scholarly journals Supercritical CO2 Mixtures for Advanced Brayton Power Cycles in Line-Focusing Solar Power Plants

2019 ◽  
Vol 10 (1) ◽  
pp. 55 ◽  
Author(s):  
Robert Valencia-Chapi ◽  
Luis Coco-Enríquez ◽  
Javier Muñoz-Antón
Keyword(s):  
Supercritical Co2 ◽  
Power Plants ◽  
Solar Power ◽  
Plant Performance ◽  
Design Parameters ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Power Cycles ◽  
Solar Power Plants ◽  
Dry Cooling

This work quantifies the impact of using sCO2-mixtures (s-CO2/He, s-CO2/Kr, s-CO2/H2S, s-CO2/CH4, s-CO2/C2H6, s-CO2/C3H8, s-CO2/C4H8, s-CO2/C4H10, s-CO2/C5H10, s-CO2/C5H12 and s-CO2/C6H6) as the working fluid in the supercritical CO2 recompression Brayton cycle coupled with line-focusing solar power plants (with parabolic trough collectors (PTC) or linear Fresnel (LF)). Design parameters assessed are the solar plant performance at the design point, heat exchange dimensions, solar field aperture area, and cost variations in relation with admixtures mole fraction. The adopted methodology for the plant performance calculation is setting a constant heat recuperator total conductance (UAtotal). The main conclusion of this work is that the power cycle thermodynamic efficiency improves by about 3–4%, on a scale comparable to increasing the turbine inlet temperature when the cycle utilizes the mentioned sCO2-mixtures as the working fluid. On one hand, the substances He, Kr, CH4, and C2H6 reduce the critical temperature to approximately 273.15 K; in this scenario, the thermal efficiency is improved from 49% to 53% with pure s-CO2. This solution is very suitable for concentrated solar power plants coupled to s-CO2 Brayton power cycles (CSP-sCO2) with night sky cooling. On the other hand, when adopting an air-cooled heat exchanger (dry-cooling) as the ultimate heat sink, the critical temperatures studied at compressor inlet are from 318.15 K to 333.15 K, for this scenario other substances (C3H8, C4H8, C4H10, C5H10, C5H12 and C6H6) were analyzed. Thermodynamic results confirmed that the Brayton cycle efficiency also increased by about 3–4%. Since the ambient temperature variation plays an important role in solar power plants with dry-cooling systems, a CIT sensitivity analysis was also conducted, which constitutes the first approach to defining the optimum working fluid mixture for a given operating condition.

S-Ethane Brayton Power Conversion Systems for Concentrated Solar Power Plant

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Luis Coco Enríquez ◽  
Javier Muñoz-Antón ◽  
José María Martínez-Val Peñalosa
Keyword(s):  
Power Plants ◽  
Solar Power ◽  
Subcritical Water ◽  
Plant Performance ◽  
Solar Collectors ◽  
Steam Generation ◽  
Concentrated Solar Power ◽  
Power Cycles ◽  
Solar Power Plants ◽  
Recompression Cycle

The objective of this investigation is the comparison between supercritical ethane (s-ethane, C2H6) and supercritical carbon dioxide (s-CO2) Brayton power cycles for line-focusing concentrated solar power plants (CSP). In this study, CSP are analyzed with linear solar collectors (parabolic trough (PTC) or linear Fresnel (LF)), direct molten salt (MS), or direct steam generation (DSG) as heat transfer fluids (HTF), and four supercritical Brayton power cycles configurations: simple Brayton cycle (SB), recompression cycle (RC), partial cooling with recompression cycle (PCRC), and recompression with main compression intercooling cycle (RCMCI). All Brayton power cycles were assessed with two working fluids: s-CO2 and s-ethane. As a main result, we confirmed that s-ethane Brayton power cycles provide better net plant performance than s-CO2 cycles for turbine inlet temperatures (TITs) from 300 °C to 550 °C. As an example, the s-ethane RCMCI plant configuration net efficiency is ∼42.11% for TIT = 400 °C, and with s-CO2 the plant performance is ∼40%. The CSP Brayton power plants were also compared with another state-of-the-art CSP with DSG in linear solar collectors and a subcritical water Rankine power cycle with direct reheating (DRH), and a maximum plant performance between ∼40% and 41% (TIT = 550 °C).

