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[EnergyPlus_Support] Sequential Boiler loading
Dear E+ Forum,
I'm modeling a "hybrid" boiler arrangement, which uses a high
efficiency boiler for the bulk of the heating season hours, and a
lower efficiency boiler for higher / peak loads.
Although I've got the Plant Loop using "SEQUENTIAL" load distribution,
I get report variables ("Boiler Gas Consumption Rate") showing rates
for Boiler 1 / Boiler 2 that look like this:
Blr1 (W) Blr2 (W)
67,000 36,920
70,685 44,458
64,868 32,556
61,983 26,647
60,268 23,133
60,332 23,265
The first boiler is not loaded fully (100% capacity = 88kW) before the
second one starts. My understanding of "Sequential" is that Boiler 1
should fully load BEFORE the second one starts. What would make the
second boiler start before the first one os fully loaded?
Relevant objects are as follows:
PLANT OPERATION SCHEMES,
PlantOperationSchemeName PltOpernScheme_Htg,
KEY--Control Scheme 1 HEATING LOAD RANGE BASED OPERATION,
Control Scheme Name 1 HtgLdRngBasedOpern_1,
Control Scheme Schedule 1 SchCpct_AlwaysOn;
HEATING LOAD RANGE BASED OPERATION,
Name HtgLdRngBasedOpern_1,
Load Range Lower Limit 1 (W) 0,
Load Range Upper Limit 1 (W) 88000,
Priority Control Equip List Name 1 PltEquipList_Htg1,
Load Range Lower Limit 2 (W) 88001,
Load Range Upper Limit 2 (W) 586000,
Priority Control Equip List Name 2 PltEquipList_Htg2;
PLANT EQUIPMENT LIST,
Equip List Name PltEquipList_Htg1,
KEY--Plant Equip 1 BOILER:SIMPLE,
Equip Name 1 Boiler_1;
PLANT EQUIPMENT LIST,
Equip List Name PltEquipList_Htg2,
KEY--Plant Equip 1 BOILER:SIMPLE,
Equip Name 1 Boiler_1,
KEY--Plant Equip 2 BOILER:SIMPLE,
Equip Name 2 Boiler_2;
BOILER:SIMPLE,
Boiler Name Boiler_1,
Fuel Type NaturalGas,
Nominal Capacity (W) 88000,
Theoretical Boiler Efficiency .893,
Design Boiler Water Outlet Temp 82.2,
Max Design Boiler Water Flow Rate Autosize,
Minimum Part Load Ratio .2,
Maximum Part Load Ratio 1,
Opt Part Load Ratio .2,
Coefficient1 of the fuel use/part load ratio curve 1.011299,
Coefficient2 of the fuel use/part load ratio curve -0.011299,
Coefficient3 of the fuel use/part load ratio curve 0,
Boiler_Water_Inlet_Node Node_Boiler1_In,
Boiler_Water_Outlet_Node Node_Boiler1_Out,
Temp Upper Limit Water Outlet 82.2,
Boiler Flow Mode ConstantFlow,
Parasitic Electric Load (W) 133;
BOILER:SIMPLE,
Boiler Name Boiler_2,
Fuel Type NaturalGas,
Nominal Capacity (W) 293000,
Theoretical Boiler Efficiency .85,
Design Boiler Water Outlet Temp 82.2,
Max Design Boiler Water Flow Rate Autosize,
Minimum Part Load Ratio .2,
Maximum Part Load Ratio 1,
Opt Part Load Ratio .2,
Coefficient1 of the fuel use/part load ratio curve 1.033824,
Coefficient2 of the fuel use/part load ratio curve -0.061497,
Coefficient3 of the fuel use/part load ratio curve 0.026738,
Boiler_Water_Inlet_Node Node_Boiler2_In,
Boiler_Water_Outlet_Node Node_Boiler2_Out,
Temp Upper Limit Water Outlet 82.2,
Boiler Flow Mode ConstantFlow,
Parasitic Electric Load (W) 533;
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