Group 073-10: Efficient Heat Pipes for Small Scale Industrial/Commercial Applications

This week in lab the heatsink was turned on the lathe from 2" 6061-T5 aluminum round stock. The finished part deviated slightly from the plans as it was determined that it would be ineffective to build the entire part after a cutting tool failure led to one of the fins breaking. The finished part is composed of only 4 fins compared to the designed 16. A CAD model was drawn up with a drawing sheet to use while machining. Figure 1: Heatsink Drawing w/ Dimensions Other than the tool failure, the machining process when fairly smooth with the completion of a finished part.  Figure 2: Cutting off a blank in the Horizontal Band Saw  Figure 3: Facing the part Figure 4: Fin cutting with a 1/16" parting tool Some tests of the finalized heat pipe were also run this week, it was tested with water and again with acetone. During the test, at about 450 s, the heater at the evaporator end was turned up to a higher setting, because a possible reason for the inefficiency o

This week in lab the team finished the construction of the final heat pipe design and was able to find a vacuum pump to test how a heat pipe would perform under vacuum. Unfortunately, the results were not promising as the new heat pipe did not nearly work as it was expected to. For the final heat pipe, one end is closed, while the other end is equipped with a valve, as shown below, that can be used to add working fluid and connect to the vacuum pump to create vacuum. After the air is pumped out, the heat pipe is tested with acetone and with water as working fluids. The result is not as well as expected. More experiments will be conducted on this heat pipe next week. The results of the experimentation done are shown below:

This week in lab, the team worked on some more testing and the construction of our final iteration of the heat pipe. A specially designed bushing had to be machined to accept the threads of the 1/8" NPT ball valve. This bushing was then soldered into the copper tube. Another angled test of Prototype 2 was conducted to compare the results from the previous tests. The data is shown below: The graph of this data is shown below: The fluctuation of T1(the temperature at the evaporating end) may be partially due to experimental error. Otherwise, this prototype performed as expected.

This week the team worked on finishing the CAD model for the heat pipe and ran simulations for the heat pipe and condenser. The model represents the heat transfer expected through the heat pipe and condenser. Some finished drawings are also provided with dimensions. Figure 1: Heat Pipe and Heat Sink Assembled Figure 2: Heat Sink Component Figure 3: Thermal Analysis of the Main Body of the Heat Pipe

The team conducted some more tests on Prototype 2 as it was the best performing heat pipe constructed thus far. The test was conducted in the angled orientation as Prototype 2 hadn't been tested in that configuration yet. The results were promising as Prototype 2 exceeded expectations and transferred heat effectively throughout the test. The condenser end increased by 52 degrees over 300 seconds which was an improvement over the horizontal test conducted with Prototype 2. In both tests, the difference between the condenser temperature and the evaporator temperature was calculated and displayed on the graphs. The graph below shows the first test for Prototype 2. To verify our results the test was run a second time but for a longer period of time in order to narrow down on where the heat pipe's maximum operating temperature would be. The results are shown below. For Prototype 2, the effective temperature limit of the heat pipe can be approximated to 125 F without a hea

It was realized during the testing in Week 4 that a significant design change was required in order to boost the function of the heat pipe. The team assumed that a smaller diameter pipe would improve working fluid circulation at higher temperature values but it was soon discovered that this was not necessarily true. Our results showed a decreased performance with smaller pipe diameters and longer heat pipe lengths. To combat this issue, a redevelopment of the heat pipe design is necessary. One of the vital pieces of a heat pipe is that the interior is in a partial vacuum or the pipe is completely evacuated of air allowing for maximum working fluid circulation. This important component in the design of a heat pipe gives it its function to rapidly disperse heat from one end to the other. As demonstrated in this video . Future heat pipe designs are going to utilize a method to evacuate air from the pipe to provide a near vacuum. The vacuum is essential to higher efficiency heat pipes in a