
NSF Org: |
CBET Division of Chemical, Bioengineering, Environmental, and Transport Systems |
Recipient: |
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Initial Amendment Date: | January 15, 2015 |
Latest Amendment Date: | September 17, 2021 |
Award Number: | 1454450 |
Award Instrument: | Standard Grant |
Program Manager: |
Ron Joslin
rjoslin@nsf.gov (703)292-7030 CBET Division of Chemical, Bioengineering, Environmental, and Transport Systems ENG Directorate for Engineering |
Start Date: | January 15, 2015 |
End Date: | January 31, 2022 (Estimated) |
Total Intended Award Amount: | $500,002.00 |
Total Awarded Amount to Date: | $552,952.00 |
Funds Obligated to Date: |
FY 2021 = $52,950.00 |
History of Investigator: |
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Recipient Sponsored Research Office: |
900 S CROUSE AVE SYRACUSE NY US 13244-4407 (315)443-2807 |
Sponsor Congressional District: |
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Primary Place of Performance: |
NY US 13244-1200 |
Primary Place of
Performance Congressional District: |
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Unique Entity Identifier (UEI): |
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Parent UEI: |
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NSF Program(s): |
TTP-Thermal Transport Process, GOALI-Grnt Opp Acad Lia wIndus |
Primary Program Source: |
01002122DB NSF RESEARCH & RELATED ACTIVIT |
Program Reference Code(s): |
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Program Element Code(s): |
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Award Agency Code: | 4900 |
Fund Agency Code: | 4900 |
Assistance Listing Number(s): | 47.041 |
ABSTRACT
1454450 - Maroo
Ability to remove heat in large amounts and in a very short time (i.e., high heat fluxes) is critical for developing next-generation heat exchangers, high-speed computing, and renewable energy technologies. The proposed study is to take advantage that a thin liquid film at the nanoscale has the potential to achieve the ultra-high heat removal rate with proper liquid supply. Both experiments and molecular level simulations will be used to gain fundamental understanding of such heat removal processes. The integrated educational initiatives of this project will expose students, including those from underrepresented groups in engineering disciplines, to multidisciplinary research and nanotechnology. Outreach includes providing yearly research opportunity to a minority undergraduate student in collaboration with ULSAMP (Upstate Louis Stokes Alliance for Minority Participation), and yearly workshops on nanotechnology to middle-school students in Syracuse City School District as part of ULSAMP outreach to underrepresented and diverse student groups.
The objective of the proposed research is to investigate the fundamental physics associated with nanoscale meniscus evaporation coupled with passive liquid flow for achieving high heat flux removal using a synergistic research methodology of molecular simulations with pool boiling and evaporation experiments. Passive liquid flow can be generated in a nanoscale meniscus due to the strong capillary and surface-generated disjoining forces which can lower the meniscus liquid pressure to absolute negative values. The research plan focuses on (1) performing molecular dynamics simulations of water nano-meniscus evaporation to elucidate its behavior and characteristics, (2) pool boiling experiments of water coupled with nanoscale evaporation to enhance the critical heat flux, and (3) experiments on nanoscale meniscus evaporation to achieve high heat flux removal with passive flow of water. The intellectual merits include implementation and validation of a novel "solid-to-liquid heat transfer model" in molecular dynamics to simulate evaporation of water from a heated surface, and fabrication of well-defined novel geometries to achieve nanoscale meniscus evaporation. The education plan includes development and implementation of a three-week module on "Nano-science and Nano-engineering" for first-year undergraduate students in Engineering 101. The module will be based on Model Development Sequences to promote and develop the need for physical and visual understanding of mathematical models and engineering concepts while using fundamental building blocks of atoms and molecules. To assess how novice students use simulation module to explore physical phenomena, assignments with a data-generating mechanism will also be designed to collect real-time performance data.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Vapor generation rate in nano/microstructured-based interfacial vapor generation devices is limited by water supply. We reported an innovative design for enhancement in vapor generation using porous nanochannel wicks. Vapor generation rate of 1.18 kg m−2 h-1 is achieved in a dark environment (without heat input) and of 17.12 kg m−2 h-1 is achieved with a heat input of 5.08 W at low temperature of 62?C, significantly higher than a typical vapor generation rate reported for interfacial solar vapor generation systems. We also demonstrated our wick?s performance under solar heat flux of 1.25 sun and attain a vapor generation rate of 4.87 kg m−2 h-1 at surface temperature below 35?C. This approach can be consequential in low-grade waste heat recovery.
