Heat Pipe Background

So, you want to build a heat pipe? This blog is a chronicle of one group's journey through heat pipe creation. However, it is a secondary goal of this project to compile the information necessary for making your own heat pipe. The most accessible way to set this up is to break the explanation into portions. The first, and probably the most important section is:

What is a Heat Pipe?

Long story short, the image above is a heat pipe. However, that's not particularly useful in and of itself, so this post will endeavor to better explain the specifics. A heat pipe is made of three vital components. The first is a sealed pipe (shocker), the second is a wicking structure inside the pipe, and the third is a liquid of some sort that will vaporize under conditions of high heat. Heat pipes are used for any number of individual tasks, but the general goal is to use a system containing both an evaporating segment and a condensing segment to transfer heat. If you're having trouble grasping the basic concept, think of sweat. Though not exactly the same thing, the theory is similar enough to help conceptualize heat pipes. When the human body begins to overheat, people sweat. The evaporation of the sweat helps dissipate the heat. In the case of a heat pipe, the liquid at one end of the structure evaporates in the high heat (although the heat of evaporation obviously varies depending on the liquid within the pipe), and the vapor travels to the other side of the compartment, taking with it the heat from the initial source. Once the vapor reaches the other end (the condensing end), the heat is released into the environment, and the vapor re-condenses into the original liquid form. The liquid then falls back into the evaporator half of the contraption via the wicking material along the sides of the pipe (or tube). Though the process is not mindbogglingly difficult to comprehend, it can be incredibly useful. For example, heat pipes are used in power plants to both dissipate some of the heat generated by the energy-creation process (which adds efficiency), and then pre-heat the air moving into the system to add efficiency from the beginning of the process as well.

How Do You Build a Heat Pipe?

This section will only present the bare-bones of construction, because most of what this group currently knows is conceptual. The step-by-step process (heat pipe recipe, if you will) is going to be provided through the weekly blogs. However, some steps are obvious from the get go. First of all, having piping or tubing is imperative. The material that the pipe is made of depends on the uses it is intended for.

Stainless Steel and Copper Pipes

For example, if the heat pipe is being used in a power plant, carbon steel is probably the best option. However, for the lower heats used in this class (between 250 and 500* Fahrenheit) copper tubing makes more sense than the more costly steel, and is more efficient. Another important consideration is the type of wicking material being used.

Pictured above are three of the various types of wick structures

In the case of this particular heat pipe, most likely the interior section will be made of wound metal screen. However, there are any number of different types of wick that can be used. For more information, refer to this article from Thermal Fluids Central. Finally, a good deal of research has to be put into which liquid will be used in the final heat pipe.

Some of the more commonly used liquids for heat pipes

Three commonly used liquids are: water, acetone, and methanol. A study conducted by researchers at the Bangladesh University of Engineering and Technology delves into the topic with more depth. Once research has been conducted on finding which wick, and which liquid to be vaporized best suit whatever the requirements for the specific heat pipe, the end goal is to combine all of the components, bleed the pipe to remove contaminants and make it as efficient as possible, and then cap the tube so that the heat pipe may be used for its final task. 

What is a HamPipe?
Now, the real question comes into play. How on earth does it  make sense to use a heat pipe in cooking? Well, the theory is simple. The heat pipe uses the oven as the evaporator, and whatever it cooks, a ham for example, as the condenser. A HamPipe is simply a name for a heat pipe which is used in cooking. This was actually something sold commercially for several years in the 1960's, but it was eventually forgotten in the depths of time.

A previously designed heat pipe for cooking

 Frequently Asked Questions:
1. What is a heat pipe?
Was the upper section too long to read? Okay, here's a condensed version. Ha. Get it? Condensed? A heat pipe uses science to transfer heat from one end of a pipe to the other.
 2. Why would you use a heat pipe in a ham?
Sometimes it's just really difficult to wait the whole recommended time for ham cooking. Have you ever overslept on Christmas morning? No longer a problem. HamPipe. You're welcome. 
3. How long does it take to build a heat pipe?
That's going to depend on experience, and how thorough you are trying to be. The prototype our group built took somewhere between 4 and 6 hours. It could take far less if you are already an experienced solderer, or if you are less easily distracted than we are. 
4. What is the meaning of life?
Hot tea and puppies.