scholarly journals DESIGN OF A 1 MWTH SUPERCRITICAL CARBON DIOXIDE PRIMARY HEAT EXCHANGER TEST SYSTEM

2020 ◽  
pp. 1-34
Author(s):  
Matthew Carlson ◽  
Francisco Alvarez
Keyword(s):  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Supercritical Carbon Dioxide ◽  
Technology Development ◽  
Ambient Air ◽  
Test System ◽  
Department Of Energy ◽  
Working Fluid ◽  
Levelized Cost Of Electricity ◽  
Supercritical Carbon

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.

scholarly journals Design of a 1 MWth Supercritical Carbon Dioxide Primary Heat Exchanger Test System

2020 ◽  
Author(s):  
Matthew Carlson ◽  
Francisco Alvarez
Keyword(s):  
Carbon Dioxide ◽  
Power Generation ◽  
Heat Exchanger ◽  
Supercritical Carbon Dioxide ◽  
Storage System ◽  
Thermal Storage ◽  
Ambient Air ◽  
Test System ◽  
Brayton Cycle ◽  
Supercritical Carbon

Abstract Concentrating Solar Power (CSP) plants have the potential to provide dispatchable renewable power generation to support the baseload need currently supplied primarily by coal and nuclear plants and peaking power capability to reduce the use of natural gas for load following. However, these plants have had difficulty achieving widespread use due to the low cost of combined photovoltaic and battery systems capable of providing similar services to the electricity grid. A new generation of CSP technologies must be developed to 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. Three promising pathways for Generation 3 CSP (Gen3CSP) technology development have been funded by the U.S. Department of Energy (DOE) leveraging solid, liquid, and gaseous HTFs to transfer heat to a supercritical carbon dioxide (sCO2) Brayton cycle. The primary heat exchangers (PHX) necessary to couple these high-temperature HTFs to sCO2 are an essential new technology that must be demonstrated at a scale relevant to commercial CSP to validate design expectations for performance, lifetime, and operability. The demonstration of these PHXs need a reliable 1 MWth-scale sCO2 test system that can provide sCO2 coolant to the PHX in a compact package suitable for installation near any Gen3CSP thermal storage system. This paper outlines the final design of such a system including the expected operating range and off-design capabilities. The system uses a dense-phase high pressure canned motor pump as the sCO2 circulator and ambient air as the ultimate heat sink operating at pressures up to 250 bar and temperatures up to 715 °C with capability to supply up to 5.3 kg/s of sCO2 flow to the primary heat exchanger. Key component requirements for this system have been frozen and procurement is underway. The expected completion date for heated acceptance testing of this system is September of 2020. This system is also capable of being upgraded through the addition of a turbo-compressor and turbo-generator to operate as a complete sCO2 Brayton cycle with power generation in order to demonstrate an integrated solar to sCO2 power pilot plant and understand transient interactions between the thermal storage system, sCO2 turbomachinery, and ambient air temperature. In addition, this upgrade would provide experience with plant operating considerations including balancing charging the thermal storage system with generating and dispatching power to the electrical grid. A roadmap for this upgrade will be discussed including limitations and requirements for the necessary turbomachinery.

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.

Design and Real Fluid Modelling of Micro-Channel Recuperators for a Nominal 100 MW Class Recuperated Recompression Brayton Cycle Using Supercritical Carbon Dioxide

2015 ◽  
Author(s):  
Joshua Schmitt ◽  
David Amos ◽  
Jayanta Kapat
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Supercritical Carbon Dioxide ◽  
Critical Point ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Micro Channel ◽  
One Dimensional ◽  
Supercritical Carbon

