1
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El-Rifai A, Perumanath S, Borg MK, Pillai R. Unraveling the Regimes of Interfacial Thermal Conductance at a Solid/Liquid Interface. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2024; 128:8408-8417. [PMID: 38807631 PMCID: PMC11129300 DOI: 10.1021/acs.jpcc.4c00536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 04/08/2024] [Accepted: 04/15/2024] [Indexed: 05/30/2024]
Abstract
The interfacial thermal conductance at a solid/liquid interface (G) exhibits an exponential-to-linear crossover with increasing solid/liquid interaction strength, previously attributed to the relative strength of solid/liquid to liquid/liquid interactions. Instead, using a simple Lennard-Jones setup, our molecular simulations reveal that this crossover occurs due to the onset of solidification in the interfacial liquid at high solid/liquid interaction strengths. This solidification subsequently influences interfacial energy transport, leading to the crossover in G. We use the overlap between the spectrally decomposed heat fluxes of the interfacial solid and liquid to pinpoint when "solid-like energy transport" within the interfacial liquid emerges. We also propose a novel decomposition of G into (i) the conductance right at the solid/liquid interface and (ii) the conductance of the nanoscale interfacial liquid region. We demonstrate that the rise of solid-like energy transport within the interfacial liquid influences the relative magnitude of these conductances, which in turn dictates when the crossover occurs. Our results can aid engineers in optimizing G at realistic interfaces, critical to designing effective cooling solutions for electronics among other applications.
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Affiliation(s)
- Abdullah El-Rifai
- Institute
for Multiscale Thermofluids, University
of Edinburgh, Edinburgh EH9 3FD, U.K.
| | | | - Matthew K. Borg
- Institute
for Multiscale Thermofluids, University
of Edinburgh, Edinburgh EH9 3FD, U.K.
| | - Rohit Pillai
- Institute
for Multiscale Thermofluids, University
of Edinburgh, Edinburgh EH9 3FD, U.K.
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2
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Hu Z, Gong S. Mesoscopic Model for Disjoining Pressure Effects in Nanoscale Thin Liquid Films and Evaporating Extended Meniscuses. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:13359-13370. [PMID: 37677082 DOI: 10.1021/acs.langmuir.3c02068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
Disjoining pressure effect is the key to describe contact line dynamics, micro/nanoscale liquid-vapor phase change heat transfer, and liquid transport in nanopores. In this paper, by combining a mesoscopic approach for nanoscale liquid-vapor interfacial transport and a mean-field approximation of the long-range solid-fluid molecular interaction, a mesoscopic model for the disjoining pressure effect in nanoscale thin liquid films is proposed. The capability of this model to delineate the disjoining pressure effect is validated. We demonstrate that the Hamaker constant determined from our model agrees very well with molecular dynamics (MD) simulation and that the transient evaporation/condensation mass flux predicted by this mesoscopic model is also consistent with the kinetic theory. Using this model, we investigate the characteristics of the evaporating extended meniscus in a nanochannel. The nonevaporating film region, the evaporating thin-film region, and the intrinsic meniscus region are successfully captured by our model. Our results suggest that the apparent contact angle and thickness of the nonevaporating liquid film are self-tuned according to the evaporation rate, and a higher evaporation rate results a in larger apparent contact angle and thinner nonevaporating liquid film. We also show that disjoining pressure plays a dominant role in the nonevaporating film region and suppresses the evaporation in this region, while capillary pressure dominates the intrinsic meniscus region. Strong evaporation takes place in the thin-film region, and both the disjoining pressure and capillary pressure contribute to the total pressure difference that delivers the liquid from the intrinsic meniscus region to the evaporating thin-film region, compensating for the liquid mass loss due to strong evaporation. Our work provides a new avenue for investigating thin liquid film spreading, liquid transport in nanopores, and microscopic liquid-vapor phase change heat/mass transfer mechanisms near the three-phase contact line region.
