Martin Griffith

Hi Prag, You can look at the property Flow | Free Air Quantity instead of Flow | Quantity. This will give the flow rate standardised to the set standard pressure. You can set the temperature and surface pressure in the settings

Hi, Thanks for your message. Please email us at ventsim@howden.com and we should be able to help you with this request.

Since the release of Ventsim 5.4 we've been busy adding new features to help with your underground ventilation modelling. On top of what came out in the original Ventsim 5.4 release (https://ventsim.com/2020/02/18/whats-new-in-ventsim-5-4/) the below is a list of what's new: Heaters & Coolers Instead of setting a heating or cooling source in your airway, you can define Heaters and Coolers with target temperatures. This works in a similar way to using a fixed temperature, but provides additional information on energy, water and fuel use, as well has having some really cool interactions with the Annual Thermal Flywheel Simulation. Just recently we've added the ability to set a maximum capacity to a cooler, making it behave more realistically. Parallel Fan Stall Predictor Use this tool to scan over your model and assess the risk of stalled fans in parallel configurations. This helps to deal with the problem where in parallel fan configurations, one of more fans will be in stall, while the others are operating normally. Traffic Features We've added new ways to deal with the number of vehicles on an Activity Track varying throughout the day. You can now set a time to a stage, and have a different amount of traffic every hour of the day. We've also improved the UI around setting a track's starting location. Advanced Message Boxes We've seen lots of models adorned with many detailed and bespoke Advanced Message Boxes, showing simulation data in new and useful ways. If you want a particular piece of information from your model, there's probably a way you can do it with the Message Box. As users have provided feedback we've added new properties as well, so just ask if there is something you need. Also available are a number of new averaging techniques, which allow you to obtain more representative averages. For example, this message box below gives an average temperature, but weighted for flow and length, rather than each airway having equal weight. This example here tells you how many fans in a particular section of the mine you have on: Diesel Simulation: Fresh Air Surplus When you run a Diesel Simulation, Ventsim now calculates a new property Diesel | Air Surplus, which keeps a track of how much fresh air you have through the mine. This is often handled globally in the model, by summing the Diesel Power of all the machines in the mine and calculating a required air flow, generally following a regulation specifying a required airflow per kW of diesel power (often something around 0.06 (m3/s)/Kw). This property will calculate this locally. The fresh air consumed is calculated using the air flow requirement specified in the Diesel Settings, or adding a machine specific flow requirement in the Presets. If the Air Surplus drops below zero and you have a diesel machine in the area, you'll get a warning with your Diesel Simulation. Fan Identifier The Fan Identifier tool lets you keep track of individual fans, rather than just fan types. Set up your Fan Identifiers, and then assign them to airways. In the Fan Identifier, you can even keep fans that aren't being used. The tool will tell you the status of each fan, where it is, and will even let you control it from the Fan Identifier database. Auto-Regulators Auto-regulators are a new resistance option for an airway. They use the same Regulator presets as the regular Regulator option, but instead of setting the opening, you set the Target flow rate, and Ventsim works out the opening; much like a control regulator would do it. If the target airflow can't be achieved you'll get a warning which tells you how much you've missed the target by. For people use to using Fixed Flows with the Restrict Only option on, autoregulators are a great option, since they won't simulate a flow as if the regulator is adding pressure; instead, the regulator will just be fully open. Electric Vehicles In the Heat, Moisture, Diesel Presets, we've added an Electric Power column. This brings the Ventsim treatment of Electric Vehicles in line with how we treat Diesel Vehicles, namely by the (more readily available) motor output, rather than heat released. This also allows users to easily compare the use of Diesel and Electric vehicles in Ventsim. That's it for now, but you'll find many other smaller improvements in Ventsim 5.4 if you update to the latest version. As always, any questions, you can respond here or contact us at ventsim.support@howden.com. We rely a lot on your feedback to make the software better, so please tell us if there is something you would like to see in Ventsim.

