Fred_K

Hello!

Quick one. Is there a possibility to export/import global parameters/settings (found under Settings -> Settings) from one project to another? Select all, then copy/paste is not possible, only individual parameters are selectable. Would I have to update everything manually? It doesn't take long to do that but it would be simpler and less human error would be incorporated that way.

Thanks!

Best regards,

Fred

Cheers Craig!

Perhaps another two small things I noticed that could perhaps be improved, if I remember them correctly:

(1) It would be nice if the chosen output fields for the "selected output" were saved, for convenience. Right now, it seems like all chosen fields are deselected when you exit the script window when clicking "OK". It's a bit inconvenient, because the list of selectable output parameters is quite large.

During the meeting with Daniel we agreed that linking the selected outputs to the "Saved Views" in the "Spreadsheet" tab would be a good idea - perhaps he has already done some work there.

(2) If there are any issues that come up when running a simulation, e.g. "Airway is getting too hot" during a heat sim, the running simulation is aborted and an error appears. There appears to be no way to abort a script once it is running and this error appears; instead, a notification appears with only the option to click "OK". Once "OK" is clicked, the next script in the sequence is run. This forces you to potentially click through all of the remaining scripts, unless you force-stop Ventsim.

While such issues of course should not occur, when it does happen for some reason, and scripts are run where multiple parameters are varied (leading to tens, hundreds, ... of scripts), then this is highly inconvenient. The addition of a "Cancel" or "Abort" button to cancel running the script file would be nice.

Best regards,

Fred

Hello,

there is a possible bug when running a static script and selecting "selected output" in Ventsim Design 5.4.6.3.

I have set up a script with some airways. When selecting "selected output", the output file always has one airway missing. The missing airway always appears to be the one with the greatest unique number. I have tested this three separate times using different airways.

The same issue does not seem to occur when selecting "native output". With this option, there are no missing airways in the output file.

Cheers,

Fred

Hello,

Following the Ventsim User Conference (which was very good!) I've participated in a nice meeting with Daniel Sepulveda, where he showed how static scripting works. I've tried to play with that functionality in the past but didn't revisit it until now. Now I have a better understanding of it. Thanks Daniel!

Some observations that I also pointed out to Daniel but would like to do again here.

When you generate the script, which is in spreadsheet format, there are a lot of columns to deal with. The problem with those columns (representing variables), is that they are:

(1) usually named differently from the variables they represent in Ventsim which makes it hard to identify them (see for example Moisture (ml/s)) and

(2) usually not in order or grouped according to the Ventsim variables. The variables in the script are sometimes quite far off (see Electric Vehicle (kW)).

(3) Also, all initial files generated include all variables from all possible simulations, regardless of the simulation option you actually want to create scripts and will tick the box for. I guess this can't be changed easily.

To make this whole thing more user friendly, my suggestions:

(a) Is it possible to generate the same or very similar names (maybe without symbols) as in Ventsim? This would make the variables of interest much easier to find.

(b) It would also help if they were grouped not only according to the tab they represent, e.g. "Heat Simulation", but also the variable group within the tab, e.g. "Point Source". Most importantly, that the variables are in order.

Maybe the static script function could get a bigger mention in the next iteration of the Ventsim Design manual. I also want to point out that the manual is missing page numbers on the bottom of the pages following the index, this should be a quick fix 😉 

Cheers!

Fred

A screenshot to illustrate this issue, after changing some variables as Daniel suggested to see where changes occur.

Stalin,

I'm interested in that document you shared. It says it's from CIM Bulletin, November 1982. Would you mind sharing the author, title (or even the file)? Or anyone, if familiar with this?

Thanks!

Best,

Fred

On 6/16/2020 at 7:06 PM, Stalin said:

Yes.

Thank you very much.

What will be the formula for calculating the necessary ventilation?

Will the calculations look like the attachment?

Hello!

I selected a couple of airways and used the spreadsheet tool to give me entry/exit/average figures for WB, DB, WBGT.

The "average WBGT" appears to be the "entry" value, not the "average"? Am I missing something?

Best regards,

Fred

I guess I can hit "copy data" and make my own charts for the values. Regardless, the "combustables" and "waterways" labels are still startling.

