History, Advances, and Challenges in Liquid Flow and Flow Boiling Heat Transfer in Microchannels: A Critical Review

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Liquid Flow ◽  
Heat Exchangers ◽  
Single Phase ◽  
Heat Dissipation ◽  
Flow Boiling ◽  
Thermal Control ◽  
Future Research ◽  
Practical Implementation ◽  
High Heat Flux

As the scale of devices becomes small, thermal control and heat dissipation from these devices can be effectively accomplished through the implementation of microchannel passages. The small passages provide a high surface area to volume ratio that enables higher heat transfer rates. High performance microchannel heat exchangers are also attractive in applications where space and/or weight constraints dictate the size of a heat exchanger or where performance enhancement is desired. This survey article provides a historical perspective of the progress made in understanding the underlying mechanisms in single-phase liquid flow and two-phase flow boiling processes and their use in high heat flux removal applications. Future research directions for (i) further enhancing the single-phase heat transfer performance and (ii) enabling practical implementation of flow boiling in microchannel heat exchangers are outlined.

History, Advances, and Challenges in Liquid Flow and Flow Boiling Heat Transfer in Microchannels: A Critical Review

2010 ◽  
Author(s):  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Liquid Flow ◽  
Heat Exchangers ◽  
Single Phase ◽  
Heat Dissipation ◽  
Flow Boiling ◽  
Thermal Control ◽  
Future Research ◽  
Practical Implementation ◽  
High Heat Flux

As the scale of devices becomes small, thermal control and heat dissipation from these devices can be effectively accomplished through the implementation of microchannel passages. The small passages provide a high surface area to volume ratio that enables higher heat transfer rates. High performance microchannel heat exchangers are also attractive in applications where space and/or weight constraints dictate the size of a heat exchanger or where performance enhancement is desired. This survey article provides a historical perspective of the progress made in understanding the underlying mechanisms in single-phase liquid flow and two-phase flow boiling processes and their use in high heat flux removal applications. Future research directions for (i) further enhancing the single-phase heat transfer performance, and (ii) enabling practical implementation of flow boiling in microchannel heat exchangers, are outlined.

Boiling Flow Interaction Between Two Parallel Microchannels

2006 ◽  
Author(s):  
Roger D. Flynn ◽  
David W. Fogg ◽  
Jae-Mo Koo ◽  
Ching-Hsiang Cheng ◽  
Kenneth E. Goodson
Keyword(s):  
Heat Transfer ◽  
Liquid Flow ◽  
Heat Exchangers ◽  
Single Channel ◽  
Flow Boiling ◽  
Parallel Channel ◽  
Flow Interaction ◽  
Boiling Flow ◽  
Parallel Microchannels ◽  
Channel Configuration

Microchannel heat exchangers predominately use a parallel channel configuration to maximize heat transfer with minimal pump demand. Previous work optimized bulk performance of liquid flow heat exchangers but noted that upon boiling, flow redistributed among parallel channels, and they ultimately found that this instability caused an uncontrollable operating condition. This work predicts and measures fully coupled boiling flow interaction in a simplified two microchannel system. A series of silicon microfabricated devices enable piecewise study of the coupled fluidic and heat transfer interactions, first uniting the fluid inlets of thermally isolated channels, then connecting neighboring channel walls to allow heat transfer between channels. Multiple combinations of boiling and liquid flow, each satisfying system boundary conditions, are identified using flow demand curves assembled from single channel data. Each unique flow condition is experimentally demonstrated and found to be heavily dependent on the prior state of the channels. Connecting channel walls, thermally, is shown to lessen the number of allowed solutions and increase instability in the two channel system, allowing distinction between purely fluidic instabilities and fluidic instabilities coupled to heat transfer between channels. This work in describing interaction between two channels is a necessary step as work continues toward characterizing flow boiling in more complex parallel channel heat sinks.

Numerical Simulation of Bubble Growth During Nanofluid Flow Boiling in a Microchannel

2014 ◽  
Author(s):  
Arman Khalighi ◽  
Matthew Blomquist ◽  
Abhijit Mukherjee
Keyword(s):  
Heat Transfer ◽  
Physical Properties ◽  
Heat Dissipation ◽  
Flow Boiling ◽  
Contact Angles ◽  
Electronic Systems ◽  
Simulation Based ◽  
Fluid Media ◽  
Thermo Physical Properties ◽  
Current Heat

In recent years, heat dissipation in micro-electronic systems has become a significant design limitation for many component manufactures. As electronic devices become smaller, the amount of heat generation per unit area increases significantly. Current heat dissipation systems have implemented forced convection with both air and fluid media. However, nanofluids may present an advantageous and ideal cooling solution. In the present study, a model has been developed to estimate the enhancement of the heat transfer when nanoparticles are added to a base fluid, in a single microchannel. The model assumes a homogeneous nanofluid mixture, with thermo-physical properties based on previous experimental and simulation based data. The effect of nanofluid concentration on the dynamics of the bubble has been simulated. The results show the change in bubble contact angles due to deposition of the nanoparticles has more effect on the wall heat transfer compared to the effect of thermo-physical properties change by using nanofluid.

