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Beigtan M, Gonçalves M, Weon BM. Heat Transfer by Sweat Droplet Evaporation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6532-6539. [PMID: 38538556 PMCID: PMC11025549 DOI: 10.1021/acs.est.4c00850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/03/2024] [Accepted: 03/12/2024] [Indexed: 04/17/2024]
Abstract
Sweating regulates the body temperature in extreme environments or during exercise. Here, we investigate the evaporative heat transfer of a sweat droplet at the microscale to unveil how the evaporation complexity of a sweat droplet would affect the body's ability to cool under specific environmental conditions. Our findings reveal that, depending on the relative humidity and temperature levels, sweat droplets experience imperfect evaporation dynamics, whereas water droplets evaporate perfectly at equivalent ambient conditions. At low humidity, the sweat droplet fully evaporates and leaves a solid deposit, while at high humidity, the droplet never reaches a solid deposit and maintains a liquid phase residue for both low and high temperatures. This unprecedented evaporation mechanism of a sweat droplet is attributed to the intricate physicochemical properties of sweat as a biofluid. We suppose that the sweat residue deposited on the surface by evaporation is continuously absorbing the surrounding moisture. This route leads to reduced evaporative heat transfer, increased heat index, and potential impairment of the body's thermoregulation capacity. The insights into the evaporative heat transfer dynamics at the microscale would help us to improve the knowledge of the body's natural cooling mechanism with practical applications in healthcare, materials science, and sports science.
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Affiliation(s)
- Mohadese Beigtan
- Soft
Matter Physics Laboratory, School of Advanced Materials Science and
Engineering, Sungkyunkwan University, Suwon 16419, South Korea
| | - Marta Gonçalves
- Soft
Matter Physics Laboratory, School of Advanced Materials Science and
Engineering, Sungkyunkwan University, Suwon 16419, South Korea
- Research
Center for Advanced Materials Technology, Sungkyunkwan University, Suwon 16419, South Korea
| | - Byung Mook Weon
- Soft
Matter Physics Laboratory, School of Advanced Materials Science and
Engineering, Sungkyunkwan University, Suwon 16419, South Korea
- Research
Center for Advanced Materials Technology, Sungkyunkwan University, Suwon 16419, South Korea
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2
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Ruiken JP, Villwock J, Kraume M. Behaviour of Acoustically Levitated Drops in Mid-Water. MICROMACHINES 2023; 14:1923. [PMID: 37893360 PMCID: PMC10609316 DOI: 10.3390/mi14101923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/06/2023] [Accepted: 10/07/2023] [Indexed: 10/29/2023]
Abstract
A low-impact acoustic levitation system has been developed to study immobilised single drops in liquid-liquid systems. The ability to observe liquid drops several millimetres in diameter for days enables fundamental research into a wide range of mechanisms. Non-invasive optical measurements with excellent optical accessibility are possible. This experimental work provides the basis for mass transfer studies, emphasizing the precise volume determination, signal noise, reproducibility, and the impact of the acoustic field on the drop and its surrounding environment. The setup can be effectively controlled and proves beneficial for research objectives provided that all liquid phases are entirely degassed, and there are no compressible voids present within the liquids. In addition to the precise, uniform, and reliable measurement conditions, we observed no acoustic streaming in the proximity of the drop and there was no significant vibration of the drop. Qualitative observations using rainbow schlieren deflectometry indicate that the nodal or anti-nodal planes of the standing waves can act as barriers to the dispersion of inhomogeneous dissolved substances in the continuous phase.
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Affiliation(s)
| | | | - Matthias Kraume
- Department of Chemical and Process Engineering, Technische Universität Berlin, Ackerstraße 76, 13355 Berlin, Germany; (J.-P.R.); (J.V.)
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3
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Yang Z, Yang G, He Y, Shi Z, Dong T. Evaporation issues of acoustically levitated fuel droplets. ULTRASONICS SONOCHEMISTRY 2023; 98:106480. [PMID: 37393855 PMCID: PMC10331844 DOI: 10.1016/j.ultsonch.2023.106480] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/30/2023] [Accepted: 06/08/2023] [Indexed: 07/04/2023]
Abstract
Fuel droplet evaporation is essential to the generation of flammable mixtures in thermal engines. Generally, liquid fuel is injected directly into the hot, high-pressure atmosphere to form scattered droplets. Many investigations on droplet evaporation have been conducted with techniques involving the influence of boundaries, such as suspended wires. Ultrasonic levitation is a non-contact and non-destructive technology that can avoid the impact of hanging wire on droplet shape and heat transfer. Besides, it can simultaneously levitate multiple droplets and allow them to associate with each other or be used to study droplet instability behaviors. This paper reviews the influences of the acoustic field on levitated droplets, the evaporation characteristics of acoustically levitated droplets, and the prospects and limitations of ultrasonic suspension methods for droplet evaporation, which can serve as references for relevant studies.
