Electrical Force Effects on Spray Cooling

Kreitzer, Paul J.; Glaspell, Shannon; Kuhlman, John M.; Mehra, Deepak; Gray, Donald D.

doi:10.4271/2006-01-3064

Cited by 5 publications

(3 citation statements)

References 17 publications

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“…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).…”

Section: Previous Workmentioning

confidence: 99%

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

Kreitzer

Kuhlman

Mehra

et al. 2007

39th AIAA Thermophysics Conference

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The effects of contact charging on the heat transfer performance of a full-cone spray of the dielectric coolant, HFE-7000, has been studied using a Thick Film Resistor (TFR) heater with an active surface area of 1.46 cm 2 at a nozzle-to-heater spacing of 13 mm. Tests have been conducted at coolant flow rates between 1.3 and 6.8 GPH (1.4 x 10 -6 to 7.1 x 10 -6 m 3 /s), for heater power ranging from 0 to 60 Watts, yielding heat fluxes between 0 and 400 kW/m 2 . Voltage levels applied to the brass spray nozzle to charge the spray range from 0 to 30 kV, using both negative and positive polarity.A dramatic change in the visual spray flow pattern is observed as the charging voltage exceeds approximately 15 kV in magnitude. Above this voltage, the spray changes from droplets and collections of clearly observable discrete sheets to what appears to primarily be a finer mist of smaller droplets between the spray nozzle and the heater surface. This is due to exceeding the Rayleigh limit for the maximum charge on the liquid droplets, resulting in electrostatic atomization to a smaller average droplet size. However, no significant change in the measured heat transfer performance is seen between the no voltage and the high voltage cases up to a maximum charging voltage of 30 kV.

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Section: Previous Workmentioning

confidence: 99%

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

Kreitzer

Kuhlman

Mehra

et al. 2007

39th AIAA Thermophysics Conference

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“…This limitation on applied voltage is necessary to prevent arcing due to the small clearance of only 2.5 mm between these electrode geometries and the heater, which is the nearest grounded metal surface. These data were initially presented by Kreitzer et al (2006).…”

Section: Electric Kelvin Force Experimentsmentioning

confidence: 99%

Electromagnetic Control of High Heat-Flux Spray Impingement Boiling Under Microgravity Conditions

Gray¹,

Kuhlman²,

Glaspell³

et al. 2007

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources. gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this cOllectioni of information, including suggestions for reducing this burden to Departnient of Defense. Washington Headquarters Services, Directorate for Information Operations and . 1215 Jefferson Davis Highway, Suite 1204, Arlington. VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information i it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)2. REPORT TYPE 14. ABSTRACT The primary goal of this project was to discover how to most effectively use electromagnetic forces to enhance spray impingement boiling heat transfer in microgravity (jg). This project was closely coordinated with the non-electromagnetic spray impingement boiling experiments conducted by Dr. Kirk L. Yerkes of the Air Force Research Laboratory (AFRL) . The West Virginia University (WVU) investigation of electrical body forces to enhance and control spray impingement boiling extended the AFRL research. The computational phase of the WVU project was based on the commercial multiphysics code CFD-ACE+, which was successfully modified to incorporate the Coulomb and electric Kelvin forces. DATES COVERED (From -ToWVU's ground-based experiments demonstrated for the first time that modest increases in heat transfer coefficient and Nusselt number can be achieved in spray impingement boiling by using electrical forces, thus confirming the fundamental hypothesis of this research.Further increases in heat transfer performance are likely to result from a better understanding of the relevant microphysics and better electrode designs. Experimental results have been used to estimate the time scales for various phenomena that occur in spray impingement boiling, which could lead to improved electrode designs. SUBJECT ABSTRACTThe primary goal of this project was to discover how to most effectively use electromagnetic forces to enhance spray impingement boiling in microgravity (ýLg). This project was closely coordinated with the non-electromagnetic spray impingement boiling heat transfer experiments conducted by Dr. Kirk L. Yerkes of the Air Force Research Laboratory (AFRL). The West Virginia University (WVU) investigation of electrical body forces to enhance and control spray impingement boiling extended the AFRL research. The computational phase of the WVU project was based on the commercial multiphysics code CFD-ACE+, which was successfully modified to incorporate the Coulomb and electric Kelvin forces. WVU's ground-based experiments demonstrated for the first time that modest increases in heat tra...

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“…Program participants have moved on to successful careers in aerospace engineering. Some have gone on to graduate school; two former MRT3 team members in particular have completed graduate degrees at WVU, working on spray cooling and continuing their reduced gravity flights through collaboration with a team of thermal researchers at the Air Force Research Laboratory in Dayton, Ohio [17][18][19] . From this information, we are convinced that students' participation in the NASA RGSFOP is extremely beneficial to both their personal and professional development.…”

Section: Lessons Learned and Benefits To Project Participantsmentioning

confidence: 99%