Martin Griffith

You need to set the direction on your fan. The assumed direction when you place the fan is the current direction of the airway. If it's not correct, then you need to reverse the direction of the fan. Do that by clicking on the Reverse button on the Fan tab, or click on the airway using the Reverse Tool. The Reverse Blade option is something else. This option maintains the direction of the fan, but reverses the blade rotation on the fan, running it in reverse. If you do this, then the fan will by default run at 50% of its defined performance. You can alter this factor in the Fan Editor. However, you would only use this option very rarely, it at all. From your description, it sounds like you want to reverse the direction of the fan, so you would use the Reverse Tool.

It's hard to tell without seeing the model. Send us an email with the model to ventsim.support@howden.com and we can take a look.

If you run the Dynamic Radon Simulation long enough (and you don't change any airflow or fixed Radon amount during the Dynamic Simulation) you should eventually arrive at the same result as the Steady-State Radon Simulation.

The default behaviour is for the Dynamic Radon Simulation to start from a resetted condition. Is this something you'd like to be able to change?

More or less, yes. The Ventsim Radon Simulation will calculate WL throughout the mine, based on the existing flow rates and radon emissions in your model. Then you can adjust flow rates to bring the WL to the required level. If we put a WL target in the Goal Seek, you could adjust a Fix Flow or Fan Speed to achieve a certain WL with the Goal Seek, taking into account the entire mine model. For now, if you want to get a Fix Flow rate for an exact WL in a part of the mine, you will have to adjust your flow rates using trial and error. We will add Radon WL to the Goal Seek as a target in a version of Ventsim soon.

In Ventsim, we currently have the Goal Seek tool, under the Tools menu. Here you can adjust everything under the Adjust menu to reach a target value of anything under the Target menu. At the moment the target options are Quantity, Pressure, Temperature, Velocity and Gas Concentrations. We could add Radon properties as target values. So this would mean you could run the Goal Seek, adjusting, say, a Fan Speed, to achieve a certain Radon concentration in another part of the mine. You would enter in the regulation limit Radon concentration as the target, then Ventism would work out the required Fan Speed or Fix Flow amount. Is this the sort of thing you're after?

Hola Sofia, ¿Le refiere a los conductos estándar? Si es así, puede modificar la selección de etapas de cada conducto en la primera pestaña del cuadro de edición: o te refieres a los tubos auxiliares?

Hi John, thank you for the helpful suggestions. We just released Ventsim 5.4.1.4 on the website here: https://ventsim.com/download/minor-releases/ We've implemented your 3 suggestions in this version. Thanks again and please let us know if there's any problem.

After you have run your simulation, press Escape to clear your airway selection, then go to Run | Summary. In this form, you have several tabs which will give you a summary of the model. If you want to summarise just a portion of the mine, then you can select airways before running the Summary. You might also find the Tools | Spreadsheet function valuable for summarising or collating data from across the model. A good explanation of the Spreadsheet function can be found here:

The power of the fans is calculated according to standard Fan Laws. A good summary of Fan Laws and Theory can be found here: https://www.mvsengineering.com/files/Subsurface-Book/MVS-SVE_Chapter10.pdf In Ventsim, the power of the fan is calculated firstly by working out the fluid power of the fan, which is the quantity multiplied by the pressure. Then the shaft power is worked out. How this is done depends on what information you have added for the fan. If you have defined a power curve as part of your fan, then the shaft power is calculated from this curve; if you have no power curve, but have an efficiency curve, then this is used instead. If no power or efficiency curve is included, then fan default efficiency from the settings is used. The shaft power and the electrical power are reported in the Fan Info box on the Fan Tab of the Edit Box.

Good discussion here of muckpile resistance:

Hi Roy, we've implemented this change for the new version of Ventsim version 5.4.1.3, available here: https://ventsim.com/download/minor-releases/ Any questions or feedback, let us know.

Hi, The Ventsim simulation code is based predominantly on the work in McPherson's Subsurface Ventilation Engineering book available here: https://www.mvsengineering.com/index.php/downloads/publications There are many examples there against which Ventsim can be tested. If you have a specific query about any aspect of Ventsim, please don't hesitate to ask.