A new enhancement mechanism based on the early evaporation of the microlayer is discovered and validated. The microlayer is a thin liquid film present at the base of a vapor bubble. The presence of microridges on the silicon dioxide surface partitions the microlayer and disconnects it from the bulk liquid, causing it to evaporate sooner, thus leading to increase in the bubble growth rate, heat transfer, departure frequency, and critical heat flux (CHF). Compared to a plain surface, an ∼120% enhancement in CHF is obtained with only an ∼18% increase in surface area. A CHF enhancement map is developed on the basis of the ridge height and spacing, resulting in three regions of full, partial, and no enhancement. The new mechanism is validated by comparing the growth rate of a laser-created vapor bubble on a ridge-structured surface and a plain surface, and the corresponding prediction of the CHF enhancement is found to be in good agreement with the experimental boiling data. This discovery opens up a new field of CHF enhancement and can potentially be coupled with existing techniques to further push the limits of boiling heat transfer.
The microlayer thin film is visualized in situ in a vapor bubble during pool boiling. Contrary to current understanding, bubbles originate on hydrophilic and silane-coated hydrophobic surfaces without a three-phase contact line, i.e., the microlayer completely covers the bubble base. The occurrence of such a wetted bubble base is found to be dependent on the liquid?solid interaction. As the bubble grows in time, the film decreases in thickness, eventually forming the contact line and dry region. We also explicitly coupled pool boiling with nanoscale evaporation by using buried nanochannels of height ∼728 nm and ∼100 nm to enhance critical heat flux (CHF) by ∼105%. Additional menisci and contact line formation in nanochannels are found to be the dominant factors of CHF enhancement. Wicking assists in creating the additional contact line but does not serve as the primary measurable factor in predicting such enhancement based on CFD simulations and wicking experiments. This work provides clarity on the roles of contact line and wicking in boiling heat transfer.
A novel surface-heating algorithm for water is developed for molecular dynamics simulations. The validated algorithm can simulate the transient behavior of the evaporation of water when heated from a surface, which has been lacking in the literature. The algorithm is used to study the evaporation of water droplets on a platinum surface at different temperatures. The resulting contact angles of the droplets are compared to existing theoretical, numerical, and experimental studies. The simplicity of the algorithm allows it to be easily extended to other surfaces and integrated into various molecular simulation software and user codes. We also performed a fundamental molecular study on passive liquid flow driven by the solid?liquid surface tension force. Very strong passive liquid flows are obtained that lead to steady-state, continuous, and high-heat flux removal close to the maximum theoretical limit, as predicted by the kinetic theory of evaporation.
A peer-reviewed conference paper in ASEE was published which evaluated the impact of introducing homework assignments, which are 1) assigned and submitted online, 2) algorithmic, and 3) not from the course textbook, on students? homework performance relative to their overall class performance. Online homework assignments, if done correctly, were found to be a powerful tool to enhance the educational impact in an engineering class.
Every year, an introduction to nanotechnology was given in Mechanical ECS 101 class in two lectures in Fall semester to incoming freshmen students. Key concepts of molecular force interaction, liquid-surface interaction and their impact on technology commercialization was discussed with real-world examples (e.g. liquiglide, geckskin).
A full semester course MAE 555-'Fundamentals of Nano-science and Nano-engineering' was designed, introduced and taught in Fall semester to undergraduate and graduate students. Several hands-on activities were part of the class, including cleanroom tour of Cornell NanoScale Science & Technology Facility (CNF), using molecular dynamics simulation software LAMMPS, and nanotechnology applications group project based on literature review and journal publications.
Last Modified: 08/01/2022
Modified by: Shalabh C Maroo
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