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Affiliation(s)
- Zhiheng Hu
- School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Shuai Gong
- School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
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3
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Jiang G, Wang L, Tian Z, Chen C, Hu X, Peng R, Li D, Zhang H, Fan P, Zhong M. Boosting water evaporation via continuous formation of a 3D thin film through triple-level super-wicking routes. MATERIALS HORIZONS 2023; 10:3523-3535. [PMID: 37255407 DOI: 10.1039/d3mh00548h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Capillary-fed thin-film evaporation via micro/nanoscale structures has attracted increasing attention for its high evaporation flux and pumpless liquid replenishment. However, maximizing thin-film evaporation has been hindered by the intrinsic trade-off between the heat flux and liquid transport. Here, we designed and fabricated nanostructured micro-steam volcanoes on copper surfaces featuring triple-level super-wicking routes to overcome this trade-off and boost water evaporation. The triple-level super-wicking routes enable the continuous formation of a 3D thin film for highly efficient evaporation by continuous self-driven liquid replenishment and extending the thin-film region. The micro-steam volcanoes increased the surface area by 225%, improving the evaporation rate by 141%, with a rapid self-pumping water transport speed up to 80 mm s-1. A remarkable solar-driven water evaporation rate of 3.33 kg m-2 h-1 under one sun vertical incidence was achieved, which is among the highest reported values for metal-based evaporators. When attached to electric-heating plates, the evaporator realized an electrothermal evaporation rate of 12.13 kg m-2 h-1. Moreover, it can also be used for evaporative cooling with enhanced convective heat transfer, reaching a 36.2 °C temperature reduction on a heat source with a heat flux of 6 W cm-2. This study promises a general strategy for designing thin-film evaporators with high efficiencies, low costs, and multi-functional compatibilities.
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Affiliation(s)
- Guochen Jiang
- Laser Materials Processing Research Center, Key Laboratory for Advanced Materials Processing Technology (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
| | - Lizhong Wang
- Laser Materials Processing Research Center, Key Laboratory for Advanced Materials Processing Technology (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
| | - Ze Tian
- Laser Materials Processing Research Center, Key Laboratory for Advanced Materials Processing Technology (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
| | - Changhao Chen
- Laser Materials Processing Research Center, Key Laboratory for Advanced Materials Processing Technology (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
| | - Xinyu Hu
- Laser Materials Processing Research Center, Key Laboratory for Advanced Materials Processing Technology (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
| | - Rui Peng
- Laser Materials Processing Research Center, Key Laboratory for Advanced Materials Processing Technology (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
| | - Daizhou Li
- Laser Materials Processing Research Center, Key Laboratory for Advanced Materials Processing Technology (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
| | - Hongjun Zhang
- Laser Materials Processing Research Center, Key Laboratory for Advanced Materials Processing Technology (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
| | - Peixun Fan
- Laser Materials Processing Research Center, Key Laboratory for Advanced Materials Processing Technology (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
| | - Minlin Zhong
- Laser Materials Processing Research Center, Key Laboratory for Advanced Materials Processing Technology (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
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4
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Ultrahigh evaporative heat transfer measured locally in submicron water films. Sci Rep 2022; 12:22353. [PMID: 36572793 PMCID: PMC9792458 DOI: 10.1038/s41598-022-26182-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 12/12/2022] [Indexed: 12/28/2022] Open
Abstract
Thin film evaporation is a widely-used thermal management solution for micro/nano-devices with high energy densities. Local measurements of the evaporation rate at a liquid-vapor interface, however, are limited. We present a continuous profile of the evaporation heat transfer coefficient ([Formula: see text]) in the submicron thin film region of a water meniscus obtained through local measurements interpreted by a machine learned surrogate of the physical system. Frequency domain thermoreflectance (FDTR), a non-contact laser-based method with micrometer lateral resolution, is used to induce and measure the meniscus evaporation. A neural network is then trained using finite element simulations to extract the [Formula: see text] profile from the FDTR data. For a substrate superheat of 20 K, the maximum [Formula: see text] is [Formula: see text] MW/[Formula: see text]-K at a film thickness of [Formula: see text] nm. This ultrahigh [Formula: see text] value is two orders of magnitude larger than the heat transfer coefficient for single-phase forced convection or evaporation from a bulk liquid. Under the assumption of constant wall temperature, our profiles of [Formula: see text] and meniscus thickness suggest that 62% of the heat transfer comes from the region lying 0.1-1 μm from the meniscus edge, whereas just 29% comes from the next 100 μm.