Hi Volker, Thanks for your message. I think the Manual entry is out of date, Stages no longer lives in the Tools menu, it has it's menu where you found it, under Stage. There are a number of different ways to handle Stages, so you should have a play with it first to find out what works for you. I recommend saving your model in a separate file before you start working with Stages. It's easy to make errors when you're starting out with Stages so it's a good idea to have your original unstaged model to check against or go back to. In the Stage List form that you found you can name your Stages. You can have up to 24. Once you give a Stage a name in the Stage List, that Stage will appear in the Stage dropdown on the main Ventsim form here: An example of Stages can be found in the Metal Mine demonstration model. Once your Stages are defined you can start assigned or removing airways from each stage. It sounds like you already have sections A1-A6 in your model. What you can do then is open Stage | Rename and give your current stage a name. Call it "Stage 3". Then Create a Shared Copy in Stage | Add Shared Copy and call the new stage "Stage 2". Now when you are in Stage 2, lock the stage with the padlock button next to the Stage dropdown. This will lock the stage which means that any change you make to the model will be limited to that stage. With the Stage Lock on on Stage 2, delete sections A5 and A6 and then unlock the stage. Now switching between the 2 stages you'll see that Stage 2 has sections A1-A4 and Stage 3 has all the sections. Repeat the process from Stage 2 to create Stage 1. What you have done is create your 3 stages. Any airways that are common to each stage are shared. So if you make any change to a airway (with the Stage Lock off) that change will apply to the airway on all stages on which it exists. If you want to limit your change to the current stage, you need to lock the stage first. To see which stages an airway belongs to, open the Edit Box and expand the stage section, which will show a tick for every stage the airway is a part of. Experiment with the system and you will soon get the hang of it. There is also another tool in the Edit Box "Apply to Specific Stage" where you can make a change to an airway (without the Stage Lock) and then decide to which Stages you want to apply the change. That's a basic introduction. There are some other options in the Stage List Manager, you can set different air temperatures and current years for each stage, as well as toggle whether Ventsim runs an air or heat simulation after changing stages. Any questions, don't hesitate to ask.

Hi Andrzej, Thank you for reporting this issue. We have fixed it in version 5.4.1.2 of Ventsim DESIGN, which you can find here: https://ventsim.com/download/minor-releases/ Please let us know if you have any further issues.

Also new in Ventsim DESIGN 5.4: Conveyors! Ventsim 5 already has a feature to model the heat from exposed waterways (which you can read about elsewhere in the forum), which we have based out design of the conveyor tool on. The conveyor heat problem is quite a complicated one; there are a lot of factors at play. The heat transferred from the conveyor will depend on: · The temperature of the transported ore · The mineral type of the transported ore (rock diffusivity, conductivity, density) · The temperature of the air around the conveyor · The surface roughness of the ore (in fact, the roughness of the ore and the conveyor) which will affect the convective heat transfer from the ore to the air · The cross-sectional area of the conveyor and transported ore (which will depend on the velocity of the conveyor, the ore mass flow rate and the ore rock density) · And of course the length of the conveyor system. Additional to this, there is a motor running the conveyor. This motor will generate energy; but where will this energy end up? We’ve assumed that the power from the conveyor motor is dispersed evenly along the conveyor via friction from the rollers as heat, which is also conducted into and conveyed by the conveyor. If the conveyor is lifting the ore any distance, then some energy from the motor is stored as gravitational potential energy and doesn’t add to the heat load. Other factors affecting the heat from the conveyor are how often it is running, is it stopping or starting and is it always fully loaded? So there are quite a few factors and we’ve tried to include all of them in the Conveyor tool. There being so many parameters and factors, it is a good idea to get parameters as accurate as you can and then seek to calibrate against real measurements. To build a conveyor, select the airways you want to place the conveyors in and then select Construct Conveyor under the Draw Tool This opens the Construct Conveyor dialog, which includes all of the parameters I discussed above. You can specify all of the parameters discussed above, as well as specify what fractions of time the conveyor is running loaded, unloaded or idle. You also need to select an Ore Temperature Method. The simplest option is Constant Temperature. If you want, in the second option you can also set a start and finish temperature, and Ventsim will distribute ore temperatures along the conveyor according to a standard heat transfer function. Lastly, the Calculated Temperature option will adjust the ore temperature during the simulation according to the amount of heat transferred. Once the conveyor is setup it will appear next to the associated airways according to the offsets (and the width) that you selected during setup, and be automatically included in the Heat Simulation. In the example here, I’ve set my offsets as X = 0 and Y= -5, so my conveyor appears below the airways. I’ve coloured my model by temperature and, since I have my conveyor in a low airflow region of the mine and I’ve generated some very high temperatures. If you want to switch off the heat from the conveyor, you can simply select it and delete it; or you can go to the Heat Settings and turn them off there, if you still want to keep your built conveyor. Please don’t hesitate to ask us more about the Conveyor feature, and let us know if you have any questions or experiences to relate