Thermo-Economic Analyses and Comparisons of Two S-CO2-Brayton-Cycle-Based Combined Power Cycles for Concentrated Solar Power Plants

2018 ◽  
Author(s):  
Yuegeng Ma ◽  
Xuwei Zhang ◽  
Ming Liu ◽  
Jiping Liu
Keyword(s):  
Power Plants ◽  
Solar Power ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Concentrated Solar Power ◽  
Power Cycles ◽  
Solar Power Plants ◽  
Cycle Efficiency ◽  
Concentrated Solar Power Plants ◽  
Residual Heat

In order to pursue superior cycle efficiency and lower power generation cost for the CSP plants, two S-CO2–Brayton–cycle–based power cycles with different utilization methods of the residual heat recover of the top S-CO2 Brayton cycle (SCBC) are investigated to seek alternatives to the stand-alone S-CO2 cycle as the power block of concentrated solar power plants. The residual heat released by the top S-CO2 cycle are either utilized to drive a LiBr absorption chiller (AC) for further chilling of the CO2 fluids exiting the precooler before entering the main compressor inlet temperature or recovered by an organic rankine cycle (ORC) for generating electricity. Thermo-economic analysis and optimization are performed for the SCBC–AC and SCBC–ORC, respectively. The results show that the thermal and exergetic efficiencies of the SCBC–AC are comparable with those of the SCBC–ORC in low pressure ratio conditions (PR<2.7) but are apparently lower than SCBC–ORC when PR is over 2.7. The LCOE of the CSP plant integrated with SCBC–AC is more sensitive to the change of PR. The optimal PR to maximum the cycle efficiency or minimize the plant LCOE for the SCBC–ORC is higher than that for the SCBC–AC, while the optimal recuperator effectiveness to minimize the LCOE of CSP plant integrated with SCBC–ORC is lower than that of SCBC–AC. The optimization results show that the thermo-economic performance of the SCBC–AC is comparable to that of the SCBC–ORC. Significant ηex improvement and LCOE reduction can be obtained by both the two combined cycles relative to the stand-alone S-CO2 cycle. The maximal ηex improvements obtained by the SCBC–ORC and SCBC–AC are 6.83% and 4.12%, respectively. The maximal LCOE reduction obtained by the SCBC-ORC and SCBC–AC are 0.70 ȼ / (kW·h) and 0.60 ȼ / (kW·h), respectively.

A Comparison Study for Off-Design Performance Prediction of a Supercritical CO2 Compressor With Similitude Analysis

2019 ◽  
Author(s):  
Yongju Jeong ◽  
Seongmin Son ◽  
Seong kuk Cho ◽  
Seungjoon Baik ◽  
Jeong Ik Lee
Keyword(s):  
Critical Point ◽  
Supercritical Co2 ◽  
Power Plants ◽  
Cycle Performance ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Power Cycle ◽  
Design Performance ◽  
Wide Range ◽  
Phase Fluid

Abstract Most of the power plants operating nowadays mainly have adopted a steam Rankine cycle or a gas Brayton cycle. To devise a better power conversion cycle, various approaches were taken by researchers and one of the examples is an S-CO2 (supercritical CO2) power cycle. Over the past decades, the S-CO2 power cycle was invented and studied. Eventually the cycle was successful for attracting attentions from a wide range of applications. Basically, an S-CO2 power cycle is a variation of a gas Brayton cycle. In contrast to the fact that an ordinary Brayton cycle operates with a gas phase fluid, the S-CO2 power cycle operates with a supercritical phase fluid, where temperatures and pressures of working fluid are above the critical point. Many advantages of S-CO2 power cycle are rooted from its novel characteristics. Particularly, a compressor in an S-CO2 power cycle operates near the critical point, where the compressibility is greatly reduced. Since the S-CO2 power cycle greatly benefits from the reduced compression work, an S-CO2 compressor prediction under off-design condition has a huge impact on overall cycle performance. When off-design operations of a power cycle are considered, the compressor performance needs to be specified. One of the approaches for a compressor off-design performance evaluation is to use the correction methods based on similitude analysis. However, there are several approaches for deriving the equivalent conditions but none of the approaches has been thoroughly examined for S-CO2 conditions based on data. The purpose of this paper is comparing these correction models to identify the best fitted approach, in order to predict a compressor off-design operation performance more accurately from limited amount of information. Each correction method was applied to two sets of data, SCEIL experiment data and 1D turbomachinery code off-design prediction code generated data, and evaluated in this paper.

Modeling Off-Design and Part-Load Performance of Supercritical Carbon Dioxide Power Cycles

2013 ◽  
Author(s):  
John J. Dyreby ◽  
Sanford A. Klein ◽  
Gregory F. Nellis ◽  
Douglas T. Reindl
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Ambient Air ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Heat Rejection ◽  
Power Cycles ◽  
Part Load ◽  
Dry Cooling ◽  
Supercritical Carbon

Continuing efforts to increase the efficiency of utility-scale electricity generation has resulted in considerable interest in Brayton cycles operating with supercritical carbon dioxide (S-CO2). One of the advantages of S-CO2 Brayton cycles, compared to the more traditional steam Rankine cycle, is that equal or greater thermal efficiencies can be realized using significantly smaller turbomachinery. Another advantage is that heat rejection is not limited by the saturation temperature of the working fluid, facilitating dry cooling of the cycle (i.e., the use of ambient air as the sole heat rejection medium). While dry cooling is especially advantageous for power generation in arid climates, the reduction in water consumption at any location is of growing interest due to likely tighter environmental regulations being enacted in the future. Daily and seasonal weather variations coupled with electric load variations means the plant will operate away from its design point the majority of the year. Models capable of predicting the off-design and part-load performance of S-CO2 power cycles are necessary for evaluating cycle configurations and turbomachinery designs. This paper presents a flexible modeling methodology capable of predicting the steady state performance of various S-CO2 cycle configurations for both design and off-design ambient conditions, including part-load plant operation. The models assume supercritical CO2 as the working fluid for both a simple recuperated Brayton cycle and a more complex recompression Brayton cycle.

