Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

# Supercritical CO2 Binary Mixtures for Recompression Brayton s-CO2 Power Cycles Coupled to Solar Thermal Energy Plants

Version 1 : Received: 31 March 2021 / Approved: 2 April 2021 / Online: 2 April 2021 (13:54:40 CEST)

A peer-reviewed article of this Preprint also exists.

Tafur-Escanta, P.; Valencia-Chapi, R.; López-Paniagua, I.; Coco-Enríquez, L.; Muñoz-Antón, J. Supercritical CO2 Binary Mixtures for Recompression Brayton sCO2 Power Cycles Coupled to Solar Thermal Energy Plants. Energies 2021, 14, 4050. Tafur-Escanta, P.; Valencia-Chapi, R.; López-Paniagua, I.; Coco-Enríquez, L.; Muñoz-Antón, J. Supercritical CO2 Binary Mixtures for Recompression Brayton sCO2 Power Cycles Coupled to Solar Thermal Energy Plants. Energies 2021, 14, 4050.

Journal reference: Energies 2021, 14, 4050
DOI: 10.3390/en14134050

## Abstract

In this work, an evaluation and quantification of the impact of using mixtures based on Supercritical Carbon Dioxide "s-CO2" (s-CO2/COS, s-CO2/H2S, s-CO2/NH3, s-CO2/SO2) are made as a working fluid in simple and complex recompression Brayton s-CO2 power cycles configurations that have pressure drops in their components. These cycles are coupled to a solar thermal plant with parabolic-trough collector (PTC) technology. The methodology used in the calculation performance is to establish values of the heat recuperator total conductance (UAtotal) between 5 and 25 MW/K. The main conclusion of this work is that the cycle's efficiency has improved due to s-CO2 mixtures as working fluid; this is significant compared to that obtained using the standard fluid (pure s-CO2). Furthermore, a techno-economic analysis is carried out that compares each configuration's costs using pure s-CO2 and a mixture of s-CO2/COS with a molar fraction (70/30) respectively as working fluid where relevant results are obtained. These results show that the best configuration in terms of thermal efficiency and cost is the RCC-RH for pure sCO2 with values ​​of 41.25% and 2811 $/kWe, while for the mixture sCO2/COS, the RCC-2RH configuration with values ​​of 45, 05% and 2621$/kWe is optimal. Using the mixture costs 6.75% less than if it is used the standard fluid (s-CO2).

## Keywords

recompression Brayton cycle; supercritical carbon dioxide; fluid mixture; solar thermal plant.

## Subject

ENGINEERING, Automotive Engineering

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