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Recent content by denniskb

  1. denniskb

    Integration

    Agent666 much appreciated as this cleans up the WA output nicely IDS yes this is also useful though WA provides the same on the second pass Can anyone suggest a way to solve directly from the original formula in Excel via macro? i.e. Sum[s^2/(n^2 - s^2), {n, 1, Infinity}]=0.40435 for s>0, s<1...
  2. denniskb

    Integration

    Thanks petb Re-entering the original formula in the form suggested by WA provides several solutions one of which is the one I want (i.e. 0 < s < 1) Is there a way to limit the range for s within the WA input? Dennis Kirk Engineering www.ozemail.com.au/~denniskb
  3. denniskb

    Integration

    petb entered and formula recognized but it does not solve for S which is the solution I need? Dennis Kirk Engineering www.ozemail.com.au/~denniskb
  4. denniskb

    Integration

    Thanks 3DDave. Yes it is a sum and not an integration. I am trying to use the online Wolfram calculator Dennis Kirk Engineering www.ozemail.com.au/~denniskb
  5. denniskb

    Integration

    How do I enter the following into an integration calculator to solve for s? Sum(n= 0 to infinity, s^2/(n^2-s^2)) when the sum value has a known value (i.e. sum() = 0.40348) Dennis Kirk Engineering www.ozemail.com.au/~denniskb
  6. denniskb

    Solar Loading on Aluminium Enclosure

    ArcEnergy, “if only things sere so simple …” You will most likely not be able to make this work with 1100 W/m2 and should change to a more realistic maximum of 850 W/m2 A. Your simple calculations have not accounted for all heat transfer paths nor included for absorptivity and emissivity...
  7. denniskb

    Solar Loading on Aluminium Enclosure

    ArcEnergy, I got your email so will try to help out. Wouldn’t it be nice if things were so simple that we had a formula to solve everything? The situation you describe is in reality complex and so is the solution unless we make some significant assumptions to simplify the solution without...
  8. denniskb

    Anchor loads for GRP lines

    Brad, You are right to be concerned about this configuration as it certainly has the capacity to overload the nozzle. With no temperature change and the two ends open the Poisson's effect will cause the pipe to get shorter (and NO C2it you must not ignore the Poisson's effect) and this may be...
  9. denniskb

    Relief valves: Outlet : Why do we avoid sonic flow

    The mach limitation of 0.7 to 0.85 is imposed on the discharge velocity from the vent pipe well downstream of the PSV (i.e. at the end of the vent to atmosphre or vent connection into a flare header) so that this does not become the flow limiting point in the system. It is critical that the PSV...
  10. denniskb

    High Velocity Air Flow in a Tube

    Thanks Latexman, Two clarifications please: Are the pressure listed kPa(g) or kPa(a)? The outlet temp seems too low for what should be isenthalpic flow? Dennis Kirk Engineering www.ozemail.com.au/~denniskb
  11. denniskb

    High Velocity Air Flow in a Tube

    I need to determine the flow of dry air to atmosphere through a small tube so we can correctly set up a series of tests. The aim is to achieve near sonic velocity (say M = 0.9) at the discharge by setting an appropriate upstream pressure. Software available to me will not cope so I am using...
  12. denniskb

    Pipeline Blowdown Thermodynamics

    sailoday28 The very high velocity inside the throat of the valve (or other choke point) drops off immediatedly downstream of the valve (so kinetic energy becomes less relevant) and the JT effect occurs between the valve upstream and downstream sections. At any instant the ENTIRE pressure drop...
  13. denniskb

    Pipeline Blowdown Thermodynamics

    Let me pick up on the postings since my last reply on 2Dec. MortenA - your gas storage cavern application is a good example of how wide a net we need our thermodynamics, fluid flow, heat transfer solutions to address. Probably the biggest difference for this case would be the near lack of flow...
  14. denniskb

    Pipeline Blowdown Thermodynamics

    MortenA, Yes the gas at the far end has minimum velocity so expands in a near isentropic process yet the gas near the exit has velocity and expands in a near isenthalpic (JT) process. And yes again, the difference between the two is the work associated with the pressure drop due to velocity...
  15. denniskb

    Pipeline Blowdown Thermodynamics

    BigInch, I use JT cooling in all of my pipeline simulation calcs. My "JT or not JT" query was about WHY is isenthalpic (which is normally associated with violent pressure drop which is not present in pipeline flow) the correct process rather then isentropic (which is better suited to these...
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