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Help with Flat Plate Solar Collector temperature out of range errors (too high and too low)

asked 2016-03-02 13:37:52 -0500

RChidwick's avatar

updated 2016-03-02 17:11:17 -0500

I am trying to use the SolarCollector:FlatPlate object in EnergyPlus to reduce the load on the boiler to provide heat for my space and swimming pool. I'm unfamiliar with this object and I don't know how to set it up correctly. I have read through the E+ documentation on the object, and I have looked through the example file for the object but I am still getting the following warnings in my simulation.

** Warning ** GetSpecificHeatGlycol: Temperature is out of range (too high) for fluid [WATER] specific heat **
**   ~~~   ** ..Called From:UpdatePlantLoopInterface,Temperature=[198.57], supplied data range=[0.00,125.00]
**   ~~~   **  Environment=LETHBRIDGE ANN CLG .4% CONDNS DB=>MWB, at Simulation time=07/21 00:00 - 00:10
** Warning ** GetDensityGlycol: Temperature is out of range (too high) for fluid [WATER] density **
**   ~~~   ** ..Called From:PlantPumps:CalcPumps: ,Temperature=[198.50], supplied data range=[0.00,100.00]
**   ~~~   **  Environment=LETHBRIDGE ANN CLG .4% CONDNS DB=>MWB, at Simulation time=07/21 00:00 - 00:10
** Warning ** GetSpecificHeatGlycol: Temperature is out of range (too low) for fluid [WATER] specific heat supplied values **
**   ~~~   ** ..Called From:UpdateSolarCollector,Temperature=[-28.33], supplied data range=[0.00,125.00]
**   ~~~   **  Environment=LETHBRIDGE ANN HTG 99.6% CONDNS DB, at Simulation time=01/21 05:10 - 05:20

I can't figure out what is causing the the temperature to be too high or too low. I have tried raising and lowering the flow rate of the water through the plate, but that did not solve the problem.

I am grateful for any ideas.

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Have anyone found a solution to this problem ? I have the same problem of temperature range warnings ( although I'm not using glycol in any of my plant loops). My other problem is that I need to define setpoint for the the system ( solar collector, storage tank with heater and water heating coil) to achieve an the output air node setpoint of the water heating coil. How can I do that ?

Aly ElHefny's avatar Aly ElHefny  ( 2018-04-15 08:11:52 -0500 )edit

@Aly ElHefny to clarify, the GetSpecificHeatGlycol algorithm in EnergyPlus is called to check the fluid properties for ANY plant loop where a liquid circulates -- even if that loop doesn't contain glycol. You can read more about this in my answer to this post.

Aaron Boranian's avatar Aaron Boranian  ( 2020-10-23 10:53:03 -0500 )edit

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answered 2016-03-02 18:46:17 -0500

Archmage's avatar

That model calculates panel stagnation temperatures when "off" and no fluid is going through the device. A cold night and a colder night sky can freeze the water. A warm day in full sun can get really hot and boil (blow up). This can be useful for controlling when to force flow to come on for thermal protection (with an availability manager). If you don't care about special operations for freeze or overheating protection, then it should be okay to just ignore the warnings.

If you have glycol instead of water, the other problem is that the data range for fluid properties is not really broad enough for the solar panel application (having been originally done for ground heat exchangers which don't see as extreme temperatures).

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Thanks for the helpful answer. But in the example file SolarCollectorFlatPlateWater.idf there are availability manager objects (e.g., see below) which seem to be meant to force flow when the fluid can freeze or gets very hot. But there are still numerous timesteps which have out of range temperature for water. Is something wrong here in the example? How can one actually model an operation which has freezing and overheating protection?

AvailabilityManager:LowTemperatureTurnOn, Low Temperature Turn On Availability Manager, !- Name Collector 1 Outlet Node, !- Sensor Node Name 0.0

Farhang Tahmasebi's avatar Farhang Tahmasebi  ( 2017-04-12 03:19:53 -0500 )edit

answered 2016-09-03 16:34:36 -0500

Alex Vlachokostas's avatar

updated 2016-09-03 22:47:17 -0500

@RChidwick I had the same error. Oddly enough, I did not have any glycol fluid type in my system. Although it might seem unrelated... what fixed the problem in my model was correcting the fileds at the WaterHeater:Mixed object. My model had a Solar Tank Storage and a Instantaneous/Tankless system. Both are modeled as WaterHeater:Mixed objects but for the Solar Tank Storage system the !- Heater Maximum Capacity {W} filed should be 0 and for the Instantaneous/Tankless system the !- Heater Maximum Capacity {W}field should be 845000

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Asked: 2016-03-02 13:37:52 -0500

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Last updated: Apr 15 '18