Cold-Chain VRP with Detachable Thermal Carriers

This is an early problem framing for cold-chain vehicle routing.

Standard cold-chain VRP usually couples thermal protection to the vehicle. A vehicle is refrigerated, and that property moves with the vehicle throughout the route. The thermal constraint is therefore treated mainly as a vehicle attribute.

The framing I am exploring tries to decouple them.

Thermal protection is modeled as a pool of portable units, such as insulated boxes, eutectic plates, or PCM packs. These units may be:

• loaded onto routes from limited inventory
• depleted during delivery
• recovered after route completion
• reused after recovery
• replenished at designated points if the model allows it

This changes the problem from vehicle assignment to resource scheduling. The route is not only constrained by vehicle capacity and time, but also by the state of a separate thermal resource.

Important caution

I should not publish a strong literature-gap claim as fact unless the bibliography has been verified.

Current working hypothesis: existing cold-chain VRP models often treat thermal protection as a vehicle-side attribute, while this framing treats it as a separable resource. The literature check is still ongoing.

Formalization challenge

The difficult part is representing cooling capacity as a state variable. It may deplete continuously with time, temperature, exposure, or delivery sequence. A simple binary variable is probably not enough.

Current weakness

Layer 3 is not yet clean. The model still needs a defensible way to represent depletion, replenishment, and reuse without inventing arbitrary parameters.