Numerical Predictions of Heat Transfer Performance in Dimple/Protrusion Channels with the Working Fluid of Supercritical Carbon Dioxide at High Re

Supercritical Carbon Dioxide (S-CO2) is an efficient and flexible working fluid for power production. Research to interface S-CO2 systems with nuclear, thermal solar, and fossil energy sources are currently underway. To proceed, we must address concerns regarding high temperature compatibility of materials and compatibility between significantly different heat transfer fluids. Dry, pure S-CO2 is thought to be relatively inert [1], while ppm levels of water and oxygen result in formation of a protective chromia layer and iron oxide [2]. Thin oxides are favorable as diffusion barriers, and for their minimal impact on heat transfer. Chromia, however, is soluble in molten salt systems (nitrate, chloride, and fluoride based salts) [3–8]. Fluoride anion based systems required the development of the alloy INOR-8 (Hastelloy N, base nickel, 17%Mo) [9] to ensure that chromium diffusion is minimized, thereby maximizing the life of containment vessels. This paper reviews the thermodynamic and kinetic considerations for promising, industrially available materials for both salt and S-CO2 systems.

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

Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy ◽

10.1115/gt2015-43761 ◽

2015 ◽

Cited By ~ 2

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.

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

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4004252 ◽

2011 ◽

Vol 3 (3) ◽

Cited By ~ 19

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.

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Performance Analysis of Printed Circuit Heat Exchanger for Supercritical Carbon Dioxide

Journal of Heat Transfer ◽

10.1115/1.4035603 ◽

2017 ◽

Vol 139 (6) ◽

Cited By ~ 21

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.

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Effect of Experimental Method on the Heat Transfer Performance of Supercritical Carbon Dioxide in Microchannel

Journal of Heat Transfer ◽

10.1115/1.4036694 ◽

2017 ◽

Vol 139 (11) ◽

Cited By ~ 2

Author(s):

Chien-Yuh Yang ◽

Kun-Chieh Liao

Keyword(s):

Heat Transfer ◽

Carbon Dioxide ◽

Pressure Drop ◽

Supercritical Carbon Dioxide ◽

Critical Point ◽

Test Section ◽

Heat Transfer Performance ◽

Test Results ◽

Test Conditions ◽

Supercritical Carbon

This paper provides an experimental investigation of heat transfer and pressure drop of supercritical carbon dioxide cooling in a microchannel heat exchanger. An extruded flat aluminum tube with 37 parallel channels and each channel of 0.5 mm × 0.5 mm cross section was used as the test section. The temperature drops of supercritical CO2 cooled inside the test section were controlled at 2 °C, 4 °C, and 8 °C separately for each test to investigate the effect of property change on the friction and heat transfer performance at various temperature cooling ranges near the critical point. The test results showed that while the test conditions were away from the critical point, both heat transfer and pressure drop performance agreed very well with those predicted by conventional correlations. However, for the test conditions near the critical point, the difference between those of the test results and the predicted values is very high. Both heat transfer and pressure drop were strongly affected by the ranges of temperature cooling in the test section while they were near the critical conditions. Since there is a drastic peak of the property change near the critical point, if we use the properties integrated but not averaged from inlet to the exit temperatures, we obtain the results that agree well with the values predicted by conventional correlations. The heat transfer and pressure drop performance of supercritical carbon dioxide in microchannels with size near 0.5 mm are indeed similar to these at normal conditions if its properties are appropriately evaluated.

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