The Development Of Phase Change Materials And Their Application On Cold Chain Of Agriculture Products

Abstract:An effective organics complex phase change coolant (PCC) with high phase enthalpy change and low Onset temperature was developed which aimed at application on storage and transportation of agricultural products with different optimal storage temperature. Glycine, Lysine, Sorbitol, Proline and Glucose were selected firstly and then were screened about their phase enthalpy change and Onset temperature with the Differential Scanning Calorimetry (DSC). Glycine was chose as the main energy storage material because of its highest phase enthalpy change at the same Onset temperature among these five materials. To achieve a lower Onset temperature, Glycine was matched with0.1mol/L Glycerol solution, with0.1%Sodium Benzoate added to extent self-life of PCCs and Super-Absorbent Polymers (SAP) as matrix. The final formula of the organics complex PCCs was0.4～0.8mol/L Glycine,0.1mol/L Glycerol,0.1%Sodium Benzoate in water, with0.75%～0.81%SAP as matrix. A series of this organics complex PCCs could be prepared by changing the concentration of Glycine solution, with phase enthalpy changes between296.4to305.9J/g and Onset temperature from-7.3to-5℃. There were almost no supercooling phenomenon and phase separation phenomenon in these PCCs.Application study was conducted on the effects of the developed PCCs on litchi’s preservation. Five groups were prepared in every4kg litchi boxes, and except control one, others’phase enthalpy changes, Onset temperature and quantity respectively were:commercial PCC-A312.0J/g,-2.2℃, lkg; developed PCC-B with0.4mol/L concentration of Glycine305.9J/g,-5℃, lkg; developed PCC-C with0.8mol/L concentration of Glycin296.4J/g,-7.3℃, lkg; developed PCC-C with0.8mol/L concentration of Glycin296.4J/g,-7.3℃,0.5kg. Compared with insufficient PCCs group which had0.5kg developed PCC-C and the control group, it showed that temperature in the boxes with commercial PCC-A, developed PCC-B and developed PCC-C could be controlled below10℃respectively as long as10h,12.5h and13h, which could alleviate the dramatic changes of respiration, browning index, the rate of good fruit, the membrane permeability of peel, color of peel, yield of juice, titratable acid content, soluble solids, pH value, secondary chew texture indexes and others related indicators in the litchis effectively, while these indicators of litchi quality in the boxes without PCCs or with insufficient PCCs changed rapidly. Totally, the efficiency of PCCs could be ranged in the following order:developed PCC-C> developed PCC-B> commercial PCC-A within72h, so appropriate amount of developed PCC-C had good effects being used in72hours’cold chain storage and preservation of the agricultural product, following by developed PCC-B.Our results proved that the developed PCCs in this project have high latent heat, low onset temperature and good safety, and could be widely applied on cold chain of agricultural products.