Adrian Halim

Thanks Martin. I need you to check my model since the WB difference between BEVs and diesels is less than what I expected. I've sent an email to you explaining what I've done. Hope that it got through since the model is 21 MB.

There is still a lot of uncertainties in input data for BEV heat simulations. For my case, I reckon that I'll use 1.1 as Water to Diesel Ratio and zero for Electric Vehicle Latent Heat Factor. Until field measurement results are available, I wouldn't dare to guesstimate vehicle work moisture production for both diesels and BEVs operating in dry conditions. In my case, I reckon that most of the extra moisture come from the broken rock, which is already inputted separately. Also, on the list of preset "Heat Moisture Diesel", using Craig's example above, if I put (500 kW x 0,25 = 125 kW) as the Electric Vehicle Power and 1 as the Utilisation factor, will it produce the same heat input as what is shown above (500 kW as the Electric Vehicle Power and 0.25 as the Utilisation factor)? I saw other users do this way. Beside uncertainties in input data for BEV heat simulations, the same is happening for BEV fire simulations. I responded to Florian's post in UVC discussion group. Perhaps you've read it. It's good that Ventsim Design 6 has features to do heat and fire simulations for BEVs, but the users must be cautioned about the uncertainties in the preset input data for these simulations. There is still a lot of work to do to make these simulations produce accurate results. I'm hoping that I'll get opportunities to do field trials and tests to obtain more accurate input data than the preset values.

Thanks Martin. I wanted to attend the user conference but it clashed with my teaching schedule. Your proposal needs to be investigated further since I strongly believe that the "vehicle work moisture production" would not be the same for BEVs and diesels. The other reason beside the regenerative braking of BEVs is that the temperatures of electric motors and battery packs are much lower than the temperature of diesel engines. Large BEVs use liquid cooling system for their motor and battery pack, but since their temperature is much lower than diesel engines, the amount of evaporated coolant is significantly less than that in diesel cooling system. Probably some small BEVs use air-cooled motor and liquid-cooled battery pack, means that the amount of evaporated coolant is even lower in these vehicles. So perhaps the "vehicle work moisture production" should be split into one for diesels and one for BEVs. Field measurements must be done in order to quantify the amount of evaporated coolant in UG mine BEVs.

Hi Martin, I see, but how much should I reduce the latent heat factor? If the airway surfaces are dry, surely zero is a reasonable, right? Because I don't see other moisture sources on the BEV in this scenario. Also, how are these moisture interactions simulated with diesel machines? I don't see "Diesel machine latent heat factor" in the settings. There is "Water to Diesel ratio", but my understanding is that it only includes moisture produced by diesel fuel combustion. I'm trying to simulate an apple-to-apple comparison between heat emitted by a BEV and its diesel version, so this is why I'm asking this question. It seems that the BEV's latent heat is overestimated from what I've read in this discussion, which is not the right way to do this simulation. There are few field measurements of heat emitted by a BEV and its diesel version / counterpart that have been done in Sweden and Canada. Unfortunately none of them measured the moisture interactions. The one done in Sweden was carried out by me and my colleagues in Epiroc where we compared Epiroc's BEVs and their diesel version at Epiroc's Kvarntorp test mine in Sweden. Unfortunately we could not measure heat emitted by both versions since the mine strata is cold and absorbs most of the heat emitted by the machines (no temperature change observed when the BEVs were running and only little temperature increase was observed when the diesels were running). Therefore, we estimated the heat output by measuring the power consumed by both versions. Attached is a paper that shows results of this trial, which was presented at a conference in Stockholm last March. It shows that the ratio between power consumption (heat output) of the BEVs and that of their diesel version is lower than the published theoretical values. The trials done in Canada also found similar results. 10 BT_Adrianus_batterimaskiner_SIMS_NEXGENSIMS v2.pdf

Hi, I notice that in Ventsim Design 6's heat calculator, the latent heat from the load carried by the BEV is included based on the latent heat factor in the settings. However, if the moisture is inputted as a separate heat source (i.e. wet broken rock carried by the BEV that is set as linear heat source or an activity track) then I should set the latent heat factor as zero, right? Otherwise, the moisture is simulated twice. Am I correct?

Thanks Martin. The test version made the conversion faster. But many airways are still not connected due to irregular floor profiles, see the attached 1st screenshot. I then ran Tools – Filter – Binding to connect these airways. I retained the default distances and selections, as shown in the attached 2nd screenshot. But it didn’t finish after running for about 4 hours so I closed VentSim and repeated the process on the next day. This time I increased the distances and only ran bind loose airway ends and bind adjacent nodes. Doing this speed up the process but I still have many airways that are not connected, as shown in the attached 3rd screenshot (the screenshot also shows the floorlines as the reference). Do I need to keep increasing the distances and repeating the process in order to connect all airways? Or is there an easier and faster way to do it? Also, I believe that in this case the last two binding options (bind airways ends to junction and bind crossed airways at intersection) are not required to be done because these options need centrelines, which is not available. Am I correct?

Hi all, I'm having a challenge in converting floor lines into airways. The mine is a large room and pillar mine that doesn't have centrelines, only surveyed floor lines, which was sent as a dgn file. I imported it then use "Convert Floor Lines". It is working but is taking ages to complete. I've been running this conversion for more than 24 hours but only about 1/5 that have been completed. The mine footprint is circa 3.5 km x 2.5 km and it has a lot of tunnel. My question is: is there a faster way to do this conversion?

Hi, Is it correct that at the moment there are no ventilation simulation software that are capable to simulate Battery Electric Vehicle fires due to the lack of input data? I know that NIOSH is currently doing a research on mine vehicles' Li-ion battery fire, but to my knowledge research on full scale BEV fire (similar to the one done by Rickard Hansen and Haukur Ingason on UG mine diesel vehicles) is yet to be proposed.

Hi Martin, What is the value of muckpile resistance that you used? And where did you get this value from? I posted a message in the forum about simulating cave materials in block and sublevel caving mines so I'm interested to know the value of muckpile resistance that you used in this simulation.

Hi all, Has anyone ever simulated cave material (cave column) in a block caving or sublevel caving mine models? If yes, what is the resistance of the muckpile inside the cave column that you use? It is extremely difficult to find "accurate" resistance value of the cave material because it depends on the porosity inside the cave column, which can vary significantly across the column itself depending on the fragmentation. You can have some parts inside the cave column that have fine fragmentation (hence low porosity and high resistance) and other parts that have coarse fragmentation (hence high porosity and low resistance). There are very few studies about this topic and all of them are based on CFD simulations and lab experiments using marbles and balls, which have many limitations. I understand that determining the resistance with PQ survey using barometer is extremely difficult but perhaps anyone has tried to do this? In this survey, one person (with a barometer) stands on the surface next to the subsidence and another (with a barometer) stands at the drawpoint. Based on measured pressure differential and air leakage into the drawpoint, the resistance of the cave path between these two people can therefore be calculated. Thanks for your help!

Thanks Martin. I missed that green button. Problem solved!

I tried to do diesel and heat simulation of trucks in two declines that are connected to each other, as shown in the attached Word doc. The number of trucks in each decline is different. One decline (the main decline) has seven trucks whilst another (a decline that branches from the main one) has one. It seems that I can only create activity track in one decline. First, I created the activity in the main decline. Then, when I was creating the activity in the branch decline, the activity in the main decline disappeared after I clicked "Add Selection", and there is no activity created in the branch decline. Is it true that the activity track can only be created in one decline? Ventsim activity track problem AHalim.docx