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Dr. Seamus O'Shaughnessy
Ussher Assistant Professor, Mechanical & Manuf. Eng

Biography

I am a Mechanical Engineer with over 11 years research experience in the field of fluid mechanics and heat transfer. I graduated with first class honours from the Dept. of Mechanical & Manufacturing Engineering in Trinity College Dublin in 2006 before pursuing a PhD, during which I studied a form of natural convection termed thermocapillary or Marangoni convection. I used a combination of analytical, numerical, experimental and computational techniques to validate my research findings, which have been published in several peer-reviewed journals.

In 2010 I was appointed to the role of Research Fellow in TCD, and since then I have been working on a variety of research projects, many of which involve collaborations with industry partners on interdisciplinary topics, such as an investigation of novel methods of cooling biomedical grade polymers during machining processes. Since 2011, my main research focus has been on energy and sustainable international development. My research team is involved in a project in Malawi which aims to bring off-grid electricity to those in the developing world by using the waste heat produced during cooking. Termed the muPower TEG-Stove, this research is in its 8th year and growing.

In September 2016 I began my role as Ussher Assistant Professor in Energy & Sustainable International Development. I am currently working towards establishing new international development energy-related projects in countries such as Benin and Tanzania.

A key focus of my research is the thermal management of the batteries used in electric vehicles, which is investigated through the use of pulsed liquid flows and two-phase mechanisms of boiling and condensation.

Publications and Further Research Outputs

Peer-Reviewed Publications

Merienne, R., Lynn, J., McSweeney, E., O'Shaughnessy, S.M., Thermal cycling of thermoelectric generators: The effect of heating rate, Applied Energy, 2019, p671-681 Journal Article, 2019 TARA - Full Text DOI URL

M.J. Gibbons, G. Saccone, S.M. O'Shaughnessy, A.J. Robinson, P. Di Marco , Local convective heat flux to evaporating water droplets in micro-g to 2-g, 13th International Conference on Two-Phase Systems for Space and Ground Applications, Xi'an, China , October 15th-19th, 2018 Conference Paper, 2018

O'Shaughnessy, S.M. and Sloane, A. and Kearns, A. and Byrne, G. and Trimble, D. and O'Donnell, G.E., Design, characterisation and performance evaluation of a Peltier-driven cryo-adhesive fixture for manufacturing operations, Materials and Design, 141, 2018, p99-109 Journal Article, 2018 DOI URL

S.M. O'Shaughnessy, A. Mooney, S. G. Yates, D.M. Murray, Natural convection from a triangular array of isothermal horizontal cylinders - a combined experimental and numerical investigation, 16th International Heat Transfer Conference (IHTC-16), Beijing, China, August 10th - 15th, 2018 Conference Paper, 2018

M.J. Deasy, S. M. O'Shaughnessy*, L. Archer, A.J. Robinson, Electricity Generation from a Biomass Cookstove with MPPT Power Management and Passive Liquid Cooling, Energy for Sustainable Development, 43, 2018, p162 - 172 Journal Article, 2018 URL TARA - Full Text DOI

G. Byrne, S.M. O'Shaughnessy, Performance Characteristics and Exhaust Gas Analysis of a Diesel Engine using Biodiesel Fuel Blends, Biofuels, 2017 Journal Article, 2017 DOI URL

M.J. Deasy, N. Baudin, S. M. O'Shaughnessy, A.J. Robinson, Simulation-Driven Design of a Passive Liquid Cooling System for a Thermoelectric Generator, Applied Energy, 205, 2017, p499 - 510 Journal Article, 2017 DOI URL TARA - Full Text

S. M. O'Shaughnessy, A. Sloane, A. Kearns, G. Byrne, D. Trimble, G. E. O'Donnell, Design, characterisation and preliminary performance evaluation of a Peltier-driven cryo-adhesive fixture for manufacturing operations , Materials & Design, 141, 2017, p99 - 109 Journal Article, 2017 TARA - Full Text DOI URL

A. Mooney, S.M. O'Shaughnessy, A Computational Fluid Dynamics (CFD) Investigation of Natural Convection from a Triangular Array of Isothermal Horizontal Cylinders, 34th International Manufacturing Conference, Insitute of Technology Sligo, Ireland, 30th August 2017, 2017 Conference Paper, 2017

