System Simulator — drag-and-drop refrigeration loop design
By DigiEntropy Engineering · 2026-02-07 · 8 min read
Compressor + condenser + evaporator + expansion valve + pipes — the full refrigeration loop simulated against vendor polynomials and a closed-loop solver. System Simulator is where you go after Cold Room when the loop topology is the unknown.
About this post — Authored by an AI assistant using DigiEntropy's polynomial corpus, the universal compressor predictor, and the project's chart-generation tooling. Charts are produced by Python scripts that read the same database the live site queries; tables and formulas are pulled from the same engineering modules. Findings reflect the project's current dataset and methodology — send corrections or deeper questions to admin@digientropy.com.
Cold Room sizes a compressor against a heat load at standard SST/SDT. Real systems have evaporators, condensers, expansion valves, line sizing, and pipework that all shift the operating point away from "standard." A 25 kW compressor sized at -10/40 might land at -12/45 once the actual evaporator and condenser are in the loop, dropping capacity by 5-10 %. To capture that, you need a system-level simulator that solves the loop simultaneously.
System Simulator does that — drag components onto a canvas, the closed-loop solver iterates SST/SDT to balance compressor capacity against evaporator + condenser duty + pipe losses.
5-10 % - capacity lost in the real loop - sized at -10/40, landed at -12/45
A 25 kW compressor sized at -10/40 might land at -12/45 once the actual evaporator and condenser are in the loop, dropping capacity by 5-10 %.
3 min - to build a loop - drag four parts, click Calculate
15-30 min - System Simulator design workflow - Cold Room: a 5-minute selection workflow
Use Cold Room when the load is the unknown. Use System Simulator when the loop topology is the unknown.
13 - brands in the compressor picker - instant matches across all of them
Choose Compressor Model picker — same ModelTypeahead as the rest of the platform. Type any model name, get instant matches across all 13 brands.
30 % - where an undersized solenoid starves - at 15 K subcooling, real winter operation
A solenoid valve sized for 100 % cooling capacity at 2 K subcooling will starve at 30 % cooling capacity at 15 K subcooling (real winter operation).
5 - Newton-Raphson iterations - to converge a typical refrigeration loop
Newton-Raphson on (SST, SDT, ṁ) converges in 5 iterations for typical refrigeration loops. Heat-pump and transcritical CO2 loops need more iterations because the cycle isn't sub-critical.
What it solves vs Cold Room
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