Hi, I believe I've sent you an email from our support email regarding this model. The problem can be fixed by addressing the fixed lengths in the model. Let me know if you haven't received it. Martin

Hi Jorge, Sorry you've had this problem. Could you please give me some more details? Is there an error message that appears? If so, can you send me a screenshot? Are you using the Convert Centreline tool, or are you doing the conversion on the DXF import window? One thing to look out for: check if the count of the number of pipes at the bottom of the Pumpsim window goes up after you use the tool. If the count goes up, but you can't see the pipes, it may be because they are being created in a Primary or Secondary Layer, or Level, that it currently not visible. Right-click | Show All should make them appear. We are looking to launch Pumpsim 4 early next year. This will be a big change from Pumpsim 3, bringing with it many of the changes that you've identified in Ventsim that are needed in Pumpsim, and more. You will be sure to hear about its availability, either here on the forum, or through messages in the software.

Hi Andrzej, My first comment would be that you are plotting the variation of airflow and velocity over time, but the variation of pressure over length, which would be for only a snapshot in time. You would need to plot the pressure over time at a single point, as you have for the airflow and the velocity. Another thing to be careful of when using the piston effect to simulate an intermittent effect like a train is that the air simulation of the Dynamic Simulation is a series of steady state simulations. This means there is effectively an instant acceleration of the flow; therefore, the inertia of the air is not taken into account. This means that the peak airspeeds during the dynamic simulation are possibly overestimated. The extra pressure from the piston effect is calculated by correcting the drag force on the train (a function of drag coefficient, frontal area and relative velocity) into a pressure across the cross-section of the tunnel. Another thing to be careful of for trains is they often have very high blockage ratios; the effect of high blockage ratios on the piston effect is something that we have not yet fully considered and are researching more. Interested to see how you go using the feature.

Hi, This is something we are considering for the future. We will consider your request in giving it more priority. If we do it, we will announce it on the forum and in other places, so you will know about it. Thank you.

Hi Fred, This issue has been fixed n the latest minor release available here: https://ventsim.com/download/minor-releases/ Thank you for bringing it to our attention!

Hi Fred, Apologies, this looks like a bug in the software. The average WBGT value is giving the inlet value. We will fix this very soon and put out a patch. I will post here again when the new version is available.

Hi Tim, Thanks for your message. This sounds like a job for the Spreadsheet tool. Clear your airway selection with the Escape key and then go to Tools | Spreadsheet. There is a Default Saved View called Fan Data. Switch to that and (if you are on a late enough version of Ventsim) you will see a spreadsheet with handy information about the fans in your model, and all grouped by fan type ( you can drag column headers up to group by that column). You can also go to Select Columns | Data Options to customize the data you see. You have access to all the Ventsim properties. For you, you could add Attributes | Coordinates Mid Entry to get the location of the fans. Once you have that, you can export from there to Excel or CSV if you want. If this is something you are going to do regularly, you can save a new Spreadsheet Saved View called, say, Fan Locations, so once you've set this up you can come back to it pretty quickly. I set up such a Spreadsheet Saved View in the image here. You have the Coordinates at right. You also can have the X, Y, Z coordinates in separate columns, but X1, Y1, Z1, X2, Y2 Z2 give the locations at the airway ends; the location of the fan is at the Mid point, so there would be a discrepancy. We may add a new property, such as X-mid, Y-mid, Z-mid. If it helps (and you are on version 5.4.5.1 or later), I've attached a Ventsim model to this message which has this Spreadsheet Saved View. You can use the File | Inherit tool to bring this Spreadsheet Saved View into your own model if you like. If you want the very latest version of Ventsim go to: https://ventsim.com/download/minor-releases/ FanLocationSpreadsheet.vsm

Hi Andre, We can't really do this with the current way layers are set up in Ventsim. What we would recommend is that you create separate layers for each part, so you would have layers that represent shared areas. Not exactly what you are looking for, but probably the best you can do with the current system.

Hi John, Does the Import options window not appear when you drag and drop? What type of reference file are you importing? (.DXF, .DWG, .....)

Hi George, I replied to your question in another thread here:

Hi George, The Stage tool allows you to have different stages in your model representing the system at different moments in time. There is an example in the Pumpsim demonstration models. Go to File | Load Demonstration | Stages, and then change between the different Stages. Before using Stages, it is a good idea to save your model in a different file. Stages can be difficult to understand when you are starting with them, so it is likely you will make mistakes and want to go back and start again. To set pu stages in your model, go to the Stages menu and have a play with the options there. You can create a new stage by making a Shared Copy. Then, to Edit a stage without changing anything in the other stage, click the StageLock button When this button is on, any changes you make are limited to the current stage. Have a play with it and let us know how you go.

