Enhancing the insulation capability of a vaccine carrier box: An engineering approach

Journal article, 2021

Being thermosensitive, Vaccines need storage at specific temperatures of 2-8 °C, and Vaccine Cold chain Carriers are the most widely utilized instruments to carry out rural vaccination drives in Low-income hot climate countries. Several developed designs for the carrier have reported superior performance, but their actual penetration into rural community medicine is limited due to reasons of cost and utility. Thus, the scope for improvement in the design is significant and it is also pertinent to quantify the effect of design features on the performance. Taking shared features possessed by such superior designs, the work presents the impact of geometry, vertically stacked vaccine tray assembly and usage of Phase Change Materials(PCM), on the final passive cooler assembly. A fabricated New Design with given features is cross-compared and analysed with a Market(Original) Design of the same scale and storage capacity. Analysis performed takes a scientific inclination towards Engineering and Insulation aspects of the Vaccine Box. It uses Conjugate Heat Transfer model(CFD simulations), Geometry analysis, experimentally derived Insulation R-values and Temperature monitoring to accomplish this. Secondly, the work presents a systematic design approach to improve upon the conventional design, PCM selection is made using DSC(Differential Scanning Calorimetry) testing, and Material of Construction(MOC) selection is made using Ashby plots based on the results of the simulations. Overall the Fabricated New Design gives an improvement of ≈16% in R-value and ≈17% improvement in the retention time of the specific temperature range, over the conventional (Original) Design.