the analysis of available seed/slag interaction data, and the documentation of the PACKAGE code. Results of the first two studies are contained in Section 3, along with a brief summary of the slag/electron interaction modeling reported earlier. A preliminary version of the PACKAGE program documentation is included as an appendix to this report. Laboratory Measurements (Task 5) The laboratory measurements task was completed with the successful sampling of positive and negative ion species found in a one atmosphere plasma produced by methane augmented combustion of pulverized Montana Rosebud with preheated air and potassium carbonate seed. In Section 4, the resulting positive and negative ion data are compared with PACKAGE predictions and needed code improvements are discussed. The final apparatus adjustments and modifications necessary to obtain the coal plasma ion data are discussed in Section 4. Full-Scale Probe Desltm A preliminary design for a mass spectrometric probe intended to sample ionic and neutral species from full-scale MHD combustors and flow trains is presented in Section 5. Particular emphasis is placed on the fluid dynamic and ion optic aspects of the proposed sampling system.