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Affiliation(s)
- Zhaochu Yang
- Chongqing Key Laboratory of Micro-nano Systems and Intelligent Transduction, National Research Base of Intelligent Manufacturing Service, Chongqing Technology and Business University, Chongqing 400067, China.
| | - Guangcan Yang
- Chongqing Key Laboratory of Micro-nano Systems and Intelligent Transduction, National Research Base of Intelligent Manufacturing Service, Chongqing Technology and Business University, Chongqing 400067, China
| | - Yongqing He
- Chongqing Key Laboratory of Micro-nano Systems and Intelligent Transduction, National Research Base of Intelligent Manufacturing Service, Chongqing Technology and Business University, Chongqing 400067, China
| | - Zhongyuan Shi
- Chongqing Key Laboratory of Micro-nano Systems and Intelligent Transduction, National Research Base of Intelligent Manufacturing Service, Chongqing Technology and Business University, Chongqing 400067, China
| | - Tao Dong
- Department of Microsystems, Faculty of Technology, Natural Sciences and Maritime Sciences, University of South-Eastern Norway, Horten, Norway
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4
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Sharma S, Jain S, Saha A, Basu S. Evaporation dynamics of a surrogate respiratory droplet in a vortical environment. J Colloid Interface Sci 2022; 623:541-551. [DOI: 10.1016/j.jcis.2022.05.061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 05/06/2022] [Accepted: 05/10/2022] [Indexed: 10/18/2022]
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5
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Hasegawa K, Murata M. Oscillation Dynamics of Multiple Water Droplets Levitated in an Acoustic Field. MICROMACHINES 2022; 13:1373. [PMID: 36143996 PMCID: PMC9500997 DOI: 10.3390/mi13091373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/15/2022] [Accepted: 08/22/2022] [Indexed: 06/16/2023]
Abstract
This study aimed to improve and investigate the oscillation dynamics and levitation stability of acoustically levitated water droplets. Contactless sample manipulation technology in mid-air has attracted significant attention in the fields of biochemistry and pharmaceutical science. Although one promising method is acoustic levitation, most studies have focused on a single sample. Therefore, it is important to determine the stability of multiple samples during acoustic levitation. Here, we aim to understand the effect of multiple-sample levitation on levitation stability in acoustic fields. We visualized the oscillatory motion of multiple levitated droplets using a high-speed video camera. To characterize the dynamics of multiple levitating droplets, the oscillation frequency and restoring force coefficients of the levitated samples, which were obtained from the experimental data, were analyzed to quantify the droplet-droplet interaction. The oscillation model of the spring-mass system was compared with the experimental results, and we found that the number of levitating droplets and their position played an important role in the levitation stability of the droplets. Our insights could help us understand the oscillatory behavior of levitated droplets to achieve more stable levitation.
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Affiliation(s)
- Koji Hasegawa
- Department of Mechanical Engineering, Kogakuin University, Tokyo 163-8677, Japan
| | - Manami Murata
- Graduate School of Engineering, Kogakuin University, Tokyo 163-8677, Japan
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6
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Senzano LM, Bovo RP, Andrade DV. Empirical estimation of skin resistance to water loss in amphibians: agar evaluation as a non-resistance model to evaporation. J Exp Biol 2022; 225:276192. [PMID: 35818822 DOI: 10.1242/jeb.243941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 07/05/2022] [Indexed: 11/20/2022]
Abstract
Total resistance (RT) to evaporative water loss (EWL) in amphibians is given by the sum of the boundary layer (rb) and the skin resistance (rs). Thus, rs can be determined if the rb component is defined (rs=RT - rb). The use of agar models has become the standard technique to estimate rb under the assumption that agar surface imposes no barrier to evaporation (rs=0). We evaluated this assumption by determining EWL rates and rb values from exposed surfaces of free water, a physiological solution mimicking the osmotic properties of a generalized amphibian, and agar gels prepared at various concentrations either using water or physiological solution as diluent. Water evaporation was affected by both, the presence of solutes and agar concentration. Models prepared with agar at 5% concentration in water provided the most practical and appropriate proxy for the estimation of rb.
