Martin Griffith

Hi, Thanks for your questions. a/ I think this is the correct way to model the drill. However, you need to check where the moisture and energy is going. Is there 1000ml/sec of water being evaporated into the air, or is there some amount which runs off in a drain or channel? The value you enter here should be what is evaporated in the air. b, c/ There is no property available which tells you how much moisture is being added, other than where you've input it. But you can see the effect in the results. You will see the dry bulb temperature immediately downstream of the moisture source go down as you add more moisture. If you add enough moisture, the air will be saturated (dry bulb = wet bulb) and Ventsim will calculate how much fog and condensate forms from the saturated air. The New Sensible Heat parameter is not much use here, as it includes heat transfer from the rock wall. I hope this helps, let us know if you have more questions.

When you build a duct, you can specify a leakage porosity in units of mm2/m2. Ventsim will then add leakage connections between the duct and its parent airways. A leakage resistance is then applied to each of the leakage connections. You can modify this leakage porosity if you wish, but if you don't build any leakage in to your duct when you create it, then the leakage connections are not built and can not be added later. To observe the effect, build a duct with high porosity and then observe the drop in Airflow Quantity along the duct. Also, you can switch to WireFrame view (hotkey "w") which will show you the leakage connections.

Hi, For ducts, the duct and leakage network structure is built and fixed at the moment of the duct creation. When you create a new duct, if you don't specify any leakage then the leakage connections are not needed, so they aren't built. They can't be added in later. Similarly, the offsets relate to the network structure and can not be modified through the Duct Builder. So you need to specify some leakage when the duct is built. If you do this, then the option to modify it later will be available. You can move the ducts using the Move Tool, but if you do so, you may change the lengths of the duct and interval distances, meaning that you could change the leakage porosity. You might also accidentally detach the leakage connections. But you shouldn't have to change the offsets very often; they are only for visual purposes and have no effect on the simulation. If you really need to change the offset of the ducts, then it's probably better to rebuild the duct.

Hi Adrian, it could be a few different things happening. If you want to add a second track, you'll need to first click the green plus button at the bottom left of the Track Editor. If you send us (either here, by email or through the forum direct message) a screenshot of the Editor and what version of the software you're using (Help | About) it might help to work out the problem.

Further to this, we've also enhanced some of the functionality around message boxes. Currently, you can set the stages on the Message Box, so that it appears only on some stages. Some users have requested that the Message Boxes be visible or invisible based on the visibility of the airway that they are attached to. We've made this change. That means that if your message box is positioned on an airway, and then you switch off the visibility of that airway (by, say, unselecting the Primary or Secondary Layer that that airway belongs to) then the Message Box will also disappear. If you want the Message Box to not follow the visibility of the airway, then move the Message Box away from the airway. There is a catch though. Because this feature is new, it won't work automatically on your existing models in Ventsim 5.4. If you want an existing Message Box (from version 5.2 or earlier) to follow the visibility of the airway, then you'll need to move the Message Box off the airway, then back on. Also, if you have airways linked to the Message Box as part of the Advanced Message Box function, then the Message Box will be visible if any of the selected airways are visible. One last thing: with these Advanced Message Box features, you might start putting a lot of work into crafting the exact outputs you're interested in. Because of this, we've added the Message Boxes to the Undo list. This means if you move, delete, add or edit a message box, your changes can be undone (or re-done) in the usual way. Any experiences or questions around the message boxes, we're keen to hear.

Hi Kyle, Thank you for getting in contact with us about this. This is a bug in Pumpsim. We've fixed the problem and have released a new version, Pumpsim version 3.1.2.0, which you can find here: http://www.pumpsim.com/download/current-downloads/ If you download and install this latest version, this problem shoudn't reoccur. Our apologies for the inconvenience caused. Please get in contact again if there is any further problem.

