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Revised vapor composition constraints fix ZeroDivisionError when gdp.hull reformulation is applied #47

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Merged
bernalde merged 6 commits into from
May 10, 2026
Merged

Revised vapor composition constraints fix ZeroDivisionError when gdp.hull reformulation is applied #47

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2838304
Revised vapor composition constraints fix ZeroDivisionError when gdp.…
tristantc Aug 13, 2024
f798d9d
replace gam with gamma
ZedongPeng Aug 13, 2024
a70395b
Address PR 47 review feedback
bernalde May 10, 2026
c19329c
Fix repository lint checks
bernalde May 10, 2026
8aceb54
Fix benchmark stdout restoration
bernalde May 10, 2026
90e289d
Address PR 47 review follow-ups
bernalde May 10, 2026
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10 changes: 5 additions & 5 deletions gdplib/hda/HDA_GDP_gdpopt.py
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ def HDA_model():

m.alpha = Param(initialize=0.3665, doc="compressor coefficient")
m.compeff = Param(initialize=0.750, doc="compressor efficiency")
m.gam = Param(initialize=1.300, doc="ratio of cp to cv")
m.gamma = Param(initialize=1.300, doc="ratio of cp to cv")
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@bernalde bernalde May 10, 2026

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Blocking: This rename collides with the existing m.gamma = Var(m.abs, m.compon, ...) later in HDA_model(). Pyomo replaces this scalar Param with the IndexedVar, and HDA_model() now fails during construction in build_compressor() with TypeError: unsupported operand type(s) for -: 'IndexedVar' and 'float' when evaluating m.gamma - 1.0. This HDA change is unrelated to the Kaibel hull fix. Please restore m.gam for the heat-capacity ratio, or choose a non-conflicting name and update all scalar references without overwriting the activity-coefficient m.gamma variable.

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@bernalde bernalde May 10, 2026

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Addressed in a70395b by renaming the HDA scalar to m.heat_capacity_ratio and updating the dependent equations. tests/test_pr47_regressions.py now checks that m.gamma remains indexed.

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@bernalde bernalde May 10, 2026

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Addressed in 90e289d. The heat-capacity ratio is back to m.gam; the existing indexed activity-coefficient m.gamma is no longer overwritten, and the regression covers both.

m.abseff = Param(initialize=0.333, doc="absorber tray efficiency")
m.disteff = Param(initialize=0.5000, doc="column tray efficiency")
m.uflow = Param(initialize=50, doc="upper bound - flow logicals")
Expand Down Expand Up @@ -1312,7 +1312,7 @@ def Compelec(_m, comp_):
* m.f[stream]
/ 60.0
* (1.0 / m.compeff)
* (m.gam / (m.gam - 1.0))
* (m.gamma / (m.gamma - 1.0))
for (comp1, stream) in m.icomp
if comp_ == comp1
)
Expand All @@ -1324,7 +1324,7 @@ def Compelec(_m, comp_):

def Ratio(_m, comp_):
if comp == comp_:
return m.presrat[comp_] ** (m.gam / (m.gam - 1.0)) == sum(
return m.presrat[comp_] ** (m.gamma / (m.gamma - 1.0)) == sum(
m.p[stream] for (comp1, stream) in m.ocomp if comp_ == comp1
) / sum(m.p[stream] for (comp1, stream) in m.icomp if comp1 == comp_)
return Constraint.Skip
Expand Down Expand Up @@ -2248,11 +2248,11 @@ def Valcmb(_m, valve, compon):

def Valt(_m, valve):
return sum(
m.t[stream] / (m.p[stream] ** ((m.gam - 1.0) / m.gam))
m.t[stream] / (m.p[stream] ** ((m.gamma - 1.0) / m.gamma))
for (valv, stream) in m.oval
if valv == valve
) == sum(
m.t[stream] / (m.p[stream] ** ((m.gam - 1.0) / m.gam))
m.t[stream] / (m.p[stream] ** ((m.gamma - 1.0) / m.gamma))
for (valv, stream) in m.ival
if valv == valve
)
Expand Down
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