DEMONSTRATION OF AN ELECTROSPRAY INJECTION SYSTEM

Year 2012, Volume: 2 Issue: 2, 13 - 19, 23.07.2016

Mahmut Can Karakaya M. Ragıp Abdullahoğlu Onur Tunçer Hüseyin Kızıl Levent Trabzon

Abstract

The use of liquid hydrocarbons as a chemical energy source is promising for the actualization of high energy density power sources in the near future. Electrospray injection method is a unique technique that provides equal droplet size distribution at very low flow rates. Therefore it is quite suited for the atomization of liquid hydrocarbon fuels in miniature energy conversion devices. This study reports the design and characterization of an electrospray system. First, the electrospray phenomenon is briefly discussed from an historical perspective. An experimental test rig is built and a proof-of-concept demonstration is provided. For the experiments methanol is used as the liquid fuel. Flow visualization is performed to identify the electrospray mode. Results suggest that a Taylor cone is cone formed when voltage is applied to the system. After a certain voltage threshold electrostatic forces overcome the surface tension forces and droplets begin to separate from the Taylor cone. For voltage values higher than 6 kV certain instabilities are observed. Starting voltage for the current configuration is measured to be 2.2 kV. This value is in close agreement the theoretical calculations which suggest that the starting voltage would be 2.5 kV. This 12% discrepancy can be attributed to experimental uncertainty. Flow rate from a single injector is found to be on the order of 2 ml/h. Therefore in order to utilize electrospray injection in practical power conversion devices manufacturing of high nozzle density multiplexed emitter arrays are needed

Keywords

Electrosprey, injection system

References

• Bocanegra R., Galan D. Marquez M., Loscertales I.G., Barrero A., (2005), “Multiple electrosprays emitted from an array of holes”, Journal of Aerosol Science, 36, 1387-1399
• Cloupeau, M. and Prunet-Foch, B. (1994), “Electrohydrodynamic spraying functioning modes: a critical Review”, Journal of Aerosol Science, 25, 1021.
• Deng, W., Klemig, J.F., Xiaohui,L., Reed, M.A., Gomez,A., (2007), “Liquid Fuel Microcombustor Using Microfabricated Multiplexed Electrosprey Sources”, Proceedings of the Combustion Institute, 31, 2239-2246.
• Deng, W., Waits, C.M., Morgan, B., Gomez, A., (2009), “Compact Multiplexing of Monodosperse Electrosprays”, Aerosol Science, 40, 907-918.
• Dole, M., Mach, L.L., Hines, R.L., Mobley, R.C., Ferguson, L.D., Alice, M.B., (1968), “Molecular Beams of Macroions”, J. Chem. Phys., 49, s. 2240-2247
• Fenn, J. B., Mann, M., Meng, C.K., Wong S.F., Whitehouse, C.M., (1989), “Electrospray Ionization for Mass Spectroscopy of Large Molecules”, Science, 246, 64-71
• Fernandez de la Mora, J. (1992),” The effect of charge emission from electrified liquid cones”, J. Fluid Mech. 243, 561–574.
• Fernandez de la Mora, J., Loscertales I. G. (1994), “The current emitted by highly conducting Taylor cones”, J. Fluid Mech., 260, 155-184
• Javorek A. (1998), “Main modes of electrohydrodynamic spraying of liquids”, Third International Conference on Multiphase Flow, Lyon, France. Retrieved from: http://www.imp.gda.pl/fileadmin/old_imp/ehd/lyon-98s.pdf
• Krpoun, R. (2009), “Micromachined Electrospray Thrusters for Spacecraft Propulsion” (Doctoral dissertation), École Polytechnique Fédérale de Lausanne
• Lozano P., Martinez-Sanchez M., (2003), “Studies on the Ion-Droplet Mixed Regime in Colloid Thrusters” (Doctoral dissertation), Massachusetts Instutude of Technology
• Macky, W. A. (1931), “Some investigations on the deformation and breaking of water drops in strong electric fields”, Proceedings of the Royal Society of London. Series A 133(822), 565–587.
• Smith, K. L., (2005), “Characterization of Electrospray Properties in High Vacuum with a View to Application in Colloid Thruster Technology”, (Doctoral dissertation), University of London
• Tang K., Lin Y., Matson D. W., Kim, T., Smith R.D., (2001), “Generation of Multiple Electrosprays using microfabricated emitter arrays for improved mass spectrometric sensitivity”, Anal. Chem., 73, 1658-1663
• Taylor, G. (1964), Desintegration of water drops in an electric field, Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences 280(1382), 383–397.
• Velasquez-Garcia, L. F., Akinwade, A. I., Martinez-Sanchez, M., (2006), A Micro-Fabricated Linear Array of Electrospray Emmiters for Thruster Applications, Journal of Microelectromechanical Systems, 15, 1260-1271
• Velasquez-Garcia, L. F., Akinwade, A. I., Martinez-Sanchez, M., (2006), “A planar array of micro-fabricated electrospray emitters for thruster applications”, Journal of Microelectromechanical Systems, 15, 1272-1280
• Valesques-Garcia BGLF, Akinwande, A., Martinez-Sanchez, M., (2008), Fabrication of a Fully Integrated Electrospray Array with Applications to Space Propulsion, 21st IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2008), 976-979.
• Zeleny, J. (1914), The electrical discharge from liquid points and a hydrostatic method to measure electric intensity at their surface, Phys. Rev., 3, 69–91