This simulator models a reciprocating (piston) compressor — crankcase, motor and shaft, crankshaft and eccentric pin, connecting rod, piston, cylinder, and automatic suction and discharge reed valves — using a cycle-average ideal-vapor reference so you can see how clearance volume, pressure ratio and valve leakage shape volumetric efficiency and delivered mass flow.
• Equipment laboratory tab: a real-time 3D cutaway of the crankcase/oil sump, drive motor and shaft, crankshaft and eccentric pin, connecting rod, piston and rings, cylinder liner and head, suction reed valve, discharge reed valve, and low-/high-pressure vapor lines, with Home view, Focus selected part, Show full enclosure / cutaway, Exploded view, Auto rotate and Expand camera controls plus a clickable component list with callouts. Controls include shaft speed (rpm), suction pressure (absolute), discharge pressure (absolute), suction vapor temperature, clearance volume / swept volume, effective compression efficiency and valve leakage capacity loss, alongside live stats, a What is happening? sequence readout, operating-history chart, switch-state tokens and a cell-readings table. • Curves & measurements tab: a mass-flow/shaft-power chart and a cylinder-pressure chart that also plots the ideal reed-valve P–V reference cycle against the shown piston position (crank motion and shown-cycle pressure are slowed 50× relative to the selected RPM, while cycle-average rates keep their physical units), the model equations, and snapshot measurement readouts. • Experiments tab: four preset investigations (baseline compressor, larger clearance, higher pressure ratio, leaking valves) plus a Run model checks verification bench and a timestamped event log with trial-report export. • Learn & assess tab: lesson cards on re-expansion of trapped vapor, filling at suction pressure, compressing the trapped mass, and delivery/repeat, a knowledge-check quiz with reset, and a scope/references note.
As the piston descends, cylinder pressure falls until it reaches suction pressure and the suction reed valve opens, admitting vapor. On the return stroke the trapped vapor is compressed, following an ideal reference relationship p·Vⁿ = constant (n = 1.13 in this model), until cylinder pressure reaches discharge pressure and the discharge reed opens to deliver compressed vapor. Because a finite clearance volume remains at top dead center, the gas trapped there must re-expand before the next suction event can begin — this re-expansion, not motor behavior, is what limits how much of the intake stroke is available to admit fresh vapor.
Volumetric efficiency captures that re-expansion loss along with an imposed valve-leakage capacity loss: ηv = max(0, 1 + c − c·(pd/ps)^(1/n))·(1 − leakage). Mass flow then follows from suction density (via the ideal-gas relation ρs = ps/(R·Ts)), swept volume, volumetric efficiency and shaft speed, while shaft power comes from a polytropic work integral divided by the selected effective efficiency.
The cylinder-pressure chart overlays the ideal reed-valve P–V reference cycle — suction, compression, discharge and re-expansion — against a marker for the shown piston position; it is a reference curve computed from the model equations, not a measured indicator diagram from a real compressor. Because the mechanism animation and this pressure trace are deliberately slowed 50× relative to the selected shaft speed, don't read the animation timing as real-time — the mass-flow and shaft-power numbers in the stats panel and history chart are the actual cycle-average physical rates.
The Run model checks button in the Experiments tab exercises independent fresh models — leaving your current trial untouched — to confirm relationships such as doubling RPM doubling cycle-average mass flow and higher clearance reducing delivered mass. This is a cycle-average ideal-vapor model (R = 81.5 J/(kg·K), n = 1.13, swept volume 180 cm³) — it excludes real refrigerant properties, two-phase ingestion, oil flow, motor transients and detailed valve losses, and the P–V trace is not a measured indicator diagram.
A cycle-average ideal-vapor reference for a reciprocating compressor with R = 81.5 J/(kg·K), a polytropic exponent n = 1.13, and a 180 cm³ swept volume. It excludes real refrigerant properties, two-phase (liquid slugging) ingestion, oil circulation, motor startup transients and detailed valve dynamics — the reed valves are treated as ideal.
At top dead center a finite volume of compressed gas remains trapped in the clearance space. That gas must re-expand back down to suction pressure before the descending piston can begin admitting fresh vapor, so a larger clearance fraction eats into the usable intake stroke and lowers volumetric efficiency.
No — it is an ideal reed-valve reference cycle computed from the model equations (p·Vⁿ = constant during compression/expansion, with instantaneous valve opening at suction and discharge pressure), not a measured indicator diagram from an instrumented compressor. The animation and this chart are also slowed 50× relative to the selected shaft speed for visibility.
The Run model checks button runs independent, freshly-initialized models to confirm invariants such as doubling shaft speed doubling cycle-average mass flow, higher clearance reducing delivered mass, and higher pressure ratio increasing compression work and discharge temperature — confirming the implemented model behaves consistently.