Hello!

I think the labels of the heat summary graphs need a small fix. I've noticed this when looking at some summary pie charts for selected airways, in which I have placed activity tracks with electric vehicles.

The heat gains show "combustables" - that seems to be a remnant of when electric vehicles were not included in Ventsim. Would be confusing when using a mixed fleet?

Same goes for moisture added by "waterways" - I haven't placed any, but I do have the latent heat factor active for the electric vehicles. That appears to be the source. Having waterways and electric vehicles would also be confusing.

In my opinion it would also be nice if there is an option to show the values , not just percentages. Makes it easier to trace to table values, and more usable. 🙂 

Cheers,

Fred

I see... so that means, when adjusting two airways starting at zero (1:1 ratio), and the output of the goal seek function is 100 000 000%, then the inerpretation would be that both airways are adjusted to 1 000 000 kW (100% = 1, assumed by Ventsim)?

Hello!

I would like to confirm that the Goal Seek function does indeed allow the adjustment of multiple airways, to reach a target value of one airway?

I've been playing around and when chosing Refrigeration, the result is not in kW but in %. I'm not exactly sure how to interpret this. The two airways merge into one airway and have almost identical mass flow. What I wanted to achieve is an overall value to be calculated and split between the airways.

It's working fine when selecting only one airway to be adjusted. Maybe the adjustment of multiple airways is not allowed, so I'm just checking whether this is a glitch or not.

Cheers,

Fred

Thank you for your answer, Martin!

I have actually removed all the combustion products from the fuel that I have set up: CO2, CO, H2O, etc. all set to "0". My assumption is that this way, only the heat would be considered in a kind of complete combustion scenario. For completeness' sake and confirmation, the Ventsim heater would not add the H2O to the intake air if the indirect option was chosen, correct? Have not checked this. Results are very different regardless.

What I'm trying to do is simply raise the dry bulb temperature from -X to +Y and find out how much energy input I would need for this.

I thought the heater option would be a nice and easy way of doing it (indirect, as I'm considering heat exchangers, with combustion products set to 0 as stated above), but the difference in results left me wondering how it works.

Cheers,

Fred

Hello!

A question on how to inerpret the Heater functionality vs. the Goal Seek function.

If I want to have a target outlet temperature (dry bulb) for my airway, and I would like to know how much energy input is required to achieve this. I can run a Goal Seek with the airway to be adjusted and the target airway to be the same. A solution for the target dry bulb will be sought for a sensible heat source.

Because that's taking a rather long time with my model, I was thinking of using the heater functionality. Set the outlet temperature to my target value, select a fuel (even though I may not use it, as I said I'm more interested in the energy) and back calculate from the amount of fuel required.

The differences between the values are quite significant. Why is that so, how does Ventsim calculate in each instance (point source?)

I understand that the Goal Seek function may not have been designed with this kind of usage in mind and the calculation is different - is that the reason? Is there a latent heat factor involved somewhere (liquid fuels such as diesel also produce water during combustion)? 

Should I be trusting the Heater option rather than the Goal Seek function?

Cheers!

Fred

Hi Martin,

so it is annual, not monthly fuel? Or is this depending on whether you run a flywheel simulation or not?

In my version (Design Premium 5.4.4.8) it says "monthly fuel", and I'm running a regular heat simulation.

Thanks!

Fred

I have a small follow-up question here.

When I run my simulations, why does Ventsim auto-adjust the surface datum of my mine grid?

Thanks Martin!

Hello!

I've noticed that during tests with the available demo files that the results of a heat simulation can be saved - the results are accessible after opening the saved file.

To me it seems that the thermal flywheel simulation is similar to the regular heat simulation, but runs two simulations for every month (preliminary and final) using changed WBT/DBT, plus an initialization and a finalization run.

However, when running an annual thermal flywheel, the results are not saved - the values for the months revert back to the pre-simulation values. Why is that so? Is there a way around this if I want to show the results to someone? I don't see a point in exporting the values for every airway into a spreadsheet.

Cheers,

Fred

Hello!

A minor thing I've noticed. This is in Design Premium 5.4.4.8.

