• Re: Calculation of pumping energy at splitters

    You're actually touching upon very pertinent issues here ...
    [quote author=Youri Amerlinck link=topic=20566.msg26524#msg26524 date=1499110157]
    The fact that you need to select between two types of splitters is complicated to explain.
    Yes and no ... it may be difficult to explain, but, on the other hand, a user may find annoying to have to replace an icon with another icon of the same type in order to switch model. Although, it's also true, now one can simply drag an icon over an existing icon and, if terminals are compatible, all the connections will be maintained.

    [quote author=Youri Amerlinck link=topic=20566.msg26524#msg26524 date=1499110157]
    And I actually have no idea what the 'true pump block' is.
    Yes, there's a new Palette in the Block Library pane called "Pumps".

    [quote author=Youri Amerlinck link=topic=20566.msg26524#msg26524 date=1499110157]
    In my opinion, for what it is worth, you should develop a model library depending on its use. Doing a generic dynamic modelling study evaluating the plant performance is another thing than doing a detailed energetic study (including pump costs, etc.). So, keep it as simple as possible.
    I tend to agree with this suggestion.
    In fact, we've been thinking about something similar lately, but indeed: we could 'package' sub-sets of models into libraries aimed at different types of modelling goals ...
  • Re: Calculation of pumping energy at splitters

    [quote author=Youri Amerlinck link=topic=20566.msg26517#msg26517 date=1498828548]
    This is getting quite complicated. But OK, if that is the way that you want to go with the standard model library
    Do you find it complicated?
    Would you be able to suggest a more convenient solution?

    [quote author=Youri Amerlinck link=topic=20566.msg26517#msg26517 date=1498828548]
    By the way, why is pumping power safer to use than pumping energy?
    Because the integral is calculated within the Cost block, including the possibly time-dependent tariff. If you would pass the energy to the Cost block, the tariff would be outside the integral, thus only work for constant tariffs.
  • Re: Calculation of pumping energy at splitters

    Hi Youri,
    correct: the one you're using (default model for the splitter block) is meant to be coupled to the true pump block - which expects the "desired" flow (i.e. what the process needs). You should then be able to see whether or not, based on the pump + system characteristics, a single pump is able to deliver that flow; or if you need more than one pump.
    With this combination of blocks, the energy / power is calculated in the pump block which can then be connected to the cost block.

    However, the splitter block allows for second model (the 'old', very basic model of WEST) which, as you expect, will expose the pumping energy and power.
    In fact, it's safer to use the power to compute the costs rather than energy (you will find the corresponding term in the cost block) because you could use variable tariffs (the tariff is now a manipulated variable!).
  • Re: Question about error

    yes: "C_1_2_3" is the expansion of the C vector (or matrix), where 1, 2, 3 denote specific indices.
    I assume you have a vector C[i, j, k] right ?
    [li]'i' may indicate the component index (in the state vector), e.g. (ref ASM1) H2O is 1, S_I is 2, etc.[/li]
    [li]'j' may be the layer index, 1-5[/li]
    [li]not sure what 'k' means in your case ...[/li]
    If you can provide more details about your model, I may be able to help you further.
  • Re: some beginner WEST questions

    [quote author=Ruben link=topic=20133.msg26104#msg26104 date=1497435249]
    1 Question: I've been checking the calculator block information and it seems to me that is possible to calculate F/M ratio (attached file question 1). I don't understand what you mean with " this has nothing to do with the calculation of the F/M ratio which is an algebraic state variable computed within the calculator block and which needs the relevant input variables." What should I do to calculate F/M ratio using the calculator block?
    You need to provide the relevant inputs (data) to the calculator: see Models Guide.
    But if you are using the oxidation ditch model, this may not be possible, as this model does not expose all the relevant outputs that are necessary for the calculation - which answers your 2nd question too.

    [quote author=Ruben link=topic=20133.msg26104#msg26104 date=1497435249]
    3 Question: I've been exploring the IFAS block and I've noticed there are two flow outputs. What's the difference between Q Under and Q Excess? I haven't found any explanation in the block information. I thought that IFAS reactors used to have obly one outlet and purge was produced in the posterior secondary settler.
    The WEST model incorporates the settler. That's why you have two outgoing fluxes for sludge: Q_Under is the flow you would extract from the clarifier; Q_Excess, the portion of excess sludge.
  • Re: Ammonia inhibition

    Based on the elements provided here, no, I cannot think of anything else.
  • Re: Parameter calibration: comparison function

    [quote author=Luís Roque Silva Lopes link=topic=20182.msg26093#msg26093 date=1497356230]
    .. for the modeling intervals (a temperature of 16 and 19 ° C) ..
    I don't understand this.
    Do you mean you are testing two temperature scenarios, at 16 and at 19 Celsius; and you get similar values for YH and muH ?

    Regarding [b]muH[/b] (parameter, i.e. max growth rate at reference temperature which is 20 Celsius): this is to be calibrated only at 20 Celsius. The actual growth rate is temperature-dependent (muH_Temp), according to the Arrhenius law and hence a state variable.
    Regarding the yield, yes: strictly speaking, [b]YH[/b] is a stoichiometric coefficient and as such constant (time- and temperature invariant).
  • Re: Ammonia inhibition

    [quote author=yohannis link=topic=20185.msg26094#msg26094 date=1497386557]
    I think the ammonia inhibits uptake of acetate and reduces the acetate uptake
    I would also assume this is the reason why acetate does not get degraded.
    Is it only the ammonia inhibition factor that affects the acetate uptake? I mean: are all the other inhibition and 'Monod' terms inactive, i.e. ~1 ?
    You need to backtrack the source of such high ammonia inhibition (low inhibition term) and potentially of the other terms negatively affecting acetate uptake.
  • Re: Parameter calibration: comparison function

    Ideally, if your model is well-defined (well-constrained), irrespective of the optimisation method, you should get the same results.
    In practice, due to a variety of possible reasons, e.g. the initial conditions, some may be more effective than others; some may completely fail.
    It's up to you as the modeller to decide which results are meaningful: e.g. if a certain method suggests growth rates, yields, .. that are totally irrealistic, they should be discarded.
  • Re: Is it possible to find a more detailed error log in west folder?

    Yes. There's an extensive logbook that you can find in the [b]Logging Pane[/b]. If this should not be immediately visible, it may be that you have closed it: you can reopen it via the View menu / System / Logging.

    Hint: your error may be related to a numerical issue with the integrator, e.g. overflow.
    Anyway, you should find more information in the Logging.

    Regarding the discrepancy between what you see in the Review page and what you actually get in a Block (or are you referring to a Plot window perhaps? this may be totally different), yes it may be related to the previous error; or not ... difficult to say.

    I suggest you first try and work out the error. If you still have a much lower flow, please provide more info regarding e.g. your actually settings and parameter values.