Study on onset of nucleate boiling with screw tube for fusion reactor application

2021 ◽  
Author(s):  
Ji Hwan Lim ◽  
Minkyu Park
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
High Heat ◽  
Transfer Mechanism ◽  
High Heat Flux ◽  
Heat Transfer Mechanism ◽  
System Parameters ◽  
Smooth Tubes

Abstract The onset of nucleate boiling (ONB) is the point at which the heat transfer mechanism in fluids changes and is one of the thermo-hydraulic factors that must be considered when establishing a cooling system operation strategy. Because the high heat flux of several MW/m2, which is loaded within a tokamak, is applied under a one-side heating condition, it is necessary to determine a correlative relation that can predict ONB under special heating conditions. In this study, the ONB of a one-side-heated screw tube was experimentally analyzed via a subcooled flow boiling experiment. The helical nut structure of the screw tube flow path wall allows for improved heat transfer performance relative to smooth tubes, providing a screw tube with a 53.98% higher ONB than a smooth tube. The effects of the system parameters on the ONB heat flux were analyzed based on the changes in the heat transfer mechanism, with the results indicating that the flow rate and degree of subcooling are proportional to the ONB heat flux because increasing these factors improves the forced convection heat transfer and increases the condensation rate, respectively. However, it was observed that the liquid surface tension and latent heat decrease as the pressure increases, leading to a decrease in the ONB heat flux. An evaluation of the predictive performance of existing ONB correlations revealed that most have high error rates because they were developed based on ONB experiments on micro-channels or smooth tubes and not under one-side high heat load conditions. To address this, we used dimensional analysis based on Python code to develop new ONB correlations that reflect the influence of system parameters.

Heat Transfer Enhancement in Compact Phase Change Microchannel Heat Exchangers for High Flux Laser Diodes

2018 ◽  
Author(s):  
Jensen Hoke ◽  
Todd Bandhauer ◽  
Jack Kotovsky ◽  
Julie Hamilton ◽  
Paul Fontejon
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Phase Change ◽  
Flow Boiling ◽  
Laser Diodes ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Maximum Heat ◽  
Average Maximum

Liquid-vapor phase change heat transfer in microchannels offers a number of significant advantages for thermal management of high heat flux laser diodes, including reduced flow rates and near constant temperature heat rejection. Modern laser diode bars can produce waste heat loads >1 kW cm−2, and prior studies show that microchannel flow boiling heat transfer at these heat fluxes is possible in very compact heat exchanger geometries. This paper describes further performance improvements through area enhancement of microchannels using a pyramid etching scheme that increases heat transfer area by ∼40% over straight walled channels, which works to promote heat spreading and suppress dry-out phenomenon when exposed to high heat fluxes. The device is constructed from a reactive ion etched silicon wafer bonded to borosilicate to allow flow visualization. The silicon layer is etched to contain an inlet and outlet manifold and a plurality of 40μm wide, 200μm deep, 2mm long channels separated by 40μm wide fins. 15μm wide 150μm long restrictions are placed at the inlet of each channel to promote uniform flow rate in each channel as well as flow stability in each channel. In the area enhanced parts either a 3μm or 6μm sawtooth pattern was etched vertically into the walls, which were also scalloped along the flow path with the a 3μm periodicity. The experimental results showed that the 6μm area-enhanced device increased the average maximum heat flux at the heater to 1.26 kW cm2 using R134a, which compares favorably to a maximum of 0.95 kw cm2 dissipated by the plain walled test section. The 3μm area enhanced test sections, which dissipated a maximum of 1.02 kW cm2 showed only a modest increase in performance over the plain walled test sections. Both area enhancement schemes delayed the onset of critical heat flux to higher heat inputs.

Comparison of 30 Boiling and Condensation Correlations for Two-Phase Flows in Compact Plate-Fin Heat Exchangers

2017 ◽  
Author(s):  
Wenhai Li ◽  
Ken Alabi ◽  
Foluso Ladeinde
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Flow Boiling ◽  
Transfer Coefficients ◽  
Two Phase Flows ◽  
Two Phase ◽  
Heat Transfer Coefficients ◽  
Heat Exchanger Design ◽  
Micro Channels ◽  
Vertical Tubes

Over the years, empirical correlations have been developed for predicting saturated flow boiling [1–15] and condensation [16–30] heat transfer coefficients inside horizontal/vertical tubes or micro-channels. In the present work, we have examined 30 of these models, and modified many of them for use in compact plate-fin heat exchangers. However, the various correlations, which have been developed for pipes and ducts, have been modified in our work to make them applicable to extended fin surfaces. The various correlations have been used in a low-order, one-dimensional, finite-volume type numerical integration of the flow and heat transfer equations in heat exchangers. The NIST’s REFPROP database [31] is used to account for the large variations in the fluid thermo-physical properties during phase change. The numerical results are compared with Yara’s experimental data [32]. The validity of the various boiling and condensation models for a real plate-fin heat exchanger design is discussed. The results show that some of the modified boiling and condensation correlations can provide acceptable prediction of heat transfer coefficient for two-phase flows in compact plate-fin heat exchangers.

