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  1. M

    Inline Mixing Pressures

    Thanks. That makes sense. Any idea how much pressure a glued cpvc joint will stand? I know the piping itself is rated to 400 psi (2" sch 80) and I suspect if I use a longer setting glue it will only take it down to around 200. My instrument flanges are rated for 150, so that's probably my limit.
  2. M

    Inline Mixing Pressures

    I have two streams at controlled flow rates that will mix via an inline static mixer. Both streams will have check valves before the mixer, however, do I have to worry about fighting pressures in this situation? If the one stream is 40 psi and the other is only 20 psi, will the 20 psi line...
  3. M

    Neutralizing a basic reaction with HCl

    Can you simply add the HCl drop-wise until your pH probe or paper yields a neutral result?
  4. M

    Van't Hoff Approach to Finding ∆H and ∆S

    The ∆H is always assumed to be constant with temp in this equation (standard enthalpy change), which is an obvious downside to the relation. If you derive it from (d ln(K)) / (d 1/T) = -∆Ho/R you will find that from the integration.
  5. M

    General Chemistry Lab, need some help

    This is just a study of density, which is a property of a substance. The density is how much mass for a given volume, thus having units of grams per milliliter (g/mL = g/cm^3). At the same temperature and pressure this property is always constant provided the substance is chemically the same...
  6. M

    Parabolic function

    If you graph two functions, y=x^2 and y=5x^2 you will notice the first graph appears "fatter" and the second graph is "skinnier". As you increase the coefficient a the more narrow the graph becomes. As you decrease the coefficient a the wider the graph becomes. I would experiment with this...
  7. M

    Energy question

    Yeah, I was just messing. So in general power (P) is similar to energy (E) the same way velocity (V) is similar to displacement (x). The derivative of energy with respect to time is equal to power. dE/dt = P vs. dx/dt = Vx
  8. M

    Energy question

    Almost. 120,000 J.
  9. M

    Why total energy equals sum of subenergies

    I don't believe the internal energy of the liquid would change if you cut the gas in half. Maybe if the container was pressurized and by removing that amount of gas you altered the pressure and as a result changed the liquid's energy, but I'm not so sure otherwise. Ask yourself why we calculate...
  10. M

    Engineering Transition to Civil from Mechanical Engineering?

    You should really check the salary statistics for ME's vs. CE's before you switch. ME's make a lot more and are rarely required to take the FE as well as PE exams like 99% of civils are required to do.
  11. M

    Simple question about ammonia/water solutions

    The first problem you would have is separating the water and ammonia that didn't react from your desired products. I can't think of any way to do that which wouldn't encourage them to react back to water and ammonia (i.e. time, mixing). Nitrogen prefers 3 bonds and oxygen 2. Therefore, the...
  12. M

    Basic Statics/Dynamics System of Equations (help!)

    Havn't studied your jpeg but if your equations are all linear then you should only need the 6 equations with the 6 unknowns. You might be over-specifying. If you think it's an algebraic mistake maybe you could try solving via matrix (6x6^-1 * 6x1)?
  13. M

    D/dx of trig function

    Actually, you're correct. I solved it numerically real quick and input values for a,b,u and got the same results from your solution. Nice job.
  14. M

    Detecting Water Flow Through Pipe

    The most reliable way would be to drill a tiny hole in the piping (PVC?) on the up side (away from the direction of gravity) and somehow tape a bag over top of the hole. The bag should inflate when there's flow. You could also just put a tire pressure gauge into the hole. Change in pressure...
  15. M

    Engineering Petroleum engineering and other engineering questions

    There is a ton of chemistry in petroleum engineering. You're looking at probably 6 courses in chemistry (minimum!) which would be 2 general chemistry, 2 organic chemistry, and another two physical chemistry courses. In addition the university that offers the degree will likely want you to take...
  16. M

    Best programming language?

