DHWSolarCollector

title: DHWSolarCollector ---

Name Type Variability Description/Comments
mult FLOAT_GZ input time multiplier (for multiple panels). Default 1.
multLR FLOAT_GZ End of run last run multiplier, re probing in chained runs

Collector

Name Type Variability Description/Comments
area FLOAT_GZ input time SRCC collector area, ft2
tilt ANGLE input time Array tilt, radians (input as degrees)
azm ANGLE input time Array azimuth, radians (input as degrees)
testFRUL number input time SRCC test (rated) slope, Btuh/F-ft2
testFRTA FLOAT_GZ input time SRCC test (rated) intercept
testMassFlow FLOAT_GZ input time collector loop SRCC rating mass flow rate, lb/h-ft2
oprMassFlow FLOAT_GZ input time collector loop operating mass flow rate, lb/h-ft2
kta60 number input time
  • incidence angle modifier at 60 deg (from SRCC rating)
  • default 0.72
  • <= 0: IAM not applied
Name Type Variability Description/Comments
piping collector piping info (length, insul, UA, ...)
PIPERUN
Name Type Variability Description/Comments
piping.len FLOAT_GEZ Start of run segment length, ft
piping.size FLOAT_GZ Start of run
  • nominal pipe size (diameter), in
  • pipe actual OD = ps_size + 0.125
piping.insulK FLOAT_GZ Start of run insulation conductivity, Btuh-ft/ft2-F
piping.insulThk FLOAT_GEZ Start of run insulation thickness, in
piping.exH FLOAT_GZ Start of run combined exterior surface coefficient, Btuh/ft2-F
Name Type Variability Description/Comments
piping.count DBL Start of run # of segments included in totals
piping.len DBL Start of run length, ft
piping.vol DBL Start of run volume, gal
piping.exArea DBL Start of run outside surface area (at insulation surface), ft2
piping.UA DBL Start of run fluid-to-surround loss, Btuh/F-hr
Name Type Variability Description/Comments
piping.beta number Start of subhour temperature loss (1 - approach-to-surround) factor
pipingTEx number End of hour collector piping surround temp

derived constants

Name Type Variability Description/Comments
areaTot FLOAT_GZ Start of run total area, ft2 (=sc_area*sc_mult)
flowCorrection number Start of run
  • flow correction factor
  • sc_oprFRxx = sc_testFRxx * sc_flowCorrection
oprFRUL number Start of run operating (flow-corrected) collector slope, Btuh/F-ft2
oprFRTA FLOAT_GZ Start of run operating (flow-corrected) collector intercept
oprMCp number Start of run operating heat capacity flow rate, Btuh/F (not per ft2)
oprVolFlow number Start of run
  • nominal collector loop volume flow rate, gpm (not gpm/ft2)
  • derived from sc_oprMassFlow
b0 number Start of run
  • incidence angle modifier coefficient
  • (derived from sc_Kta60)
ktaDS number Start of run
  • tau-alpha modifier (kta) for sky diffuse radiation
  • (constant, depends on sc_tilt only)
ktaDG number Start of run
  • tau-alpha modifier (kta) ground-reflected diffuse radiation
  • (constant, depends on sc_tilt only)

Calculated values

Name Type Variability Description/Comments
incA number End of hour beam angle of incidence, radians (PI/2 if no beam)
ktaDB number End of hour tau-alpha modifier (kta) for beam (varies by hour)
  • plane of array irradiance, Btu/ft2
  • adjusted by sc_ktaXX if incidence angle modifier (IAM) active
Name Type Variability Description/Comments
poaRadDB number End of hour beam
poaRadDS number End of hour diffuse from sky
poaRadDG number End of hour diffuse from ground
poaRadTot number End of hour total
poaRadIAM number End of hour
  • component-weighted IAM factor
  • = sc_poaRadTot / radTot_unadjusted

Pump

Name Type Variability Description/Comments
pumpPwr FLOAT_GEZ Start of run pump power, W
tickPumpQ number Start of run pump input energy per tick, Btu
pumpLiqHeatF number Start of run
  • fraction of sc_pumpPwr added to liquid stream
  • remainder is discarded
pumpDT number Start of run fluid temp increase due to pump, F
pumpOnDeltaT number Start of run
  • temperature difference between the
  • tank and collector outlet where pump
  • turns on, F
pumpOffDeltaT number Start of run
  • temperature difference between the
  • tank and collector outlet where pump
  • turns off, F
  • this hour linear coefficients
  • tOutlet = sc_tOutletM*tSup + sc_tOutletB
  • eff = sc_effM*tSup + sc_effB
Name Type Variability Description/Comments
tOutletM number End of hour
tOutletB number End of hour
effM number End of hour
effB number End of hour
Name Type Variability Description/Comments
tInlet number End of subhour tick inlet temp, F (at tank / before to-collector piping)
eff number End of hour fraction of incident heat added to the fluid
tickQFluid number End of subhour tick heat added to the fluid, Btu
hrQFluid number End of hour hour total heat added to fluid, Btu
totQFluid DBL End of run run total sc_qFluid total, Btu
tOutletP number End of hour
  • tick potential outlet temp, F
  • used to determine if collector should run
tOutlet number End of hour tick outlet temp, F (at tank / after from-collector piping)
Name Type Variability Description/Comments
tickVol number End of subhour volume moved during this tick, gal
tickOp number End of subhour nz iff pump is operating during prior tick
Name Type Variability Description/Comments
pumpInElec number End of hour actual electricity use (note not kWh)