Comparative study of a bottoming SRC and ORC for Joule-Brayton cycle cooling modular HTR exergy losses, fluid-flow machinery main dimensions, and partial loads

摘要

Energy conversion efficiency increase in power plants with high-temperature gas-cooled reactors via implementation of the bottoming cycle was investigated under nominal and minimal thermal load of a high-temperature reactor (HTR). Heat transfer surface area and turbine outlet volumetric flow rate in bottoming cycles was also investigated. Water and two low-boiling point working fluids (ammonia and ethanol) were analyzed. Analyzed thermodynamic cycles consisted of a closed Joule-Brayton cycle with helium as working medium, which was investigated in configurations with heat regeneration, compressor intercoolers, and in a simple design. Organic versus steam Rankine cycles were compared; low-boiling point fluids under supercritical conditions in some configurations provide higher cycle energy efficiency than the gas-steam cycle. Volumetric flow rates in the last turbine stages were reduced against the steam turbine to 38% and 0.8% with ethanol and ammonia, respectively. The steam Rankine cycle configuration provided the smallest heat transfer surface increase compared with the base cycle.