Penn State professor, Chao-Yang Wang, was recently named a fellow of the National Academy of Inventors for his work on batteries and fuel cells. The Academy honors distinguished individuals who have created inventions that have made an impact on the quality of life, economic development, and welfare of society.
Wang’s research has helped lead to the creation of an all-climate electric vehicle battery, and he currently has over 20 patents for his work and has 25 pending patent applications.
Meet Makeshift/Jack. Jack lives with her foster father “Uncle” in a junkyard in the outskirts of Rothaven, a once great automotive city but has since been abandoned and fallen apart. With a lot of the jobs gone, many resident turn to crime, including some of the politicians. Jack makes a combination of gadgets and mechanical battle armor with parts she gets in the junkyard to fight the bad guys as the superhero Makeshift! But with the bad guys becoming more and more high tech, will Makeshift be able to outsmart them?
This is another story I’ve been working on that I want to someday make into a cartoon. I’m still fleshing out the character designs but I’m happy with my progress so far!
Edit: a producer from Cartoon Network’s Steven’s Universe suggested I send it to them once I’m finished polishing the story, this could be good!
I love watching How It’s Made. Though I wish they would go one level deeper. They show all of these manufacturing processes with gigantic proprietary custom engineered machines that spit out 4 billion Cheetos at once. I want to see how those are made. I want to see a show called How They Make the Things That Make Things.
That is truly some of the most creative engineering I’ve ever seen. Like, my brother designs airplane wings for fighter jets. Which is cool… but wings haven’t changed much in decades. He’s kind of a… re-engineer. (Sorry, bro.)
Whereas a custom built machine that sharpens dozens of pencils at once must have had some interesting trial and error problem-solving. How did they settle on this design and what other designs did they try?
Or how did they make this ice cream sandwich masturbation mechanism.
I want to see the messy test footage of ice cream going everywhere on the beta version.
Who engineers these things? How are they built? How much do they cost?
I might have to go on a YouTube hunt.
Having worked in a factory, a lot of machines are *extremely* specific. Like, there is no generic Pencil Making Machine company or Shingle Stamper you can order.
Sometimes it’s a hybrid: Electric guitar manufacturing might use CNC routing to do major first-step carving/shaping of bodies and necks from blanks, but then there’s a lot of hand operations with traditional woodworking tools: bandsaws, table saws, planers, rasps / chisels, drill presses, belt sanders, table routers, glue and clamps for laminates, etc.
Some things look custom but in fact are made by many different companies, like industrial rug drying centrifuges for the carpet cleaning business.
In the case of things for fine manufacturing and food, almost everything is made custom.
Often, the company themselves will have a full machine shop where they keep big billets of stainless steel and aluminum, TIG welding setups, and industrial lathes and punches to make replacement parts from scratch.
And there is lore about the machines and how they work and the factory employees need to be trained on them by people who in turn were trained by someone else, sometimes going back over a hundred years for factories that have been continuously running since the 1800s.
Let’s look in detail at the process of boiling a pure substance.
We’ll start out with a compressed liquid. We’ll say it’s water at 25 deg C. Moreover, let’s say it’s contained in a cylinder with a piston so that the pressure inside the cylinder is always at atmospheric pressure.
If we start heating up the cylinder, the water inside will expand slightly. The pressure will remain constant as the piston moves with the water’s expansion. Once we get to 100 deg C, the water exists as a saturated liquid - any additional heat will cause it to vaporize.
If we keep adding heat to it, things get interesting. The water will start to boil. It’s volume will increase drastically, but its temperature will remain the same. All the energy you’re putting into it is going into the phase change. The amount of energy it takes to go from a liquid to a vapor is called the latent heat of vaporization. (Similarly, the amount of heat it takes for a solid to melt into a liquid is the latent heat of fusion.) So while the water in your cylinder is in the process of boiling, it exists as a mixture of saturated liquid and saturated vapor. Its temperature will remain at a constant 100 deg C throughout the process. Although its apparent volume will increase, its specific volume - the volume per unit mass - will also remain constant.
Once all the water has been vaporized, if you continue adding heat to the cylinder, the water will start to rise in temperature again and its specific volume will start to increase. In this state, it exists as a superheated vapor.
The entire process we just described looks like this.
Note that this show temperature vs. specific volume for only one pressure - if we varied the pressure as well, things would look quite different. The interdependence of temperature, volume, and pressure will be important in our analysis of thermodynamic processes.
We’ve spent some time going over the basics of heat enginesandrefrigerators. These are machines which manipulate a working fluid through some sort of cycle in order to move heat from one location to another. We have some idea of the overall way they work, but to really understand the details of what’s going on, we’re going to have to know a little more about how this working fluid behaves.
For right now, we’ll restrict our discussion to materials which qualify as pure substances. A pure substance has the same chemical composition throughout - all its molecules are the same. We’re all familiar with phases of matter - solid, liquid, and gas are the ones we see on a daily basis. Matter in solid form has its molecules arranged in a regularly structured lattice. In a liquid, molecules have about the same distance from each other as they do in a solid, but they’re not held in a structure and can move around each other freely, although their close spacing means that intermolecular forces play a large part in their motion. In a gas, molecules are widely spaced and careen about as they please, interacting with each other only through collisions.
For thermodynamics-related purposes, we’re really interested most in liquids and gases. Controlling the transition between these two states is the key to moving a lot of energy around. So let’s define some terms.
Acompressed liquidorsubcooled liquid is one that is in no danger of vaporizing.
Asaturated liquid is one that is about to vaporize.
Asaturated vapor is one that is about to condense.
Asuperheated vapor is one that is not in any danger of condensing.
Distinguishing between these is important from a thermodynamics because a fluid will have different properties related to its ability to absorb and release energy in each state. In coming articles, we’ll look a little more closely at the exact process of transition between phases.