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5
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Lou J, Shi S, Ma C, Zhou X, Huang D, Zheng Q, Lv C. Polygonal non-wetting droplets on microtextured surfaces. Nat Commun 2022; 13:2685. [PMID: 35562518 PMCID: PMC9106735 DOI: 10.1038/s41467-022-30399-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 04/25/2022] [Indexed: 11/09/2022] Open
Abstract
Understanding the interactions between liquids and solids is important for many areas of science and technology. Microtextured surfaces have been extensively studied in microfluidics, DNA technologies, and micro-manufacturing. For these applications, the ability to precisely control the shape, size and location of the liquid via textured surfaces is of particular importance for the design of fluidic-based systems. However, this has been passively realized in the wetting state thanks to the pinning of the contact line, leaving the non-wetting counterpart challenging due to the low liquid affinity. In this work, confinement is imposed on droplets located on well-designed shapes and arrangements of microtextured surfaces. An active way to shape non-wetting water and liquid metal droplets into various polygons ranging from triangles, squares, rectangles, to hexagons is developed. The results suggest that energy barriers in different directions account for the movement of the contact lines and the formation of polygonal shapes. By characterizing the curvature of the liquid-vapour meniscus, the morphology of the droplet is correlated to its volume, thickness, and contact angle. The developed liquid-based patterning strategy under active regulation with low adhesion looks promising for low-cost micromanufacturing technology, DNA microarrays, and digital lab-on-a-chip. Exploring the interactions between liquids and solids is critical for improving control over fluidic systems. Here, authors develop an active way to tailor various polygonal shapes of non-wetting droplet on microtextured surfaces, resulting from the anisotropic energy barriers of the contact line.
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Affiliation(s)
- Jing Lou
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, AML, Tsinghua University, Beijing, 100084, China
| | - Songlin Shi
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, AML, Tsinghua University, Beijing, 100084, China
| | - Chen Ma
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, AML, Tsinghua University, Beijing, 100084, China
| | - Xiaohuan Zhou
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, AML, Tsinghua University, Beijing, 100084, China
| | - Dong Huang
- National Key Laboratory of Science and Technology on Micro/Nano Fabrication, Institute of Microelectronics, Peking University, Beijing, 100871, China
| | - Quanshui Zheng
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, AML, Tsinghua University, Beijing, 100084, China
| | - Cunjing Lv
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, AML, Tsinghua University, Beijing, 100084, China.
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6
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Liu R, Liu Z. Enhanced Evaporation of Ultrathin Water Films on Silicon-Terminated Si 3N 4 Nanopore Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:10046-10051. [PMID: 34383493 DOI: 10.1021/acs.langmuir.1c01212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Water evaporation confined in nanoscale is a ubiquitous phenomenon in nature and has crucial importance in a broad range of technical applications. With the nonequilibrium molecular dynamics simulation, we elucidate nanothin water film evaporation characteristics on a silicon nitride nanopore membrane considering the effects of pore size and pore chemistry. Pore chemistry plays the main role in regulating the evaporation flux. The terminated Si atoms on the pore surface lead to a higher evaporation intensity than the N ones. We attribute this enhancement to the transition of the structural properties of fluid, where liquid molecules are packed loosely and disorderedly under the inducement of terminated silicon atoms. The findings in the present work can contribute to the fundamental understanding of the nanopore-enhanced evaporation process and provide new guidance to the design of advanced nanopore membrane materials.
