Distribution operations involving numerous delivery points per route—typically 10-40+ stops for courier services—creating thermal load patterns fundamentally different from long-haul transport that equipment manufacturers use as their design baseline. Multi-stop operations represent the most demanding application for transport refrigeration, yet receive the least engineering attention from equipment designers focused on the simpler steady-state requirements of point-to-point transport.
Why Multi-Stop is Different
Long-haul transport refrigeration faces primarily steady-state loads:
- Wall transmission (conduction through insulation)
- Solar radiation on roof and sides
- Occasional door openings at origin and destination
Multi-stop delivery adds massive variable loads:
- Door opening infiltration at every stop (40+ times daily)
- Incomplete recovery between stops
- Cumulative thermal drift across route duration
- Product loading/unloading heat introduction
- Extended stationary periods with reduced airflow
Thermal Load Comparison
| Load Component | Long-Haul | Multi-Stop Courier | Difference |
|---|---|---|---|
| Wall transmission | 60% | 30% | Base load similar |
| Solar radiation | 25% | 15% | Reduced due to shorter routes |
| Door openings | 10% | 45% | 4.5x higher |
| Product handling | 5% | 10% | More frequent handling |
Multi-stop operations experience 3-7 times the door opening thermal load of long-haul transport. Equipment sized for long-haul assumptions operates continuously at maximum capacity in courier applications, unable to achieve temperature recovery between stops.
The Equipment Sizing Problem
Manufacturer sizing guides assume “delivery operations” involve 4-8 stops per day. Courier operations with 15-40 stops require fundamentally different capacity:
Example – 12m³ Cargo Space:
- Long-haul sizing: 3.5 kW adequate
- Manufacturer “delivery” sizing: 4.5 kW recommended
- Actual Gauteng courier requirement: 6.5-8 kW necessary
The 85% capacity shortfall explains why “appropriately sized” equipment fails to maintain temperatures during summer courier routes.
South African Multi-Stop Challenges
Beyond the basic thermal load multiplication, South African conditions add:
- Altitude effects: 21% capacity loss at Johannesburg
- Security complexes: Extended waits at access-controlled estates
- Traffic delays: Reduced vehicle speed limiting ram air cooling
- Customer unavailability: Multiple delivery attempts increasing stops
- Summer heat: Ambient temperatures reaching 35-40°C
Professional Multi-Stop Strategy
The Frozen Food Courier addresses multi-stop demands through:
- Equipment oversizing: 50-100% above manufacturer recommendations
- Route optimization: Minimizing total stops while maintaining coverage
- Delivery windows: Scheduling to reduce customer unavailability
- Pre-cooling protocols: Ensuring maximum thermal reserve before route start
- Recovery monitoring: Tracking temperature between stops to identify problems
Route Economics
Multi-stop operations face inherent cost structures:
- Higher fuel consumption from frequent thermal recovery
- Accelerated equipment wear from continuous maximum operation
- Reduced payload efficiency from smaller per-stop volumes
- Higher labor cost from customer interaction time
These realities explain why professional frozen courier delivery costs R216-350 per stop versus R75-120 for operators gambling with ice packs and prayer.
Related Terms: Door Openings (Thermal Load), Last-Mile Cold Chain Delivery, Route Optimization