In February 2018, Howden released Version 5 of its VentSim™ DESIGN simulation software which comes with many improvements and enhancements. For example, VentSim DESIGN models in mines are typically getting larger and more detailed. To ensure models can be quickly and reliably solved, the VentSim DESIGN software team has developed a new type of solver to rapidly simulate even huge ventilation networks.

The VentSim DESIGN Matrix Solver will be available alongside the existing Sequential solver. The Matrix Solver is based on a hybrid node-loop approach to the flow continuity and pressure equations, often referred to as the “Gradient Method”. It has several advantages over the Sequential method, the most important of which are greater numerical robustness and faster-solving times, in particular for very large models and when solving the model without initialization from a previous solution.

Modern computers have CPUs with multiple cores to allow simultaneous processing of different tasks. VentSim DESIGN 5.0 has harnessed this power with the implementation of parallel process for many of the simulation and interface tasks in VentSim.

This results in a significant increase in speed of simulation. In fire simulations there is a sizeable increase in speed between Ventsim 4 and VentSim DESIGN V5 (users who have large models and are using the dynamic simulation options should experience these types of gains). Improvement results may vary on different models.

Thin ventilation duct travelling through hot or cold areas can transfer significant heat and temperature to and from the surrounding air. VentSim DESIGN heat simulations now feature heat exchange between airways and ventilation ducts. Ventilation ducting is often lightweight and thin. In particular mine conditions where a large temperature difference exists between the temperatures of the air inside and outside of the duct, significant heat loss or gain can occur through the ducting material. A setting will be available to toggle the effect and VentSim DESIGN presets will allow the addition of different ducting materials.

Water flows into mines can add significant heat and humidity. VentSim DESIGN users will be able to add running waterways to airways, setting parameters such as water speed, volume flow and temperature. The user will have the option to set a constant temperature to the water, have it vary over a temperature range along the length of the waterway, or have the solver calculate the water temperature drop as it transfers to the air.

Distribution of heat producing machines and equipment in large mine ventilation models can be time consuming and confusing. The new Activity Track tool allows wide selections of equipment such as trucks, loaders or conveyor belts to be automatically included along typically travelled pathways. Instead of placing a fixed heat source, selecting a track will spread the heat through the whole pathway, simplifying inputs for heat studies.

Finding the fastest and safest escape route through larger mines can be complicated, particularly if there is smoke or gas present. A new measure tool called “Escape Routes” can be used to calculate the fastest routes from any location in the ventilation network to the closest refuge bays or to the closest surface exits. To place a refuge bay in an airway users simply use the draw tool select “construct refuge bay” and click on the airway and a refuge bay will be displayed in that airway, to mark an airway as impassable go the airway and edit its properties, by clicking on the “no thoroughfare” option, the airway will then be excluded from escape routes calculation.

“Using the measure tool “Escape Routes” you can select any airway and VentSim DESIGN will calculate multiple routes to both the surface exits and the closest refuge bays. Clicking on the bar chart will display each route in the model, and by using the model transparency setting you can easily make the path more visible.”

The escape path includes some statistics about time required to walk and climb, it also includes time spent in travelling in smoke or contaminant areas, STEL limits and other settings can be changed in the model settings.

Modelling simulation results depend on the accuracy of user input. In some areas of the mine ventilation model, even very small inaccuracies of user input such as airway resistance can cause large changes in predicted mine airflow. “The Resistance Sensitivity Analysis allows the user to analyse the sensitivity of the simulated airflows to potential errors in airway resistance. The airflow quantity and direction in some airways will be stable to changes elsewhere in the network, while some airways (such as cross-cuts between high-flow rate airways) may be very sensitive. The airflow confidence tool runs 100 (or more) simulations of the mine airflow, with each simulation adding a random perturbation to each airway resistance. A statistical analysis is then run, which gives the user a derived confidence level on the simulated airflow and airflow direction in each airway, as well as providing the statistical quantities, such as mean and standard deviation.”

Users of Microsoft Excel have long enjoyed a tool to help find a solution in one cell, by changing numbers in another cell. In ventilation, downstream ventilation goals or targets are often influenced by the design parameters of upstream airways. The Goal Seeking tool is useful for quickly adjusting a new parameter (say, a fan speed) to achieve a given output (such as airflow) in another part of the model. Where a user could use trial and error, the Goal Seeking tool will run the simulation multiple times, calculating the required parameter setting using an efficient root-finding numerical algorithm. Adjustable parameters include Resistance, Fan Speed, Sensible Point Heat Source and Refrigeration load, while targets options are Pressure, Airflow, Dry Bulb Temperatures and Wet Bulb Temperatures.

VentSim users have long wished to be able to control ventilation devices such as fans and regulators as easily as they can in ventilation simulations. An option is now offered to interface with ventilation devices directly, allowing users to dynamically control real devices underground. “If your mine has implemented communication and control of ventilation devices (such as fan speed or regulator openings), VentSim DESIGN now has the ability to connect to these devices through a number of industry standard communication protocols. The rich graphical 3D design interface provides a unique way to view, interact and change ventilation settings in a natural and intuitive way.”

Devices are simply configured in normal VentSim DESIGN model airways and assigned properties to allow connection and manipulation of the required settings. Users can then dynamically change actual settings (such as fan speed) and watch in VentSim DESIGN as the system responds to changes.

The EDIT form is the hub of all design input and changes in a ventilation model. In the new docking window the edit form can now be docked to the left or right of the screen, making it easier to view the airway properties. “By default, the edit window will work exactly as previous versions of Ventsim™, but you can now dock the form to the left or right of the screen, try it out and see if you like it. To dock the window, select the top of the edit form and drag the window to the left or right and a small icon will appear – drop the window on the icon and you’ve docked the window.”

Advanced Find & Select have been improved and it is now much easier to find and select different devices and airways. Creating lists of levels in mine ventilation models is very useful to assist in viewing specific parts of the mine but can be a time consuming process. “VentSim DESIGN can now automatically setup a series of default levels; this should save time and make it a lot easier to adjust the levels to suit each site.”

Charts and Graphs provide a visual feedback to many of the VentSim DESIGN simulation functions. All charting tools in VentSim DESIGN have been refreshed and any customisations you make to the way they look are now saved and apply across all charts in VentSim DESIGN.

VentLOG is a popular tool to help externally manage data measured and collected by underground engineers and ventilation officers. The new VentLOG integration option in VentSim DESIGN provides a much improved way to correlate actual data versus VentSim DESIGN simulated data. Mapped VentLOG data can now be selected as a display option for both colour and text in VentSim DESIGN. The new VentLOG Data Comparison tool allows you to compare recorded VentLOG™ records with simulated VentSim DESIGN data:

All historical records for every VentLOG station can now be viewed in either a chart or in datatable view where all historical records can now be edited directly from within VentSim™ DESIGN. The new “Hide Station” feature allows you to remove the station from future imports to VentSim™ DESIGN, allowing you to only import to your model the VentLOG data that you want to see.

When adding a new station to VentLOG from VentSim DESIGN, the Group and Level info can now be recorded. You can also use the Link Existing Station feature to map a station that already exists but could not be matched to any airways due to missing or incorrect co-ordinates.

“You can also use the Link Existing Station to move an already mapped station to a new location. When moving an existing station you can either leave the previous records assigned to the old airway (this would be handy if you are using a temporary recording station and you don’t want the historical data to be mapped to the new location) or you can move all existing records to the new location (if you are fixing a mistake).”