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India is an agriculture-based economy with more than 55 per cent of the land being cultivable as compared to the global average of 11 per cent. However, due to a poorly integrated agro-supply chain industry that poses multiple challenges at each step of operation, there are huge gaps in the terms of capacity and integration of the cold chain supply system. According to Ken Research reports, the Indian cold storage capacity has grown only 20 per cent during 2012 to 2017 and its cold chain logistics market is estimated to grow at a compound annual growth rate of 27 per cent. This is expected to expand at an annual growth rate of 23.88 per cent in terms of value by 2019 end. With the awareness towards supply chain of temperature-sensitive products, there has been a dramatic improvement in transportation facilities and storage mechanisms. This unique technology has enabled longevity in the shelf life of these consumable products and retains their quality up to the last mile.

However, logistic solutions based on refrigerated vehicles are dependent on fossil fuels. As an outcome, the cost of the logistics solutions is twice as that of general commodities. The shift from conventional trucks dependent on diesel-run refrigerated systems to non-diesel based refrigerated systems has a huge potential in bringing down the costs in an affordable range. Using passive cooling materials i.e. phase change materials (PCM), as thermal energy storage (TES) media, enables transportation of goods at a constant temperature. Refrigerated trucks lined with PCM panels are charged through active cooling while the truck is idle. Once charged, the temperature of the container is maintained in the desired range with zero consumption of diesel. Different PCM based logistics solution caters to different applications and temperature with its unique formulations. PCM ranging from -30oC to -10oC is suitable to suffice cooling requirements of products like meat, frozen food, fresh vegetables, ice creams and similar. PCM ranging from -10 to 50C provides a suitable environment for chilled products i.e.dairy products (like milk, yogurt etc..) and beverages. Integrating suitable temperature PCM to meet the transportation requirements of sensitive goods has a significant impact on diesel consumption. The diesel requirement cuts down to more than 50 per cent along with precise temperature control by implementing the TES system.

Figure 1: PCM filled thermoTab active plates being used in reefer trucks for last mile delivery of temperature-sensitive food products.

Case Study

The advantage of using this system can be easily understood by going through an example of its usage in an 8 feet container truck (let’s say, a TATA 407 reefer truck). If we compare a PCM integrated truck with a conventional diesel operated reefer truck, the savings on its running cost are phenomenal. Such a system is charged (or freezing the PCM below its phase change temperature) during the non-operational hours using grid-power supply, there is complete saving on the diesel cost which in the other case of conventional reefer truck is needed continuously for temperature maintenance inside the insulated container. The cost of operation through diesel, in comparison to electric power for cooling, is almost two times. Owing to this great advantage, thermoTab active based reefer trucks have a very short payback period of fewer than six months, in spite of having a little higher initial investment cost involvement. Apart from savings on running cost, it also ensures that the system remains intact and long-lasting due to non-moving parts and components. Compared to a conventional system, this technology also ensures that the perishables and temperature sensitive consumer products are safe even in a situation where the truck breakdowns and no alternative provision for active cooling is present. A face to face comparison of this system with the conventional reefer truck systems is shown in Table 1.

The graphs in figure 2 clearly demonstrates that for an ambient temperature rising more than 30oC, the PCM filled themoTab active plates maintain the temperature of the product for more than 12 hours of operation. Therefore, it will be safe to conclude that the temperature-sensitive products under the safeguard of this passive cooling technique will not suffer any damage or wastage.

Figure 2: Temperature-performance graphs of thermoTab active based reefer trucks.

Conclusion

The following are the benefits of using the passive cooling techniques instead of a conventional Diesel-run reefer truck.

  • Lower dependency on the Fossil Fuel.
  • Ensures temperature maintenance for temperature-sensitive products even during truck breakage
  • Lower operating cost.
  • Lower maintenance cost.
  • Quick to charge.
  • Green Energy.