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Experimental Analyses of Internal Pressure and Temperature Measurements in an Annular Wrapped Screen Wick Heat Pipe
Abstract
In this study, an investigation was conducted to characterize the flow behavior of a wrapped screen wick annular heat pipe, using distilled water as the working fluid. To achieve the experimental outcomes, high-resolution pressure transducers, optical fiber distributed temperature sensors (OFDTS), and K-type thermocouples were employed to measure the internal and external temperatures as well as the local static pressures at different axial positions of the heat pipe. The heat pipe was tested at multiple orientations with respect to the horizon (θ = 0◦, 45◦, and 90◦), heat loads (25 W, 50 W, and 75 W), and condenser coolant temperatures (Tw,in = 10◦C, 20◦C, and 30◦C). Temporal and frequency analyses using one-dimensional continuous wavelet transform (CWT) was performed on the differential pressure experimental data to characterize flow behavior and infer the flow regime occurring within the heat pipe. The Lockhart-Martinelli correlation was used to estimate the vapor-phase flow friction factor for multiple vapor Reynolds numbers. This study provides critical experimental data and analyses for complex two-phase flow behavior for an annular wick heat pipe geometry. The experimental results characterize internal vapor core and external surface temperatures, orientation-dependent start-up times, and pressure and temperature transient response. The thermal resistance and effective thermal conductivity were estimated as a function of the heat pipe orientation and operating condition. The results of this study provide a valuable database that supports the advancement of heat pipe modeling and validation.
Citation
Orea, Daniel (2023). Experimental Analyses of Internal Pressure and Temperature Measurements in an Annular Wrapped Screen Wick Heat Pipe. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /199195.