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Week 3

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During week 3, the team built and tested the first two prototypes of the heat pipe. The construction of the heat pipes was straightforward as these two prototypes had very little complexity to them. A process of rapid prototyping was utilized to come up with two working devices that would be able to obtain useful data for quick design iterations. Below are two construction photos of the first heat pipe. The first image shows the interior mesh used as a wick and the bottom picture is the crimped pipe end before soldering.
A detailed construction log can be viewed on the Heat Pipe Fabrication page.

Testing
The testing involved using a clamp to hold the pipe in place while hot air was applied to one of the ends of the pipe. Two thermocouple probes were used to measure the change in temperature of the ends of the heat pipe over time. A picture of the apparatus used is shown below:

The results for the first prototype show that it was relatively inefficient, due to the fact that not much acetone fluid was inside the pipe. More fluid will be included in future prototypes to produce better results. Trial 1 was conducted in a horizontal orientation while Trial 2 was conducted at an angle. This was to examine if orientation had an effect on the efficiency. A table of the results in two trials is shown below:
Temperature 1 represents the evaporator end of the heat pipe and temperature 2 is the condenser end.

The results for the second prototype show that it was more efficient as more acetone was added to the inside of the pipe. The results for the second prototype are shown below:
Since a substantial improvement was observed with the second prototype, the team decided not to run a test in the angled orientation because the first test proved that heat pipe design and functionality was heading in the proper direction. 

Data Analysis:
Condensing the raw data into plots allows the function of the heat pipe to be visualized. Graphs 1 and 2 represent the three initial trial runs for the heat pipe prototypes.
Graph 1:

Graph 2:
The two graphs demonstrate the inefficiencies of the first two heat pipe prototypes but show increasing performance between the two. The first tests of prototype 1 show that over the course of 240 seconds there was only an increase of 10 degrees over two trials in the horizontal and angled orientations. Prototype 2 was capable of a temperature increase of 24 degrees over the same interval. Comparing the efficiencies of the two heat pipes, Prototype 2 had a 140% increase in performance over Prototype 1, a massive improvement. There was no change to the construction methods between Prototype 1 and 2 but acetone filling was altered on Prototype 2. The original method was to vaporize some of the acetone and then quickly seal off the end with solder. On the first attempt, an estimated 50-75% of the acetone was lost due to overheating which would severely hamper the heat pipe's ability to transfer heat. The filling and heating process on Prototype 2 was changed to limit this loss. The data proves that the new method works in practice.We were able to conduct all of our week 3 goals to expedite the heat pipe design and testing  allowing the team to narrow on the most effective heat pipe design with the highest performance that can be achieved.  
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