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Week 4: Pre-Lab

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Some new design considerations were taken into account in order to test a proposed idea with smaller diameter heat pipes. After doing some basic research it was determined that capillary action has a greater effect the smaller your system gets. Larger diameter heat pipes will still experience capillary action but other factors such as gravity will have different effects on how the working fluid flows in the wick. The diagram in Figure 1 illustrates the proposed problem with larger diameter heat pipes compared to their smaller counterparts.
Figure 1: Large and Small Heat Pipe Capillary Force Comparison

By reducing the pipe diameter to half of Prototypes 1 and 2, capillary action should be able to happen more efficiently due to surface tension and lower liquid weight (less volume in a smaller pipe). Gravitational effects overcoming surface tension demonstrated in Figure 1 is why we believe that a smaller heat pipe would theoretically run more efficiently. Furthermore, as temperature goes up, the effects of surface tension goes down. Relating to larger heat pipes with wicks, a significant decrease in surface tension would be detrimental to the efficiency and function of the heat pipe during operation. Further into the term, the team will conduct efficiency tests at different temperature ranges to hopefully demonstrate that principle.
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