Hypothetical scenario – simplified illustration
Pharmaceuticals are required to be transported regularly by road and air from a plant in France to a remote location in West Africa. The products are chilled and stored at -27oC at the manufacturing plant in France. The products must be maintained at below -12oC to avoid spoilage. The journey to West Africa requires a total of 24 hours but in-transit delays can extend the trip up to 72 hours. Even with exhaustive insulation, the product risks deterioration if the journey takes more than 36 hours. For most of the journey no active cooling provisions are readily available.
The inclusion of a suitable quantity of encapsulated PC-21 (chilled to -27oC) inside the packaging of the pharmaceutical product can guarantee that the product will not spoil within four days without any active cooling.
The ingress of heat energy over 36 hrs of transport is known to raise the temperature of a 10kg (net) consignment by 15oC. One can assume that the heat capacity of the product is no greater than water (4.2 kJ/kgC).
The quantity of PC-21 required is:
4.2 x 10kg x 15C(temp change) x 96hrs/36hrs = 1680 kJ
“Useful heat capacity” of PC-21 = 249 kJ/kg
Therefore quantity of PC-21 = 1680/249 = ~6.7kg PC-21