"Intelligent Temperature Control" for Blood Bags: How Phase Change Materials Maintain a Constant Temperature of 2-6℃ During Transportation

Blood bags need to be maintained at a constant temperature of 2-6℃ during transportation. Phase change materials (PCMs) achieve this through their unique phase change properties, specifically as follows:

1. Characteristics of Phase Change Materials: During a phase change (usually a first-order phase change), PCMs can absorb or release a large amount of energy (i.e., phase change enthalpy), and theoretically, the temperature remains constant during the first-order phase change. This characteristic gives them an advantage in temperature regulation, enabling them to absorb or release a large amount of energy during the phase change while maintaining a relatively stable temperature.

2. Application of Phase Change Materials in Blood Bag Transportation

Encapsulation: The blood bag is first wrapped in a tight-fitting bag containing a molecular alloy PCM energy storage material, and then the tight-fitting bag is placed in a sturdy plastic carrying bag. When using insulation equipment containing the molecular alloy PCM energy storage material for insulation, the tight-fitting bag containing the material is first placed in a refrigerator to allow the material to completely change from a liquid to a solid state. The blood bag is then placed inside the tight-fitting bag containing the material for later use.

Temperature Regulation Principle: At room temperature, the phase change energy storage material in the insulated bag absorbs heat from the external environment and undergoes a phase change, thus maintaining the blood bag's temperature within the range of 4℃±2℃. In other words, during the phase change process, the molecular alloy phase change energy storage material ensures the blood bag remains in a near-isothermal state until the material completely transforms into a liquid state, achieving the insulation effect.

3. Experimental Verification of Effect

High-Temperature Experiment: The phase change material was kept at -20℃ for 12 hours, the stored blood (in the blood bag) was at 4℃, and the ambient temperature was 30℃. After 24 hours, the blood temperature was 4℃; after 48 hours, the temperature was 6℃; and after 72 hours, the temperature was 9℃. This experiment demonstrates that the blood transport box with temperature regulation using a shape-stabilized phase change material can maintain the blood temperature within the range of 4℃-10℃ for 72 hours in a relatively hot environment, and the stored blood is suitable for use.

Low-temperature experiment: The phase change material was maintained at 20℃ for 12 hours, the stored blood (in a blood bag) was at 8℃, and the ambient temperature was -20℃. After 24 hours, the blood temperature was 4℃; after 48 hours, the temperature was 3℃; and after 72 hours, the temperature was 1℃. This experiment demonstrates that the blood transport box with temperature regulation using a shape-stabilized phase change material can maintain the blood temperature within the range of 4℃ - 1℃ for 72 hours in a relatively cold environment, and the stored blood is suitable for use.