Metamodels for Economically Optimized Closed Brayton Cycles

Abstract

Closed Brayton Cycles (CBC) can be integrated with many different energy sources, such as heliothermic, biomass, geothermal, etc. However, simplified models for the cycle components are required to optimize the system in its entirety due to all possible cycle configurations like the use of recuperation, intercooling, reheating, etc, together with operating variables such as rate of heat input and its temperature. This work discusses, therefore, the development of a surrogate model for a supercritical CO2 CBC with recuperation, intercooling and reheating. It can indicate the optimal CBC from an economic point of view under varying boundary conditions. The cycle is first optimized for different heat inputs through its operational parameters (mass flow, minimum cycle pressure and cycle pressure ratios) and heat exchangers area. Compressor and expanders costs are obtained as a function of power while heat exchangers cost is obtained as a function of their area and pressure. Each solution is used to train a surrogate model that will act as an approximator for the optimized CBC and predict cost based on heat input.