01whole.pdf (1.25 MB)
Download file

On the enhancement of biodiesel droplet vaporisation using electrostatic charge

Download (1.25 MB)
thesis
posted on 28.03.2022, 16:03 by Ahmed Tushar
An electrostatic atomiser is an energy-efficient device that can be used to promote theatomisation of highly viscous fluids, for example biodiesel. It imposes an electrical chargeonto the liquid that creates enough Coulombic repulsive force to lower the surface-tensionforce of the liquid and result in atomisation.In this study, the vaporisation of electrically charged fatty-acid methyl-ester (FAME)droplets are reported as a function of the initial charge density, ambient temperature, anddroplet Reynolds number. Existing data from a direct numerical simulation (DNS) of chargeinjection are also post-processed to better understand the physics of electro-convection as afunction of the average bulk-flow velocity and the electrical Rayleigh number.The model predictions are assessed by comparing with experimental results, and themaximum deviation in evaporation time is reported to be 13.6% for C12:0. The effectof charge increases with increasing initial charge density and decreases at high ambient temperatures, while the droplets Reynolds number shows a mixed effect. The DNS dataprocessing reveals that the developed electro-convective instabilities force the liquid into aroll-like structured motion and in a high-flow-rate atomiser, higher instability could maximisethe amount of charge in the middle of the domain.

History

Table of Contents

Acknowledgements -- Nomenclature -- Abstract -- List of Publications -- List of Figures -- List of Tables - 1 Introduction -- 2 Literature Review -- 2.1 Introduction -- 2.2 Evaporation models for a single biodiesel droplet -- 2.2.1 Biodiesel as a single-component fuel -- 2.2.2 Biodiesel and its constituent components -- 2.3 Electrostatic atomiser -- 2.4 Chapter summary -- 3 Methodology -- 3.1 Introduction -- 3.2 Model formation -- 3.2.1 Assumptions -- 3.2.2 The governing equations -- 3.2.3 Fuel Properties -- 3.3 Solution approach -- 3.4 Evaporation of charged droplet -- 3.4.1 Charge-only case -- 3.4.2 Charge and combustion case -- 3.5 Chapter summary -- 4 Results and Discussion 4.1 Introduction -- 4.2 Model validation -- 4.3 Model predictions -- 4.3.1 Effect of initial charge density -- 4.3.2 Effect of ambient temperature -- 4.3.3 Effect of Reynolds number -- 4.4 Chapter summary -- 5 EHD flow inside the atomiser -- 5.1 Introduction -- 5.2 Theoretical study -- 5.3 Governing equations -- 5.4 Charge distribution analysis -- 5.4.1 Effect of electrical Rayleigh number (T) -- 5.4.2 Effect of average bulk-flow velocity (Uav) -- 5.5 Chapter summary -- 6 Conclusions and future work -- 6.1 Introduction -- 6.2 Main Findings -- 6.2.1 The effect of charge on FAMEs' droplet vaporisation -- 6.2.2 The charge distribution between the electrodes -- 6.3 Future work --A Appendix -- References

Notes

Theoretical thesis. Bibliography: pages 65-70

Awarding Institution

Macquarie University

Degree Type

Thesis MRes

Degree

MRes, Macquarie University, Faculty of Science and Engineering, Department of Engineering

Department, Centre or School

Department of Engineering

Year of Award

2017

Principal Supervisor

Sammy Diasinos

Rights

Copyright Tushar Ahmed 2017. Copyright disclaimer: http://mq.edu.au/library/copyright

Language

English

Extent

1 online resource ( xx, 70 pages) illustrations, tables

Former Identifiers

mq:70778 http://hdl.handle.net/1959.14/1267641