The goal of this study is to design and assess the effectiveness of a micro-channel recuperator using supercritical carbon dioxide as a working fluid. A one-dimensional thermal analysis is performed for a micro-channel recuperator suitable for a Brayton cycle with a nominal 100 MW class turbomachine. The impact of supercritical carbon dioxide properties near the critical point on the thermal performance of the recuperator is studied in detail. The cycle parameters are first obtained from an overall cycle analysis. Two adjacent flow passages with square cross-section in counter-flow configuration are considered for this analysis along with appropriate symmetry. The high pressure of SCO2 is also addressed and the structural stresses on the micro-channel walls are analyzed. Only the axial temperature variations in the hot stream and the cold stream are considered in the one-dimensional analysis. Each channel is discretized in the axial direction. Axial conduction through the wall is included in the energy balance. Of particular interest in this analysis is the variation of transport properties of the CO2 working fluid as thermodynamic conditions approach the critical point. These property variations are provided to the computer code through the REFPROP database. Over the length of the heat exchanger local changes in Reynolds number, Nusselt number, and heat transfer coefficient are charted. From the results of the heat transfer calculations, the log mean temperature difference and heat exchange effectiveness of the heat exchanger is calculated. Using the code to produce multiple results, the optimum heat exchanger design is found. Recommendations on the manufacturing method of a micro-channel recuperator are made.

Heat Transfer of Supercritical Carbon Dioxide in Printed Circuit Heat Exchanger Geometries

2011 ◽  
Vol 3 (3) ◽  
Author(s):  
Alan Kruizenga ◽  
Mark Anderson ◽  
Roma Fatima ◽  
Michael Corradini ◽  
Aaron Towne ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Supercritical Carbon Dioxide ◽  
Test Section ◽  
Heat Exchangers ◽  
Working Fluid ◽  
Printed Circuit ◽  
Supercritical Carbon

The increasing importance of improving efficiency and reducing capital costs has led to significant work studying advanced Brayton cycles for high temperature energy conversion. Using compact, highly efficient, diffusion-bonded heat exchangers for the recuperators has been a noteworthy improvement in the design of advanced carbon dioxide Brayton cycles. These heat exchangers will operate near the pseudocritical point of carbon dioxide, making use of the drastic variation of the thermophysical properties. This paper focuses on the experimental measurements of heat transfer under cooling conditions, as well as pressure drop characteristics within a prototypic printed circuit heat exchanger. Studies utilize type-316 stainless steel, nine channel, semi-circular test section, and supercritical carbon dioxide serves as the working fluid throughout all experiments. The test section channels have a hydraulic diameter of 1.16 mm and a length of 0.5 m. The mini-channels are fabricated using current chemical etching technology, emulating techniques used in current diffusion-bonded printed circuit heat exchanger manufacturing. Local heat transfer values were determined using measured wall temperatures and heat fluxes over a large set of experimental parameters that varied system pressure, inlet temperature, and mass flux. Experimentally determined heat transfer coefficients and pressure drop data are compared to correlations and earlier data available in literature. Modeling predictions using the computational fluid dynamics (CFD) package FLUENT are included to supplement experimental data. All nine channels were modeled using known inlet conditions and measured wall temperatures as boundary conditions. The CFD results show excellent agreement in total heat removal for the near pseudocritical region, as well as regions where carbon dioxide is a high or low density fluid.

Performance Analysis of Printed Circuit Heat Exchanger for Supercritical Carbon Dioxide

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Jiangfeng Guo ◽  
Xiulan Huai
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Supercritical Carbon Dioxide ◽  
Entropy Generation ◽  
Thermal Performance ◽  
Transfer Entropy ◽  
Working Fluid ◽  
Printed Circuit ◽  
Supercritical Carbon

A printed circuit heat exchanger (PCHE) was selected as the recuperator of supercritical carbon dioxide (S-CO2) Brayton cycle, and the segmental design method was employed to accommodate the rapid variations of properties of S-CO2. The local heat capacity rate ratio has crucial influences on the local thermal performance of PCHE, while having small influences on the frictional entropy generation. The heat transfer entropy generation is far larger than the frictional entropy generation, and the total entropy generation mainly depends on the heat transfer entropy generation. The axial conduction worsens the thermal performance of PCHE, which becomes more and more obvious with the increase of the thickness and thermal conductivity of plate. The evaluation criteria, material, and size of plate have to be selected carefully in the design of PCHE. The present work may provide a practical guidance on the design and optimization of PCHE when S-CO2 is employed as working fluid.

