Temperature-controlled courier operations involving multiple sequential deliveries from a single loaded vehicle, creating cumulative thermal loads from repeated door openings, extended operational duration, and variable ambient conditions throughout routes. Multi-stop cold chain delivery faces fundamentally different thermal challenges than long-haul transport: each door opening introduces warm air requiring refrigeration energy to remove, recovery time between stops determines equipment capacity requirements, and sustained operation over 4-8 hours accumulates ambient heat infiltration. A typical Gauteng route with 15 deliveries involves 30 door openings (open for delivery, close, open for next access, close), each introducing 15-20 MJ thermal load in summer conditions – total door opening loads exceeding steady-state heat infiltration. Yet transport refrigeration units are designed and rated for long-haul operations with minimal door openings, systematically undersized for multi-stop courier duty cycles. Professional multi-stop operations require refrigeration systems oversized 30-50% compared to long-haul applications, enhanced insulation to reduce recovery time between stops, and operational protocols minimizing door opening duration and frequency.
Engineering Formulas: For detailed door opening thermal load calculations and multi-stop system sizing requirements, see Thermal Load Calculations in our Technical Formulas Reference.
Related Terms: Door Openings (Thermal Load), Last-Mile Cold Chain Delivery, Temperature Excursion, Route Optimization