Refrigerated transport is a critical component of the cold chain and is explained in the infographic.
The benefit of refrigerated transport is emphasised by the food losses that occur in its absence. A recent article states that new partnerships, technologies, government efforts and better cold chain infrastructure, temperature-controlled supply chains are being implemented in Africa to address losses due lack of refrigeration and other related factors Annual food losses for fruits and vegetables are an estimated 40 to 50 percent.
Technical requirements for refrigerated transport systems are very complex. They have to operate over a wide range of weather conditions, carry different cargos at different temperatures, sometimes with two different compartments at different temperatures. They have to be very robust and reliable to withstand vibrations and shocks and must meet ship and road safety requirements. HFC refrigerants have been the refrigerant of choice for the majority of refrigerated containers, refrigerated vans, trucks or trailer-mounted refrigerated systems and refrigerated railcars.
Flammability risks are a main concern, along with energy efficiency and reliability, for refrigerated transport applications and affect current and future refrigerant choices, but lower GWP HFC/HFO blend refrigerants are being implemented.
Non-flammable HFCs continue to be widely used and lower GWP non-flammable alternatives such as HFC/HFO blends are being used or developed as replacements in some applications. R-744 (CO2) has inferior energy performance at medium to high ambient temperatures when compared to the non-flammable fluorocarbons used for refrigerated transport. Flammability mitigation still represents a major challenge, but research continues for the use of mildly flammable A2L refrigerants, including lower GWP HFCs, HFC/HFO blends and HFOs.
Refrigerated containers (reefers) that are designed for use with R-134a are being offered as compatible with R-513A for future conversion or are available with non-flammable HFC/HFO refrigerant R-513A. This refrigerant has a GWP of 631 compared to 1430 for R-134a. Non-flammable R-452A has a good match of properties and discharge temperature to R404A and has a GWP of 2140 (compared to 3922 for R-404A) and is suitable as an alternative to R-404A for refrigerated containers. It has good match of properties and discharge temperature. Hermetic modules are being adopted, using R-452A, and are less susceptible to faults and can be exchanged in the event of failure which would not require a certified refrigeration technician.
Truck and trailer refrigeration units in Europe, are using non-flammable HFC/HFO blend R-452A is the preferred refrigerant choice, replacing R-404A. It is also suitable for retrofit as it has similar discharge temperature and performance.
All electric small refrigerated vans. Diesel free solutions are being used more widely with electric compressors to provide zero emissions for the ‘last kms’ of cold food delivery particularly in urban areas. Full electric refrigeration units for medium size vans and trucks are using non-flammable HFC-134a or the HFC/HFO refrigerant R-452A. When used with electric vehicles it offers zero-emission refrigerated transport for food deliveries for urban populations, creates refrigerated transport that delivers food and perishable items safely with zero-emission, low noise and maximum convenience for urban populations. Hermetic electric refrigeration systems can be factory assembled and pre-tested to ensure containment. Stationary cooling can be used to boost efficiency and save vehicle battery power by connecting the vehicle cooling system to a mains socket a few hours before delivery to provide a pre-cooled cargo compartment.
Reducing energy consumption and energy related emissions, and electrification of compressor drives for ‘last kms deliveries’, are a main focus for the refrigerated transport sector.
Reducing energy consumption and energy related emissions, are a main focus for the refrigerated transport sector. Electric drive compressors, for last mile delivery, hermetic module systems for refrigerated trailers and improved control systems to reduce energy consumption are improving environmental performance. As truck manufacturers and suppliers begin to move toward electric-powered vehicles and components, the same trend is emerging for trailer refrigeration. Reducing energy consumption has been a major focus for reefer manufacturers for many years, but now there is an increased focus on reefer energy consumption, in part due to the increased cost of low sulphur fuel for shipping lines. Energy consumption reduction means a reduction in fuel consumption which means a cost reduction in general. Power management control software and systems can reduce energy consumption by over 50%. Intelligent cycling of the refrigeration unit compressor and fans provides energy savings in the range from 10% to 65%, dependent on the commodity carried and the refrigeration unit model.