A double-pinch criterion for closed feedwater heaters (FWH) of regenerative Rankine cycles is presented. The FWHs are modeled as counter-current heat exchangers. Thus, two potential pinch positions in the FWH exist: (i) at the exit of the bleed (drain) and (ii) at the onset of condensation. For...

A pressurized oxycoal combustion process is optimized for variable thermal loading (100%–30%). The steam expansion line behavior is accurately represented based on manufacturer data. Simulations with the nominal design and nominal operation are then performed with variable loads to determine...

Simultaneous multi-variable gradient-based optimization is performed on a 300 MWe wet-recycling pressurized oxy-coal combustion process with carbon capture and sequestration. A direct contact separation column is utilized for practical and reliable low-temperature thermal recovery. The models...

Simultaneous multi-variable gradient-based optimization with multi-start is performed on a 300 MWe wet-recycling pressurized oxy-coal combustion process with carbon capture and sequestration. The model accounts for realistic component behavior including heat losses, steam leaks, pressure drops,...

Simultaneous multi-variable gradient-based optimization with multi-start is performed on a 300 MWe wet-recycling pressurized oxy-coal combustion process with carbon capture and sequestration, subject to uncertainty in fuel, ambient conditions, and other input specifications. Two forms of flue...

Hammerstein–Wiener models constitute a significant class of block-structured dynamic models, as they approximate process nonlinearities on the basis of input–output data without requiring identification of a full nonlinear process model. Optimization problems with Hammerstein–Wiener models...

The proof of convergence of adaptive discretization-based algorithms for semi-infinite programs (SIPs) usually relies on compact host sets for the upper- and lower-level variables. This assumption is violated in some applications, and we show that indeed convergence problems can arise when...

The computation of lower bounds via the solution of convex lower bounding problems depicts current state-of-the-art in deterministic global optimization. Typically, the nonlinear convex relaxations are further underestimated through linearizations of the convex underestimators at one or several...

The performance of a regenerative solid TES (thermal energy storage) system with enhancement heat transfer structures is analyzed. Thermal energy is transferred from a hot heat transfer fluid to the storage unit core elements during charge, and from the core elements to the cold heat transfer...