scholarly journals Dual Loop line-focusing solar power plants with supercritical Brayton power cycles

2017 ◽  
Vol 42 (28) ◽  
pp. 17664-17680 ◽  
Author(s):  
L. Coco-Enríquez ◽  
J. Muñoz-Antón ◽  
J.M. Martínez-Val
Keyword(s):  
Power Plants ◽  
Solar Power ◽  
Power Cycles ◽  
Solar Power Plants

scholarly journals Sistem Kendali Dan Monitoring Dengan Syaraf Tiruan Pada Pembangkit Listrik Tenaga Surya

Petir ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 119-127
Author(s):  
Hengki Sikumbang ◽  
Abdul Haris ◽  
Muhammad Jafar Elly
Keyword(s):  
Power Plants ◽  
Solar Power ◽  
Plant Performance ◽  
Small Scale ◽  
Solar Panels ◽  
High Investment ◽  
Solar Power Plants ◽  
Web Control ◽  
And Control ◽  
Computerized System

The problem with the condition of the Solar Power Plant is still not optimal due to position of the solar cells in generator is still static so that absorption of light is still not even though Hybrid technology is now available but cannot be optimized properly and still cannot be optimized implemented especially in small scale and remote areas. Another problem that needs attention is the continued operation of installed Solar Power Plants (SPPs), considering the installation and maintenance of the plant requires high investment costs because the installation of solar panels requires a large amount of land and costs besides requiring qualified technical personnel to handle problems and monitoring plant conditions are needed quickly and accurately. From the description of the problem, the first step is to identify the technology used in the factory, the second is the need to design a new system to be able to solve important problems in the plant and the third is to build a computerized system that uses the Hybrid Method on the plant used. is a combination of Artificial Intelligence and Data Mining Processes so that it can present accurate data so that it can help and analyze plant performance, monitor and control plants remotely quickly by using Web Control.

Thermodynamic Cycles for a Small Particle Heat Exchange Receiver Used in Concentrating Solar Power Plants

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Kyle Kitzmiller ◽  
Fletcher Miller
Keyword(s):  
Heat Exchange ◽  
Small Particle ◽  
Power Plants ◽  
Solar Power ◽  
Tube Wall ◽  
Brayton Cycle ◽  
Concentrating Solar Power ◽  
Thermodynamic Cycles ◽  
Process Gas ◽  
Solar Power Plants

Gas-cooled solar receivers for concentrating solar power plants are capable of providing high temperature, pressurized gas for electrical power generation via a Brayton cycle. This can be accomplished by expanding hot, pressurized gas directly through a turbine, or through using a heat exchanger to indirectly heat pressurized air. Gas-cooled receivers can be divided into two basic technologies. In tube based solar receivers, thermal energy is transferred to air through convection with the heated tube wall. This limits receiver efficiency since the tube wall needs to be substantially hotter than the gas inside due to the relatively poor gas heat transfer coefficient. In volumetric receivers, solar energy is absorbed within a volume, rather than on a surface. The absorption volume can be filled with ceramic foam, wires, or particles to act as the absorbing medium. In a small particle heat exchange receiver, for example, submicron sized particles absorb solar radiation and transfer this energy as heat to a surrounding fluid. This effectively eliminates any thermal resistance, allowing for higher receiver efficiencies. However, mechanical considerations limit the size of volumetric, pressurized gas-cooled receivers.In order to solve this problem, several thermodynamic cycles have been investigated, each of which is motivated by key physical considerations in volumetric receivers. The cyclic efficiencies are determined by a new MATLAB code based on previous Brayton cycle modeling conducted by Sandia National Laboratories. The modeling accounts for pressure drops and temperature losses in various components, and parameters such as the turbine inlet temperature and pressure ratio are easily modified to run parametric cases.The performance of a gas-cooled solar receiver is largely a function of its ability to provide process gas at a consistent temperature or pressure, regardless of variations in solar flux, which can vary due to cloud transients or apparent sun motion throughout the day. Consistent output can be ensured by combusting fuel within the cycle, effectively making a solar/fossil fuel hybrid system. Several schemes for hybridization with natural gas are considered here, including externally fired concepts and combined receiver/combustor units. Because the efficiency of hybridized cycles is a function of the solar thermal input, the part load behavior of the recuperated cycle is examined. However, off-design models are simplistic in this research, as the goal of the work is an introductory evaluation of different potential cycles.

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