ENGR 103 - Spring 2016
Freshman Engineering Design Lab
Freshman Engineering Design Lab
“Heat Pipes”
Project Design Proposal
Date Submitted: April 06, 2016
Group Members {Palak Bhargava, pb494@drexel}
{Sally Cheng, sc3467@drexel.edu}
{Sally Cheng, sc3467@drexel.edu}
{Kyle Prekeris, kcp37@drexel.edu}
{Vinitha Punnoose, vmp56@drexel.edu}
Technical Advisor {John Speidel, jhs66@drexel.edu}
Abstract:
The motivation for this project is to build a sustainable, durable, cost efficient heat pipe that can withstand the temperature of 500oF. Goals include making the heat pipe withstand temperatures exceeding 500oF and completing the project in a timely manner. Technical challenges that are to be expected include understanding the subject of heat pipes, the calculations necessary to make a proper heat pipe, and the actual crafting of the heat pipe. These are also considered as the major tasks to be done for this project. Final deliverables include the actual heat pipe product, a final report, and an account of the progress of this project through a blog that will be constantly updated.
1. Introduction
The project’s purpose is to create an effective, yet cost efficient heat pipe. Constructing the heat pipe is an opportunity to strengthen engineering and design skills. The purpose of a heat pipe is to transfer “heat efficiently between two locations by using the evaporation and condensation of a fluid contained therein” (Reay). The liquid inside the heat pipe will absorb the applied heat so that it will eventually evaporate into a gas. The gas will expand towards the top, and the heat will pass through the pipe itself and release into the atmosphere. The remaining gas will then condense back into a liquid and will drop to the base of the pipe due to the force of gravity, where it will be prepared to repeat the entire process.
The project promises numerous learning objectives. One of the most important goals is to learn how to construct a heat pipe from its most basic components. Another goal is to comprehend the relationship between the material used to build the pipe and the liquid contained within the pipe, so that the process of transferring heat from one location to another will be better understood. Another learning objective is to understand and learn how to use the tools provided by Drexel University’s machine shop, so that the construction of the heat pipe will flow smoothly without any obstacles.
The project will consist of assembling component materials to design a heat pipe that will be able to endure the range of heat from 250oF – 500oF. A technical challenge that will be faced is designing the pipe in such a way that the inside of the pipe will be a vacuum with a liquid inside of it. Another challenge that will have to be overcome is making sure that the diameter of the pipe is only a few millimeters long.
The desired outcome of this project is to create a functional heat pipe that will be able to transfer heat from one location to another. With multiple test trials and helpful instruction from the experienced faculty members, an effective heat pipe will be constructed and therefore bring success to this undertaking.
2. Deliverables
The final deliverable will be a functioning heat pipe that will be effective in transferring heat from one location to another. The heat pipe will be tested throughout numerous trials, and the results will be used to improve the pipe. Another deliverable that will be submitted at the conclusion of the project is the final report, detailing the evolution of the entire design project. A completed blog will also be produced at the end, and this will provide information on the weekly activities that were fulfilled throughout the term of the design project.
3. Technical Activities
3.1) Purpose of Literature Study
The first and most important step before actually constructing the heat pipe is making sure that the concept of the function and creation of general heat pipes are fully understood. Literature study will aid in understanding the background information connected to heat pipes. Having a better understanding of the subject will avoid unnecessary errors or questions that may arise during the construction of the heat pipe.
3.2) Mechanical Design/Calculations
Before the actual construction of the heat pipe, a design of the heat pipe should and must be completed. The design will allow for a better visualization and understanding of what will be made. It will be a 3D model view of the heat pipe, with appropriate dimensions. An example of such a model is found in Figure 1. Another major task that will affect the project is doing correct calculations. The calculations should be accurate and precise so that the heat pipe will function without coming across any difficulties, and also to avoid errors that may lead to injuries and waste of materials. If the calculations for the heat pipe aren’t correct, then another heat pipe will have to be created, which demands more money and supplies. Therefore, it is best to be careful with the calculations in the beginning of the project.
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| Figure 1: Model Heat Pipe in Centimeters (not to scale) |
3.3) Construction/Materials
It is extremely important to create a list of the necessary supplies that need to be bought to construct the heat pipe. The materials must be bought or ordered in a timely manner, so that there won’t be any shipping or manufacturing delays. In order to actually create the heat pipe, assistance from Drexel University’s machine shop will be required. On that account, scheduled appointments must be made with those working at the machine shop to use necessary equipment that may involve safety training.