K.J. Brown, R. Farrelly, S.M. O'Shaughnessy, A.J. Robinson, Energy Efficiency of Electrical Infrared Heating Elements, Applied Energy, 162, 2016, p581 - 588 Journal Article, 2016 TARA - Full Text DOI URL

Seamus M O'Shaughnessy, Maurice Deasy; Vincent Doyle; Anthony Robinson, Performance analysis of a prototype small scale electricity-producing biomass cooking stove, Applied Energy, 156, 2015, p566 - 576 Journal Article, 2015 URL TARA - Full Text DOI

S. M. O'Shaughnessy, M.J. Deasy, V. Doyle, A.J. Robinson, Adaptive Design of a Prototype Electricity-Producing Biomass Cooking Stove, Energy for Sustainable Development , 28, 2015, p41 - 51 Journal Article, 2015 TARA - Full Text DOI URL

C.E. Kinsella, S.M. O'Shaughnessy, M.J. Deasy, M. Duffy, A.J. Robinson, Battery Charging Considerations in Small Scale Electricity Generation from a Thermoelectric Module, Applied Energy, 114, 2014, p80 - 90 Journal Article, 2014 URL DOI TARA - Full Text

S. M. O'Shaughnessy, M.J. Deasy, J.V. Doyle, A.J. Robinson , Field Trial Testing of an Electricity-Producing Portable Biomass Cooking Stove in Rural Malawi, Energy for Sustainable Development, 20, (1), 2014, p1 - 10 Journal Article, 2014 URL DOI TARA - Full Text

S.M. O'Shaughnessy, A.J. Robinson, Convective heat transfer due to thermal Marangoni flow about two bubbles on a heated wall, International Journal of Thermal Sciences, 78, 2014, p101 - 110 Journal Article, 2014 URL DOI TARA - Full Text

O'Shaughnessy, S.M., Robinson, A.J., Heat transfer near an isolated hemispherical gas bubble: The combined influence of thermocapillarity and buoyancy, International Journal of Heat and Mass Transfer, 62, (1), 2013, p422-434 Journal Article, 2013

S.M. O'Shaughnessy, A.J. Robinson, Heat Transfer near an isolated gas bubble: The Combined Influence of Thermocapillarity and Buoyancy, International Journal of Heat & Mass Transfer, 62, 2013, p422 - 434 Journal Article, 2013 TARA - Full Text URL DOI

S.M. O'Shaughnessy, M. Deasy, C. Kinsella, V. Doyle, A.J. Robinson, Small Scale Electricity Generation from a Portable Biomass Cookstove: Prototype Design and Preliminary Results, Applied Energy, 102, (0), 2013, p374 - 385 Journal Article, 2013 DOI URL TARA - Full Text

Seamus M O'Shaughnessy, Anthony Robinson, The μPower Stove Generator, National Research Dissemination Conference, Lilongwe, Malawi, 16/05/12, 2012 Conference Paper, 2012

O'Shaughnessy, S.M., Robinson, A.J., The Influence of the Magnitude of Gravitational Acceleration on the Marangoni Convection about an Isolated Bubble under a Heated Wall, Heat Transfer Engineering, 30, (13), 2009, p1096 - 1107 Journal Article, 2009 DOI TARA - Full Text URL

O'Séhaughnessy, S.M., Robinson, A.J., The influence of the magnitude of gravitational acceleration on marangoni convection about an isolated bubble under a heated wall, Heat Transfer Engineering, 30, (13), 2009, p1096-1107 Journal Article, 2009

S. M. O'Shaughnessy, A. J. Robinson, Numerical investigation of bubble-induced marangoni convection, Interdisciplinary Transport Phenomena: Ann. N.Y. Acad. Sci, 1161, 2009, p304 - 320 Journal Article, 2009 DOI TARA - Full Text URL

O'Shaughnessy, S.M., Robinson, A.J., Numerical Investigation of Bubble Induced Marangoni Convection: Some Aspects of Bubble Geometry, Microgravity Science and Technology, 20, (3-4), 2008, p319 - 325 Journal Article, 2008 DOI TARA - Full Text URL

O'Shaughnessy, S.M., Robinson, A.J., Numerical Investigation of Marangoni Convection around a Bubble, ICHMT International Symposium on Advances in Computational Heat Transfer, Marrakech, Morocco, May 11-16, 2008, 2008 Conference Paper, 2008

