The thermal energy required to change air or material temperature without phase change (no condensation, freezing, or evaporation). In refrigerated transport, sensible heat loads come from warm air infiltration during door openings, heat conduction through insulation, solar radiation on vehicle surfaces, and urban heat island radiant effects. Each door opening in 35°C ambient conditions introduces approximately 243 kJ of sensible heat into a 12m³ cargo space at Johannesburg altitude – thermal energy that must be removed by the refrigeration system to restore target temperature. Multi-stop delivery operations with 15-40 door openings per route accumulate massive sensible heat loads (7-20 MJ per route) far exceeding steady-state thermal infiltration through insulation. Understanding sensible heat calculations explains why equipment sized for long-haul transport systematically fails in multi-stop courier duty cycles – the cumulative door opening load alone can equal or exceed the steady-state insulation losses that standard sizing methods account for.
Engineering Formula: For detailed sensible heat calculations including door opening thermal loads and multi-stop route analysis, see Fundamental Thermodynamics in our Technical Formulas Reference.
Related Terms: Door Openings (Thermal Load), Multi-Stop Delivery (Cold Chain), Heat Transfer (Thermal), Temperature Excursion