Effects of the electric Kelvin force on spray cooling performance

Effects of Contact Charging on Spray Impingement Heat Transfer Performance and Spray Behavior

“…Spray cooling performance results for the present apparatus without electrical body force effects have been presented by Hunnell (2005) and by Hunnell et al (2006) under conditions of terrestrial gravity for both vertically-downward directed and horizontal sprays. Effects of the Coulomb force via inductive charging electrode designs (Law, 1978) have been described in the thesis by Kreitzer (2006), while effects of electrodes using the electric Kelvin force have been presented in the thesis by Glaspell (2006). The present results using the Coulomb force via contact charging are consistent with these earlier results.…”

“…Thus, it is expected that the length and time scales for the impacts of these large liquid ligaments or sheets with the heater surface should significantly influence the heat flux and especially CHF . Also, for both the previous electric Kelvin force electrode results (Glaspell, 2006) and the previous inductive charging Coulomb force results (Kreitzer, 2006), the heat flux enhancements that were observed occurred only when the EHD forces on the droplets were directed away from the heater surface, while for the present contact charging Coulomb force results, the EHD force is directed towards the heater. Thus, future work should focus on developing electrode geometries that will lead to EHD forces that are directed away from the heater surface.…”

“…The 3M Corporation dielectric coolant, FC-72 was used in these studies. An initial study of the use of the electric Kelvin force has been summarized in the thesis by Glaspell (2006) and by Kreitzer et al (2006). The use of the Coulomb force via inductive charging electrode designs (Law, 1978) is described in the thesis by Kreitzer (2006) and by Kuhlman et al (2007).…”

“…The use of the Coulomb force via inductive charging electrode designs (Law, 1978) is described in the thesis by Kreitzer (2006) and by Kuhlman et al (2007). Both the Kelvin force studies by Glaspell (2006) and the inductive charging Coulomb force work by Kreitzer (2006) used FC-72 and a second 3M dielectric coolant, HFE-7000. Also, both of these studies demonstrated small (order of 5-15%) but repeatable EHD enhancements in heat flux using HFE-7000.…”

“…Instead of using the coolant used in the AFRL work (FC-72; see Yerkes et al, 2006), a second dielectric coolant, HFE-7000, has been used due to its lower resistivity and higher dielectric constant . Detailed descriptions of the current apparatus have been given in the theses by Hunnell (2005), Glaspell (2006), and Kreitzer (2006). A schematic of the spray nozzle, heater surface, pedestal, and sump is shown in Fig.…”