Robin11112 Posted June 18, 2021 Report Share Posted June 18, 2021 (edited) Hi, I am working on a project which aims to extract geothermal energy from abandoned mines. Concept is simple, input cold water and extract hot water through pipe. The Ventsim manual says that water in waterway will absorb/release heat energy to surroundings so I build up sample mine and waterways I built waterways under 4 straight airways and flow rate is 100L/s and inlet temperature is 10C. However heat simulation shows that inlet water temperature become 27.6C same as surrounding. It means water absorb heat energy within a second and I think this can't happen in real world. In the last image, I connected waterways on underground tunnels as well as inclined shafts and entrance tunnels. But waterways are not constructed on inclined shaft and entrance tunnels. Therefore I assume that it is impossible to construct a waterway on inclined tunnels, am I correct? Finally, I'd like to ask that if it is possible to simulate heat exchange of water flowing through a pipe or temperature change of tunnels which are fully filled with water (every number in images is dry bulb temperature) Edited June 18, 2021 by Robin11112 Quote Link to comment Share on other sites More sharing options...
Martin Griffith Posted June 21, 2021 Report Share Posted June 21, 2021 Hi Robin, Thanks for your message and interest in the waterway feature. It's hard to tell what is happening. Is this a natural ventilation driven model? Do you have any airflow? If there is no airflow, then it probably won't simulate any heat exchange. If you want to send me the model (ventsim.support@howden.com) I should be able to work out why it's not working. As for the inclined airways, it may be that the waterways are simply hidden. Try clicking W to switch to wireframe mode. Just a note, that the waterway feature models heat exchange between the exposed water surface and the air, it won't handle heat exchange between the water and the rock wall. As for your other question, and related to the previous point, Ventsim won't simulate the heat exchange in a tunnel filled with water. We will likely have a feature in the future which simulates the exchange between an insulated water pipe and an airway. Quote Link to comment Share on other sites More sharing options...
Robin11112 Posted June 22, 2021 Author Report Share Posted June 22, 2021 (edited) 22 hours ago, Martin Griffith said: Hi Robin, Thanks for your message and interest in the waterway feature. It's hard to tell what is happening. Is this a natural ventilation driven model? Do you have any airflow? If there is no airflow, then it probably won't simulate any heat exchange. If you want to send me the model (ventsim.support@howden.com) I should be able to work out why it's not working. As for the inclined airways, it may be that the waterways are simply hidden. Try clicking W to switch to wireframe mode. Just a note, that the waterway feature models heat exchange between the exposed water surface and the air, it won't handle heat exchange between the water and the rock wall. As for your other question, and related to the previous point, Ventsim won't simulate the heat exchange in a tunnel filled with water. We will likely have a feature in the future which simulates the exchange between an insulated water pipe and an airway. Isn't there an option to change setting of the Ventsim software? I can simulate temperature drop/increase of the air flow through a tunnel. So what about if I replace specific heat, density, thermal conductivity of air to water? I think it would be very cool to simulate heat exchange between insulated water pipe and air. Do you have any idea which version or when that option become possible? I am using ventsim 5.2. Edited June 22, 2021 by Robin11112 Quote Link to comment Share on other sites More sharing options...
Martin Griffith Posted June 22, 2021 Report Share Posted June 22, 2021 You can try changing the air density in the Environment Settings to 998 kg/m3, but the rock heat exchange is designed for exchange with air, doing calculations of temperature, pressure and density based on standard psychrometric functions for air, not water. So I can imagine some problems around air wet bulb and dry bulb temperatures that Ventsim is used to working with. You could try it and see what sort of numbers you get and whether they make sense. Quote Link to comment Share on other sites More sharing options...
Robin11112 Posted June 22, 2021 Author Report Share Posted June 22, 2021 Do you have any idea which version or when that heat exchange between insulated water pipe and air become possible? I am using ventsim 5.2. Quote Link to comment Share on other sites More sharing options...
Martin Griffith Posted June 22, 2021 Report Share Posted June 22, 2021 I can't say exactly, we have a lot of development on. But I imagine sometime later this year. Quote Link to comment Share on other sites More sharing options...
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