Quickstart

This page solves one flowsheet — a once-through Rankine cycle on IAPWS-95 water — first from Python, then from the command line, and reads the result and its certificate. The flowsheet is written out member by member in Your first flowsheet; here it is taken ready-made from the repository's examples/rankine-cycle.changeset.json (download), a change set that creates the revision.

From Python

import json
from openflowsheet.application.local import LocalApplication
from openflowsheet.application.types import Change

with open("rankine-cycle.changeset.json") as handle:
    change_set = json.load(handle)
change, expected_revision, key = Change.from_change_set(change_set)

with LocalApplication.create("plant") as app:          # a project directory, created empty
    committed = app.commit_change(change, expected_revision, key)
    report = app.validate(committed.revision_id, "simulation")
    print(report.status)                               # READY_FOR_SIMULATION

    run = app.solve(committed.revision_id, "default")
    print(run.outcome, run.verification_status)        # CONVERGED VERIFIED

    bundle = next(o.artifact_id for o in run.outputs if o.kind == "replay_bundle")
    state = json.loads(app.artifact_bytes(f"{bundle}/solution-state.json"))["variables"]
    print(state["T.W"], state["B.Q"])                  # turbine work, boiler duty (W)

solve runs a job to its end and returns a RunResult: whether the job completed, the solver's outcome, the verifier's verdict, and the artifacts the run registered — the solution certificate, the run manifest and a replay bundle. The bundle's solution-state.json holds every solved variable by id: stream states as <stream>.T, <stream>.P, <stream>.n.<component>, and unit works and duties as <unit>.W, <unit>.Q in watts, positive into the fluid.

From the command line

The same steps, through the same operations:

openflowsheet project init plant
openflowsheet api --project plant commit_change --json-file rankine-cycle.changeset.json
openflowsheet api --project plant solve --json '{"revision_id": "rev-000001", "policy_id": "default"}'

Each api call prints the operation's response as JSON, exactly the document Python's as_document() gives. Read single values out of the run's artifacts with a JSON pointer:

openflowsheet api --project plant get_artifact \
  --json '{"artifact_id": "job-000001:bundle/solution-state.json", "pointer": "/variables/T.W"}'
openflowsheet api --project plant get_artifact \
  --json '{"artifact_id": "job-000001:bundle/solution-certificate.json", "pointer": "/verification_status"}'

The first prints a projection whose value is the turbine work, -15905.09… W; the second, "VERIFIED". The exit status of api is 0 for a domain result — a failed solve included — and 2–16 for a refusal, by error code (openflowsheet api --help lists them).

Reading the certificate

The certificate lists every check the verifier ran, each with its result and value. Inside the with block above:

certificate = json.loads(app.artifact_bytes(f"{bundle}/solution-certificate.json"))
for check in certificate["checks"]:
    if check["result"] != "pass":
        print(check["id"], check["result"], check["reason"])
print(*certificate["statements"], sep="\n")

For this cycle every residual, material and energy balance and specification check passes; the two independent phase-split checks are not_applicable, because the state is a saturated pure fluid. The statements say what VERIFIED means — residuals at registered tolerances, not an experimental validation or an optimality claim. Concepts explains the four verdicts.

Next

• Your first flowsheet builds the revision document yourself.
• The examples carry this further: a sweep, a refrigeration cycle and a distillation column.