• Strange temperature effects in simple ATES-simulation

    Dear Feflow-community, I'm quite new to working with feflow and hence, am struggling with some issues. I've built a quite simple structured 3D-model with several layers including an aquifer that is confined by low-permeable layers. This aquifer should serve as an ATES-aquifer with several injection and production wells. All wells are already implemented with the ideal cell size, according flow rates as well as a temperature bc at the bottom node of each well. First simulations are working quite well, however, I'm observing a weird effect, as after the first year (1 injection and 1 production cycle), I can extract more energy/heat than I injected, although I injected 90°C into a reservoir with 13°C ambient temperature. Has anyone observed a similar effect and explain the reason? I am seeing another effect I cannot explain, as after each switching point (from injection to quiet phase and from quiet phase to production), the temperature shortly drops by ~20°C...why? What's the problem here? And one last question: If I group the wells and want to assign a temperature difference in the "Open Loop" property of this well group, how do I need to prepare the t-difference time series/how do I use this option? What t-difference is meant here (I don't really understand the feflow documentation explanation)? Can anyone maybe help me with these three issues? Many thanks, Simon