    Have you considered matlab? It's almost the same as c++. In college I knew a lot of electrical engineers on computer tracks who used matlab extensively. In general, Java seems to be more for web designers, and is easy to pick up anyway. If you're good with code then once you become fluent in...
  17. M

    Thermal Physics - Efficiency

    Hi Peter, It is true that all power plants generally run better in the winter than in the summer. I've experienced this myself working at a nuclear power plant. You're on the right track but it looks like you just misinterpreted the Carnot equation. When Tc decreases then the Carnot efficiency...
  18. M

    Cooling Tower

    But there's one equation and 2 unknowns. So the duty the air supplies, Q = water flow*Cp*(T1-T2). We don't have T2 and mass flow of water. We need to take a different path. We have to use the 3% loss in water mass that leaves the tower as steam.
  19. M

    Cooling Tower

    I guess you need to assume standard cooling tower outlet conditions - 25 or 30 C maybe. Are there any design parameters to go by?
  20. M

    Making methane

    What form is your pure carbon in? If you meant pure carbon dioxide then maybe you could do 4H2 + CO2 = CH4 + 2H2O
  21. M

    Cooling Tower

    Have you considered using CpΔT instead of enthalpy? This should be close enough if you use the average heat capacity between temperatures.
  22. M

    How can I write an Email to Professor?

    Unless you're very familiar with the professor then you should address him formally. Use "Dr. Newman" as his name. Always assume they have a PhD and address as "Dr. Last Name" unless they have their masters, in which case "Professor Last Name" is sufficient. Some PhD's will be ok with with...
  23. M

    Engineering books recommendation

    'Advanced engineering mathematics' by Kreyszig (9780470084847) is pretty good. ODEs, linear algebra, PDEs, complex analysis, numeric analysis software, optimization / graphs, probability / statistics. I used it in my graduate engineering math course.
  24. M

    Thermal Physics - Gas Problems:

    The contractor or aka compressor's job is to compress the fluid. So while it is adiabatic, there is still work being used by the compressor to rotate its gears and vanes and in the process the pressure of the fluid is increased and the specific volume is decreased. If the energy enters the fluid...
  25. M

    Thermal Physics - Gas Problems:

    Peter, Everything looks good! I got the same numbers. The only part I disagree with is in the last part for "(b) the number of molecules in 1 kg of the gas" In 1 kg of CO2 you will have a gigantic amount of molecules. Have you ever used a constant in class called Avogodro's Constant, NA...
  26. M

    Pressure Calculation in pipe

    Are you given any equations, the viscosity, or the piping material? To solve this I would assume a roughness factor for the piping (e=0.00015 ft is good) and calculate the reynolds number, then the fraction factor, then head loss, and then finally a pressure drop. Unless the problem...
  27. M

    Heat Exchanger in Ansys

    It sounds like you're looking for the overall heat transfer coefficient, U. This value is always given from the vendor in the TEMA sheet for the heat exchanger (HX). The TEMA sheet has all of the data you would ever need to do any type of analysis. A heuristic value for U is 0.8517 kJ/m2-K-s...
  28. M

    Find the first three non zero terms in the Taylor Series about z=0 of exp(z sin z)

    See my attached picture for the Taylor series equation. For Taylor series all you have to do is substitue your given value (zo = 0) into the original function, the second derivative of the function, the third derivative... and multiply that result by (z-zo)n/n! and so on until you obtain 3 terms...
  29. M

    Mass of inerts in a mixture?

    Hello! You have to convert these from mole fraction to mass fraction, right? The conversion is wi=XiMi / ΣXiMi X = mole frac., w = mass frac., M = molar mass. Leave M for the inerts unknown. You need another equation to solve for the inert's molar mass or cancel it out. Hint: the...
  30. M

    Calculating Error

    You have error bars so I'm guessing you know the error for each point. You can make a seperate column on excel, add or subtract the error from each point (new point = old point + 0.05... for example), and then add this data set to the graph. That should be your error curve.
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