Seamus M. O'Shaughnessy, Anthony J. Robinson, Numerical Investigation of Bubble Induced Marangoni Convection: Influence of Bubble Size and Shape, Third International Topical Team Workshop on Two-Phase Systems for Ground and Space Applications, Brussels, Belgium, September 10-12, 2008 Conference Paper, 2008

Non-Peer-Reviewed Publications

Irish times, Irish invention is giving people in Malawi the power they need, 2015, - Miscellaneous, 2015 URL

Engineers Ireland, TCD/Irish Aid project looking to shine some light in the developing world, 2015, - Miscellaneous, 2015

BBC World News, This is how to charge your phone with a mud oven, 2015, - Miscellaneous, 2015 URL

Sunday Business Post, TCD generator brings electricity to Malawi's poor, 2013, - Miscellaneous, 2013

Seamus M O'Shaughnessy, Off Grid Electricity for the Developing World, TCD Research Showcase 2011, Trinity College Dublin, 2011 Oral Presentation, 2011

Seamus M O'Shaughnessy, Anthony Robinson, Bubble Induced Marangoni Convection, Sir Bernard Crossland Symposium, University of Limerick, Ireland, 2008 Poster, 2008

Research Expertise

Description

I am particularly interested in the the development of sustainable and renewable energy processes for international development and I am currently involved in several projects in this area, including but not limited to Photo-voltaic, Thermoelectric, and Heat Pump technologies. I also have much experience in thermal management of electronics using single and two-phase flows, as well as passive and forced convective methods, and my current projects in this field focus on battery thermal management for electric vehicles, dual jet cooling and enhanced heat transfer using pulsed flow. My research spans the following areas: Renewable energy, Sustainable development, Fluid mechanics, Heat transfer, Electric vehicles, Thermo-electricity, Thermo-capillary flows, Thermal interface materials, Boiling, Bubble dynamics, Two-phase flows, Peltier cooling, Electronics cooling, Heat transfer in manufacturing, Human power devices, Solar power for off-grid development, Human centred design