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Affiliation(s)
- Runkeng Liu
- School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zhenyu Liu
- School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
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7
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Li J, Zhang Z, Zhao R, Zhang B, Liang Y, Long R, Liu W, Liu Z. Stack Thermo-Osmotic System for Low-Grade Thermal Energy Conversion. ACS APPLIED MATERIALS & INTERFACES 2021; 13:21371-21378. [PMID: 33905242 DOI: 10.1021/acsami.1c03395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Thermo-osmotic energy conversion (TOEC) technology, developed from membrane distillation, is an emerging method that has the potential of obtaining electricity efficiently from a low-grade heat source but faces the difficult problem of pump power loss. In this study, we build a novel TOEC system with a multistage architecture that can work without pump assistance. The experiment system, made of cheap commercial materials, can obtain a power density of 1.39 ± 0.25 W/m2, with a heating temperature of 80 °C, and its efficiency increased linearly with the total stage number. A theory calculation shows that a 30-stage system with a specific membrane and a working pressure of 5.0 MPa can obtain an efficiency of 2.72% with a power density of 14.0 W/m2. By a molecular dynamics simulation, it is shown that a high-performance membrane has the potential to work at 40 MPa. This study proves that TOEC technology is a practical and competitive approach to covert low-grade thermal energy into power efficiently.
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Affiliation(s)
- Ji Li
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zikang Zhang
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Runze Zhao
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Bo Zhang
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Yunmin Liang
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Rui Long
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Wei Liu
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zhichun Liu
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
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8
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Li R, Wang J, Xia G. New Model for Liquid Evaporation and Vapor Transport in Nanopores Covering the Entire Knudsen Regime and Arbitrary Pore Length. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:2227-2235. [PMID: 33534588 DOI: 10.1021/acs.langmuir.1c00023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Liquid evaporation and the associated vapor transport in micro/nanopores are ubiquitous in nature and play an important role in industrial applications. Accurate modeling of the liquid evaporation process in nanopores is critical to achieving a better design of devices for enhanced evaporation. Although having high impact on evaporation rate, vapor transport resistance in micro/nanopores remains incompletely understood. In this study, we proposed a new model which, for the first time, considered vapor transport in finite-length pores under various Knudsen regimes and then coupled the transport resistance to liquid evaporation. Direct Simulation Monte Carlo and laboratory experiments were conducted to provide validation for our model. The model successfully predicts the variation of pore transmissivity with Knudsen number and nanopore size, which cannot be revealed by prior theories. The relative error of model-predicted evaporation rate was within 1% in L/r = 0 cases and within 3.5% in L/r > 0 cases. Our model is featured by its applicability under the entire range of Knudsen numbers. The evaporation of various types of liquids in arbitrarily sized pores can be modeled using a universal relation.
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Affiliation(s)
- Ran Li
- MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Beijing Key Laboratory of Heat Transfer and Energy Conversion, Beijing University of Technology, Beijing 100124, China
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Jiahao Wang
- MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Beijing Key Laboratory of Heat Transfer and Energy Conversion, Beijing University of Technology, Beijing 100124, China
| | - Guodong Xia
- MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Beijing Key Laboratory of Heat Transfer and Energy Conversion, Beijing University of Technology, Beijing 100124, China
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9
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Li J, Long R, Zhang B, Yang R, Liu W, Liu Z. Nano Heat Pump Based on Reverse Thermo-osmosis Effect. J Phys Chem Lett 2020; 11:9856-9861. [PMID: 32991184 DOI: 10.1021/acs.jpclett.0c02475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Heat pumps are widely used in domestic applications, agriculture, and industry. Here, we report a novel heat pump based on the reverse thermo-osmosis (RTO) effect in a nanoporous graphene (NPG) membrane. Through classical molecular dynamics (MD) simulation, we prove that the heat pump can transport mass and heat efficiently. The heat and mass fluxes are increased linearly with the hydraulic pressure provided. Ultrahigh heat fluxes of 6.2 ± 1.0 kW/cm2 and coefficient of performance (COP) of 20.2 are obtained with a temperature increment of 5 K and a working pressure of 80 MPa. It is interesting that water molecules on the NPG membrane can evaporate in a cluster state, and the cluster evaporations reduce the vaporization enthalpy of the processes.
