The Influence of Flow Behavior on the Efficiency of a Passive Thermosiphon

Ian Bashor, Elizabeth Gifford


The influence of different flow behaviors was investigated experimentally on the efficiency of passive thermosiphons, which contain no moving parts. The thermosiphon, comprising a collector, reservoir, and interconnecting tubing, was instrumented with thermistors and flow meters to calculate the thermal efficiency of the collector. The location of the inlet and outlet of the collector, the orientation of the reservoir from vertical to horizontal, and the height between the outlet of the collector and the inlet of the reservoir (i.e., the hot leg height), were varied along with concomitant changes in flow behaviors to show the effect on collector efficiency. The thermal efficiency increased when the inlet and outlet on the collector were diagonally opposed, which resulted in more uniform flow throughout the collector based on thermal imaging. The efficiency also increased when quasi-steady flow was observed for the horizontal reservoir as compared to oscillatory flow observed with the vertical reservoir. Variations in the hot leg height did not have a large impact on the collector efficiency as long as the flow remained steady.


Thermo; Fluid; Thermosiphon; Passive; Flow; Behavior

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