EXPERIMENTAL INVESTIGATION OF AN ELECTROSPRAY INJECTOR


Karakaya M. C. , Abdullahoglu R., Tunçer O. , Kızıl H. , Trabzon L.

ISI BILIMI VE TEKNIGI DERGISI-JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY, vol.34, pp.63-76, 2014 (Journal Indexed in SCI) identifier

  • Publication Type: Article / Article
  • Volume: 34
  • Publication Date: 2014
  • Title of Journal : ISI BILIMI VE TEKNIGI DERGISI-JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY
  • Page Numbers: pp.63-76

Abstract

Many devices can be produced in micro, even nano scales with the aid of MEMS technology. These devices' requirements are associated with their respective dimensions. For example, required thrust for the orbital control of a nano satellite is in the order of millinewtons, or the required droplet size for operating a small combustion system is only in the order of a few microns. These requirements dictate old methods to be put aside. Nevertheless, electrospray technique is quite suitable for such applications. This is a unique technique in the sense that it provides equal droplet size distribution at very low flow rates. Thus, electrospray injection is a rather proper choice for liquid hydrocarbon atomization in miniature energy conversion devices. In this study, electrospray theory is briefly described, and then design and characterization of an electrospray system presented and the effect of extractor electrode on electrospray behavior is discussed. Methanol and ethanol are used as dielectric liquids in the experiments. Glass capillary tube and insulin needle were used as conduits for electrospray injection with their respective radiuses of 0.1 mm and 0.23 mm respectively. Ratio between the liquid extractor voltages can be adjusted by means of a rheostat. Various extractor radius values and different extractor to capillary distances are examined during parametric study. Starting and ending voltages are measured for 3 mm and 3.8 mm extractor radius values. At the ending voltage the conical form of electrospray injection is altered such that the electrospray is not able to flow regularly. Starting and ending voltages increase in direct proportion to the increase of extractor to liquid voltage ratio. These results are consistent with the theory. Besides, measured starting voltage is quite similar to the calculated value. Only starting voltage was measured for 5.2 mm extractor radius. These results can be utilized for the design of multiplexed array of fuel emitters. Especially, ending voltage values provide an idea to designer in terms of maximum hole diameter on the extractor ring, which could be used in multiplexed electrospray systems.