scholarly journals Modeling and experimental results for condensing supercritical CO2 power cycles.

2011 ◽  
Author(s):  
Steven Alan Wright ◽  
Thomas M. Conboy ◽  
Ross F. Radel ◽  
Gary Eugene Rochau
Keyword(s):  
Supercritical Co2 ◽  
Experimental Results ◽  
Power Cycles

Design of an Annular-Radial Diffuser for Operation With a Supercritical CO2 Radial Inflow Turbine

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Joshua A. Keep ◽  
Ingo H. J. Jahn
Keyword(s):  
Supercritical Co2 ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Geometric Feature ◽  
Small Scale ◽  
Rear Side ◽  
Power Cycles ◽  
Reynolds Averaged Navier Stokes ◽  
Inlet Conditions ◽  
Conventional Manner

Radial inflow turbines are a relevant architecture for energy extraction from supercritical CO2 power cycles for scales less than 10 MW. To ensure stage and overall cycle efficiency, it is desirable to recover exhaust energy from the turbine stage through the inclusion of a suitable diffuser in the turbine exhaust stream. In supercritical CO2 Brayton cycles, the high turbine inlet pressure can lead to sealing challenges at small scale if the rotor is supported from the rotor rear side in the conventional manner. An alternative is a layout where the rotor exit faces the bearing system. While such a layout is attractive for the sealing system, it limits the axial space claim of the diffuser. Designs of a combined annular-radial diffuser are considered as a means to meet the aforementioned packaging challenges of this rotor layout. Diffuser performance is assessed numerically with the use of Reynolds-averaged Navier--Stokes (RANS) and unsteady Reynolds-averaged Navier--Stokes (URANS) calculations. To appropriately account for cross coupling with the stage, a single blade passage of the entire stage is modeled. Assessment of diffuser inlet conditions, and off-design performance analysis, reveals that the investigated diffuser designs are performance robust to high swirl, high inlet blockage, and highly nonuniform mass flux distribution. Diffuser component performance is dominated by the annular-radial bend. The incorporation of a constant sectional area bend is the key geometric feature in rendering the highly nonuniform turbine exit flow (dominated by tip clearance flows at the shroud) more uniform.

scholarly journals Recuperated versus single-recuperator re-compressed supercritical CO2 Brayton power cycles for DEMO fusion reactor based on dual coolant lithium lead blanket

Energy ◽  
2017 ◽  
Vol 140 ◽  
pp. 307-317 ◽  
Author(s):  
José Ignacio Linares ◽  
Alexis Cantizano ◽  
Eva Arenas ◽  
Beatriz Yolanda Moratilla ◽  
Víctor Martín-Palacios ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Fusion Reactor ◽  
Power Cycles

Analysis of supercritical CO2 Brayton power cycles in nuclear and fusion energy

2019 ◽  
Vol 146 ◽  
pp. 1520-1523 ◽  
Author(s):  
Jan Syblik ◽  
Ladislav Vesely ◽  
Slavomir Entler ◽  
Jan Stepanek ◽  
Vaclav Dostal
Keyword(s):  
Supercritical Co2 ◽  
Fusion Energy ◽  
Power Cycles

scholarly journals Laboratory Study on Changes in the Pore Structures and Gas Desorption Properties of Intact and Tectonic Coals after Supercritical CO2 Treatment: Implications for Coalbed Methane Recovery

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3419 ◽  
Author(s):  
Erlei Su ◽  
Yunpei Liang ◽  
Lei Li ◽  
Quanle Zou ◽  
Fanfan Niu
Keyword(s):  
Pore Structure ◽  
Coalbed Methane ◽  
Supercritical Co2 ◽  
Total Pore Volume ◽  
Experimental Results ◽  
Methane Recovery ◽  
Enhanced Coalbed Methane Recovery ◽  
Gas Desorption ◽  
Pore Structures ◽  
Tectonic Coal

Tectonic coals in coal seams may affect the process of enhanced coalbed methane recovery with CO2 sequestration (CO2-ECBM). The main objective of this study was to investigate the differences between supercritical CO2 (ScCO2) and intact and tectonic coals to determine how the ScCO2 changes the coal’s properties. More specifically, the changes in the tectonic coal’s pore structures and its gas desorption behavior were of particular interest. In this work, mercury intrusion porosimetry, N2 (77 K) adsorption, and methane desorption experiments were used to identify the difference in pore structures and gas desorption properties between and intact and tectonic coals after ScCO2 treatment. The experimental results indicate that the total pore volume, specific surface area, and pore connectivity of tectonic coal increased more than intact coal after ScCO2 treatment, indicating that ScCO2 had the greatest influence on the pore structure of the tectonic coal. Additionally, ScCO2 treatment enhanced the diffusivity of tectonic coal more than that of intact coal. This verified the pore structure experimental results. A simplified illustration of the methane migration before and after ScCO2 treatment was proposed to analyze the influence of ScCO2 on the tectonic coal reservoir’s CBM. Hence, the results of this study may provide new insights into CO2-ECBM in tectonic coal reservoirs.

