Design and Analysis of a Solar Energy Driven Tri-generation Plant for power, Heating and Refrigeration

A tri-generation plant producing power, heat and refrigeration has been designed and analyzed. Using solar energy as input. The power side of the plant employs supercritical carbon dioxide (sCO2) recompression cycle. The refrigeration side includes an aqueous lithium bromide absorption system. Thermal energy has been extracted from many places in the plant for heating purposes. A detailed thermodynamics model has been developed to determine performance of the plant for many different conditions. Thermal efficiency, energy effectiveness and exergetic efficiency of the system has been calculated for different operating conditions. It turns out that the pressure ratio of the recombination cycle and effectiveness of the energy exchanger for transferring energy from the power side to the refrigeration side play important roles.

Research on Dynamic Modeling of the Supercritical Carbon Dioxide Power Cycle

The supercritical carbon dioxide (SCO2) Brayton cycle, as a substitute for the steam cycle, can be widely used in a variety of power generation scenarios. However, most of the existing SCO2 cycle studies are restricted to basic thermodynamics research, parameter optimizations, system design in different application fields, and even economic analysis. Considering the load variability and control flexibility of the power generation system, the dynamic performance research of the SCO2 cycle is also crucial, but the work done is still limited. Based on the previous studies, Simulink software is used in this paper to develop a dynamic model of the 20 MW-SCO2 recompression cycle, which specifically includes component models that can independently realize physical functions and an overall closed-loop cycle model. A series of comparative calculation are carried out to verify the models and the results are very positive. The SCO2 recompression power system is built with the developed models and the dynamic model runs stably with a maximum error of 0.56%. Finally, the simulation of the dynamic switching conditions of the 20 MW-SCO2 recompression cycle are performed and the analysis results supply instructive suggestions for the system operation and control.

Optimized Performance and Cost Potential for Indirect Supercritical CO2 Coal Fired Power Plants

Indirect-fired supercritical CO2 (sCO2) power cycles are being explored as an attractive alternative to steam Rankine cycles for a variety of heat sources including fossil, concentrated solar power (CSP), nuclear, waste heat etc. Therefore, understanding their performance and cost potential is important for commercialization of the technology. This study presents the techno-economic global optimization results of coal-fired utility scale power plants based on indirect sCO2 power cycles with and without carbon capture and storage (CCS). Four power cycle configurations are considered for optimization – recompression cycle (RC) with and without turbine reheat and partial cooling cycle (PCC) with and without turbine reheat. Several design variables are identified for each power cycle configuration and these design variables are optimized to minimize the levelized cost of electricity (LCOE) for each plant. The optimization design variables included parameters such as turbine inlet temperatures and pressure, sCO2 cooler outlet temperatures, recuperator approach temperatures and pressure drops etc. The optimization is conducted using automated derivative free optimization algorithms available under NETL’s Framework for Optimization and Quantification of Uncertainty and Sensitivity (FOQUS) platform. For sCO2 power plants both with and without CCS, recompression cycle with reheat (RC with reheat) has the highest plant efficiency and lowest LCOE among the considered power cycle configurations. For plants with CCS, the RC with reheat configuration offered 8 percentage points higher plant efficiency (HHV basis) and 14.6% lower LCOE compared to a state-of-the-art (SOA) PC-fired supercritical steam Rankine plant with CCS. For plants without CCS, the RC with reheat configuration offered 4.7 percentage points higher plant efficiency and 7% lower LCOE compared to a SOA PC-fired supercritical steam Rankine plant without CCS.

On the Supercritical Carbon Dioxide Recompression Cycle

Supercritical carbon dioxide Brayton (sCO2) cycle has been studied in recent years and its high efficiency and environmental safety has been investigated. One of the most promising sCO2 design is the Recompression cycle described in the Introduction of the paper. In this paper, an effort has been made to optimize operation of a recompression cycle by performing parametric analyses on pressure ratio, split fraction, and maximum temperature. The effects of varying these parameters on thermal efficiency as well as exergetic efficiency have been determined.

Applications of Supercritical Carbon Dioxide Brayton Cycle for Nuclear Engineering

Supercritical carbon dioxide Brayton cycle is attracting increasing attention in various energy conversion systems due to its high cycle efficiency and high compactness. This chapter performs a review about the application of supercritical carbon dioxide Brayton cycle in nuclear engineering. The different cycle layouts developed from the original direct Brayton cycle are presented, in which the recompression cycle is the most typical layout. The thermodynamic analysis approach is discussed for the direct cycle and recompression cycle. Moreover, the key facilities, including heat transfer, compressor, and turbine, are outlined for the application of Brayton cycle in nuclear engineering.

Selected Issues of the Structures and Parameters of Supercritical CO2 Gas Turbine Cycles

The paper presents a variant analysis of the structures of closed gas turbines using supercritical carbon dioxide (super-CO2) as a working fluid. Several configurations covered in the available literature were collected, commented on and compared. The parameters of the cycles, such as operating temperature and heat supply are noted and commented on. There are three main configurations considered in the available literature: the precompression cycle, partial cooling cycle, and recompression cycle.

Parametrized Analysis and Multi-Objective Optimization of Supercritical CO2 (S-CO2) Power Cycles Coupled with Parabolic Trough Collectors

Supercritical CO2 (S-CO2) Brayton cycles have become an effective way in utilizing solar energy, considering their advantages. The presented research discusses a parametrized analysis and systematic comparison of three S-CO2 power cycles coupled with parabolic trough collectors. The effects of turbine inlet temperature and pressure, compressor inlet temperature, and pressure on specific work, overall efficiency, and cost of core equipment of different S-CO2 Brayton cycles are discussed. Then, the two performance criteria, including specific work and cost of core equipment, are compared, simultaneously, between different S-CO2 cycle layouts after gaining the Pareto sets from multi-objective optimizations using genetic algorithm. The results suggest that the simple recuperation cycle layout shows more excellent performance than the intercooling cycle layout and the recompression cycle layout in terms of cost, while the advantage in specific work of the intercooling cycle layout and the recompression cycle layout is not obvious. This study can be useful in selecting cycle layout using solar energy by the parabolic trough solar collector when there are requirements for the specific work and the cost of core equipment. Moreover, high turbine inlet temperature is recommended for the S-CO2 Brayton cycle using solar energy.