Development Of High Efficiency Phase Change Energy Storage Material And Its Application In Vaccine Cold Storage Box

Now that the world's energy crisis is becoming more and more serious,it is imperative to use new materials and develop new technologies to improve energy efficiency.The energy crisis means the gradual closure of factories and power plants,transportation interruptions,reduced gasoline use for vehicles,closure of schools in winter,grounding of aircraft,etc.In the past 100 years,energy dependence has increased dramatically,and we are heavily dependent on fossil fuels that are being exhausted.Coal,natural gas and oil account for about 80% of the world's energy consumption.Phase-change energy storage technology,as a new energy-saving technology integrating circular economy,energy regulation,environmental protection,energy saving and comprehensive utilization,has attracted wide attention from scholars at home and abroad.Energy storage is carried out in mechanical,electrical and thermal forms.Thermal energy storage is divided into sensible heat(through the specific heat of water,soil and other substances)and latent heat(by phase transformation of paraffin,hydrated salt).According to the special temperature requirements of vaccine cold chain logistics,a new type of cold storage incubator was proposed and designed in this study,which can monitor the temperature of vaccine in real time through mobile phone at the user end,and is suitable for the transportation of inactivated vaccine.A vaccine reagent tube can be placed in the storage hole of the cold storage box of the new cold storage incubator.During the refrigerated transportation,the cold storage agent in the cold storage box can be released and transferred more evenly among the articles,so that the temperature of each vaccine reagent tube can be kept consistent and the temperature fluctuation during storage and transportation can be reduced.In this study,tetradecane(TD)-lauryl alcohol(LA)were used as main cold storage agents,expanded graphite(EG)and hydroxylated multi-walled carbon nanotubes(MWCNT-OH)were used as additives,respectively.The cold insulation effect of composite phase change material in the new type of thermal insulation box was studied by experiment,and the cold insulation characteristics of the new type of thermal insulation box under different working conditions were studied by simulation.The specific research contents and results are as follows:(1)The phase transition temperature of the substrate TD-LA is 4.3 ?,the latent heat is 247.1 J/g,and the thermal conductivity is 0.2737 W/(m·K).After adding expanded graphite,the thermal conductivity of TD-LA/EG is 0.9657W/(m·K);with Hydroxylated multi-walled carbon nanotubes(MWCNT-OH)as the additive and Sodium Dodecyl Benzene Sulfonate(SDBS)as the dispersant,the thermal conductivity of TD-LA/MWCNT-OH/SDBS is 0.3343 W/(m·K).Adding nano materials to the base solution to improve the thermal conductivity is not as effective as adding expanded graphite.Therefore,expanded graphite is preferred as an additive to improve the thermophysical properties of the base solution.The phase change temperature of TD-LA/EG is 4.3 ?,and the latent heat is 245.1 J/g,which is 3.53 times higher than the thermal conductivity of TD-LA composite phase change material.The TD-LA/EG was subjected to 400 charge-discharge cooling cycle stability experiments,the phase transition temperature was-3.1 ?,the latent heat was 243.9 J/g,and the phase transition temperature was 4.9 ?.(2)During storage and transportation,most vaccines should be kept in a constant temperature environment of 2?8 ?.This research designed a new type of cold chain transportation equipment to ensure that the cold storage agent in the cold storage box releases and transfers the cold more evenly between items,so that the temperature of each vaccine reagent tube is consistent,and the temperature fluctuation during storage and transportation is reduced.Through experimental research,it is found that when the cold storage incubator is empty,the cold storage box maintains 2?8 ? for the longest time,about 47.73 h,and the top plate maintains 2?8 ? for the shortest time,about 40.78 h,and the average cold storage time is 44.37 h.When the cold storage incubator is loaded,the longest time to maintain 2?8 ? in the cold storage box,about 52.36 h,and the shortest time to maintain the top plate at 2?8 ?,about 44.05 h.The average cold storage time is 46.04 h.The goods are effective Keep cold for 50.02 h.(3)TD-LA/EG was used as a phase change material for cold storage.The cold storage time of cold storage box was simulated under the action of cold storage plate,cold storage box and cold storage plate and cold storage box.When the cold storage plate and the cold storage box are used together in the cold storage box,the temperature of the vaccine at the top corner exceeds 8 ? at 72.2 h,so the shortest effective cold storage time of the vaccine in the cold storage box is 20.4 h.When only the cold storage plate was used in the cold storage box,the top plate of the cold storage plate reached 8 ? first,and the shortest effective cold storage time of the vaccine was 37.7 h.When the cold storage box is used in the cold storage box,the charge quantity of PCM in the cold storage box is the same as that of the cold storage plate.The vaccine in the cold storage box at the top of the box reached 8 ? at first,and the shortest effective cold holding time of the vaccine was39.6 h.