The percentage of temperature deviation that a refrigeration system can restore between consecutive door openings during multi-stop delivery operations. Recovery ratio measures actual cooling capacity against real-world thermal intrusion—the metric that separates equipment sized for courier duty cycles from systems designed for long-haul transport and sold to courier operators anyway.
The Hidden Capacity Requirement
When your refrigerated cargo space opens for a delivery, warm ambient air floods in. The refrigeration system must remove this heat before the next stop. Recovery ratio quantifies this capability:
- 100% recovery: System restores target temperature completely between stops
- 80% recovery: System restores 80% of deviation; 20% accumulates
- 60% recovery: Temperature drifts progressively across route
A 15-stop route with 80% recovery per stop compounds to significant drift:
- Stop 1: -18°C → -14°C → recovers to -14.8°C
- Stop 8: Temperature has drifted to -12°C
- Stop 15: Product delivered above -10°C
The mathematics are unforgiving. A system achieving “adequate” 80% recovery fails across a typical courier route.
Why Recovery Ratio Matters More Than Rated Capacity
Manufacturer specifications quote cooling capacity under steady-state conditions—continuous operation with doors closed. This metric is irrelevant for courier operations experiencing 30-60 door openings daily.
Recovery ratio depends on:
- Peak cooling capacity (not average capacity)
- Time between stops (typically 8-15 minutes in urban routes)
- Thermal load per opening (ambient temperature, humidity, door size, opening duration)
- Cargo thermal mass (frozen product stabilizes temperature; empty space doesn’t)
A 4kW rated system might achieve only 60% recovery ratio if peak capacity matches average—it cannot surge to handle thermal intrusion events. A 6kW system with the same average load achieves 95%+ recovery because surplus capacity addresses peaks.
The Industry’s Convenient Omission
Equipment suppliers don’t quote recovery ratio because it exposes undersizing. Selling a 4kW unit for courier applications costs less and appears adequate on paper. When temperature drifts across routes, operators blame “too many stops” or “doors open too long”—not the fundamental capacity mismatch.
Professional courier operations require systems sized for peak thermal events, not average loads. Recovery ratio is the metric that reveals whether equipment matches duty cycle—which is precisely why you won’t find it in sales brochures.
Related Terms: Door Openings (Thermal Load), Multi-Stop Delivery (Cold Chain), Transport Refrigeration Unit (TRU), Peak Load vs Average Load
Related Articles: Door Opening Recovery: The Hidden Capacity Requirement