Research On The Phase Change Materials Used In Cold Storage Containers

Refrigerated container can be used for the storage and transportation of fresh fruits, vegetables and medicines like vaccines, blood and insulin to keep their quality. This was a new technology that the Phase change material can be put inside the wall of refrigerated container to slow down the temperature rise in cargo space.In this study, a new type of phase change coolant was formulated which has a suitable phase transition temperature, large latent heat, non-toxic and harmless. The heat transfer process across the wall of refrigerated container and between the products inside the container was simulated by COMSOL. An experimental system with a semiconductor refrigerator was set up. The results showed that this new phase change coolant fulfill the requirements for storing foods and medicines.1、The fourteen alkanes with twelve alkane were mixed at a specific ratio. The new miscible phase change materials was formed by ultrasonic vibrating the mixture for a certain amount of time.2 、 The thermal parameters of the composited phase change material were determined by differential scanning calorimetry(DSC). Its phase change temperature and latent heat are 2.15℃ and 175 J/g, respectively.3、The heat transfer and temperature profile across the wall and inside of the container was simulated and calculated by COMSOL software. The results proved that: the inside of the container was completely isolated to the outside environment by the addition of the new phase change materials. Also the temperature fluctuations inside the box was reduced and the rise of interior temperature was delayed.4、A experimental system was designed and set up. The phase change materials was encapsulated into thin flat containers, which were contained in a well-insulated case. The semiconductor refrigeration system was applied and high density polyethylene system was taken as insulation.5 、 In order to simulate the transportation process, the temperature change of Shanghaiqing was studied. Three thermal couples were stuck into the large veins, small veins and blades of the selected leaf respectively. The temperature distribution during the cooling and warming process with/without phase change materials was systematically recorded and analyzed. The results indicated that the temperature fluctuation degree during cooling process can be reduced to 2℃(p≤0.01), when the phase change materials was incorporated into the refrigerated container. The temperature difference between large vein and small vein, blades were reduced because water around the large veins could be delivered to the area of small veins. While during the storage process, the phase change materials could balance the temperature change and the temperature fluctuation could be reduced up to 25.8%.On the other hand, during the warming process, The increase of temperature inside the container and the Shanghaiqing was slowed down with the addition of phase change material.In summary, application of phase change materials in a refrigerated container could reduce the temperature fluctuation and benefit the cold storage of fruits and vegetables.