Projects

  • Title
    • A Novel Method for the Thermal Management of Electric Vehicle Batteries
  • Summary
    • The transport sector is currently undergoing massive change as battery-powered Electric Vehicles (EV) are being rapidly developed to replace fossil fuels for use in sustainable urban and inter-city transport, short-haul aviation and marine applications. The environmental and public health impact of this strategy is clear: the transport sector is currently responsible for roughly 25% of European greenhouse gas emissions, whereas EV produce no harmful local exhaust emissions during operation. Within the automotive industry, the push towards EV is supported by an ever-increasing number of manufacturers, each vying for their share of a market which is growing by 11% annually and expected to be worth ~$130 billion by 2022. The vision for an Electric Vehicle future is also shared by many governments; following on the heels of a French Government declaration, the UK Government revealed intentions to ban all new petrol and diesel cars and vans from 2040. A similar strategy has been suggested in the Irish Government's National Mitigation Plan. Public policy towards EV is encouraging, but the reality is that most consumers still do not trust EV technology. As of 31/12/17, EV represented just 0.11% and 0.1% of vehicles on Irish and UK roads, respectively. Clearly, consumer adoption of EV will need to increase dramatically if government targets are to be realised. To do this, substantial improvements in the technology are required. At the heart of every EV is the rechargeable battery which is by far the largest single cost item. Regardless of the battery chemistry, every current EV technology is significantly hindered by the same thermal problems. This is because EV batteries are efficiently employed only within a specific, narrow temperature range: at high temperatures (>35°C) the batteries degrade rapidly and at low temperatures (<15°C) the available power output and energy are radically reduced. An inability to maintain batteries within these limits during use also reduces driving range and lifespan. Thus, there is a critical need for innovation in this space, as traditional battery thermal management systems such as fans and blowers are wholly inadequate to meet the various long-term requirements of Electric Vehicles. In this research project, a novel battery cooling approach will be investigated. The method relies upon existing fundamental knowledge of multiphase heat transfer mechanisms (e.g. boiling, condensation) but is entirely innovative in their application. The approach will be bench-marked against existing market solutions and has the potential to become disruptive in the space.
  • Funding Agency
    • University of Dublin, Trinity College
  • Date From
    • 01 September 2019
  • Date To
    • 30 August 2023
  • Title
    • Dual Jet Cooling: An Experimental-Numerical Investigation and Optimisation Study
  • Summary
    • Dual jet flows are commonly encountered in waste water disposal into seas, rivers and water channels but such flow configurations are also relevant for convective cooling of electronic equipment, nuclear fuel rods and turbine blading. Thus, improved understanding of their behaviour has wide ranging potential from an energy efficiency and sustainability viewpoint. A jet flow occurs when a stream of fluid discharges into an ambient environment. An offset jet (Figure 1, Assoudi [4]) is one whose axis is parallel to but offset from the solid wall whereas a wall jet is generated when the jet flows tangentially along a solid wall. The proposed research involves a combined wall jet and offset jet, known as a dual jet configuration and also shown in Figure 1. The flow pattern shows that after issuing from two nozzles, the jets deflect towards each other, joining at the merge point with an interaction that continues up to the combined point. Downstream of the combined point, the two jets form a single wall jet. The detailed flow behaviour of dual jets depends on the geometry and inlet flow parameters. For example, it is known that in some conditions the flow field exhibits unsteady behaviour with periodicity, which is likely to influence the heat transfer behaviour. However, this issue remains substantially unexplored. Thus, the proposed work seeks to address this gap in knowledge. The proposed work will be investigated both experimentally and computationally. Advanced measurement techniques will be used to experimentally quantify the local and time resolved flow and heat transfer parameters. A novel and efficient computational method is proposed to explore and characterise the near wall flow structure of dual jet flow. The outcomes of the proposed research will be significant for optimisation of the heat transfer cooling rates associated with dual jet flows.
  • Funding Agency
    • Irish Research Council
  • Date From
    • 01 September 2019
  • Date To
    • 30 August 2023
  • Title
    • An Investigation of Pulsed Liquid Flow in Mini-channels
  • Summary
    • Pulsed flow has demonstrated higher heat transfer capacity compared to steady flow heat transfer. This project focuses on gaining a deeper understanding of the fluid properties and flow parameters that dictate the local heat transfer when employing pulsed liquid flow in small hydraulic diameter channels. Correlations will be developed for pulsed flow heat transfer in mini-channels for both laminar and turbulent flows, by employing experimental and computational techniques. Pulsed flow liquid heat transfer will then be evaluated as a mechanism for electric vehicle battery thermal management in response to typical and extreme battery charge and discharge conditions.
  • Funding Agency
    • University of Dublin, Trinity College
  • Date From
    • 01 March 2018
  • Date To
    • 28 February 2022
  • Title
    • TEMPER - Thermally Energised Magnetic Pump for Energy Recovery
  • Summary
    • This project investigates the use of magnetism to aid in energy recovery for heat-pump like devices. Details of this project are subject to a non-disclosure agreement.
  • Funding Agency
    • Enterprise Ireland
  • Date From
    • 01 September 2019
  • Date To
    • 30 August 2021
  • Title
    • The Wanrou Stove Gemerator
  • Summary
    • An investigation into electricity generation, using thermoelectric generators, from stoves locally made in parts of Benin. The TEGs are cooled using completely passive means, relying only on natural convection. The TEGs are integrated into stoves that are part of a large scale carbon credit financing project. This project involves both private partners and investors, as well as local NGOs in Benin. The project began in April 2018 and field trials of the technology began in February 2019.
  • Funding Agency
    • Private industry funding
  • Date From
    • 01 April 2018
  • Date To
    • 31 March 2021
  • Title
    • Thermal Cycling of Thermoelectric Generators (TEGs)
  • Summary