Hi George, sure thing, feel free to post here, or, send us an email at ventsim.support@howden.com regards, Martin

Hi, For diesel machines, it is better to use the Diesel Simulation, which will find any Diesel Heat inputs in your mine and generate the appropritate amounts of contaminant. You can add Diesel Power on the Heat tab of the Edit form. But from what you are saying you probably want to use an Activity Track This tool will allow you to choose a path that the vehicles use and you can then add any number of units of vehicles to this track. Then the Diesel Simulation will pick find these and generate the contaminants. Have a go and get back to us with any questions you have. Feel free to send us a model to take a look at.

Hi Fred, we fixed something around this in versino 5.4.5.5, so please download and install the latest version, that might fix the problem. https://ventsim.com/download/minor-releases/ Although, I've checked over it now and I think that the new Electric Vehicles might be causing a problem with the Energy Losses graph. Will fix that. I will look at providing an option to switch between percentages and values.

Hi Fred, This has been implemented in the latest patch of Ventsim 5.4.5.6, available here: https://ventsim.com/download/minor-releases/ You will now be prompted if you want to save your flywheel data. Any problems, please let me know!

Hi Kevin, Sorry you've had this problem. It'd be best to see the model to work out what is going on. You can email us at ventsim.support@howden.com. If the file is bigger than 10MB then you can either send it to me through this forum's direct message service, or email us and we will set up a oneDrive link for you to upload to. All models sent to us for support are treated confidentially. Also please let us know which version of the software you are using (Help | About)

In the latest patch, version 5.4.5.5, this change has been made, so that multiple adjusting airways with the same starting point, show the adjustment value in its true units. Thank you for the feedback! https://ventsim.com/download/minor-releases/

Thanks again for the feedback, this has been implemented in the latest patch, version 5.4.5.5, available here: https://ventsim.com/download/minor-releases/

Hi Roy, thank you for this suggestions, we will make them go grey in the next version, out soon.

I think so. You can close the Goal Seek, keep the result and look at what the Goal Seek has actually put on the airway to verify. One thing you can do is set the refrigeration to a non-zero value before you launch the Goal Seek, say 100kW. Then the percentage increase will be based off that starting point, and be a little more comprehensible. I will change it so the percentage only applies if the starting values are not equal. I'll post in this thread again when we release a version with this.

Remember that there are a variety of ways to get the drybulb temperature up from one temperature to the next. Consider your psychrometric chart (below), you can increase the drybulb temperature by going to the right on the x-axis. Therefore this could involve a de-humidification process at constant wetbulb temperature. Or it could involve pure sensible heating, or a combination of sensible heating + latent heating or cooling. Also bear in mind that in an underground environment, there is rarely ever a purely sensible heat transfer process. Underground environments are often humid and there is always some degree of wetness on the hot rock walls. Any heat transfer process will involve surrounding ambient moisture. For the Heater tool we are trying to model an actual Heater underground. We are setting a dry bulb temperature, but not the wet bulb temperature. We make an assumption that the resulting air state will have the same relative humidity + any extra moisture from the burnt fuel. This is ok for underground Heating where we are generally heating from sub-zero temperatutes to slightly greater than zero to avoid surface entries icing up, so, along with the moisture from the burning, we're generally at higher humidity. But I think for other Heating scenarios (such as say increasing to higher temperatures of ~30 degrees), this might not be a valid assumption, and I've seen in my own models investigating this that indeed that might be a problem. Your other option is to not use the Heater function and instead set the drybulb AND the wetbulb temperature, thus removing any assumptions in the simulation. But then you would have to come up with a target wetbulb temperature. But if you are modelling for human comfort and safety then you're probably more interested in the wet bulb temperature, but I don't know what temperatures you are modelling.

Hi Neil, Sorry you've had this problem. This is most likely an incomplete save of the Ventsim model file. We can try to recover it for you if you send it to us. You can send us an email at ventsim.support@howden.com . If the file is too big for email (>10MB) we can set up a OneDrive folder for you to upload it. You can also send it to me as a direct message on this forum. You can attach files up to 500MB.