3.4) Testing
In order to create a functioning and good quality heat pipe, numerous test trials must be completed. The heat pipe should be tested more than once, so that the design of the pipe may be changed or improved, if necessary. Results of the trials will be recorded, so that one may see the overall improvement and evolution of the pipe. The findings from the trials will lead to a better engineered heat pipe that will perform well by the end of the project time period.
4. Project Timeline
Shown in Table 1 is a timeline outlined for the project that spans over a time period of ten weeks. To start, it is necessary that everyone has a decent solid understanding of the workings of a heat pipe to confirm or address any misconceptions. Calculations will begin to be formulated based on the findings of the background research, and will be implemented into the actual draft design throughout weeks two to five. Once these calculations are finalized, the parts will be ordered. While waiting for these parts to arrive, training required to use the machine shop will begin. Once the parts arrive, members will assemble the final product. Shipment of materials, machine shop training, and product assembling are done during weeks four through eight. Testing is to be done during weeks six to eight, which coincides with the assembling task. Multiple trials must be done to determine abnormalities or weaknesses connected to the constructed heat pipe. After an assembled final product has been successfully tested, a final report will be prepared during weeks eight through ten based on the data and results that are observed throughout the multiple trials.
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| Table 1: Design Proposal Timeline |
5. Facilities and Resources
Multiple resources will be utilized throughout the duration of this design project. Drexel University’s library database will be used to access journals and scientific publications to increase the quality of literature study and research about heat pipes. The machine shop will aid in the construction of the pipe, in terms of welding the two ends of the pipe closed using a blue torch and extracting the air in the pipe. A copper rod will be purchased from a certain vendor. The liquid within the pipe will be distilled water, retrieved from a chemistry laboratory.
6. Expertise
Before this project can commence, physics, chemistry, and a knowledge of basic materials must be understood. Metal pipes can only withstand a certain amount of pressure. When heat is applied, a heat pipe will break if the pressure inside the pipe exceeds the amount of pressure it can withstand. It must be understood that when air is taken out of the heat pipe to create a vacuum, the liquid inside the pipe will instantly “boil” because its vapor pressure is greater than the atmospheric pressure. This will mean that water vapor will fill the inside of the pipe even though the water has not reached its normal boiling point of 100oC (212oF).
It is known from physics, chemistry, and materials classes that each metal has a different thermal conductivity and a different melting point. The metals that can be used for the heat pipe include copper, brass, and nickel, among other metals. Copper would be the best metal because it has a high thermal conductivity as well as a high melting point. This means that the applied heat of 250oF – 500oF will not melt the copper and the heat applied will slowly distribute throughout the metal.
Principles from chemistry teach that different liquids have different specific heat capacities and different boiling points. The liquids that can be used inside of the heat pipe include water, ethanol, toluene, and many other liquids. However, water would be the best to use because it has a high specific heat capacity, meaning that it is able to absorb heat well, it has a high boiling point, and it has a temperature working range between 303oF – 550oF (Faghri).
The one skill that must be learned is how to use the tools in the machine shop. The machine shop will provide training to use a blue torch and a saw, which will allow the heat pipe to be fabricated. With all of the previous knowledge as well as new knowledge gained, the heat pipe can be constructed and will hopefully function to all expectations.
7. Budget
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| Table 2: Design Project Budget |
*The budget does not include distilled water because it will be retrieved from the Drexel University’s chemistry laboratory. Also, the tools needed to construct the heat pipe will be provided by Drexel University’s machine shop.
7.1) Copper
The copper that will be purchased will have a length of twelve inches and a diameter of one-eighth of an inch. It will be bought from amazon.com, and it costs $2.00 for each copper rod. Copper was chosen as the ideal metal to construct the pipe due to its high thermal conductivity and melting point.
References
Faghri, Amir. "Working Fluids and Temperature Ranges of Heat Pipes." ThermalFluidsCentral. N.p., 12 Mar. 2014. Web. 05 Apr. 2016. <https://www.thermalfluidscentral.org/encyclopedia/index.php/Working_Fluids_and_Temperature_Ranges_of_Heat_Pipes>
Reay, David A. “Heat Pipe.” AccessScience. McGraw-Hill Education, 2014. Web. 7 Apr. 2016. <http://accessscience.com/content/heat-pipe/757297#757297FG0010>
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