    • Thermoelectric generators, or TEGs, are solid state devices that convert heat (temperature differences) directly into electrical energy through a phenomenon called the Seebeck effect. TEGs have recently been used in a variety of waste heat recovery applications, including with cooking stoves used in the developing world. For applications involving relatively steady-state conditions, thermoelectric module reliability is extremely high. However, thermal shocks and temperatures much higher than the desired operating range could cause structural failure of the thermoelectric elements. This limitation is a significant difficulty when designing a system for transferring waste heat from cooking stoves to thermoelectric elements, since temperatures may vary widely and frequently. The aim of this research study is to quantify the effects of thermal cycling on commercially available TEG modules.
  • Date From
    • September 2016
  • Date To
    • ongoing
  • Title
    • The Effect of Hydrophilic and Hydrophobic Surfaces on Condensation Heat Transfer
  • Summary
    • Condensation heat transfer is a common natural phenomenon. There are two modes of condensation: film condensation or dropwise condensation that can form on a condensation surface depending on surface properties. Heat transfer coefficients tend to be higher with dropwise condensation (up to 5.5 times greater than film condensation). Modifications will be made to condensation surfaces as a method to enhance two-phase heat transfer for many applications. An experiment is designed to study the condensation heat transfer of pure steam over hydrophilic and hydrophobic surfaces. The heat transfer coefficient, heat flux and the mode of condensation as a function of sub-cooling temperature on different surfaces were analysed to understand the effects of wettability.
  • Date From
    • September 2018
  • Date To
    • ongoing
  • Title
    • A Computational Fluid Dynamics Investigation of Natural Convection from a Triangular Array of Isothermal Horizontal Cylinders
  • Summary
    • Natural convection heat transfer occurs when the fluid motion is caused by buoyancy forces that are induced by density differences due to the variation of temperature in the fluid. This type of heat transfer depends on the geometry, orientation and roughness of the surface and the temperature difference between the fluid and the surface. Some applications that make use of natural convection are water heating systems, ventilation systems and power transmission cables. For the case of heated horizontal cylinders, the heat that is transferred from the surface of the cylinders results in the formation of both thermal and velocity boundary layers adjacent to the surface of the cylinder. This boundary layer flow is caused by the density difference related to the large temperature gradient that exists between the heated fluid and the surface of the cylinder. Most of the studies focusing on natural convection heat transfer from isothermal horizontal cylinders have been conducted on a single cylinder. Further research has been conducted with a focus on cylinder pairs and columns. For the case of three isothermally heated horizontal cylinders, some experimental research has been conducted but only for equilateral triangular formations. This numerical study investigates the effects of natural convection heat transfer and fluid flow from a triangular array of isothermal horizontal cylinder contained within an infinite fluid medium. Applications that incorporate natural convection as the primary mode of heat transfer for an array of cylinders include electrical wires and heating elements. The overarching objective of this research is to develop a Computational Fluid Dynamics (CFD) model to investigate the buoyancy-driven fluid flow and associated heat transfer for three isothermally heated cylinders in an equilateral arrangement and to compare the numerical predictions with previous experimental research. The CFD model focusses on the interaction between the buoyant plumes of the triangular array of cylinders and the relationship between unsteady fluid flow and heat transfer enhancement. The results of the three-cylinder simulations are compared with both experimental and computational data for the single cylinder case.
  • Date From
    • 01 September 2017
  • Date To
    • ongoing
  • Title
    • Development of a low-cost PV cell solar tracker for use in developing countries
  • Summary
    • Solar photovoltaic (PV) has been suggested as a means of mitigating the energy access problem in developing countries, but there are many obstacles to overcome before this becomes a reality. This research project aims to address the issue at a domestic household level by developing a low cost solar tracker for use with very small scale PV panel installations. A solar tracker is a device that orients a payload (such as a lens, mirror or solar panel) toward the sun. For flat-panel PV systems, trackers are used to minimize the angle of incidence between the incoming sunlight and a photovoltaic panel. This increases the amount of energy produced from a fixed amount of installed power generating capacity.
  • Date From
    • September 2016
  • Date To
    • ongoing
  • Title
    • The mPower Stove Generator
  • Summary
    • Approximately 2.5 billion people burn biomass as a primary energy source and this number is expected to grow to 5 billion by 2050. Half of those who burn biomass lack access to grid electricity. This study details the devel-opment of a prototype stove with integrated thermoelectric generator (TEG). A single thermoelectric module is utilised to convert a small portion of heat to electricity. The electricity produced is used to charge a single 3.3 Volt Li-ion battery and drive a low power fan, as well as some other auxiliary features. From experiments conducted using wood as a fuel source, a maximum TEG power output of 5.9W has been obtained. Over the course of three one hour-long experiments, 9Whrs of power was stored in the battery. Furthermore, the cooking performance of the stove has not been negatively impacted. Field trials have taken place in Malawi, Africa in Dec 2011 and July 2012.
  • Funding Agency
    • ICRSET & INTEL Enterprise Partnership, Irish aid
  • Date From
    • January 2011
  • Date To
    • ongoing
  • Title
    • Cryo-milling of biomedical grade polymers
  • Summary
    • This project is ongoing and currently funded by a large private industrial partner in collaboration with the Advanced Materials and Bio-Engineering Research centre (AMBER). Involves the investigation of novel methods for cooling polymer components undergoing manufacturing processes such as milling. The project has direct application in industry, with the project partner looking to implement a successful design into their production line immediately. Key responsibilities include CAD design, analytic and numerical modelling, experimentation and data acquisition, budget management, report generation and liaising with the industrial partner.
  • Funding Agency
    • Science Foundation Ireland
  • Date From
    • July 2015
  • Date To
    • August 2016
  • Title
    • Solid State Thermal Interface Material
  • Summary