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Affiliation(s)
- Luis M Senzano
- Departamento de Biodiversidade, Instituto de Biociências, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil
| | - Rafael P Bovo
- Departmento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Denis V Andrade
- Departamento de Biodiversidade, Instituto de Biociências, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil
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Bunio LB, Wang J, Kannaiyan R, Gates ID. Evaporation and crystallization of NaCl-water droplets suspended in air by acoustic levitation. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2022.117441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Liu K, Allahyari M, Salinas JS, Zgheib N, Balachandar S. Peering inside a cough or sneeze to explain enhanced airborne transmission under dry weather. Sci Rep 2021; 11:9826. [PMID: 33972590 PMCID: PMC8110525 DOI: 10.1038/s41598-021-89078-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 04/13/2021] [Indexed: 12/23/2022] Open
Abstract
High-fidelity simulations of coughs and sneezes that serve as virtual experiments are presented, and they offer an unprecedented opportunity to peer into the chaotic evolution of the resulting airborne droplet clouds. While larger droplets quickly fall-out of the cloud, smaller droplets evaporate rapidly. The non-volatiles remain airborne as droplet nuclei for a long time to be transported over long distances. The substantial variation observed between the different realizations has important social distancing implications, since probabilistic outlier-events do occur and may need to be taken into account when assessing the risk of contagion. Contrary to common expectations, we observe dry ambient conditions to increase by more than four times the number of airborne potentially virus-laden nuclei, as a result of reduced droplet fall-out through rapid evaporation. The simulation results are used to validate and calibrate a comprehensive multiphase theory, which is then used to predict the spread of airborne nuclei under a wide variety of ambient conditions.
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Affiliation(s)
- Kai Liu
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Majid Allahyari
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Jorge S Salinas
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, 32611, USA.
| | - Nadim Zgheib
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, 32611, USA
- School of Engineering, Lebanese American University, Byblos, 1401, Lebanon
| | - S Balachandar
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, 32611, USA.
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Dangi BB, Dickerson DJ. Design and Performance of an Acoustic Levitator System Coupled with a Tunable Monochromatic Light Source and a Raman Spectrometer for In Situ Reaction Monitoring. ACS OMEGA 2021; 6:10447-10453. [PMID: 34056197 PMCID: PMC8153768 DOI: 10.1021/acsomega.1c00921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 03/29/2021] [Indexed: 06/12/2023]
Abstract
The design and performance of a custom-built reaction chamber combined with an acoustic levitator, a tunable monochromatic light source, and a Raman spectrometer are reported. The pressure-compatible reaction chamber was vacuum-tested and coupled with the acoustic levitator that allows contactless sample handling, free of contingent sample requirements such as charge and refractive index. The calibration and performance of the Raman spectrometer was studied utilizing gated detection and three different gratings that can be interchanged within seconds for a desired resolution and photon collection range. A wide range of 186-5000 cm-1 Raman shift, with a small uncertainty of ±2 cm-1, can be recorded covering a complete vibrational range in chemical reaction monitoring. The gating of the detector allowed operation under the room light and filtration of unwanted sample fluorescence. The in situ reaction perturbation and monitoring of physical and chemical changes of samples by the Raman system were demonstrated by degradation of polystyrene by monochromatic UV light and photobleaching of a potato slice by visible light. This instrument provides a versatile platform for in situ investigation of surface reactions, without external support structures and under controlled pressure and radiation conditions, relevant to various disciplines such as materials science, astrochemistry, and molecular biology.
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Affiliation(s)
- Beni B. Dangi
- Department of Chemistry, Florida
Agricultural and Mechanical University, Tallahassee, Florida 32307, United States
| | - Daniel J. Dickerson
- Department of Chemistry, Florida
Agricultural and Mechanical University, Tallahassee, Florida 32307, United States
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Basu S, Kabi P, Chaudhuri S, Saha A. Insights on drying and precipitation dynamics of respiratory droplets from the perspective of COVID-19. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2020; 32:123317. [PMID: 33746480 PMCID: PMC7976039 DOI: 10.1063/5.0037360] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 11/25/2020] [Indexed: 05/20/2023]
Abstract
We isolate a nano-colloidal droplet of surrogate mucosalivary fluid to gain fundamental insights into airborne nuclei's infectivity and viral load distribution during the COVID-19 pandemic. The salt-water solution containing particles at reported viral loads is acoustically trapped in a contactless environment to emulate the drying, flow, and precipitation dynamics of real airborne droplets. Similar experiments validate observations with the surrogate fluid with samples of human saliva samples from a healthy subject. A unique feature emerges regarding the final crystallite dimension; it is always 20%-30% of the initial droplet diameter for different sizes and ambient conditions. Airborne-precipitates nearly enclose the viral load within its bulk while the substrate precipitates exhibit a high percentage (∼80-90%) of exposed virions (depending on the surface). This work demonstrates the leveraging of an inert nano-colloidal system to gain insights into an equivalent biological system.
