How this calculator works
The CA atmosphere designer calculates the O₂, CO₂, and N₂ setpoints and gas-management equipment sizing required for controlled-atmosphere storage of 12 Pakistan crops. Target gas compositions follow USDA Agriculture Handbook 66 and ASHRAE Refrigeration Handbook 2022, Chapter 25. Respiration rate data (mL CO₂/kg·h at storage temperature) from peer-reviewed post-harvest physiology literature are used to calculate daily O₂ depletion and CO₂ accumulation in the sealed room. The N₂ generator (PSA type) is sized to make up oxygen consumed by respiration plus infiltration, maintaining the target O₂ level. CO₂ scrubber capacity (kg activated-carbon or catalytic) is sized against daily CO₂ accumulation. Ethylene concentration is estimated from crop variety and storage stage; the tool recommends catalytic ethylene removal (Swingtherm-BS class) when predicted levels exceed the crop's threshold. ULO (Ultra Low Oxygen) and DCA (Dynamic CA) protocols are flagged for eligible crops. This tool covers design estimation; actual setpoints require in-situ tuning during the first fill cycle.
References: USDA Agriculture Handbook 66 (2016); ASHRAE Refrigeration Handbook 2022 Ch. 25; Wills et al. Postharvest: An Introduction 5th ed.; Fruit Control Italiana GAC 5000 commissioning manual.