Abstract

Supercritical carbon dioxide (S-CO2) Brayton cycles (BC) are promising alternatives for power generation. Many variants of S-CO2 BC have already been studied to make this technology economically more viable and efficient. In comparison to other BC and Rankine cycles, S-CO2 BC is less complex and more compact, which may reduce the overall plant size, maintenance, and the cost of operation and installation. In this paper, we consider one of the configurations of S-CO2 BC called the recompression Brayton cycle with partial cooling (RBC-PC) to which some modifications are suggested with an aim to improve the overall cycle’s thermal efficiency. The type of heat source is not considered in this study; thus, any heat source may be considered that is capable of supplying temperature to the S-CO2 in the range from 500 °C to 850 °C, like solar heaters, or nuclear and gas turbine waste heat. The commercial software Aspen HYSYS V9 (Aspen Technology, Inc., Bedford, MA, USA) is used for simulations. RBC-PC serves as a base cycle in this study; thus, the simulation results for RBC-PC are compared with the already published data in the literature. Energy analysis is done for both layouts and an efficiency comparison is made for a range of turbine operating temperatures (from 500 °C to 850 °C). The heat exchanger effectiveness and its influence on both layouts are also discussed.

Highlights

  • Rapid technological advancements and increasing industry all around the world have significantly increased the demand of energy

  • The cycle operates under steady-state conditions [11,16,17]; Energy losses in the pipelines are negligible [11,16,17]; The compression and expansion processes are adiabatic [11,16,17]; The turbine and compressor efficiencies are 93% and 89%, respectively [11,16,17]; The heat exchanger effectiveness is 95% with a minimum pinch point temperature (∆Tmin ) of 5 ◦ C for all heat exchangers [11,16,17]; The cycle maximum pressure is 25 MPa [11,16,17]; The turbine inlet temperature varies from 500 ◦ C to 850 ◦ C; The cycle intermediate pressure is 7.5 MPa; The split ratio (SR) is 0.5

  • We proposed a modified version of a recompression Brayton cycle with partial cooling (RBC-PC)

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Summary

Introduction

Rapid technological advancements and increasing industry all around the world have significantly increased the demand of energy. Back into the limelight in 2004 after the refined version was proposed by Dostal [10] with its They achieved a cycle thermal efficiency of close to 55% under ideal conditions. Different configurations for the S-CO2 came back into the limelight in 2004 after the refined version was proposed by Dostal [10] with its Brayton cycle have been reported in the literature, including the simple cycle, the pre-compression application to next-generation nuclear reactors. Sarkar and Bhattacharyya [14]a performed an exergyHe analysis for the and optimized of heat exchangers are found considerably in comparison those of turbo-machineries They that thegreater differences in specifictoheat capacities at the compressor outlet [14]. Turbinewith inletS-CO temperature range (450 ◦ C to 600 ◦ C)

Brayton cycles has also been
Supercritical
Cycle Configurations
Energy Model
Simulation Environment
Parametric Adjustments
Model Validation
Validation
Cycle Thermal Efficiency
Conclusions

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