    • Funded by Science Foundation Ireland and in conjunction with the Centre for Research on Adaptive Nanostructures and Nano-devices (CRANN), this project involves the design and testing of novel solid state thermal interfaces. Key responsibilities include experimental rig design and construction, LabVIEW instrument control and data acquisition, and data analysis.
  • Funding Agency
    • Science Foundation Ireland
  • Date From
    • March 2014
  • Date To
    • July 2016
  • Title
    • The Ice Clamp
  • Summary
    • Workholding and fixturing is a critically important aspect of manufacturing that has direct implications for the quality of the manufactured component during processing as well as a direct impact on the cost of the component. The field of workholding is mature with numerous techniques employed, mostly using contact pressure, but also using magnetics and adhesives. Looking to nature for inspiration presents us with the use of ice as a mechanism for adhesion, referred to as cryo-adhesion. Cryo-adhesion offers some advantages over more traditional fixturing methods such as removing contact pressure and therefore reducing the dependence on the machining of complex, intricate bespoke fixtures. While the concept of ice adhesion is known, there is minimal research presented on the application of ice adhesion in manufacturing processes. This research reports on the development of a novel Peltier-based cryo-cooling fixture for workholding in manufacturing operations. The research provides insight into the main interactions that might be experienced in manufacturing type scenarios and presents preliminary findings on the cryo fixture's thermal and geometric characteristics, the use of the novel cryo fixture for holding various materials under tensile and shear loads, as well as a consideration of contact area and surface roughness on the cryo fixture performance.
  • Date To
    • ongoing
  • Title
    • Valve Feasibility Study
  • Summary
    • Funded by the Schuf Group and under the supervision of Dr Craig Meskell, this project involved the use of ANSYS CFX to quantify the effects of sudden valve closure on the properties of a multiphase fluid flowing through an oil pipeline.
  • Funding Agency
    • Schuf Group
  • Date From
    • March 2013
  • Date To
    • June 2013
  • Title
    • Thermal Cycling of Insulated Gate Bipolar Transistors (IGBTs)
  • Summary
    • The study was conducted for a multinational electronics company. The IGBTs were subjected to an accelerated lifetime test of 50,000 cycles, each cycle comprising approximately two minute long heating and cooling periods with large electrical currents and thermal gradients imposed. Key responsibilities included project management, experimental rig design and construction, extensive LabVIEW instrument control and data acquisition, data analysis and reporting to the industrial partner.
  • Funding Agency
    • Private
  • Date From
    • June 2012
  • Date To
    • November 2013
  • Title
    • Long-term Extreme Condition Storage of Insulated Gate Bipolar Transistors (IGBTs)
  • Summary
    • The effects of long-term storage of the IGBTs at high temperature, high humidity, and a combination of high temperature and humidity were investigated. Key responsibilities included the design and construction of a special pressurised chamber to achieve the required conditions, high-voltage/current experimentation and data analysis.
  • Funding Agency
    • Private
  • Date From
    • June 2012
  • Date To
    • November 2013
  • Title
    • Investigation of Bubble Induced Marangoni Convection
  • Summary
    • Thermal Marangoni convection about a 1mm radius air bubble situated under a heated wall of constant temperature immersed in a silicone oil layer (Pr = 220) of constant depth 5mm was experimentally investigated using a flow imaging technique known as particle image velocimetry, or PIV. The response to increasing temperature gradient and Marangoni numbers in the range 145≤Ma≤363 was investigated. For all experiments, steady-state convection was observed and primary, thermocapillary-driven vortices were seen to develop on both sides of the bubble, along with a jet-like flow of liquid from the bubble tip. Beneath these primary flow structures, secondary, slower-moving vortices were also observed, and these buoyancy-driven vortices rotated in opposite direction to the primaries. The results of the experiments were compared with numerical simulations and good agreement was observed. Two-dimensional axisymmetric simulations were conducted to investigate the influence of Marangoni number, Prandtl number and the magnitude of gravitational acceleration on the flow and temperature fields and ultimately their influence on local heat transfer. Simulations were carried out for Marangoni numbers in the range 0≤Ma≤915 under zero-gravity conditions. It was determined that the enhanced heat transfer penetrated a distance of approximately seven bubble radii along the hot wall, and four bubble radii along the cold wall. For the range of Marangoni numbers tested, a 20% improvement in the average heat transfer in the vicinity of the bubble has been calculated for the hot wall, and up to 90% for the cold wall. For a Marangoni number of Ma = 915, increasing the gravity level above a certain magnitude caused the formation of secondary vortices and a reduction in the effective radius and area of enhancement. Maximum enhancement occurred under zero-gravity conditions. The gravity level was also varied at different Marangoni numbers in the range 0≤Ma≤915. It was determined that at low temperature gradients and therefore low Ma, increasing the gravity level actually increased heat transfer, which contrasted the behaviour at higher values of Ma. It was postulated that when the Marangoni number was increased in the presence of gravity, the primary vortices lost some mechanical energy to the secondary vortices. The influence of Prandtl number was also investigated. It had been suggested by some authors that an inverse relationship between heat transfer enhancement and Prandtl number existed, but following the dimensionless solution obtained in this study, it has been concluded that the Prandtl number has little to no effect on the heat transfer. Three-dimensional numerical grids were constructed which included a second bubble. The spacing between the two bubbles was varied between simulations to analyse the influence of the separation distance between them. For zero gravity conditions, it was determined that the local wall heat flux was greatest for the smallest separation of three bubble radii, but that the increase in heat transfer over the whole domain was greatest for a separation of ten bubble radii. When the effects of gravity were included in the model, the behaviour was observed to change between the cases. At large separations between the bubbles, increasing the gravity level was found to decrease the local wall heat flux, which was consistent with much of the two-dimensional work. At small separations however, the increase in gravity led to an increase in the local wall heat flux, which was caused by a buoyancy-driven flow formed by the interaction of secondary vortices.
  • Funding Agency
    • IRCSET
  • Date From
    • October 2006
  • Date To
    • October 2010

