Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
(definitely NOT an answer ... just too many chars for a comment).
@HoussemYounes, how do you associate storage capacity (J, or m3) to a PCUD? It seems to support only inlet/outlet state variables (°C, rho, Cp) or rates (W, kg/s). My understanding is that a loop-connected, heat storage device could be approximated using a WaterUse:Storage component that is either charged or discharged, possibly by 1x or 2x PCUDs (or similar EMS-enabled components) working in tandem. One can definitely link up a WaterUse storage component (I haven't experimented, my bad), although it's unclear if/how stored water temperature is tracked using EMS (not spotting it here).
In such a scenario, a charging PCUD would definitely have a fixed Maximum Loading Capacity, e.g. sized coil(s). One can imagine an EMS controller activating a charging event (similar to cooling storage), e.g. based on a combination of variables including predicted outdoor temperatures (brr!) over a 24h period. There would likely be a maximum storage temperature, but the target temperature for a given event could vary (e.g. discharge duration, required peak power).
During discharging events, the SOC would be approximated by the temperature and volume of stored water. As it discharges at each time step, the SOC would diminish over the course of the event. Of course this would be an approximation, as these devices hold high capacity materials that exceed water rho/Cp (likely requiring exaggerated storage volume and/or temperatures).
Again, I have not experimented. Most of the variables can be EMS sensed/actuated, but likely not all of them. Hope this is somehow useful.
| | 2 | No.2 Revision |
(definitely NOT an answer ... just too many chars for a comment).
@HoussemYounes, how do you associate storage capacity (J, or m3) to a PCUD? It seems to support only inlet/outlet state variables (°C, rho, Cp) or rates (W, kg/s). My understanding is that a loop-connected, heat storage device could be approximated using a WaterUse:Storage component that is either charged or discharged, possibly by 1x or 2x PCUDs (or similar EMS-enabled components) working in tandem. One can definitely link up a WaterUse storage component (I haven't experimented, my bad), although it's unclear if/how stored water temperature is tracked using EMS (not spotting it here).
In such a scenario, a charging PCUD would definitely have a fixed Maximum Loading Capacity, e.g. sized coil(s). One can imagine an EMS controller activating a charging event (similar to cooling storage), e.g. based on a combination of variables including predicted outdoor temperatures (brr!) over a 24h period. There would likely be a maximum storage temperature, but the target temperature for a given event could vary (e.g. discharge duration, required peak power).
power). During discharging events, the SOC would be approximated by the temperature and volume of stored water. As it discharges at each time step, the SOC would diminish over the course of the event. event.
Of course this would be an approximation, as these devices hold high capacity materials that exceed water rho/Cp (likely requiring exaggerated storage volume and/or temperatures).
temperatures). Again, I have not experimented. Most of the variables can be EMS sensed/actuated, but likely not all of them. Hope this is somehow useful. useful.