Activity Tracks are a useful way to simulate heat along a path, rather than at discrete points. For example, you might have a number of trucks going up and down a decline; using the Activity Track, you can distribute the Heat and the DPM from these trucks along their path, rather than at discrete points. In the example here I am going to replace the three trucks in the decline with three trucks on an Activity Track. The trucks are set in the Heat, Moisture, Diesel Presets; they can also be used in the Activity Tracks. The first thing I’ll do is remove the existing trucks from the decline. Then I’ll go to Tools | Activity Tracks. After opening the Track Editor, I’ve renamed the Track as “Decline”. Then, using the Shortest Horizontal Tool, I’ve selected the entirety of the decline. Once I’ve selected the airways I want as part of the track, I’ve clicked on Add selection. Now, a transparent green strip is visible above the airways that are part of the track. I can also change this colour on the Track Editor. (Clicking with the Edit Tool, or double-clicking with the Zoom tool, on the transparent strip will open the Track Editor for that Activity Track) Now I want to add the trucks. My existing AD55 truck preset is available under Heat type. I’ve then added 3 units. If I click OK and run a Heat Simulation (or a Diesel Simulation) the effect of these trucks is now distributed along the length of the track. There are several more advanced options to the Activity Tracks. If you want to include an amount of time that the trucks are outside of the mine, or parked, then you can use the ‘Delay restart’ option. This will reduce the amount of Heat released by the trucks corresponding to the amount of time specified. However, to use this option, Ventsim will need to know how fast the trucks go and how long it takes to traverse the track. You will need to specify a Vehicle type to get the right velocity. Also you will need to specify if the track is ‘Bi-directional’, that is, are the trucks going up and down, or only in one direction. Finally, if Ventsim needs to know this information, then if there are parts of the track that are disconnected from other parts of the track, then the simulation won’t work and you’ll get a warning telling you which track is causing the problem. On the Track Editor, you can select ‘Highlight in 3D view’, which will show you in the viewer which airways belong to the track. If you have any questions about Activity Tracks, experiences to share or feedback, then please reply to this thread; or, contact us at Howden Ventsim. COMING IN VENTSIM 5.4: the Track Editor will have a button to generate a graph showing the variation of properties along the track.

Hi JB, When configuring the fire, make sure to press Apply on the Edit form. Also, go to the Visibility Manager (blue cog on the left toolbar) and check that Heat is checked on in the left column under Icons. If it still doesn't come up then send us an email at ventsim.support@howden.com and if possible, send us your model.

Hi, It looks like some of the VentSim HVAC features are running here. Could you please tell us what version of the software you're using (Help | About). Also, send us an email with your license number to ventsim.support@howden.com and we'll work out what's going on.

Hi, Ventsim has a feature to model free-standing fans, or jet fans. You will find a description and rundown of how to do it in this thread: Any questions, don't hesitate to ask.

In Ventsim DESIGN version 5.4, we are developing a tool to simulate the air blast result from caving events. The tool will model the peak air velocities experienced through out the mine resulting from a caving event. Currently, the caving model operates as a simple piston, pressurising the air in the void and then modelling the resulting air velocities throughout the mine. The existing resistances of the mine model are used, as well as a muckpile resistance which is added to any cave connection situated lower than the muckpile height. More complex models of the caving dynamics will be incorporated into the model with user feedback, but for now we have the basic setup for the simulation. In the test model pictured here, I have specified the three close airways here as Caving Blast Connections, and have also placed dynamic monitors. I then launch the Caving Air Blast Simulation from the dropdown menu beneath the Fire Simulation button. This brings up a window to specify the size of the cave, the Cave Diameter, the highest and lowest point in the cave and the MuckPile height. The Highest and Lowest Point reference the true coordinates of the model. The Highest Point has a minimum value equal to the highest caving blast connections, while the Lowest Point has a maximum value equal to the lowest caving blast connection. The Muckpile Height is the height of the muckpile above the lowest point. Click OK and the simulation will launch. The air in the cave will be compressed and vent through the connections and the model. Any connection between the lowest point and the muckpile height will have an additional resistance based on the air pushing through the muckpile. The resulting airflows can be seen by opening the dynamic monitors. Any seals which have the Strength rating exceeded should fail. If you are interested in using the tool and its further development , or have any questions, please let us know.

Hi Roy, we removed this limit some time ago. Now, Ventsim doesn't limit the reference size. The reference to this in the manual is out of date. Are you having some problem loading or saving a model?

Hi Andre, sorry you're having this problem. I've tried recreating the issue with Ventsim version 5.2.9.7 and I haven't had any success. Can I ask which version of Ventsim you are using? If you are using a version of Ventsim 5.2, are you using the new or old Edit Form? If you are not on the latest version of Ventsim 5.2 (available here: https://ventsim.com/download/currentdownloads/ ) then I suggest you update, this may resolve the issue. Let me know how you go.