Turbomachinery for Supercritical CO2 Power Cycles

2012 ◽  
Author(s):  
Robert Fuller ◽  
Jason Preuss ◽  
Jeff Noall
Keyword(s):  
Coal Combustion ◽  
Supercritical Co2 ◽  
Waste Heat ◽  
Heat Sources ◽  
Clean Coal ◽  
Power Cycles ◽  
Different Types ◽  
Type Size ◽  
Turbo Machinery ◽  
Machinery Design

Supercritical CO2 (S-CO2) power cycles offer high plant efficiencies and beneficial economics for variety of heat sources. Nuclear, solar, waste heat, energy storage, and clean coal combustion are some of the applications under consideration for S-CO2 power production. Different types of cycles, topping and bottoming, have been conceptualized based on the heat source. These cycles have the possibility of being economically beneficial and competitive against incumbent steam cycles, primarily due to reduced material costs. Often the turbo-machinery capabilities are overlooked during the cycle design process, or are not well understood. A method and guideline for turbo machinery selection is offered. Several examples are offered to give the S-CO2 cycle designer to judge the compatibility of the turbo-machinery with the overall system including type, size, and efficiency. The guideline includes turbo machinery design limitations. Understanding the turbo machinery implications relative to cycle design will allow the system designer to optimize the plant for efficiency and positive economic outcome.

Supercritical CO2 Brayton power cycles for DEMO fusion reactor based on Helium Cooled Lithium Lead blanket

2015 ◽  
Vol 76 ◽  
pp. 123-133 ◽  
Author(s):  
José Ignacio Linares ◽  
Luis Enrique Herranz ◽  
Iván Fernández ◽  
Alexis Cantizano ◽  
Beatriz Yolanda Moratilla
Keyword(s):  
Supercritical Co2 ◽  
Fusion Reactor ◽  
Power Cycles

scholarly journals Corrosion and Erosion Behavior in Supercritical CO2 Power Cycles

2014 ◽  
Author(s):  
Darryn Fleming ◽  
Alan Kruizenga ◽  
James Pasch ◽  
Tom Conboy ◽  
Matt Carlson
Keyword(s):  
Carbon Dioxide ◽  
Stainless Steel ◽  
Intergranular Corrosion ◽  
Supercritical Co2 ◽  
Power Production ◽  
Operating Conditions ◽  
Working Fluid ◽  
Power Cycles ◽  
Power Cycle ◽  
Potential Issue

Supercritical Carbon Dioxide (S-CO2) is emerging as a potential working fluid in power-production Brayton cycles. As a result, concerns have been raised regarding fluid purity within the power cycle loops. Additionally, investigations into the longevity of the S-CO2 power cycle materials are being conducted to quantify the advantages of using S-CO2 versus other fluids, since S-CO2 promises substantially higher efficiencies. One potential issue with S-CO2 systems is intergranular corrosion [1]. At this time, Sandia National Laboratories (SNL) is establishing a materials baseline through the analysis of 1) “as received” stainless steel piping, and 2) piping exposed to S-CO2 under typical operating conditions with SNL’s Brayton systems. Results from ongoing investigations are presented. A second issue that SNL has discovered involves substantial erosion in the turbine blade and inlet nozzle. It is believed that this is caused by small particulates that originate from different materials around the loop that are entrained by the S-CO2 to the nozzle, where they impact the inlet nozzle vanes, causing erosion. We believe that, in some way, this is linked to the purity of the S-CO2, the corrosion contaminants, and the metal particulates that are present in the loop and its components.

Heterogeneity-aware Multicore Synchronization for Intermittent Systems

2021 ◽  
Vol 20 (5s) ◽  
pp. 1-22
Author(s):  
Wei-Ming Chen ◽  
Tei-Wei Kuo ◽  
Pi-Cheng Hsiu
Keyword(s):  
Energy Harvesting ◽  
Memory Access ◽  
Experimental Results ◽  
Data Consistency ◽  
Adaptive Synchronization ◽  
Power Cycles ◽  
Cpu Time ◽  
Multiple Cores ◽  
Non Volatile Memory ◽  
Memory Accesses

Intermittent systems enable batteryless devices to operate through energy harvesting by leveraging the complementary characteristics of volatile (VM) and non-volatile memory (NVM). Unfortunately, alternate and frequent accesses to heterogeneous memories for accumulative execution across power cycles can significantly hinder computation progress. The progress impediment is mainly due to more CPU time being wasted for slow NVM accesses than for fast VM accesses. This paper explores how to leverage heterogeneous cores to mitigate the progress impediment caused by heterogeneous memories. In particular, a delegable and adaptive synchronization protocol is proposed to allow memory accesses to be delegated between cores and to dynamically adapt to diverse memory access latency. Moreover, our design guarantees task serializability across multiple cores and maintains data consistency despite frequent power failures. We integrated our design into FreeRTOS running on a Cypress device featuring heterogeneous dual cores and hybrid memories. Experimental results show that, compared to recent approaches that assume single-core intermittent systems, our design can improve computation progress at least 1.8x and even up to 33.9x by leveraging core heterogeneity.

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