Transient liquid movement in heat-pipe wicks

Thesis/Dissertation · Sat Dec 31 23:00:00 EST 1988

OSTI ID:6185642

Ambrose, J H

Transient liquid flow in porous wick materials is an important area in many types of heat transfer equipment, particularly heat pipes. During pulsed heat loading, significant gradients in saturation usually occur, and local drying of the wick may also occur. The continuous distribution of the saturation in the wick is modeled, where previous models had assumed a uniformly saturated structure. Solution of the liquid flow model requires that the saturation dependence of the capillary flow properties be known. These properties must be determined experimentally because of the complex geometry of the porous wick structures. An experimental study of the flow properties was performed for the case of multilayer mesh wicks. X-ray radiography was used to determine saturation distributions in the wicks for a variety of conditions. Capillary pressure and relative permeability were determined from independent experiments. These properties show predictable dependence upon the saturation and are well correlated using the equations developed from studies of granular porous media. A heat pipe with beryllium walls was designed and fabricated to allow transient saturation measurements in the wick during operation. The heat pipe was tested under pulsed loading conditions. Measurements of the internal temperatures were made to confirm operating conditions. Results of the transient liquid flow model compare favorably with the results from the heat pipe experiments. The saturation distributions predicted by the model for pulse heat loads of various magnitudes were compared with experimental results.

• Research Organization: Kentucky Univ., Lexington, KY (USA)
• OSTI ID: 6185642
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420400* -- Engineering-- Heat Transfer & Fluid Flow
ALKALINE EARTH METALS
BERYLLIUM
CAPILLARY FLOW
DESIGN
ELEMENTS
ENERGY STORAGE
ENERGY TRANSFER
FABRICATION
FLOW MODELS
FLUID FLOW
HEAT PIPE WICKS
HEAT PIPES
HEAT STORAGE
HEAT TRANSFER
INDUSTRIAL RADIOGRAPHY
MATERIALS
MATHEMATICAL MODELS
METALS
PERMEABILITY
POROUS MATERIALS
PRESSURE DEPENDENCE
SATURATION
STORAGE
TEMPERATURE DISTRIBUTION
TEMPERATURE MEASUREMENT
TRANSIENTS
X-RAY RADIOGRAPHY