Hi, It could be that your license needs to be activated. Go to File | Licensing Manager to check. If this doesn't fix the problem, send us an email at ventsim.support@howden.com, with a screenshot, and we'll work out what's going on.

Hi Roy, this is a good idea. It should be possible to do for our next version of Ventsim, 5.3. I'll keep you posted.

Hi Kevin, Is this problem ongoing? If so, can you let me know which version of the software you're using? Do you mean the Edit Preset option on the Presets form? Generally if this is greyed-out it means that there is no special way to Edit them. In the case of the Tunnel Profiles, you can edit the shape by clicking once on the image of the Profile. If, for example, you go to the Fan or Regulator tabs, then the Edit Preset option is available and will open the respective form. We could make it so that the Edit Preset form is enabled for Tunnel Profiles and it simply opens the custom shape builder. We'll consider this for Ventsim version 5.3, which is out soon.

If you're using a Round shape, then you can enter a value for Height or Width and this will interpreted by the software as a diameter. But it is confusing and has been brought up before by other users. We will fix this in the next version of VentSim, 5.3, which will be available soon. Thank you for this suggestion.

Hi Bruno, It's possible to enter the data manually to the database using Access, but you would need to know your way around Microsoft Access. The other option is that we do it for you. I will send you a message through the forum Messages tool.

You can model this situation in a Heat Simulation using an Activity Track with the Delay Restart option. Set up your Activity Track. Then calculate the amount of time that the truck will be outside the mine and enter the value in the field for "Delay restart". Doing this, Ventsim will discount the amount of heat generated by the truck corresponding to the time the truck is out of the mine. However, using the Delay Restart means that Ventsim will need to know the amount of time it takes to travel along the path. That means that for the Delay Restart to have an effect, you need to also: specify a vehicle type to set the speed of the truck, and specify whether the track is bi-directional. A vehicle travelling on a track specified as bi-directional will start at one end of the track, travel the length of the track, turn around and travel the length of the track again and then finish where it started. So specifying the track as bi-directional will affect the relative portion of time that the truck spends outside of the mine. The direction of the track will only be important for a Dynamic Simulation. For a steady-state Heat Simulation, it shouldn’t make a difference at which end the track starts.

In your model, you have a pump set up as a positive displacement pump, named FMC1620. You can use this one, it's available in the pump dropdown on the Pump Edit form; it appears to match the fix flow you had setup originally. There also appears to be a problem with the software in adding new positive displacement pumps, which I will take a look at and get back to you about.

Yes, that's right; however in reducing the pipe diameter you also need to be mindful of the warnings you will receive on exceeding the pipe nominal pressure, and also of any pressure limitations on your positive displacement pump. If you enter the pump as a Positive Displacement Pump rather than a Fixed Flow, you can include a maximum pressure for the pump which Pumpsim will warn you about if you exceed.

Hi Jorge, The cavitation warning is indicating that you have negative pressure and the simulation results are likely inaccurate. In this case, the pressure created by the fix flow is too low to pump along the entire length of the pipe. You can experiment with removing the cavitation by, for example, putting in a greater fix flow or reducing the pipe diameter or adding a missing valve or demand device to increase the pressure drop required. The irregularity of the path in your model is not a problem for Pumpsim.

Hi Marko, This is an issue that has affected a couple of other users as well. You can try switching your units to Metric then going to File > Defaults > Save. This should save the unit setting to the default file Ventsim uses when creating a new model. If this doesn't work, I suggest uninstalling and then reinstalling Ventsim. If this still doesn't work, then please contact me directly via email or through the forum direct messages and we will work through another solution. regards, Martin

Hi, The gradient indicates, as a percentage, the vertical component of the airway length compared to the horizontal component. A gradient of 26118.1% indicates a vertical component of the airway length 261.181 times greater than the horizontal component; that is, a very nearly vertical airway. A gradient of 10% would indicate an airway increasing 1m in height for every 10m in horizontal length. If the airway is completely vertical (no horizontal component) then the gradient field will say "Up" or "Down".

Hi, As Dinchev has written we believe this issue is resolved in version 5.2.8.6, available on the website.