Stay cool – innovations in fridge trailers

Refrigerated transport makes a relatively significant contribution to greenhouse gases, but manufacturers are already making strides to produce options that address that problem.                                 How to decarbonise road transport is one of the biggest challenges in the sector and for governments internationally if they are to meet their climate change targets in the coming years and up to 2050. While much of the focus has been on finding alternatives to traditional diesel power such as electric and hydrogen for commercial vehicles, the importance of decarbonising auxiliary components such as refrigeration units should not be overlooked.

Recent research published by Zemo Partnership found that diesel-powered auxiliary transport refrigeration units (TRUs) used in the cold chain distribution system make a significant contribution to transport-related greenhouse gas emissions and have an even greater impact on polluting emissions of NOx and particles, which have directly damaging health effects. The study, funded by Transport Scotland, tested two representative, conventional diesel auxiliary TRUs for a range of operating scenarios, designed to mirror typical usage patterns. Throughout the tests, measurements were taken of the auxiliary TRU’s fuel consumption, internal and external temperatures as well as emissions of NOx and particulates.

The study also used official data to estimate the number of diesel-powered auxiliary TRU systems in Scotland and found that 4-6% of the 37,000 HGVs registered in the country may be fitted with a separate auxiliary TRU unit or frequently pull trailers so fitted. Estimates derived in the study found that these systems contribute an additional 1-2% greenhouse gas emissions to current official figures reported from all the 37,000 HGV propulsion engines operating in Scotland. Moreover, the study showed that the units contribute an additional 5-14% NOx and 9-26% particle mass emissions to the respective official emissions baselines for HGVs working in Scotland.

“This research has… shone a light on the likely scale of the environmental impacts of diesel auxiliary TRUs,” says Brian Robinson, Zemo’s study author. “We now need to work at pace with the cold-chain industry and government to encourage the uptake of cleaner, greener solutions.” Changing landscape Scott Dargan, managing director, UK and Northern Europe, Carrier Transicold, adds that with the expansion of clean air zones and similar in many towns and cities in the UK, increasing noise restrictions and the impending removal of the red diesel rebate: “it is fair to say the dynamics are starting to change for temperature-controlled fleet operators.”

He adds that this has already resulted in significant advances in trailer technology. For instance, Carrier Transicold has developed the Vector eCool. “The Vector eCool is a fully autonomous, all-electric engineless refrigerated trailer system, which combines a myriad of new technology to deliver a genuine zero tailpipe-emission solution,” explains Dargan. “We’ve designed the Vector eCool to help customers improve fleet sustainability and better futureproof their operations – it is already on the road with customers in the UK and 10 countries throughout Europe.”

Dargan adds that the Vector eCool is suitable for operation with the engineless versions of the Carrier Transicold Vector HE 19 MT and Vector 1550 E and combines Carrier’s established E-Drive all-electric technology with a new energy recovery and storage system. “This converts kinetic energy generated by the trailer’s axle and brakes into electricity, which is then stored in a battery pack to power the refrigeration unit. This loop creates a fully autonomous system that produces no direct CO2 or particulate emissions,” he explains. “The Vector eCool’s E-Drive technology means there is no need for the mechanical belts and drive train seen in competitor systems, these traditional systems suffer a loss of up to 40% kilowatts cooling power when converting electrical energy into their required mechanical drive – the E-Drive ensures the eCool has consistent, efficient cooling power and pull-down speeds, whether operating on battery power or when plugged into the mains grid.”

Dargan adds that the eCool is PIEK-compliant, operating significantly below the PIEK 60 dB(A) standard. But it doesn’t only reduce the environmental cost of operation, it also has operating costs lower than those of a standard diesel refrigeration system, Dargan adds, although the total cost of ownership depends on an individual customer’s specific application. The system is also built to last, with the generator designed to have a similar operational life to that of a traditional transport refrigeration unit (>25,000 hours), while the cell technology in the battery pack can endure 4,000 recharging cycles, which should equate to 10 years plus on the road for a typical fleet, Dargan adds.

This is part of a range of alternative technologies that can be used to power existing trailer systems, Dargan adds. “Carrier Transicold’s ECO-DRIVE modules, for example, allow operators to run multi-brand rigid and trailer fridges on electric power using the truck or tractor unit’s own motive power source, be that diesel, gas, electric or even hybrid.” But Dargan points out that there is no demise of diesel imminent, so the company continues to develop and improve its range of standard temperature-controlled units. “Every engine on a Carrier system in the EU being notably cleaner than the Stage V Non-Road Mobile Machinery standard,” he adds. But while the demise of diesel isn’t imminent, there are electric alternatives on the market.

