The heat transfer performance of an ionic jet impinging on the upper surface of a heated plate is investigated. Ions are injected by a point, set at high voltage. The working fluid is the space-qualified coolant H-Galden ZT 85. Different tests are performed on the working fluid, varying the composition, the shape and the polarity of the point, the applied voltage, the point-to-plane distance and the imposed heat flux. The technique produces a heat transfer augmentation up to 230% with respect to thermogravitational convection and heat transfer coefficients as high as 1.07 kW/(m2K). The electrohydrodynamic enhancing effect is obtained with relatively low power input. The ionic flow has remained active for 750 hours of continuous monitored operation. The heat transfer performance of H-Galden ZT 85 under electric fields positively compares with dielectric liquids tested in previous experimental campaigns, such as FC-72, HFE-7100, Vertrel XF, and MIDEL 7131, and with water in pure natural convection.
Heat Transfer Promotion by Electric Fields in a Coolant for Spacecraft Thermal Control
TESTI, DANIELE
2010-01-01
Abstract
The heat transfer performance of an ionic jet impinging on the upper surface of a heated plate is investigated. Ions are injected by a point, set at high voltage. The working fluid is the space-qualified coolant H-Galden ZT 85. Different tests are performed on the working fluid, varying the composition, the shape and the polarity of the point, the applied voltage, the point-to-plane distance and the imposed heat flux. The technique produces a heat transfer augmentation up to 230% with respect to thermogravitational convection and heat transfer coefficients as high as 1.07 kW/(m2K). The electrohydrodynamic enhancing effect is obtained with relatively low power input. The ionic flow has remained active for 750 hours of continuous monitored operation. The heat transfer performance of H-Galden ZT 85 under electric fields positively compares with dielectric liquids tested in previous experimental campaigns, such as FC-72, HFE-7100, Vertrel XF, and MIDEL 7131, and with water in pure natural convection.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
