| name | neqsim-reciprocating-compressor-screening |
| calculation_basis | screening |
| version | 0.1.0 |
| description | Educational reciprocating-compressor screening using the public clearance volumetric-efficiency relation (API 618 / API 619 style). USE WHEN: a task needs a public, screening-level estimate of volumetric efficiency, actual inlet capacity, staging, discharge temperature, and rod-load utilisation for a reciprocating compressor before detailed selection. |
| last_verified | 2026-06-25 |
| requires | {"python_packages":[],"java_packages":[],"env":[],"network":[]} |
Reciprocating Compressor Screening
Use this skill for public, educational reciprocating-compressor screening. It estimates clearance volumetric efficiency, actual inlet capacity, the required number of stages, discharge temperature, and a rod-load utilisation ratio so an agent can scope a reciprocating-compression study before detailed selection.
When to Use
- When a user asks how many stages a reciprocating compressor needs or what its volumetric efficiency is.
- When an agent needs a quick actual-capacity and discharge-temperature estimate for a positive-displacement machine.
- When examples must run without confidential compressor data, vendor curves, or company specs.
Inputs
suction_pressure: stage suction pressure P1 in bar absolute.discharge_pressure: final discharge pressure P2 in bar absolute.suction_temperature: suction temperature T1 in kelvin.swept_volume_rate_m3_h: geometric (swept) volume rate in m3/h.clearance_fraction: cylinder clearance fraction C, default 0.12.specific_heat_ratio: ratio of specific heats k, default 1.3.leakage_allowance: leakage/loss allowance L, default 0.03.rated_rod_load_kn: optional rated rod load in kN for the rod-load comparison.piston_area_m2: optional piston area in m2 for the rod-load comparison.
Outputs
pressure_ratio: overall P2 / P1.stages: integer number of stages keeping each stage below max_stage_ratio.stage_pressure_ratio: per-stage pressure ratio.volumetric_efficiency: clearance volumetric efficiency.actual_inlet_capacity_m3_h: swept rate multiplied by volumetric efficiency.discharge_temperature_k: first-stage isentropic discharge temperature.rod_load_ratio: gas rod load divided by rated rod load, or null.capacity_warning: ok, watch, low-volumetric-efficiency, or discharge-temp-high.rod_load_warning: ok, watch, rod-load-exceeded, or no-rating.assumptions: public assumptions used by the placeholder model.
Engineering Method
The Python class ReciprocatingCompressorModel uses open positive-displacement relations only:
- staging splits the overall ratio so
stage_ratio = (P2 / P1)^(1/stages) stays below max_stage_ratio (default 4.0).
- volumetric efficiency uses
VE = 1 - C (r^(1/k) - 1) - L.
- actual inlet capacity uses
Q_actual = swept_rate * VE.
- discharge temperature uses
T2 = T1 r^((k-1)/k).
- gas rod load uses
F = dP * piston_area, compared to the rated rod load.
This is educational and screening-only logic. It assumes constant k, ideal staging, no valve or pulsation losses, and gas-only rod load. It is not a replacement for validated reciprocating-compressor sizing or qualified rotating-equipment review.
Python Usage Pattern
from reciprocating_compressor_screening import ReciprocatingCompressorModel
model = ReciprocatingCompressorModel()
result = model.evaluate(
suction_pressure=2.0,
discharge_pressure=120.0,
suction_temperature=313.15,
swept_volume_rate_m3_h=800.0,
rated_rod_load_kn=120.0,
piston_area_m2=0.04,
)
print(result.stages)
print(result.volumetric_efficiency)
print(result.rod_load_warning)
Related NeqSim Functionality
For validated compression calculations, redirect to NeqSim classes:
neqsim.process.equipment.compressor.Compressor — rigorous polytropic compression with real-gas properties.neqsim.process.equipment.compressor.ReciprocatingCompressor — proposed reciprocating-compressor model (volumetric efficiency, valve losses, rod load); candidate NeqSim gap.neqsim.process.mechanicaldesign.compressor.CompressorMechanicalDesign — compressor mechanical design and feasibility.
This skill is a public triage layer that decides when to invoke a validated reciprocating-compressor model.
Validation Checklist
Common Mistakes
| Symptom | Cause | Fix |
|---|
| Volumetric efficiency near zero | Single high-ratio stage | Let the staging logic add stages |
| Discharge temperature too high | High stage ratio | Add stages or intercooling |
| Rod-load ratio missing | No rated rod load or piston area supplied | Provide both for the comparison |
Limitations
- No proprietary compressor data, vendor curves, or company specs are included.
- No valve losses, pulsation, or real-gas property variation are modelled.
- Rod load uses gas load only; inertia and load reversal are not included.
References
- API Standard 618, Reciprocating Compressors for Petroleum, Chemical, and Gas Industry Services.
- API Standard 619, Rotary-Type Positive-Displacement Compressors.
- NeqSim repository: https://github.com/equinor/neqsim