For instance, Schmitz Cargobull has developed an electric solution; the S.KOe COOL SMART reefer, which is equipped with an electric axle and an electric refrigeration unit, S.CUe with integrated power electronics and battery system. “Our first full-electric S.KOe semi-trailers are currently on trial with customers and we received very positive feedback,” says Alan Hunt, UK managing director – sales and marketing at Schmitz Cargobull. “As with all Schmitz Cargobull reefers, they are fitted with Schmitz Cargobull’s telematics system, TrailerConnect, which enables key features such as the battery charging level, remaining range and remaining charging time to be monitored via the telematics portal. “The trailer structure itself also contributes to reducing energy consumption.

Due to the optimal insulation effect of the vapour diffusion-tight FERROPLAST panels, a K-value of 0.33 W/m2K is achieved which can reduce energy consumption by up to 15%.”

Battery capacity Another development on the electric S.CUe cooling unit is that it has its own self-sufficient energy system, Hunt adds. “Batteries are installed in the place of the diesel tank between the landing gear,” he says. “Due to its modular design principle, it is possible to scale the battery capacities at the start of series production. With the smallest battery design (34kWh), electrical operation of up to 4.5 hours can be guaranteed, depending on use and requirements.

Recharging from the mains is done via the standard CEE three-phase connection and takes about two hours for the 34kWh battery variant for a full battery charge. “If the vehicle is also equipped with the electrified Schmitz Cargobull trailer axle, energy is recuperated during braking. This means that the battery is already recharged during the journey, so recharging the battery via the power grid at the distribution centre is either unnecessary or can at least be minimised.

“An intelligent strategy ensures that the battery’s state of charge is kept as high as possible to provide as much safety as possible for standstill situations, such as traffic jams. The power class of the electrified axle is precisely matched to the needs of the refrigeration machine.” This solution is aimed at companies that provide urban distribution services or primarily serve routes between different distribution centres. “The entire system is specifically tailored to these applications,” Hunt adds.

“In many large cities, especially in the Netherlands, distribution traffic will be characterised by ‘zero emission zones’ in the inner cities as of 2025. With this product, Schmitz Cargobull offers a solution that ensures that supermarkets in city centres can still be supplied with fresh and frozen produce due to the electrically powered cooling unit in combination with an emission-free truck unit.” Developing trends

Hunt adds that many of its customers are now looking for greater flexibility in their transport fleets. “The increased use of multi-temp vehicles with movable partitions wall for the transport of goods in different temperature zones is one way to achieve this,” he says. “Therefore, the demand for multi-temp vehicles is generally increasing, albeit at a restrained level. “Another trend can be seen in the securing of goods. More and more carriers are turning to trailer telematics systems.

With TrailerConnect, the customer receives absolute transparency and overview of their vehicle fleet. With the data provided, the fleet manager can optimise internal processes and reduce the total cost of ownership. “Since 2018, Schmitz Cargobull has equipped all refrigerated semi-trailers with a digital temperature recorder, the necessary sensor technology and therefore TrailerConnect as standard.

All services are coordinated with vehicle options and can be monitored and operated via the telematics portal.” Allied to this, Schmitz Cargobull’s S.KO COOL SMART has been fitted with a new air distribution system that enables the load to be refrigerated more evenly and more efficiently. “Additional sensors used in conjunction with our TrailerConnect telematics system document and monitor the homogeneous air distribution for even greater efficiency and transport quality,” adds Hunt. “We have also introduced a new electronically controlled door lock to improve security with our box trailers, which can be controlled by geofencing. “The security standards of our vehicles have also been improved in accordance with the new TAPA certification guidelines.”

Hunt adds that Schmitz Cargobull plans to push further with the networking and digitalisation of vehicles via TrailerConnect to make the scheduling and control of networked logistics chains easier.

But in the long-term, the focus for Schmitz Cargobull, and all refrigerated trailer manufacturers, is on 2039, the date for the end of production of diesel engines.

“We will only reconcile the challenge of increasing transport volumes with climate protection by working together,” Hunt says. “We see the 2039 target as a very important and ambitious goal and country-specific measures as well as an overarching legislation in Europe can contribute to achieving this goal.”