Public API (using `qsdsan` without `biosteam`)¶

QSDsan is built on top of BioSTEAM and BioSTEAM’s thermodynamic library Thermosteam. QSDsan re-exports the parts of those libraries that a typical user needs.

Everything below is reachable through import qsdsan as qs.

Streams, chemicals, and thermo configuration¶

Name	Notes
`qs.Chemical`	Thermosteam `Chemical` (see also `qs.Component`).
`qs.Chemicals`	Thermosteam `Chemicals` (see also `qs.Components`).
`qs.CompiledChemicals`	Compiled chemical package.
`qs.Stream`	BioSTEAM `Stream` (see also `qs.SanStream` / `qs.WasteStream`).
`qs.MultiStream`	Multiphase stream.
`qs.MissingStream`	Placeholder used during unit initialization.
`qs.set_thermo`	Set the thermodynamic property package.
`qs.get_thermo`	Get the active thermo package.
`qs.get_components`	Get the active components.
`qs.settings`	Process-wide settings object (e.g. `qs.settings.thermo.ideal()`).
`qs.preferences`	Display/diagram defaults (dark mode, stream labels, graphviz format, etc.).
`qs.Thermo`	Build a custom thermo package.

Units, systems, and TEA¶

Name	Notes
`qs.Unit`	Base BioSTEAM unit (see also `qs.SanUnit`).
`qs.System`	Process system (`qsdsan` subclass).
`qs.AgileSystem`	System evaluated across multiple operating scenarios.
`qs.Facility`	Base class for facility units.
`qs.get_OSBL`	Collect outside-battery-limit (facility) units of a system.
`qs.TEA`	Techno-economic analysis (`qsdsan` subclass of BioSTEAM `TEA`).
`qs.Model`	Uncertainty/sensitivity model.
`qs.Metric` / `qs.Parameter`	Model metrics and parameters.
`qs.Scope`	Dynamic-simulation scope.
`qs.report`	Reporting helpers (e.g. `qs.report.voc_table`).

Utilities and costing globals¶

Name	Notes
`qs.HeatUtility`	Heating/cooling agents (e.g. `qs.HeatUtility.get_agent('cooling_water')`).
`qs.PowerUtility`	Electricity; set the price via `qs.PowerUtility.price = ...`.
`qs.UtilityAgent`	Define a custom heating/cooling agent.
`qs.default_utilities`	Reset utilities to their defaults.
`qs.stream_utility_prices`	Mapping of stream-based utility prices.
`qs.CEPCI`	Chemical Engineering Plant Cost Index; a live, settable view of BioSTEAM’s `CE` (e.g. `qs.CEPCI = qs.CEPCI_by_year[2023]`).
`qs.CEPCI_by_year`	Lookup table of CEPCI values by year.

Note

qs.CEPCI is the only cost/utility global that needs a special accessor: it is a settable property that writes through to BioSTEAM’s CE. The others above are the same objects/classes as in BioSTEAM, so setting an attribute on them (for example qs.PowerUtility.price or qs.settings.thermo) updates the shared, process-wide state directly.

Reactions¶

The full reaction API is re-exported: qs.Reaction (qs.Rxn), qs.ParallelReaction (qs.PRxn), qs.SeriesReaction (qs.SRxn), qs.ReactionItem (qs.RxnI), qs.ReactionSet (qs.RxnS), and qs.ReactionSystem (qs.RxnSys).

BioSTEAM-inherited units¶

qsdsan wraps many BioSTEAM units (mixers, splitters, pumps, tanks, heat exchangers, distillation, flash) under qsdsan.unit_operations.bst. Several BioSTEAM units that qsdsan does not customize are also surfaced there as raw re-exports so systems can be built without import biosteam:

from qsdsan.unit_operations import bst as su

su.IsenthalpicValve, su.Stripper, su.MolecularSieve, su.BatchBioreactor,
su.VacuumSystem, su.Boiler, su.BoilerTurbogenerator, su.ChilledWaterPackage,
su.CoolingTower, su.SolidsCentrifuge

See the unit operations reference for the full list.

Helper functions in `qsdsan.utils`¶

Name	Notes
`qs.utils.rho_to_V`	Convert density to molar volume.
`qs.utils.V_to_rho`	Convert molar volume to density.
`qs.utils.cost`	The `@cost` decorator for adding cost/design to a unit.
`qs.utils.var_columns`	Column labels for a `Model` parameter/metric DataFrame.
`qs.utils.var_indices`	Index labels for `Model` parameters/metrics.

What is intentionally not re-exported¶

A small set of lower-level, unit-authoring tools are deliberately left in biosteam (import them directly when you need them):

biosteam.units.design_tools (e.g. PressureVessel, flash_vessel_design, size_batch, material_densities_lb_per_ft3)
biosteam.exceptions (e.g. DesignError, DesignWarning, bounds_warning)

These are needed only when building custom unit operations, and they fall outside the common surface qsdsan aims to cover.