Refrigerated freight: chilled and frozen road distribution

Insulated bodies and the machinery attached to them

A refrigerated body is insulated on every surface, with sealed doors and a floor designed to let air travel beneath the load. The cooling unit may be driven from the vehicle engine or run independently on its own power source, which matters because a load must stay cold while the vehicle is parked or its engine is off. Multi-temperature bodies divide the space with movable bulkheads so chilled and frozen goods can travel together at their own setpoints, at the cost of usable volume and complexity.

Every door opening costs something

Warm humid air enters the moment the doors open, and the unit has to remove it again. On a round with many calls, that happens repeatedly, which is why strip curtains and air curtains are fitted, why side doors are used to reach only the relevant compartment, and why the load is sequenced so each drop is nearest the door when its turn comes. A crew that opens the rear doors fully to retrieve one carton undoes work the unit spent the previous leg performing.

Pre-cooling, loading and airflow

The body is brought down to temperature before loading, and the goods arrive already at their carriage temperature. Product is stacked so cold air can circulate around and beneath it rather than being packed solid against the walls and up to the ceiling, and the return air path to the evaporator is kept clear. Loading directly from a chilled dock with a sealed dock shelter avoids the exposure that loading in a yard creates.

Proving the temperature, not just achieving it

Recorders log the air temperature throughout the journey, and receivers frequently check product temperature on arrival before accepting a delivery. Where a reading falls outside specification the consignment may be rejected at the bay, so the record is a commercial instrument as much as a safety one. Requirements for equipment, calibration and record retention are set by food safety and transport authorities in each jurisdiction.

Mixed loads and the things that spoil each other

Products taint one another, ethylene from some produce ripens the rest, raw and ready-to-eat goods must be separated, and a setpoint that suits one commodity damages another. Compartmentalisation, packaging and load planning handle most of this, but some combinations should not share a vehicle at all, and the planning stage is where that is decided.

Frequently asked questions

Why does the unit run when the vehicle is parked?

Because insulation only slows heat entering; it does not stop it. An independently powered unit keeps cooling during driver rest, overnight standing and long delivery stops, which is exactly when an engine-driven system would otherwise be off.

Can chilled and frozen goods travel on the same vehicle?

Yes, in a multi-temperature body divided by movable bulkheads, with each compartment held at its own setpoint. It costs usable space and demands careful load sequencing, but it avoids sending two vehicles on the same round.