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Affiliation(s)
- Saptarshi Basu
- Department of Mechanical Engineering, Indian
Institute of Science, Bengaluru 560012, India
| | - Prasenjit Kabi
- Department of Mechanical Engineering, Indian
Institute of Science, Bengaluru 560012, India
| | - Swetaprovo Chaudhuri
- Institute for Aerospace Studies, University of
Toronto, Toronto, Ontario M3H 5T6, Canada
| | - Abhishek Saha
- Department of Mechanical and Aerospace
Engineering, University of California San Diego, La Jolla, California
92093, USA
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11
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Dbouk T, Drikakis D. On coughing and airborne droplet transmission to humans. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2020; 32:053310. [PMID: 32574229 PMCID: PMC7239332 DOI: 10.1063/5.0011960] [Citation(s) in RCA: 263] [Impact Index Per Article: 65.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Our understanding of the mechanisms of airborne transmission of viruses is incomplete. This paper employs computational multiphase fluid dynamics and heat transfer to investigate transport, dispersion, and evaporation of saliva particles arising from a human cough. An ejection process of saliva droplets in air was applied to mimic the real event of a human cough. We employ an advanced three-dimensional model based on fully coupled Eulerian-Lagrangian techniques that take into account the relative humidity, turbulent dispersion forces, droplet phase-change, evaporation, and breakup in addition to the droplet-droplet and droplet-air interactions. We computationally investigate the effect of wind speed on social distancing. For a mild human cough in air at 20 °C and 50% relative humidity, we found that human saliva-disease-carrier droplets may travel up to unexpected considerable distances depending on the wind speed. When the wind speed was approximately zero, the saliva droplets did not travel 2 m, which is within the social distancing recommendations. However, at wind speeds varying from 4 km/h to 15 km/h, we found that the saliva droplets can travel up to 6 m with a decrease in the concentration and liquid droplet size in the wind direction. Our findings imply that considering the environmental conditions, the 2 m social distance may not be sufficient. Further research is required to quantify the influence of parameters such as the environment's relative humidity and temperature among others.
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12
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Hasegawa K, Watanabe A, Kaneko A, Abe Y. Coalescence Dynamics of Acoustically Levitated Droplets. MICROMACHINES 2020; 11:E343. [PMID: 32224992 PMCID: PMC7231308 DOI: 10.3390/mi11040343] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/22/2020] [Accepted: 03/24/2020] [Indexed: 02/07/2023]
Abstract
The contactless coalescence of a droplet is of paramount importance for physical and industrial applications. This paper describes a coalescence method to be used mid-air via acoustic levitation using an ultrasonic phased array system. Acoustic levitation using ultrasonic phased arrays provides promising lab-on-a-drop applications, such as transportation, coalescence, mixing, separation, evaporation, and extraction in a continuous operation. The mechanism of droplet coalescence in mid-air may be better understood by experimentally and numerically exploring the droplet dynamics immediately before the coalescence. In this study, water droplets were experimentally levitated, transported, and coalesced by controlled acoustic fields. We observed that the edges of droplets deformed and attracted each other immediately before the coalescence. Through image processing, the radii of curvature of the droplets were quantified and the pressure difference between the inside and outside a droplet was simulated to obtain the pressure and velocity information on the droplet's surface. The results revealed that the sound pressure acting on the droplet clearly decreased before the impact of the droplets. This pressure on the droplets was quantitatively analyzed from the experimental data. Our experimental and numerical results provide deeper physical insights into contactless droplet manipulation for futuristic lab-on-a-drop applications.
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Affiliation(s)
- Koji Hasegawa
- Department of Mechanical Engineering, Kogakuin University, Tokyo 163-8677, Japan
| | - Ayumu Watanabe
- Graduate School of Systems and Information Engineering, University of Tsukuba, Tsukuba 305-8573, Japan
| | - Akiko Kaneko
- Faculty of Engineering, Information and Systems, University of Tsukuba, Tsukuba 305-8573, Japan
| | - Yutaka Abe
- Faculty of Engineering, Information and Systems, University of Tsukuba, Tsukuba 305-8573, Japan
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Alieva A, Boyes M, Vetter T, Casiraghi C. Selective polymorphism of α-glycine by acoustic levitation. CrystEngComm 2020. [DOI: 10.1039/d0ce00856g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
This work demonstrates the selective crystallisation of α-glycine from water and a binary solvent mixture by acoustic levitation.
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Affiliation(s)
- Adriana Alieva
- Department of Chemistry
- University of Manchester
- Manchester
- UK
| | - Matthew Boyes
- Department of Chemistry
- University of Manchester
- Manchester
- UK
| | - Thomas Vetter
- Department of Chemical Engineering and Analytical Science
- University of Manchester
- Manchester
- UK
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