Effect of Dimensionless Number (KN and RE) on Performance Index of Concentric Circular Micro Channel

Overall performance of any type of heat channel is largely depends upon Knudsen number and Reynolds number [1]. In present work the outcome of dimensionless number on heat transfer properties of micro channel heat exchanger [2]are investigated. CFD analysis of counter flowmicro channel was performed for both slip and no slip flow using Fluent as CFD code. Based on results obtain, pressure drop increases with increment in Reynolds number and Knudsen number. The effectiveness reduces with increment in Reynolds number. The comparison of thermal and hydrodynamics performance between slip and no slip flow for heat exchanger is investigated. The effectiveness increases with decreasing values of Reynolds number for counter flow. For higher effectiveness of the micro channel heat exchanger, Reynolds number should be less.

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Design and Evaluation of Copper Metal Foams in Cold Plates

Heat Transfer, Volume 3 ◽

10.1115/imece2006-14897 ◽

2006 ◽

Cited By ~ 1

Author(s):

Donald E. Floyd ◽

Mark J. Topolski ◽

Jeff Darabi

Keyword(s):

Experimental Investigation ◽

Heat Exchanger ◽

Heat Exchangers ◽

Metal Foams ◽

Micro Channel ◽

Cfd Analysis ◽

Copper Metal ◽

Cold Plates ◽

Impinging Flow

This paper present an analytical and experimental investigation of the performance of metal foams in an impinging flow application. Microstructures of the foam as well as the foam-to-solid braze interface are presented. Aditionally, the effects of brazing procedure on the performance of the heat exchanger are investigated and the results are compared to CFD analysis assuming perfect braze joints. Finally, the results are compared to commercially available micro-channel heat exchangers.

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CFD analysis of innovative protracted finned counter flow heat exchanger for diesel engine exhaust waste heat recovery

10.1063/5.0036457 ◽

2021 ◽

Author(s):

Rajesh Ravi ◽

Senthilkumar Pachamuthu ◽

K. V. Shivaprasad ◽

Padmanathan Kasinathan ◽

Shanmuga Sundaram Anandan ◽

...

Keyword(s):

Heat Exchanger ◽

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Cfd Analysis ◽

Counter Flow ◽

Engine Exhaust ◽

Diesel Engine Exhaust ◽

Exhaust Waste Heat ◽

Flow Heat

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Optimization of Micro-Channel Features in a Ceramic Heat Exchanger

ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference, Volume 2 ◽

10.1115/ht2007-32181 ◽

2007 ◽

Author(s):

Merrill A. Wilson ◽

Charles Lewinsohn ◽

James Cutts ◽

Yitung Chen ◽

Valery Ponyavin

Keyword(s):

Heat Exchanger ◽

Micro Channel ◽

Cross Sectional ◽

Flow Paths ◽

Pressure Drops ◽

Microchannel Heat Exchanger ◽

Empirical Performance ◽

Overall Performance ◽

Chemical Cycle ◽

Validation Testing

It has been proposed that compact ceramic heat exchangers can be used for high temperature, corrosive applications. This paper discusses the development and optimization of a microchannel heat exchanger for the decomposition of sulfuric acid as part of the hydrogen producing sulfur iodine thermo-chemical cycle. The optimization process combines thermal-hydraulic and structural modeling (UNLV) with empirical performance and validation testing (Ceramatec, Inc.). Within the designs investigated, the micro-channel features were varied to adjust the cross-sectional profiles and the “tortuosity” of the serpentine flow paths to increase the thermal performance while maintaining low pressure drops and thermo-mechanical stresses within system. The results of these coupled optimization efforts and the associated overall performance improvement will be reported.

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Performance of Supercritical CO2 Power Cycle and Its Turbomachinery with the Printed Circuit Heat Exchanger with Straight and Zigzag Channels

Energies ◽

10.3390/en14010062 ◽

2020 ◽

Vol 14 (1) ◽

pp. 62

Author(s):

Muhammed Saeed ◽

Khaled Alawadi ◽

Sung Chul Kim

Keyword(s):

Reynolds Number ◽

Heat Exchanger ◽

Pressure Drop ◽

Heat Exchangers ◽

Straight Channel ◽

Printed Circuit ◽

Cycle Simulation ◽

Overall Performance ◽

Channel Configuration ◽

The Impact

Since printed circuit heat exchangers (PCHE) are the largest modules of a supercritical carbon dioxide Brayton cycle, they can considerably affect the whole system’s performance and layout. Straight-channel and zigzag-channel printed circuit heat exchangers have frequently been analyzed in the standalone mode and repeatedly proposed for sCO2−BC. However, the impact of heat exchanger designs with straight and zigzag-channel configurations on the performance of the cycle and its components, i.e., the turbine and compressor, has not been studied. In this context, this study evaluates the effect of different heat exchanger designs with various values of effectiveness (ϵ), inlet Reynolds number (Re), and channel configuration (zigzag and straight channel) on the overall performance of the sCO2−BC and its components. For the design and analysis of PCHEs, an in-house PCHE design and analysis code (PCHE-DAC) was developed in the MATLAB environment. The sCO2−BC performance was evaluated utilizing an in-house cycle simulation and analysis code (CSAC) that employs the heat exchanger design code as a subroutine. The results suggest that pressure drop in PCHEs with straight-channel configuration is up to 3.0 times larger than in PCHEs with zigzag-channel configuration. It was found that a higher pressure drop in the PCHEs with straight channels can be attributed to substantially longer channel lengths required for these designs (up to 4.1 times than zigzag-channels) based on the poor heat transfer characteristics associated with these channel geometries. Thus, cycle layouts using PCHEs with a straight-channel configuration impart a much higher load (up to 1.13 times) on the recompression compressor, this in turn, results in a lower pressure ratio across the turbine. Therefore, the overall performance of the sCO2−BC using PCHEs with straight-channel configurations is found to be substantially inferior to that of layouts using PCHEs with zigzag-channel configurations. Finally, optimization results suggest that heat exchanger’s design with inlet Reynolds number and heat exchanger effectiveness ranging from 32 k to 42 k and 0.94>ϵ>0.87, respectively, are optimal for sCO2−BC and present a good bargain between cycle efficiency and its layout size.

