Week Seven Update

Radiator Fin Construction

Since the size of the radiator fins could not be reliably calculated using mathematics, it was decided to use the size and shape of the radiator fins in the CAD model. It was also decided that the material for these fins -- aluminum-- should be used for its low price and relatively high thermal conductivity.

Figure 1: Cut out of the fins

Since the sheet aluminum is very thin, it was decided that attaching the fins to their pipe would be unrealistic and would not transmit enough heat to make a difference in the performance of the pipe. Therefore, it was decided to cut the fins two at a time. Two fins would be connected together and the bent into a "V" shape with a flat bottom. Several of these "V" shapes would then be attached to the pipe with thermal paste and held into place with epoxy. This attachment will be done next week. During this week, the fins will be cut, sanded, and bent into shape. 

Second Test

                                              Figure 2: Result of the 2nd test

The heat pipe underwent a second, more thorough test to determine its feasibility as a heat pipe. The results of this test would largely dictate if the project was heading in the right direction. The results, as shown above, show a steady increase in temperature on the respective ends of the pipe as time progressed. Most importantly, the increase in temperature readings on the condenser end of the pipe shows that there is indeed a transfer of heat from the evaporator end of the pipe to the condenser end of the pipe via the wick. This is the basis of the working of the heat pipe and as per the data collected, the project will prove to be a success.

Leakage

The result was of the pipe was not as it needs to be. The temperatures at the evaporator end and condenser end are too far apart. The reason for the condenser barely going up in temperature could very much be the leakage that happened during the test. 

Figure 3: Leaked water on the table after the test. 

As shown from figure 3, it is a bit blended into the background but there was a leakage from the pipe during the test. This is due to the brass cap not twisted tight enough. The thread on the pipe had a few layers of PTFE and the cap was twisted on with the wrench but it was not enough. 

As for conclusion, the team decided to add more PTFE layers and twist the cap on more tightly to make sure the the cap will be completely air tight. If the group could get the cap securely on, the result could be alter drastically. However, it could be that the leakage is not the main reason why the pipe does not work. This is not completely clear until this problem of the cap is fixed and tested for another time. If the water does not leak anymore but the pipe still does not work then the team has to try and diagnosed the problem.