scholarly journals Low-Cost Recuperative Heat Exchanger for Supercritical Carbon Dioxide Power Systems, Final Scientific/Technical Report

2019 ◽  
Author(s):  
John Kelly
2020 ◽  
pp. 1-34
Author(s):  
Matthew Carlson ◽  
Francisco Alvarez

Abstract A new generation of Concentrating Solar Power (CSP) technologies is under development to provide dispatchable renewable power generation and reduce the levelized cost of electricity (LCOE) to 6 cents/kWh by leveraging heat transfer fluids (HTF) capable of operation at higher temperatures and coupling with higher efficiency power conversion cycles. The U.S. Department of Energy (DOE) has funded three pathways for Generation 3 CSP (Gen3CSP) technology development to leverage solid, liquid, and gaseous HTFs to transfer heat to a supercritical carbon dioxide (sCO2) Brayton cycle. This paper presents the design and off-design capabilities of a 1 MWth sCO2 test system that can provide sCO2 coolant to the primary heat exchangers (PHX) coupling the high-temperature HTFs to the sCO2 working fluid of the power cycle. This system will demonstrate design, performance, lifetime, and operability at a scale relevant to commercial CSP. A dense-phase high pressure canned motor pump is used to supply up to 5.3 kg/s of sCO2 flow to the primary heat exchanger at pressures up to 250 bar and temperatures up to 715 °C with ambient air as the ultimate heat sink. Key component requirements for this system are presented in this paper.


2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Alan Kruizenga ◽  
Hongzhi Li ◽  
Mark Anderson ◽  
Michael Corradini

Competitive cycles must have a minimal initial cost and be inherently efficient. Currently, the supercritical carbon dioxide (S-CO2) Brayton cycle is under consideration for these very reasons. This paper examines one major challenge of the S-CO2 Brayton cycle: the complexity of heat exchanger design due to the vast change in thermophysical properties near a fluid’s critical point. Turbulent heat transfer experiments using carbon dioxide, with Reynolds numbers up to 100 K, were performed at pressures of 7.5–10.1 MPa, at temperatures spanning the pseudocritical temperature. The geometry employed nine semicircular, parallel channels to aide in the understanding of current printed circuit heat exchanger designs. Computational fluid dynamics was performed using FLUENT and compared to the experimental results. Existing correlations were compared, and predicted the data within 20% for pressures of 8.1 MPa and 10.2 MPa. However, near the critical pressure and temperature, heat transfer correlations tended to over predict the heat transfer behavior. It was found that FLUENT gave the best prediction of heat transfer results, provided meshing was at a y+ ∼ 1.


Author(s):  
Alessandro Romei ◽  
Paolo Gaetani ◽  
Andrea Giostri ◽  
Giacomo Persico

Abstract The successful penetration of supercritical carbon dioxide (sCO2) power systems in the energy market largely depends on the achievable turbomachinery performance. The present study illustrates a systematic framework where both the compressor and the turbine are designed via validated (within ±2% pts against experiments) mean-line tools and the related impact on cycle performance estimates is quantitatively and qualitatively assessed. A significant effort is devoted to the analysis of centrifugal compressor performance operating close to the critical point, where sharp thermodynamic property variations may make critical the compression process. The analysis is performed for different compressor sizes and pressure ratios, showing a comparatively small contribution of compressor-intake fluid conditions to the machine efficiency, which may achieve technological competitive values (82 ÷ 85%) for representative full-scale sizes. Two polynomial correlations for both turbomachinery efficiencies are devised as a function of proper similarity parameters accounting for machine sizes and loadings. Such correlations can be easily embedded in power cycle optimizations, which are usually carried out assuming constant-turbomachinery efficiency, thus ignoring the effects of plant size and cycle operating parameters. Efficiency correlations are finally exploited to perform several optimizations of a recompressed sCO2 cycle, by varying multiple cycle parameters (i.e. maximum and minimum temperature, pressure ratio and net power output). The results highlight that the replacement of constant-efficiency assumption with the proposed correlations leads to more accurate performance predictions (i.e. cycle efficiency can differ by more than 4% pts), showing in particular that an optimal pressure ratio exists in the range 2 ÷ 5 for all the investigated configurations.


2020 ◽  
Vol 29 (3) ◽  
pp. 546-575 ◽  
Author(s):  
Zhaozhi Li ◽  
Xuejiao Liu ◽  
Yingjuan Shao ◽  
Wenqi Zhong

2017 ◽  
Author(s):  
Dan Hancu ◽  
◽  
Benjamin Wood ◽  
Sarah Genovese ◽  
Tiffany Westendorf ◽  
...  

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