Keywords

Applied thermodynamics and energy; BIOMASS ENERGY; Combined Heat and Power Systems; Computer aided engineering; Control Engineering; convective heat transfer; COOLING; Cooling of Manufacturing Processes; Design Engineering; Direct Energy Conversion; Electronic circuit design; Electronic Cooling Techniques; Electronics Cooling; Emission; Energy and Climate Change; Energy from biomass (see Forestry also); Energy from waste; Energy management system; Energy/Environmental Studies--Developing Coun; Environmental engineering; EVAPORATIVE COOLING; FLUID MECHANICS; Fluids and Heat Transfer; HEAT TRANSFER; Industrial Engineering; INFRARED, GENERAL; Integration of Renewable Energy Systems; International development; JET IMPINGEMENT HEAT TRANSFER; Manufacturing engineering; Renewable energies; Software Engineering; SOLAR ENERGY; Solar, Thermoelectric Conversion; Sustainable Development; Telecommunication Engineering; THERMAL ENERGY; Thermal Engineering; Thermoelectric Generators; THERMOELECTRIC-POWER; Thermoelectricity; TRANSIENT AND UNSTEADY HEAT TRANSFER; Two-phase Flow and Heat Transfer; WATER-IMMERSION COOLING

Recognition

Representations

I am a member of the technical committee for the HEFAT-2019 conference which will take place in July 2019.

Awards and Honours

Irish Research Council & Intel Corporation Postdoctoral Enterprise Partnership Scholarship 2011

1st Prize, Poster Presentation, Sir Bernard Crossland Symposium, University of Limerick 2008

Irish Research Council (formerly IRCSET) Embark Postgraduate Research Scholarship 2006