Perpetual motion machines are a perennial staple of fringe science. Many of them are very clever and seem, at first glance, as if they should work. If they did work, they would violate the laws of thermodynamics - you’d be getting energy for free. This video walks through a few simple ones and shows how they work. (Or don’t work.)
We’ve talked about the second law of thermodynamics as the idea that energy naturally flows from a point of high potential to low potential. There are a couple of other ways you can think about this.
One is called the Kelvin-Planck statement of the second law:
A device which operates on a cycle cannot exchange heat with a single heat reservoir and produce a net amount of work.
Compare this to the heat engine we looked at earlier. A heat engine schematically looks like this:
It exchanges heat with both a high- and low-temperature reservoir and produces a net amount of work. If instead it only exchanges heat with a single reservoir, it looks like this:
Looking at it like this, you see clearly why this is impossible: in this schematic, there is no Q_L - all of the heat coming in is converted to work. In other words, this device has 100 percent efficiency - something we know can’t happen.
Another formulation of the second law is the Clausius statement of the second law:
A device which operates on a cycle cannot move heat from a lower temperature reservoir to a higher temperature reservoir as its only effect.
This one also becomes clear if we look at it schematically. Here’s a regular refrigerator schematic:
And here’s a refrigerator which violates the Clausius statement:
There’s no net work input here, so the energy taken in as Q_L magically increases in quality to be output as Q_H without any other energy input.
Note that all of these formulations of the second law can be expressed mathematically in the same way: Q_H is equal to the sum of Q_L and W_net.
If you have a device in which any of these terms are zero, something is wrong.
We’ve spent some time on the second law of thermodynamics - energy flows naturally from high potential to low, from hot to cold. Most of us have refrigerators or air conditioners in our dwellings - devices which seem to violate this law. They somehow move heat out of a colder space and into a hotter space. So what is going on here?
The short answer is that the refrigerant in these devices acts as a temporary energy storage medium - by some clever manipulation, we can move the refrigerant through a cycle such that at the point it travels through the space we want to cool it absorbs energy, which it needs to dump when it gets to the warmer exhaust space.
Here’s a typical refrigerator schematic.
Refrigerant enters the compressor as vapor. The compressor does work to increase its pressure. Increasing its pressure also increases its temperature, so by the time it hits the condenser it’s relatively hot. In fact, it’s hot enough relative to the surrounding environment that it sheds heat as it flows through the condenser. By the time it leaves, it’s condensed and much cooler, although it’s still at a very high pressure. It goes through an expansion valve from here, which drastically drops both its temperature and pressure. So it enters the evaporator as a low temperature, low pressure liquid. In this state, it is low enough energy that it absorbs energy from the surrounding environment going through the evaporator. When it leaves, it’s a vapor again, ready reenter the compressor and start another cycle.
This works because we are injecting energy into the cycle in the form of work done by the compressor in order to get the refrigerant to a state where the heat it absorbed from the refrigerated space can be dumped to the outside environment.
We have a heat engine taking in heat at a rate of 100 MW from a high temperature reservoir. 75 MW of this energy is rejected to a low temperature reservoir. The rest is converted to useful work. How much net work output does this heat engine produce and how efficient is it?
The only source of energy in the system is Q_H, so we know that the energy leaving in the form of W_net out and Q_L must be equal to the energy input, Q_H. Or, put another way, W_net out must be equal to the difference between Q_H and Q_L.
In this case, we get a net work output of 25 MW from this engine.
Efficiency is the ratio of your desired output to your input. In this case, the output we care about is useful work, and the input to the system is Q_H. So we get a thermal efficiency for the engine of 25%.
So I am an avid reader of Hackadayfor a long time now and they have been putting out a lot of great introductions to tools and processes to get makers up to speed on the resources that are available. This is just a splattering of links that I have found lately that you guys might be interested in.
Hackaday has done a terrific write up of the engineering behind the Othermill cnc machine. In the article, which is way too long to post, they compare it to another generic desktop CNC kit, but at the same time they point out all the key areas that the designers had to take into account in order to build the machine. One detail is the hdpe frame vs aluminum extrusion that results in greater machinabililty (yep, it is a word), lighter weight, and cheaper cost of goods. It’s a great demonstration of how engineering doesn’t happen in a vacuum. There are many factors that have to be taken into account like materials, vibrations, loose material, wiring, fasteners, cost of goods, and ease of use.
While Hackaday is mainly an electronics and software blog, they occasionally branch out into the mechanical area. Definitely check it out.
Note: Just like Hackaday, we have not received any form of compensation for posting this from Othermill, I just think its a well designed machine.
If we’re going to talk about heat transfer, we’ve got to talk a little bit about thermodynamics. We’ll take it one law at a time.
The first law of thermodynamics just boils down to conservation of energy.
In a closed system, the total energy present remains constant. The only way the amount of energy present can change is if energy is put into the system or taken out. There are two ways to make energy cross system boundaries like this: either by heat transfer or by work done. So for a closed system, the total change in energy of the system is the net amount of heat put in minus the net amount of work out.
In addition to a closed system, this principle can also be applied to a control volume - that is, a defined region of space that mass can enter and leave. Mass entering will carry energy in with it, and mass leaving will carry energy out with it.
In the situation in which you are considering a control volume in the midst of a constant flow of incompressible fluid, you can consider the heat transfer occurring to be a function of the temperature difference between the fluid entering and the fluid exiting, the mass flow rate of the fluid (mass transferred per unit time), and the specific heat of the fluid, c, which is a physical property of the fluid - basically, how much energy you have to put into it to raise its temperature.
This is a simplified equation, and many situations involving fluid flow require consideration of additional factors, but for now it’ll work for us. We’ll get into the more complicated stuff later.
