DHW simulation w/ solar panels + diesel boiler
Hello!
I'm trying to model a DHW system with 135 solar panels and a 400kW diesel boiler for backup. Storage tank has 5m3. The objective of this modelling is to audit an existing system.
The objects I used for the simulation are:
- SolarCollector:FlatPlate:Water to model the solar panels;
- WaterHeater:Stratified to model the storage tank;
- DistrictHeating to model the diesel boiler (for simplicity at the beginning)
I started the modelling based on the example file SolarCollectorFlatPlateWater, and changed components to meet my necessities.
However, when running, the following error message appears:
* Severe * InitWaterThermalTank: Detected problem for stratified tank model. Model cannot be applied. * ~~~ * Occurs for stratified tank name = STORAGE TANK * ~~~ * Tank volume = 5.0000 [m3] * ~~~ * Tank use side volume flow rate = 3.8893 [m3/s] * ~~~ * Tank source side volume flow rate = -99999.0000 [m3/s] * ~~~ * Nominal tank change over rate = 1.29 [s] * ~~~ * Change over rate is too fast, increase tank volume, decrease connection flow rates or use mixed tank model
Attached are the printscreens of the main components of the modelling.
Sizing:Plant
SolarCollector:FlatPlate:Water
DistrictHeating
WaterHeater:Stratified
PlantLoop
PlantEquipmentList
WaterUse:Equipment
WaterUse:Connections
Does anyone has the idea of where the problem could be?
Thanks a lot in advance.
I don't get the Sizing:Plant for DHWLoop_SS (what are your naming conventions? SS = Source Side, DS =?), design exit temp is 25 but delta is 35? So you get water at -10°C and heat it up to 25°C? Deadband temp diff for the stratified heater is 40C which seems large, not sure what the setpoint temp is since the HotWaterSetpointTemp schedule isn't included. Also, did you specify only one 10 m2 panel? Or a bunch?
Hey Julien, thanks for the answer.
DHWLoop_SS stands for the storage tank source side <-> collectors loop. (Supply Side)
DHWLoop_DS stands for the storage tank use side <-> water equipment loop. (Demand Side)
From what I got from the I/O reference, DHWLoop_SS exit temperature will be the storage tank outlet temperature of the source side (before going to the collectors). Delta T will be the temperature difference (rise) on the collectors. On that case, 25+35 - 60C.
Could the problem here be that I defined the storage tank as the equipment of the DHWLoop_SS, instead of the collectors?