Chiller loop getting to 322C in first timestep of design day and causing Severe error
I'm having some difficulty running a simulation. The error is below. There's no reason why the chiller loop should be this hot. I think it's just a numerical error because it's during the simulation of the first time step of a design day, the previous design days simulate just fine, and I bet the rest of the simulation would run just fine if I could get EnergyPlus to ignore the high temperature for a couple time steps. Oddly, I can get the error to go away by changing the storage capacity of the thermal energy storage ice tank that the chiller is feeding into. Any ideas on how I could get energyplus to ignore the high temp for just a little bit?
Workaround below, but still no solution.
** Severe **
Plant temperatures are getting far too hot, check controls and relative loads and capacities
During Warmup, Environment=TORRANCE-MUNICIPAL ANN CLG 1% CONDNS DB=>MCWB, at Simulation time=08/21 00:04 - 00:06
PlantLoop Name (SupplySide)= CHILLED WATER LOOP PRIMARY WATER LOOP ICE TANK CHILLER HEAT EXCHANGER HALF
PlantLoop Setpoint Temperature=-5.0 {C}
PlantLoop Outlet Node (SupplySide) "CHILLED WATER LOOP CHW PRI SUPPLY OUTLET" has temperature=322.3 {C}
PlantLoop Inlet Node (SupplySide) "CHILLED WATER LOOP CHW PRI SUPPLY INLET" has temperature=-4.5 {C}
Post Script
I just tried the obvious idea of changing the time step. A timestep of 10 minutes gave the 322C error, a timestep of 1 minute gave a 491C error, and a timestep of 30 minutes gave a 359C error.error.
Post Post Script
I came up with a workaround. I increased the Maximum Loop Temperature field of the PlantLoop object to 400C and got these errors for a simulation running from 5/1 to 10/1.
Warning GetSpecificHeatGlycol: Temperature out of range (too high) for fluid [ETHYLENEGLYCOL40PERCENT] specific heat
************* ** ~~~ ** This error occurred 718 total times;
************* ** ~~~ ** during Warmup 0 times;
************* ** ~~~ ** during Sizing 0 times.
************* ** ~~~ ** Max=595.421006 {C} Min=127.188615 {C}
*************
************* ** Warning ** GetDensityGlycol: Temperature out of range (too high) for fluid [ETHYLENEGLYCOL40PERCENT] density **
************* ** ~~~ ** This error occurred 144 total times;
************* ** ~~~ ** during Warmup 0 times;
************* ** ~~~ ** during Sizing 0 times.
************* ** ~~~ ** Max=595.421006 {C} Min=127.191025 {C}
*************
************* ** Warning ** Plant loop exceeding upper temperature limit, PlantLoop="CHILLED WATER LOOP PRIMARY WATER LOOP ICE TANK CHILLER HEAT EXCHANGER HALF"
************* ** ~~~ ** This error occurred 2 total times;
************* ** ~~~ ** during Warmup 0 times;
************* ** ~~~ ** during Sizing 0 times.
************* ** ~~~ ** Max=521.753501
I also looked the System Node Temperature for the node that was getting to 322C before and it does not report a termperature outside -10C to 10C. So looks like something's wrong with energyplus, possibly as simple as an overly aggressive error condition.