The "take a picture" feature that opens up an image ready for editing does not seem to work. It opens up a completely black image. This is from the Calculator, but same issue in Presets.

Edit -> Copy Image does work, however.

Cheers,

Frédéric

Hi Craig, 

I'm running Design Premium 5.4.4.8, 64bit.

What I would like to achieve is simulating different scenarios as well as sensitivity analyses where I would vary only one parameter at a time, and see the effect on the heat load. I want to be able to do this partly for my curiosity, but also because some parameters vary depending on where and how they were measured. That means the rock thermal parameters, the geothermal gradient and the outside air temperatures (= an extreme summer/winter) mostly.

I guess with the few parameters I'm interested in it's relatively simple to do a sensitivity analysis. And I could set up a list of combinations that I could go back to, and manually change my parameters. But it would be nice to not have to do that and just feed such a list into VentSim or tell VentSim to run scenarios and change X in steps of Y.

Since I can't open the script file, I don't really know what parameters I can change, but it looks like from your screenshot it looks like it's the properties of the airways?

On 8/5/2021 at 1:37 AM, Craig Christensen said:

Best regards,

Frédéric

Thanks Martin!

Hi Craig,

thank you for your clear and detailed guide, it is much appreciated!

What I would like to do, and I apologize, I should've been a little clearer, is to set up a range of heat simulation scenarios, by changing some of the parameters in the Settings -> Settings -> Simulation window.

I've attempted to follow your guide.

My problem starts fairly early:

9 hours ago, Craig Christensen said:

Open the file that was generated and you should see that the output will contain all of the airways, but you can delete the ones you aren't intending to modify across the scripts.

I can't open it. Instead, I get the following messages (second message after clicking Yes) 

The file itself also seems a little off, as it's only 26 bytes, and that just seems way too small.

Finally, when I want to open the generated file from VentSim by clicking the Show button in the window, I get the following message:

I don't know what this means exactly, whether it is something that I have done wrong or if this is a bug. I have checked the static script function with a model made up of one airway, but the problem is the same.

Best regards,

Frédéric

Hello!

How do I go about running simulation scenarios automatically in VentSim, without having to manually change simulation parameters and then running each scenario individually? Is there a guide available for using the scripting function? I'm getting an "EOF in header" error when trying to read a script file I've created, and I can't open the file itself either ("... file format or extension is not valid..."). What am I doing wrong?

Cheers!

Frédéric

I think I answered my own question, changing the theoretical Surface Datum RockTemp is what I will be doing...

I also played around with the settings a little too much. I made corrections and it's much closer to the measured VRT now.

Hello!

In VentSim, the simulated VRT appears to be calculated from this line function: Geotheromal Gradient * Surface Datum of Mine Grid + Surface Datum RockTemp

It is this simulated VRT that is used in other calculations, correct?

I have a geothermal gradient, from temperatures that can be considered VRT, obtained from borehole data (several boreholes, different locations). However, the simulated VRT for a target level does not match the measured temperatures at all. To match my temperatures, Surface Datum RockTemp or Geothermal Gradient would need to be a lot higher.

Since it is theoretical and not calculated from other values, I would think that I can simply change the Surface Datum RockTemp to match my temperatures? Or would this affect other calculations beyond those making use of the simulated VRT?

By the way, the manuals from the Howden website do not have page numbers beyond the table of contents. Makes things just a little harder to find quickly 😉 

Thanks!

Frédéric

Hello!

Novice user here, still figuring out VentSim. I was playing around with the settings and found this.

In the rock parameter settings in the Simulation --> Environment section.

For the density, it says "optional if diffusivity set". That I would inerpret as being able to set the diffusivity to a custom value.

If I want to change the value for diffusivity, it won't let me - the value will revert back to its original, calculated from density, specific heat and conductivity. These other parameters I can change, no problem.

Am I missing something here, is it supposed to be like this? It's not really an issue because the lab would provide all parameters anyway, but it appears that density is not "optional" at all?

This was tested on VentSim Design Premium 5.4.4.8 64bit and on Ventsim Lite 5.2.8.5 64bit.

Have a great day!

Frédéric