Whether it’s frozen pizza, vegeta­bles, or the finest salmon, the Advancer trailer cooling system from Thermo King ensures that all food is fresh and deli­cious when it arrives at the super­market. Driven by its own engine, it always keeps the goods in the trucks at the right temper­a­ture. It offers the fastest cooling system currently avail­able and oper­ates almost a third more effi­ciently than the industry average. “When it comes to energy consump­tion, nothing else on the market can compare to it,” says Wayne Donnellan, senior engi­neer for refrig­er­a­tion and air flow systems at Thermo King, with pride. “We have set new stan­dards here.”

There is a reason for that: because the air flow is gener­ated inde­pen­dently of the combus­tion engine, the customer can adjust the airflow of the evap­o­rator to suit their exact load and needs. This protects the goods and reduces costs. The Thermo King’s Advancer Controller auto­mat­i­cally adjusts the condenser fan speed depending on the cooling capacity and there­fore maxi­mizes fuel economy. For example, if the refrig­er­a­tion unit is not oper­ating at full load it auto­mat­i­cally reduces condenser fan speed. The Advancer uses up to 30 percent less fuel than its prede­cessor.

“When it comes to energy consump­tion, nothing else on the market can compare to it. We have set new stan­dards here.“

Wayne Donnellan, senior engi­neer for refrig­er­a­tion and air flow systems at Thermo King 

This is made possible by step­lessly adjustable RadiCal DC fans from ebm-papst, which precisely cool the contents in the cargo area. Two fans are located in the evap­o­rator and blow cool air into the trailer, two are located in the condenser and dissi­pate the heat produced by the cooling liquid to the outside. It sounds simple, but is in fact the result of many years of inten­sive project work. After all, when Thermo King contacted its long­standing partner, ebm-papst, five years ago with an inquiry, they had quite a different solu­tion in mind.

The trailer cooling system Advancer uses up to 30 percent less fuel than its prede­cessor. There is a reason for that: because the air flow is gener­ated inde­pen­dently of the combus­tion engine, the customer can adjust the airflow of the evap­o­rator to suit their exact load and needs. (Photo | Thermo King)

Solu­tion with DC instead of AC fans

Martin Münz, Head of Trans­porta­tion at ebm-papst, was a sub-project manager in the tech­nology depart­ment. He explains: “Thermo King envis­aged a simple cooling system oper­ated by high-voltage AC fans. However, we saw an oppor­tu­nity to imple­ment an inno­v­a­tive, future-oriented solu­tion with DC fans here. The fans are exposed to vibra­tions, rapid temper­a­ture changes and humidity on the road, meaning that lower volt­ages are better suited here. In addi­tion, DC fans are control­lable and espe­cially effi­cient.”

So, the team at ebm-papst devel­oped an alter­na­tive solu­tion using DC fans. They deliver a lot of power in the smallest space and save fuel thanks to reduced power consump­tion.

However, the engi­neers had to over­come a few hurdles during devel­op­ment. They had the right DC fans ready: 48-volt RadiCal DC fans were a good starting point. However, the desired solu­tion stip­u­lated an even lower power consump­tion. A motor that could do this and could also with­stand the road condi­tions hadn’t been invented yet.

“The effi­ciency of RadiCal DC fans impressed us. We were also pleased that the fans were very compact and light­weight.”

Wayne Donnellan, senior engi­neer for refrig­er­a­tion and air flow systems at Thermo King 

Four RadiCal DC fans from ebm-papst are located in the Advancer and cool the contents in the cargo area precisely. (Photo | Thermo King)

So the devel­opers got to work. The next chal­lenge that awaited them was a lack of space in the cooling unit. To adapt the fans to the tight space, they had to design a smaller impeller for the fan that would do its job without losing effi­ciency or power. Of course, the new combi­na­tion of motor and impeller also put other demands on the elec­tronics that control every­thing. So the team adapted them for the new job. ebm-papst presented the proto­type person­ally at Thermo King’s produc­tion plant in Galway in Ireland.

Wayne Donnellan from Thermo King explains: “The effi­ciency of RadiCal DC fans impressed us. We were also pleased that the fans were very compact and light­weight. This made handling them in the produc­tion process easier. The noise level was another impor­tant factor for us, as the newly devel­oped trailer cooling system needed to be better than its prede­cessor. The noise level of the RadiCal fans in the stan­dard product is already very low. With a Flow­Grid air inlet grille, we can reduce it even further.”

Close part­ner­ship for devel­op­ment

With regard to the proto­type, Thermo King still had some concerns that a few compo­nents might not be robust enough. There­fore, the elec­trical team at ebm-papst inte­grated protec­tive circuits into the elec­tronics, longer-lasting connector systems with gold-plated coat­ings and connector greases to make the fans even more durable and reli­able. After all, reli­a­bility is the top priority for Thermo King.

It took around three years to get to the final product. Wayne sums it up: “It was a devel­op­ment based on part­ner­ship. Whether it was the motors, the voltage, or the arrange­ment of the fans, we discussed every­thing openly with ebm-papst. They under­stood our require­ments and knew how to get the best out of their fans. Together, we were able to set new stan­dards for trailer cooling.”