Re: [EnergyPlus_Support] SolarCollectorFlatPlateWater Warnings

[Santiago Velez <santiagogvelez@xxxxxxxxx>]

Hi Marko, I had a very similar problem some time ago.  In my case the problem was either below freezing temperatures at night in winter or above boiling temperatures in full summer and a related bug, because it was reporting warnings for no  flow moments, for the wrong fluid!

 This was the answer from  Helpserve, I hope it helps. 

Regards,

Santiago.

"You seem to have stumbled upon a problem with the simulation. The -0.09C water temp warning is triggered, but I do not see those temps in the output file (*.csv). This usually means that the warning was tripped before the simulation completed the time step simulation. In addition, the error is tripped when thesolar collector flow rate = 0. This is one of my favorite types of errors (or false errors).

I am not sure what the model should do here, store heat or set outlet = inlet. I will have to ask for help on this one.

As far as your simulation goes, it looks like it's working as you have programmed it. I would review the temps and flow through the collectors to see if the operation is as you intend. For example, during the winter design day, the collectors are cycling on and off. Is this what you intended?

I turned off the differential availability manager and this cycling nearly disappeard. I recommend plotting some collector temps and flow rates and you will see how the system responds to your inputs. 

AvailabilityManagerAssignmentList,
Collector Loop Availability Manager List, !- Name
AvailabilityManager:HighTemperatureTurnOff, !- Availability Manager 1 Object Type
High Temperature Turn Off Availability Manager, !- Availability Manager 1 Name
AvailabilityManager:LowTemperatureTurnOn, !- Availability Manager 2 Object Type
Low Temperature Turn On Availability Manager; !- Availability Manager 2 Name
! AvailabilityManager:DifferentialThermostat, !- Availability Manager 3 Object Type
! Differential Thermostat Availability Manager; !- Availability Manager 3 Name


Good job on reporting variables related to the error message. I didn't need to add any report variables to diagnose this problem. You couldn't see what caused the problem because it did not show up in the final results. 

Move on with your simulation while we investigate the solution.



'Richard Raustad
EnergyPlus Support'*******************************
Standard EnergyPlus Support is provided free of charge by the U.S. Department of Energy, as part of the continuing effort to improve this building simulation tool. Expedited, priority support may be available from other sources. For a list of EnergyPlus Consultants, see http://simulationresearch.lbl.gov/projects/energyplus 

Ticket Details"

---

Ticket ID: 6091
Department: General
Type: Issue
Status: Open
Priority: Medium

2013/2/10 marko_m_miletic <marko_m_miletic@xxxxxxxxx>

 

Hello everyone,

In versions before 7.0 i did simulations with solar collectors flat plate water and it all went ok. But, since new versions arrived starting 7.0 problems with warnings started. It is same in 7.1 and 7.2.

Actually, even in example file i have too many warnings about working fluid. For summer months there are about 5000 warnings each month, about overheating or freezing of working fluid. For example:

** Warning ** GetSpecificHeatGlycol: Temperature is out of range (too low) for fluid specific heat **
** ~~~ ** ..Called From:UpdateSolarCollector Fluid name =WATER,Temperature=-17.30
** ~~~ ** Environment=CHICAGO ANN HTG 99% CONDNS DB, at Simulation time=01/21 00:00 - 00:15
** Warning ** GetSpecificHeatGlycol: Temperature is out of range (too high) for fluid specific heat **
** ~~~ ** ..Called From:UpdateSolarCollector Fluid name =WATER,Temperature=134.81
** ~~~ ** Environment=CHICAGO ANN CLG 1% CONDNS DB=>MWB, at Simulation time=07/21 08:45 - 09:00

************* ===== Recurring Error Summary =====
************* The following recurring error messages occurred.
*************
************* ** Warning ** GetSpecificHeatGlycol: Temperature out of range (too low) for fluid specific heat
************* ** ~~~ ** This error occurred 4913 total times;
************* ** ~~~ ** during Warmup 0 times;
************* ** ~~~ ** during Sizing 0 times.
************* ** ~~~ ** Max=-4.065460E-002 {C} Min=-17.295834 {C}
*************
************* ** Warning ** GetSpecificHeatGlycol: Temperature out of range (too high) for fluid specific heat
************* ** ~~~ ** This error occurred 155 total times;
************* ** ~~~ ** during Warmup 0 times;
************* ** ~~~ ** during Sizing 0 times.
************* ** ~~~ ** Max=194.066101 {C} Min=128.447614 {C}

My question is have someone also had this problem. Is there a solution for this problem like adding valves or something. Thank you in advance. Example file name is SolarCollectorFlatPlateWater.idf.

Regards,
Marko Miletic
Faculty of Engineering in Kragujevac, Serbia

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