Researchers at the Karlsruhe Institute of Technology have developed a unique commercial vehicle test rig to analyse the effectiveness of air conditioning systems in a variety of climates.
With truck drivers behind the wheel for anything up to 10 hours a day, providing a comfortable climate in the driver’s cab is of utmost importance to driver performance and safety.
However, the use of air conditioning systems can have a penalty on fuel consumption. Michael Frey and his team at the Institute of Vehicle System Technology (FAST) are testing under realistic conditions to develop more efficient solutions.
The FAST team deals with a wide range of variables. “Air conditioning efficiency depends on the driving mode of the vehicle and the surrounding climate conditions, such as solar irradiation, air temperature and air humidity,” says Frey.
Then there are the dimensions of the cab and the type of commercial vehicle being operated to consider. Couriers will open and close the doors on their vans regularly, whereas engines on long-distance trucks run for longer periods of time.
The test rig, therefore, is based on a four-wheel roller dynamometer: the truck stands on four separately driven rollers that simulate the forces acting on the truck in different driving situations.
FAST’s test rig uses air ducts to simulate wind, a series of six spotlights to mimic sunlight falling through cabin windows, while an infrared light reproduces the effects of the sun heating up the cabin roof.
“Contrary to a road test, the driver’s cab can be exposed to any weather-dependent and geographical conditions,” explains team member Michael Fritz.
FAST’s new test rig could change the landscape of this kind of experimentation. A traditional wind tunnel test can simulate the same conditions, but with the caveat of being designed for testing a whole vehicle, which requires up to 10 times more spotlights and air blowers.
FAST’s new test rig aims to reduce this cost, concentrating solely on the driver’s cab where the benefits of an effective air conditioning system are felt the most.
