On efficient solution of large-scale Newton-Raphson-based flowsheeting problems in limited core

Abstract

A strategy is presented for solving in limited core the very large sparse linear equation systems that arise in the Newton-Raphson approach to large-scale flowsheeting problems. Such systems may be too large to handle in core all at once and thus must be decomposed. The strategy employs a bordered-block-triangular decomposition and solves the system by block elimination. This prevents loss of sparsity in off-diagonal blocks and facilitiates the efficient use of core and mass storage. Results indicate the strategy to be more effective in this regard than strategies based on a bordered-block-diagonal decomposition.