Cold chain: difference between revisions
Diff·revision 36 → 37·22:52, 19 Dec 2024
Difference between revision 36 and revision 37 of Cold chain. 5 lines changed; the page grew by 978 bytes.
| Revision 36 — 13:02, 14 Dec 2024 CounterfeitCato (talk) British spelling per PP:MOS 15,700 bytes +177 | Revision 37 — 22:52, 19 Dec 2024 ForestPlotFinn (talk) replace bare ref with full citation 16,678 bytes +978 | ||
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| 105 | ; Payload arrangement : A qualified configuration specifies coolant placement, payload volume and the minimum and maximum payload for which the qualification holds. A shipper qualified for a full payload frequently fails when shipped part-full, because the reduced thermal mass follows the coolant more closely.{{r|pda_tr39}} | 105 | ; Payload arrangement : A qualified configuration specifies coolant placement, payload volume and the minimum and maximum payload for which the qualification holds. A shipper qualified for a full payload frequently fails when shipped part-full, because the reduced thermal mass follows the coolant more closely.{{r|pda_tr39}} |
| 106 | 106 | ||
| + | 107 | === Phase-change materials === | |
| + | 108 | Water ice melts at 0 °C and therefore holds a payload close to that temperature while any ice remains — well below the 2 °C lower bound of the cold range, and a recognised cause of freezing excursions in 2–8 °C distribution. Phase-change materials are formulated to melt at a temperature inside the target range, commonly around 5 °C for refrigerated shipments and around 22 °C for controlled-room-temperature shipments, so that the latent heat of the transition buffers the payload at a temperature that is itself compliant.{{r|pda_tr39}} | |
| + | 109 | ||
| + | 110 | The trade-off is that a material with a higher melting point stores its latent heat at a smaller temperature difference from ambient and therefore protects for a shorter time against a warm environment, while providing protection against freezing that water ice cannot. Where a shipment must survive both a hot and a cold ambient profile, dual-material configurations are used.{{r|matthias2007}} | |
| + | 111 | ||
| 107 | == References == | 112 | == References == |
| 108 | {{reflist}} | 113 | {{reflist}} |