 Hello! My name is John, and I'm here to answer three questions. First, what is engineering equation solver? Two, in what ways is it useful to me? And three, how do I use it? This video will be focused on those first two questions. All the subsequent videos will be tutorials on how to use ease in different situations. So if you feel like you already have a good grasp on what ease is and how it's useful, you might consider jumping ahead to one of those videos. Also note that this video will be focused on applications of ease in thermodynamics for mechanical engineering. So pretty much everything we do will be in an effort to try to calculate heat transfer, work, or some measure of efficiency. The same concepts could be equally applied to other scopes. For example, engineering equation solver is very useful in analyzing chemical reactions, but we won't be covering those capabilities in this series. Yeah, I take that back. Maybe just a pinch of combustion. Anyway, at its core, engineering equation solver, which is abbreviated EES and pronounced ease, by the way, is a simultaneous equation solver. It takes input in the form of equations and defined variables, and numerically solves the equations for whichever variables aren't known. The equations can be linear or nonlinear, algebraic or differential. Oh, and you can enter thousands of them. The different licenses are capped at different equation limits. I'll be using the professional version, which I think is capped at 12,000. I think the biggest program I've ever used ease for was about 200 equations, but it's nice to know that we have that headroom available. One of the things that makes ease especially versatile is that it solves the equations simultaneously. EES doesn't care where the equations appear or the order that they are listed or even which terms are on which side of the equations. Most similar software packages would have you type in equations with the known inputs on the right-hand side with the target output by itself on the left. That software would step from equation to equation, sequentially finding outputs until it reached the end of the program. That's how we solve problems by hand, after all, not ease. EES works by guessing values for all the variables it doesn't know, running all of the equations in the programs at once, using the outputs to compare to the variables it does know, using the difference between the two to guess new values and repeating this process until it converges on an answer. Exactly what qualifies as an answer is defined by a residual threshold that you can control. The most useful feature of EES, though, at least in my opinion, is that it has a built-in library of material properties. You want to know the thermal conductivity of nitrous oxide at 25 degrees Celsius when it's compressed to 75 psi? EES has got your back. It's about 0.018 watts per meter Kelvin. In case any of you were curious, you probably weren't. But it's not just thermal conductivity. It's got a variety of macroscopic properties built in for lots of homogenous substances relative to lots of independent variables. If you've been through a thermodynamics class, you're probably begrudgingly familiar with the steam tables. Given a temperature, pressure, and plenty of time, you could tell me the specific internal energy, the specific volume, etc. EES can do that for you, and for many more properties. And not just steam. It's got thermophysical and transport properties built in for hundreds of materials. And in the unlikely use case that EES doesn't have the property tables you want built in, you can enter them yourself. Either manually, with direct tabular data, or dynamically, with libraries, functions, and procedures written in Pascal, C, or Fortran. There are probably more ways to enter that data, but I've never needed to use them. EES has always had what I used built in. Now, I know what you're thinking. You're thinking, John, that's a great technical explanation. You've managed to use macroscopic and homogenous in the same sentence, and we're all very impressed. But how does that help me, and the very important and prestigious work that I do? Well, think about the process of solving a full-on engineering problem. Say you were trying to size a radiator for a car. Your analysis might look something like this. First, you do the fluid mechanics analysis, and then you go back and forth. Your analysis might look something like this. First, you do the fluid mechanics analysis on the inlet conditions to figure out how much air is being inhaled into the engine. Then you use the air-fuel ratio of your setup to calculate the amount of fuel burning during the combustion process. Then you do the chemistry to figure out how much energy was released as heat during the combustion process. Then you do the thermodynamics analysis to figure out how much of that energy exiting the fuel as heat was leaving the engine as heat. Then you do the heat transfer calculations to figure out how much of that heat actually makes it into the coolant. Then you do the thermodynamics analysis to figure out how much of that heat energy makes it to the radiator and how much heat will need to be rejected across the radiator. Then you do some heat transfer analysis to figure out how much of that heat makes it from the coolant to the air blowing through the radiator. Then you do some fluid mechanics analysis to figure out how much surface area you need to collect all of that heat into the airstream. Doing that entire analysis by hand would be tedious and arduous and other synonyms for an all-around bad time. And if you made a mistake at any point in the process, you'd have to recalculate a lot of things by hand. Worse yet, your solution is only good for one set of input conditions. If you redesigned the intake manifold or you changed the compression ratio or you were running a different type of fuel, you'd essentially have to start over. This kind of analysis is easy as bread and butter. You can figure easy to do the calculations for you and then it can spit out many useful things. Not only the solution to your problem, but you could, for example, plot how the radiator requirements change at different car speeds or at different compression ratios or different ambient temperatures or different amounts of fuel in the engine, etc. I prefer to think of it like this. If I actually gave the task of sizing a radiator to a student, they'd probably think that they had two options. One would be to do all of the analysis by hand and the other, faster method would be to simulate it. Well, there are pros and cons to both. Doing it by hand gives you complete and total control over your analysis, every assumption that you make in the process you actually have to make yourself. The downsides is slow and arduous and all those other things that I mentioned. The solution method is probably faster in the long run. It's a much more versatile and much more elegant solution. The downside is that it can be extremely easy to make a mistake. You could enter some numbers into the simulation software. It could spit out an answer, but if you haven't done the analysis by hand to back it up, you can't be positive that what it spat out is useful at all. You always have to back up simulations with real data. Software packages like Ease and Matlab and MathCAD and Mathematica and Maple are sort of a nice middle ground. You still have to input the calculations. You still have to actually do all the analysis yourself, but the software takes the burden of the algebra and the arithmetic off of your shoulders. That way you can spend more time on the actual engineering side of things. An engineering student solving an analysis problem by hand probably spends, what, 70 to 80% of their time typing numbers into their calculator, looking things up in a table, and I don't think that really promotes a better understanding of the material. Sure, looking stuff up in the steam tables has value, but only the first or second time. After that it's just another hurdle that you have to jump in solving a problem. I'd much prefer that my students spend that same time working more problems, doing more examples. I think that gives them a better understanding of the material for the same amount of time invested. Anyway, in the next video we'll talk about Ease's interface and we'll enter equations for the first time. Stay tuned.