DHWLoopSeg

title: DHWLoopSeg ---

Name Type Variability Description/Comments
len FLOAT_GEZ input time segment length, ft
size FLOAT_GZ input time
  • nominal pipe size (diameter), in
  • pipe actual OD = ps_size + 0.125
insulK FLOAT_GZ input time insulation conductivity, Btuh-ft/ft2-F
insulThk FLOAT_GEZ input time insulation thickness, in
exH FLOAT_GZ input time combined exterior surface coefficient, Btuh/ft2-F
Name Type Variability Description/Comments
absSlr number Start of subhour solar (SW) absorptance, dimless
awAbsSlr DBL Start of subhour
  • area-weighted solar absorptance
  • = sb_absSlr * area / zn_surfASlr
  • exterior surf outside: always 0
  • windows inside: TBD 12-8-10
  • ducts: always 0
epsLW number Start of subhour thermal (LW) emittance
zi TI Start of subhour adjacent zone idx, 0 if exposed to ambient
F DBL Start of subhour solar (short wave) fraction ? TODO: NOT USED? as of 4-2012
Fp DBL Start of subhour
  • "view factor" to zone radiant temp, dimless. Includes Oppenheim surface conductance.
  • aka "F-prime" in CZM documentation.
Name Type Variability Description/Comments
frRad DBL Start of subhour re radiant to radiant temp (room radiant node or sky)
fSky DBL Start of subhour "view factor" to radiant surround at sky temp
fAir DBL Start of subhour "view factor" to radiant surround at air temp (ground, horizon)
Name Type Variability Description/Comments
hcNat FLOAT_GEZ End of subhour surface natural convection coefficient, Btuh/ft2-F
hcFrc FLOAT_GEZ End of subhour surface forced (wind) convection coefficient, Btuh/ft2-F
hcMult FLOAT_GEZ End of subhour surface convection coefficient multiplier, dimless
hxa FLOAT_GEZ End of subhour overall coeff to sb_txa = sb_hcMult*(sb_hcNat + sb_hcFrc), Btuh/ft2-F
hxr FLOAT_GEZ End of subhour
  • surface (linearized) radiative coefficient, Btuh/ft2-F
  • = coupling to sb_txr
hxtot number End of subhour sb_hxa + sb_hxr
uRat DBL End of subhour
  • ratio uC/(sb_hxa + sb_hxr + uC)
  • = 1/(1 + rC*(sb_hxa + sb_hxr))
  • where uC = surface-to-surface conductance
  • rC = 1/uC
  • but: duct model outside surf to duct air
Name Type Variability Description/Comments
fRat DBL End of subhour
  • sb_hxtot * sb_uRat, Btuh/ft2-F
  • = overall conductance not including other side
  • surface resistances
  • (ducts: overall conductance from duct air to sb_txe)
cx DBL End of subhour air/radiant coupling due to this surface, Btuh/ft2-F
Name Type Variability Description/Comments
sgTarg solar gain target: bm, df gain from insolation
SGTARG
Name Type Variability Description/Comments
sgTarg.bm DBL End of subhour beam
sgTarg.df DBL End of subhour diffuse
sgTarg.tot DBL End of subhour total
sg DBL End of subhour absorbed solar total, Btuh (NOT Btuh/ft2), summed from sb_sgTarg
Name Type Variability Description/Comments
tSrf number End of subhour most recently calculated surface temp, F
tSrfls number Start of subhour
  • last step surface temp, F
  • copied from sb_tSrf at step end
  • not *e (available for probing)
qrAbs DBL End of subhour
  • total absorbed radiant heat gain at surface, Btuh/ft2 (+ = into surface)
  • = (sb_sg + sb_rIg)/area
txa number End of subhour
  • adjacent air temp, F (from prior step)
  • inside: prior step zone tz
  • outside: current step ambient dry bulb temp
txr number End of subhour
  • adjacent radiant temp, F
  • inside: prior step zone tr
  • outside: current step sky temp
txe number End of subhour
  • adjacent environmental temp, F
  • combined sb_txa and sb_txr; simplifies calcs in some cases
  • set but unused? for inside
  • set/used for ASHWAT outside
w DBL End of subhour
  • adjacent air humidity ratio if known (else 0)
  • used re duct leakage
qSrf DBL End of subhour
  • conduction into surface, Btuh/ft2
  • updated at end of timestep
Name Type Variability Description/Comments
pPS PIPESEGP Start of subhour pointer to parent PIPESEG
Name Type Variability Description/Comments
exCnd choice:EXCND input time adjacent cond: adiabatic/ambient/specT/adjZn.
exT number Start of hour surround temperature, F
Name Type Variability Description/Comments
totals
  • segment totals (re st_Accum() to parents)
  • also retains vol, UA, exArea used in calcs
SEGTOTS
Name Type Variability Description/Comments
totals.count DBL Start of run # of segments included in totals
totals.len DBL Start of run length, ft
totals.vol DBL Start of run volume, gal
totals.exArea DBL Start of run outside surface area (at insulation surface), ft2
totals.UA DBL Start of run fluid-to-surround loss, Btuh/F-hr
fRhoCpX FLOAT_GZ Start of run
  • fluid volumetric heat flow factor, Btuh/gpm-F
  • initialized for water, code otherwise general
fvf number End of hour fluid volumetric flow rate, gpm (note: not ft3/hr)
tIn number End of hour current hour inlet fluid temp, F
tOut number End of hour current hour outlet fluid temp, F
PLWF number End of hour current hour heat loss when flowing, Btu
PLCD number End of hour current hour standing (noflow) heat loss, Btu
PL number End of hour ps_PLWF + ps_PLCD
Name Type Variability Description/Comments
ty choice:DHWLSEGTY input time type: C_DHWLSEGTYCH_SUP / _RET
wbCount number Start of run
  • total # of child [DHWLOOPBRANCHs][dhwloopbranch]
  • note: may be non-integer
fNoDraw number Start of hour fraction of hour when there is no draw
LL number End of hour
  • current hour loop loss, Btu
  • = ps_PL - loss attributed to draw flow
Name Type Variability Description/Comments
BL number End of hour current hour child DHWLOOPBRANCH losses, Btu
t24WL number End of hour
  • current hour child [DHWLOOPBRANCH][dhwloopbranch] waste loss volume, gal
  • associated energy is in wg_BL