Lead-to-CO2 Heat Exchangers for Coupling of the STAR-LM LFR to a Supercritical Carbon Dioxide Brayton Cycle Power Converter

2004 ◽  
Author(s):  
Anton V. Moisseytsev ◽  
James J. Sienicki ◽  
David C. Wade
Keyword(s):  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Supercritical Carbon Dioxide ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Natural Circulation ◽  
Power Converter ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Supercritical Carbon

Recent development of the Secure Transportable Autonomous Reactor-Liquid Metal (STAR-LM) lead-cooled natural circulation fast reactor (LFR) has been directed at coupling to an advanced power conversion system that utilizes a gas turbine Brayton cycle with supercritical carbon dioxide (S-CO2) as the working fluid. A key ingredient in achieving a coupled plant having a high efficiency are the modular lead-to-CO2 heat exchangers that must fit within the available volume inside the reactor vessel and must heat the S-CO2 to a high temperature. Thermal hydraulic performance and feasibility of seven different heat exchanger concepts has been investigated with respect to the achievement of a suitably high Brayton cycle efficiency for the coupled LFR-S-CO2 plant. The relative merits of the different heat exchanger configurations are revealed by the analysis which provides a basis to select the most promising concepts for further development.

Development of a Solar Receiver Based on Compact Heat Exchanger Technology for Supercritical Carbon Dioxide Power Cycles

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Saeb M. Besarati ◽  
D. Yogi Goswami ◽  
Elias K. Stefanakos
Keyword(s):  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Supercritical Carbon Dioxide ◽  
Mechanical Strength ◽  
Pressure Vessels ◽  
Maximum Temperature ◽  
Working Fluid ◽  
Compact Heat Exchanger ◽  
Operating Pressure ◽  
Supercritical Carbon

Supercritical carbon dioxide (s-CO2) can be used both as a heat transfer and working fluid in solar power tower plants. The main concern in the design of a direct s-CO2 receiver is the high operating pressures, i.e., close to 20 MPa. At such high pressures, conventional receivers do not exhibit the necessary mechanical strength or thermal performance. In this paper, a receiver based on compact heat exchanger technology is developed. The receiver consists of a group of plates with square-shaped channels which are diffusion bonded together to tolerate the high operating pressure. A computational model is developed and validated against data in the literature. Inconel 625 is used as the base material because of its superior resistance against corrosion in the presence of s-CO2. The receiver heats s-CO2 with mass flow rate of 1 kg/s from 530 °C to 700 °C under a solar flux density of 500 kW/m2. The influence of different parameters on the performance of the receiver is evaluated by a parametric analysis. Subsequently, a multi-objective optimization is performed to determine the optimal geometry of the heat exchanger considering the tradeoff between objective functions, such as unit thermal resistance and pressure drop. The design variables are hydraulic diameter, number of layers, and distance between the channels. The mechanical strength of the system is the constraint to the problem, which is evaluated using an ASME code for the pressure vessels. Finally, the temperature profiles inside the channels and the surface of the receiver are presented. It is shown that the fluid reaches the desired temperature while the maximum temperature of the surface remains well below the material limit.

Supercritical Carbon Dioxide Heat Transfer in Horizontal Semicircular Channels

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Alan Kruizenga ◽  
Hongzhi Li ◽  
Mark Anderson ◽  
Michael Corradini
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Supercritical Carbon Dioxide ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Brayton Cycle ◽  
Heat Exchanger Design ◽  
Transfer Behavior ◽  
Supercritical Carbon

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.

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