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CFD Analysis of Heat Transfer Characteristics of Helical Coil Heat Exchangers

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.787.172 ◽

2015 ◽

Vol 787 ◽

pp. 172-176

Author(s):

R. Maradona ◽

S. Rajkumar

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Nusselt Number ◽

Heat Exchanger ◽

Heat Exchangers ◽

Helical Coil ◽

Cfd Analysis ◽

Compact Size ◽

Coil Diameter ◽

Coil Heat

The applications of heat exchangers are vast and the enhancement of heat transfer and compact size are the key factors for designing the heat exchangers in order to achieve energy savings. In the field of tubular heat exchangers one of the possible ways for reducing the space occupied by the exchanger is by bending tube axis in helical shape. This option is particularly suitable when construction simplicity is needed and the geometry of the place in which the exchanger has to be housed is the cylindrical one. In this paper, an attempt is made to enhance the heat transfer rate without application of any external power. This is achieved by providing the helical tube in tubes. The parameters influencing the nature of flow in a helical coil heat exchanger are the tube geometry namely pitch coil diameter, pitch and tube diameter. CFD analysis is carried out to study these geometry effects on heat transfer and hydraulic characteristics by varying Reynolds number (hot fluid). The CFD results of velocity and temperature distribution in the heat exchanger are used to estimate the Nusselt number and heat transfer coefficient. This helps to arrive at an optimum value of Reynolds number and Nusselt number for the corresponding tube-to-coil diameter ratios.

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Low-Speed DSMC Simulations of Hotwire Anemometers at High-Altitude Conditions

Fluids ◽

10.3390/fluids6010020 ◽

2021 ◽

Vol 6 (1) ◽

pp. 20

Author(s):

Christopher A. Roseman ◽

Brian M. Argrow

Keyword(s):

Reynolds Number ◽

High Altitude ◽

Knudsen Number ◽

Slip Flow ◽

Molecular Flow ◽

Fast Time ◽

Transition Regime ◽

Dsmc Method ◽

Low Speed

Numerical simulations of hotwire anemometers in low-speed, high-altitude conditions have been carried out using the direct simulation Monte Carlo (DSMC) method. Hotwire instruments are commonly used for in-situ turbulence measurements because of their ability to obtain high spatial and temporal resolution data. Fast time responses are achieved by the wires having small diameters (1–5 μm). Hotwire instruments are currently being used to make in-situ measurements of high-altitude turbulence (20–40 km). At these altitudes, hotwires experience Knudsen number values that lie in the transition-regime between slip-flow and free-molecular flow. This article expands the current knowledge of hotwire anemometers by investigating their behavior in the transition-regime. Challenges involved with simulating hotwires at high Knudsen number and low Reynolds number conditions are discussed. The ability of the DSMC method to simulate hotwires from the free-molecular to slip-flow regimes is demonstrated. Dependence of heat transfer on surface accommodation coefficient is explored and discussed. Simulation results of Nusselt number dependence on Reynolds number show good agreement with experimental data. Magnitude discrepancies are attributed to differences between simulation and experimental conditions, while discrepancies in trend are attributed to finite simulation domain size.

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Investigation on Helical Coiled Tube Heat Exchanger for Parallel and Counter Flow Using CFD Analysis

Lecture Notes in Mechanical Engineering - Proceedings of ICDMC 2019 ◽

10.1007/978-981-15-3631-1_56 ◽

2020 ◽

pp. 571-588

Author(s):

P. Saravana Bhavan ◽

J. Selwin Rajadurai

Keyword(s):

Heat Exchanger ◽

Cfd Analysis ◽

Counter Flow ◽

Coiled Tube ◽

Tube Heat Exchanger

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Experimental Research on Resistance and Heat Transfer Properties of Corrugated Plate Air-Cooled Heat Exchanger

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.354-355.153 ◽

2011 ◽

Vol 354-355 ◽

pp. 153-158

Author(s):

Xiao Qing Huang ◽

Xu Zhang ◽

Chun Guang Li

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Heat Exchanger ◽

Experimental Research ◽

Convection Heat Transfer ◽

Hot Water ◽

Water Side ◽

Coefficient Corrélation ◽

Air Cooled Heat Exchanger ◽

Transfer Properties

Experimental research on resistance and heat transfer properties of corrugated plate air-cooled heat exchanger under the condition of variable air and hot water flow rates has been conducted. The pressure drop and convection heat transfer coefficient correlation expressions both the air side and hot water side are acquired, where the Reynolds number for air side ranges from 401 to 6602 and the Reynolds number for water side ranges from 2536 to 19301 are adaptable.

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