A new feature in Ventsim DESIGN 5.4: Heaters! In cold climate mines, heaters are used to prevent the entrance to the mine from icing over. The heat added by the heater can be adjusted to maintain a specific temperature minimum, often around 3 or 4 degrees Celsius. This can now be modelled in Ventsim, rather than specifying a heat addition in kilowatts. To set up a heater, edit the airway where you want to place the heater, then go to the Heat Tab Here you can specify the minimum temperature and also which fuel is being used to power it. Ventsim will run the Heat Simulation and adjust the temperature upwards to this minimum temperature should it fall below. If the temperature is greater than the minimum, then the Heater will have no effect. There are 2 types of heaters to choose from, Indirect and Direct; this will have an effect on the efficiency. Direct heaters are assumed to run at 100% efficiency and Indirect heaters at 85%. Also shown is an output field Heater Annual Fuel. This will show how much fuel is needed per year to maintain the minimum temperature specified. However, colder climates being generally seasonal, the output of the heater will need to change throughout the year. Helpfully, the heater combines with the Annual Thermal Flywheel to give a model of how the fuel consumption of the heater will vary through the year. Running the flywheel simulation (with appropriate summer and winter temperatures), the heater output will adjust accordingly to maintain the temperature in its airway greater than the specified minimum. The see the fuel usage through the year, you can open the flywheel results on the heater (by clicking on the airway with the flywheel graphing mouse mode) and go to the new tab “Fuel”. In the example here, I’ve set the coldest month to February, which you can see by the maximum fuel usage in that month. The Heaters are a new feature in Ventsim DESIGN that we’re keen to develop further. If you want to use it, please contact us with any questions, feedback or suggestions you have.

Hi Neil, Ventsim 5.4 should be available to you. Sometimes, the automatic updater in Ventsim can not get around security restrictions on your computer. Sometimes it just takes a really long time. If the updater is not working for you, the best way to get the new version is to download and install directly from our website. You can do so here: https://ventsim.com/download/currentdownloads/ Please let us know if you have any problems.

Hi Mick, I'm not seeing this problem. I'd recommend upgrading to either Ventsim 5.2.9.9 here: https://ventsim.com/download/minor-releases/ or getting Ventsim 5.4. If you keep seeing it, please contact us again and if possible, send us the model on which it occurs. Martin

Hi Hamish, We're not getting any errors coming through when we import this file to Ventsim. Is it possible the file is only made up of point data? Ventsim normally only supports lines and surfaces. We also tried loading it in a free DWG viewer (DWGSee) and couldn't see anything there, only layer titles. What do you expect to see in this import?

Hi Roy, this issue has been fixed in the latest release of Ventsim version 5.4.0.7, available here: https://ventsim.com/download/minor-releases/

Hi Roy, thank you for the report, it looks like a bug. We'll get it fixed for the next version.

Hi Roy, thanks for the suggestion, we will have a look at whether we can do this for the next version. Will get back to you soon.

The reason you can't modify the leakage is because if you don't select the whole duct together, then the leakage connections are not included in the selection, so therefore the leakage fields are disabled on the form. If you want to be able to modify the leakage you need to include the leakage connections in your selection. To do this, what you need to do is switch to wireframe mode so that you can see the leakage connections. Then select the portion of the duct you are interested in, but also select the relevant leakage connections. Now if you open the duct form, the option should be there.

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.