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Affiliation(s)
- Ji Li
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Rui Long
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Bo Zhang
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Ronggui Yang
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Wei Liu
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zhichun Liu
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
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10
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Hanks DF, Lu Z, Sircar J, Kinefuchi I, Bagnall KR, Salamon TR, Antao DS, Barabadi B, Wang EN. High Heat Flux Evaporation of Low Surface Tension Liquids from Nanoporous Membranes. ACS APPLIED MATERIALS & INTERFACES 2020; 12:7232-7238. [PMID: 31951381 DOI: 10.1021/acsami.9b20520] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Water is often considered as the highest performance working fluid for liquid-vapor phase change due to its high thermal conductivity and large enthalpy of vaporization. However, a wide range of industrial systems require using low surface tension liquids where heat transfer enhancement has proved challenging for boiling and evaporation. Here, we enable a new paradigm of phase change heat transfer, which favors high volatility, low surface tension liquids rather than water. We utilized a nanoporous membrane of ≈600 nm thickness and <140 nm pore diameters supported on efficient liquid supply architectures, decoupling capillary pumping from viscous loss. Proof-of-concept devices were microfabricated and tested in a custom-built environmental chamber. We used R245fa, pentane, methanol, isopropyl alcohol, and water as working fluids with devices of total membrane area varying from 0.017 to 0.424 cm2. We realized a device-level pure evaporation heat flux of 144 ± 6 W/cm2 for water, and the highest evaporation heat flux was obtained with pentane at 550 ± 90 W/cm2. We developed a three-level model to understand vapor dynamics near the interface and thermal conduction within the device, which showed good agreement with experiments. We then compared pore-level heat transfer of different fluids, where R245fa showed approximately 10 times the performance of water under the same working conditions. Finally, we illustrate the usefulness of a figure of merit extracted from the kinetic theory for evaporation. The current work provides fundamental insights into the evaporation of low surface tension liquids, which can impact various applications such as refrigeration and air conditioning, petroleum and solvent distillation, and on-chip electronics cooling.
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Affiliation(s)
- Daniel F Hanks
- Department of Mechanical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Zhengmao Lu
- Department of Mechanical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Jay Sircar
- Department of Mechanical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Ikuya Kinefuchi
- Department of Mechanical Engineering , University of Tokyo , Bunkyo , Tokyo 113-8656 , Japan
| | - Kevin R Bagnall
- Department of Mechanical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Todd R Salamon
- Nokia Bell Laboratories , 600 Mountain Avenue , Murray Hill , New Jersey 07974 , United States
| | - Dion S Antao
- Department of Mechanical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Banafsheh Barabadi
- Department of Mechanical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Evelyn N Wang
- Department of Mechanical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
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11
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Lu Z, Kinefuchi I, Wilke KL, Vaartstra G, Wang EN. A unified relationship for evaporation kinetics at low Mach numbers. Nat Commun 2019; 10:2368. [PMID: 31147534 PMCID: PMC6542818 DOI: 10.1038/s41467-019-10209-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 04/26/2019] [Indexed: 11/10/2022] Open
Abstract
We experimentally realized and elucidated kinetically limited evaporation where the molecular gas dynamics close to the liquid–vapour interface dominates the overall transport. This process fundamentally dictates the performance of various evaporative systems and has received significant theoretical interest. However, experimental studies have been limited due to the difficulty of isolating the interfacial thermal resistance. Here, we overcome this challenge using an ultrathin nanoporous membrane in a pure vapour ambient. We demonstrate a fundamental relationship between the evaporation flux and driving potential in a dimensionless form, which unifies kinetically limited evaporation under different working conditions. We model the nonequilibrium gas kinetics and show good agreement between experiments and theory. Our work provides a general figure of merit for evaporative heat transfer as well as design guidelines for achieving efficient evaporation in applications such as water purification, steam generation, and thermal management. Evaporation plays a key role in applications such as cooling and desalination. Here, the authors experimentally demonstrated a unifying relationship between dimensionless flux and driving potential for evaporation kinetics under different working conditions.