Dropwise Condensation on Carbon Steel Surface

2016 ◽  
Author(s):  
Fangyu Cao ◽  
Sean Hoenig ◽  
Chien-hua Chen
Keyword(s):  
Heat Transfer ◽  
Carbon Steel ◽  
Power Plants ◽  
Heat Dissipation ◽  
Low Cost ◽  
Condensation Heat Transfer ◽  
Working Fluid ◽  
High Heat Flux ◽  
Dropwise Condensation ◽  
Two Phase

The increasing demand of heat dissipation in power plants has pushed the limits of current two-phase thermal technologies such as heat pipes and vapor chambers. One of the most obvious areas for thermal improvement is centered on the high heat flux condensers including improved evaporators, thermal interfaces, etc, with low cost materials and surface treatment. Dropwise condensation has shown the ability to increase condensation heat transfer coefficient by an order of magnitude over conventional filmwise condensation. Current dropwise condensation research is focused on Cu and other special metals, the cost of which limits its application in the scale of commercial power plants. Presented here is a general use of self-assembled monolayer coatings to promote dropwise condensation on low-cost steel-based surfaces. Together with inhibitors in the working fluid, the surface of condenser is protected by hydrophobic coating, and the condensation heat transfer is promoted on carbon steel surfaces.

Experimental Studies of Hydrodynamics and Heat Transfer in Channels With High-Porous Cellular Materials in Single-Phase Forced Convection and Flow Boiling of Working Fluids

1999 ◽  
Author(s):  
Yury F. Gortyshov ◽  
Igor A. Popov ◽  
Konstantin E. Gulitsky
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Pore Diameter ◽  
Flow Boiling ◽  
Experimental Studies ◽  
Internal Heat ◽  
Cellular Materials ◽  
Heat Fluxes ◽  
Working Fluids ◽  
Resistance Surface

Abstract In this paper we consider experimental studies of hydraulic resistance, surface heat transfer, internal heat exchange and critical heat fluxes for the flow of single-phase and boiling working fluids in channels with high-porous inserts. Experiments were carried out with more than 40 samples of high-porous cellular materials with the porosity 0.8...0.98 and mean pore diameter 0.62...4 mm and with more than 10 samples of regular porous inserts and porosity ε = 0.512...0.86 and mean pore diameter 1.5...3.5 mm. These samples were made of porcelain, invar, nichrome, bronze and copper.

Состояние разработок двухфазных систем терморегулирования космических аппаратов

2021 ◽  
pp. 36-51
Author(s):  
Рустем Юсуфович Турна ◽  
Артем Михайлович Годунов
Keyword(s):  
Heat Transfer ◽  
Control System ◽  
Power Consumption ◽  
High Power ◽  
Single Phase ◽  
Thermal Control ◽  
Two Phase ◽  
Thermal Control System ◽  
Intensification Of Heat Exchange ◽  
Large Heat

The progress of space technology is leading to more and more energy-equipped spacecraft. The International Space Station already has the capacity of solar panels of more than 100 kW. Autonomous spacecrafts and satellites (including stationary ones) have the capacity of power units of kW, in the nearest future - more than 10 kW. Forced heat transfer using single-phase liquid coolants is still considered as the main method of thermal control on high-power spacecraft (SC). Single-phase mechanically pumped fluid loop is a fully proven means of thermal control of spacecraft with a moderate heat load. A significant disadvantage of such systems is that the coolant temperature varies significantly within the loop. The temperature difference can be reduced by increasing the coolant flow rate, but for this, it is necessary to increase the pump capacity, which inevitably leads to an increase in power consumption, pipeline diameters, and weight of the system as a whole. In the case of spacecraft with high power capacity (more than 5-10 kW) and large heat transfer distances (10 m and more), a two-phase mechanically pumped fluid loop for thermal control is more preferable in terms of weight, the accuracy of thermoregulation, power consumption (and other parameters). The use of a two-phase loop (2PMPL) as a spacecraft thermal control system allows to reduce significantly mass and power consumption for own needs in comparison with a single-phase thermal control system (TCS). The effect is achieved due to the accumulation of transferred heat in the form of latent heat of vaporization and intensification of heat exchange at boiling and condensation of coolant. The article provides a critical review of published works on 2PMPL for spacecraft with high power (more than 5...10 kW) and a large heat transfer distance (more than 10...100 meters) from 1980 up to nowadays. As a result, a list of the main problems on the way of practical implementation of two-phase loops is formed.

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