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T0006-P

Electric Field Effects on Pool Boiling Heat Transfer in Low-G Environments

PI: Jungho Kim, University of Maryland

Pool boiling is a highly effective mode of heat transfer allowing high heat flux levels driven by relatively small temperature differences between the heated wall and the liquid. In spite of its efficiency, cooling based on liquid-vapor phase change processes has not yet found wide application in aerospace engineering due to specific process uncertainties and related reliability problems associated with the low gravity environment. Even less is known about the impact of electric fields on heat transfer in boiling in microgravity and their potential for heat transfer enhancement under such conditions. The primary objective of the experiment is to determine the effect of electric fields on pool boiling in low-g.

Technology Areas (?)
  • TA03 Space Power & energy Storage
  • TA14 Thermal Management Systems
Problem Statement

Previous measurements have shown that heat transfer in boiling in microgravity can be higher than that in earth gravity at low wall superheats due to an increase in the number of nucleation sites on the surface, with a corresponding decrease in the critical heat flux. The measurements to date indicate that critical heat flux in microgravity under saturated conditions decreases to roughly 30% of that in earth gravity. Based on the remarkable improvements accomplished under terrestrial conditions, the use of electric fields to replace the gravitational body force shows great potential to increase the amount of heat that can be transferred from a surface in microgravity. This experiment describes work where local heat transfer is measured simultaneously at many points on the heater surface in an effort to determine how boiling heat transfer is affected by the missing gravity and as an additional parameter by the electric field.

Technology Maturation

N/A

Future Customers

NASA

Flight Experiment Objectives

Experiments will be carried out from the nucleate boiling regime through critical heat flux into the transition boiling regime. Heat transfer data will be obtained at various gas concentrations and/or bulk fluid subcooling levels with and without electric fields using a microheater array.

Payload Description

The primary rack (see below, left rack) contains a sealed chamber containing about three liters of n-perfluorhexane at 1 atm (boiling temperature is 56°C), a microheater array to measure heat transfer distribution during boiling, a rack of electronic feedback circuits, two 30 Hz video cameras, a computer, and a LCD display. All components are contained within a Vertical Equipment Rack (VER) provided by NASA and designed for use on the parabolic aircraft. The secondary rack (right) contains a high-voltage power supply for the electric field measurements, and a triple output power supply, and a 28 VDC power supply. The components are contained in an AMCO 50” Equipment Rack (AER) provided by NASA and qualified for parabolic aircraft flights.

Technology Details

  • Selection Date
    AFO1 (May 2011)
  • Program Status
    Testing Complete
  • Current TRL (?)
    N/A
    Successful FOP Campaigns
  • 1 Parabolic

Development Team

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