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Affiliation(s)
- Zhengmao Lu
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Ikuya Kinefuchi
- Department of Mechanical Engineering, University of Tokyo, Bunkyo, Tokyo, 113-8656, Japan
| | - Kyle L Wilke
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Geoffrey Vaartstra
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Evelyn N Wang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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12
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Li Y, Chen H, Xiao S, Alibakhshi MA, Lo CW, Lu MC, Duan C. Ultrafast Diameter-Dependent Water Evaporation from Nanopores. ACS NANO 2019; 13:3363-3372. [PMID: 30836750 DOI: 10.1021/acsnano.8b09258] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Evaporation from nanopores plays an important role in various natural and industrial processes that require efficient heat and mass transfer. The ultimate performance of nanopore-evaporation-based processes is dictated by evaporation kinetics at the liquid-vapor interface, which has yet to be experimentally studied down to the single nanopore level. Here we report unambiguous measurements of kinetically limited intense evaporation from individual hydrophilic nanopores with both hydrophilic and hydrophobic top outer surfaces at 22 °C using nanochannel-connected nanopore devices. Our results show that the evaporation fluxes of nanopores with hydrophilic outer surfaces show a strong diameter dependence with an exponent of nearly -1.5, reaching up to 11-fold of the maximum theoretical predication provided by the classical Hertz-Knudsen relation at a pore diameter of 27 nm. Differently, the evaporation fluxes of nanopores with hydrophobic outer surfaces show a different diameter dependence with an exponent of -0.66, achieving 66% of the maximum theoretical predication at a pore diameter of 28 nm. We discover that the ultrafast diameter-dependent evaporation from nanopores with hydrophilic outer surfaces mainly stems from evaporating water thin films outside of the nanopores. In contrast, the diameter-dependent evaporation from nanopores with hydrophobic outer surfaces is governed by evaporation kinetics inside the nanopores, which indicates that the evaporation coefficient varies in different nanoscale confinements, possibly due to surface-charge-induced concentration changes of hydronium ions. This study enhances our understanding of evaporation at the nanoscale and demonstrates great potential of evaporation from nanopores.
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Affiliation(s)
- Yinxiao Li
- Department of Mechanical Engineering , Boston University , Boston , Massachusetts 02215 , United States
| | - Haowen Chen
- Department of Mechanical Engineering , Boston University , Boston , Massachusetts 02215 , United States
| | - Siyang Xiao
- Department of Mechanical Engineering , Boston University , Boston , Massachusetts 02215 , United States
| | - Mohammad Amin Alibakhshi
- Department of Mechanical Engineering , Boston University , Boston , Massachusetts 02215 , United States
| | - Ching-Wen Lo
- Department of Mechanical Engineering , Boston University , Boston , Massachusetts 02215 , United States
- Department of Mechanical Engineering , National Chiao Tung University , Hsinchu 300 , Taiwan
| | - Ming-Chang Lu
- Department of Mechanical Engineering , National Chiao Tung University , Hsinchu 300 , Taiwan
| | - Chuanhua Duan
- Department of Mechanical Engineering , Boston University , Boston , Massachusetts 02215 , United States
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13
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Preston DJ, Wilke KL, Lu Z, Cruz SS, Zhao Y, Becerra LL, Wang EN. Gravitationally Driven Wicking for Enhanced Condensation Heat Transfer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:4658-4664. [PMID: 29578348 DOI: 10.1021/acs.langmuir.7b04203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Vapor condensation is routinely used as an effective means of transferring heat or separating fluids. Filmwise condensation is prevalent in typical industrial-scale systems, where the condensed fluid forms a thin liquid film due to the high surface energy associated with many industrial materials. Conversely, dropwise condensation, where the condensate forms discrete liquid droplets which grow, coalesce, and shed, results in an improvement in heat transfer performance of an order of magnitude compared to filmwise condensation. However, current state-of-the-art dropwise technology relies on functional hydrophobic coatings, for example, long chain fatty acids or polymers, which are often not robust and therefore undesirable in industrial conditions. In addition, low surface tension fluid condensates, such as hydrocarbons, pose a unique challenge because common hydrophobic condenser coatings used to shed water (with a surface tension of 73 mN/m) often do not repel fluids with lower surface tensions (<25 mN/m). We demonstrate a method to enhance condensation heat transfer using gravitationally driven flow through a porous metal wick, which takes advantage of the condensate's affinity to wet the surface and also eliminates the need for condensate-phobic coatings. The condensate-filled wick has a lower thermal resistance than the fluid film observed during filmwise condensation, resulting in an improved heat transfer coefficient of up to an order of magnitude and comparable to that observed during dropwise condensation. The improved heat transfer realized by this design presents the opportunity for significant energy savings in natural gas processing, thermal management, heating and cooling, and power generation.
