• ### Re: OTR_Energy

Hi,

.. an OTR Energy (Oxygen tansfer rate per energy unit) in g/KWh units. I assume that this variable means the SAE (standard aeration efficiency) of the aerator type. Am I right?
[/quote]
Yes.

.. 1.800 g/kWh is typical for jets or turbines. If I use a fine pore (fine bubble), should I work with higher values, for instance, 4.2-4.8 kg/kWh?
[/quote]
Correct.
And yes, you should observe a difference in the calculated Aeration Energy (Power).

.. OUR measurement data (OUR_ASU) in g/(m3d). I assume this value means AOR (actual oxygenation rate or requirements). So, in order to calculate SOTR, I would use an excel template to correct the obtained value (OUR_ASU) to SOTR by alpha, beta factors, etc. Is that correct?
[/quote]
Yes.

I would also recommend, you take a look at the [b]aeration model[/b] (Irvine with Carbon Footprint) associated with a control block - it should be coupled with a controller, e.g. PI that regulates the airflow (Q_Air) in order to maintain the desired DO set-point: this model should calculate the energy consumption for aeration more accurately.
• ### Re: Loop breaker

A loop breaker is a special block that [b]breaks an algebraic loop[/b], by introducing a small (negligible) delay between its input and its output

An algebraic loop occurs when a term appears on both sides of an equation.
For instance, the flow balance around a flow combiner for e.g. the RAS recycle is something like:

[tt]Output = Input + Recycle[/tt]

but the recycle is a function of the output; and therefore:

[tt]Output = Input + f(Output)[/tt]

which can be simplified to / seen as:

[tt]O(t) = I(t) + O(t) + other terms(t)[/tt]

Such equation cannot be solved numerically.
By introducing a small delay, a loop breaker allows to rewrite the previous equation as:

[tt]O(t) = I(t) + O(t-dt) + other terms(t-dt)[/tt]

which can be solved numerically.
• ### Re: Template for DWA procedure A131 (2000)

Among the "categories" of the standard WEST model library is the [b]ASM3P_EAWAG[/b], i.e. a variation of ASM3 which includes biological P removal originally developped at EAWAG, Switzerland.
• ### Re: error message

By coincidence, I received the same exact question through our technical support.
It appears that the problem may be related to the collection of "recent" projects.
You may have [b]deleted or renamed[/b] one of those projects [b]manually[/b]: when you then restart WEST, one or more projects in the list of Recent Project will find no match.
• ### Re: error message

Hi,
no I don't believe the error has anything to do with the update of your OS.
Similar error messages are usually related to the influent models vs. underlying instance ..
• ### Re: TIMER Manipulated variables

Hi,
if you hover your mouse pointer over the name of a quantity in the Block Details pane, the description of that quantity will pop-up.
There's another way to make this "description" field permanent, in the same pane - please take a look at the User Guide.

The easiest way to understand what each model does is to select the block on the canvas and use the F1 key: this will bring up the corresponding page of the Models Guide.

In any case, I cannot tell you the meaning of the timer's variables in relation to another model (PI controller in your case), because all depends on how the two block are connected.
However, u1 is the 1st output signal, and subscripts 1, 2 correspond to the phases, i.e. the value of u1 in phase 1 and in phase 2 respectively; T1 and T2 indicate the two phases.
• ### Re: Unit consistency problem

Hi,
what you are saying is not entirely correct: the concept of units is unknown to a block / terminal, it is an attribute of the 'absolute' figures you move from one terminal to the other.

So if the units associated with the Outflow vector of the digester are kg/m3, then the same units will necessarily be associated with the Inflow vector of any other block that is directly connected to the digester.
If the model associated to the second block uses g/m3 units, you will have to take care of the [b]unit conversion within the model itself[/b].

Now I realise, you may have a problem if the splitter (or combiner) block that receives the outflow of the digester is to receive another input from a block the Ouflow of which uses g/m3, because you cannot write a model containing an IF-THEN statement based on the units of the incoming terminals. First of all because, as I said before, units are unknown; and second because they would be only at design time.

Anyways, I guess the only solution is to have a [b]special model[/b] in which one particular terminal (you may consider to make it visually different) can only be associated with ADM1 type vectors.

Obviously a cleaner solution would be to re-arrange the ADM1 model so that it uses Inflow and Outflow vectors in g/m3 (or g/d) like any other model in the library.
• ### Re: Format series

Hi Jacopo,
you need to use the Line or the Point type plot, rather than the FastLine (default).
• ### Re: Preprocessing failed: exit code 33

It can be anything - or rather: many things :)
Can you be more specific?
What were you trying to implement? Can you clearly identify the line that may have resulted in that error?
Is there anything else in the Logging Pane, besides this message (you may have to scroll up) that could point to the actual cause?
• ### Re: Problem of filter-wash cycle

Dear Jialu ZHU,
I reply to your question has been sent to you via email.