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Affiliation(s)
- Daniel J Preston
- Department of Mechanical Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
| | - Kyle L Wilke
- Department of Mechanical Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
| | - Zhengmao Lu
- Department of Mechanical Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
| | - Samuel S Cruz
- Department of Mechanical Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
| | - Yajing Zhao
- Department of Mechanical Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
| | - Laura L Becerra
- Shiley-Marcos School of Engineering , University of San Diego , San Diego , California 92110 , United States
| | - Evelyn N Wang
- Department of Mechanical Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
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Hanks DF, Lu Z, Sircar J, Salamon TR, Antao DS, Bagnall KR, Barabadi B, Wang EN. Nanoporous membrane device for ultra high heat flux thermal management. MICROSYSTEMS & NANOENGINEERING 2018; 4:1. [PMID: 31057891 PMCID: PMC6220170 DOI: 10.1038/s41378-018-0004-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 01/10/2018] [Accepted: 01/18/2018] [Indexed: 05/03/2023]
Abstract
High power density electronics are severely limited by current thermal management solutions which are unable to dissipate the necessary heat flux while maintaining safe junction temperatures for reliable operation. We designed, fabricated, and experimentally characterized a microfluidic device for ultra-high heat flux dissipation using evaporation from a nanoporous silicon membrane. With ~100 nm diameter pores, the membrane can generate high capillary pressure even with low surface tension fluids such as pentane and R245fa. The suspended ultra-thin membrane structure facilitates efficient liquid transport with minimal viscous pressure losses. We fabricated the membrane in silicon using interference lithography and reactive ion etching and then bonded it to a high permeability silicon microchannel array to create a biporous wick which achieves high capillary pressure with enhanced permeability. The back side consisted of a thin film platinum heater and resistive temperature sensors to emulate the heat dissipation in transistors and measure the temperature, respectively. We experimentally characterized the devices in pure vapor-ambient conditions in an environmental chamber. Accordingly, we demonstrated heat fluxes of 665 ± 74 W/cm2 using pentane over an area of 0.172 mm × 10 mm with a temperature rise of 28.5 ± 1.8 K from the heated substrate to ambient vapor. This heat flux, which is normalized by the evaporation area, is the highest reported to date in the pure evaporation regime, that is, without nucleate boiling. The experimental results are in good agreement with a high fidelity model which captures heat conduction in the suspended membrane structure as well as non-equilibrium and sub-continuum effects at the liquid-vapor interface. This work suggests that evaporative membrane-based approaches can be promising towards realizing an efficient, high flux thermal management strategy over large areas for high-performance electronics.
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Affiliation(s)
- Daniel F. Hanks
- Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
| | - Zhengmao Lu
- Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
| | - Jay Sircar
- Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
| | - Todd R. Salamon
- Nokia Bell Labs, 600 Mountain Avenue, New Providence, NJ 07974 USA
| | - Dion S. Antao
- Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
| | - Kevin R. Bagnall
- Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
| | - Banafsheh Barabadi
- Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
| | - Evelyn N. Wang
- Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
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