Urea or AdBlue® injection into the exhaust system of diesel engines reduces nitrogen oxide emissions by up to 90 %. With a freezing point of -11.5 ºC and a precipitation process starting at +30 ºC, the liquid that has to be stored in a separate tank is very sensitive to temperature. To test its use under reproducible conditions and to gain insights relevant to series production, Weiss Umwelttechnik has now developed the world's first AdBlue® temperature control unit for fuel-filling tests.
AdBlue® as per ISO 22241-1/AUS 32 is an aqueous urea solution, consisting to 32.5 % of high-purity urea and to 67.5 % of demineralised water. When injected into the exhaust system of diesel engines, it leads to a selective catalytic reaction in which nitrogen oxides and ammonia are converted to water and nitrogen. This lowers the emission of nitrogen oxides considerably, making it particularly interesting for vehicle manufacturers.
As a long-time partner of the automotive industry, Weiss Umwelttechnik is one of the leading developers of test equipment for temperature tests. The mobile AdBlue® system is technically based on the well-proven and internationally deployed fuel temperature control system. It facilitates the rapid heating of AdBlue® to 10 - 45 °C without having to cool or heat the entire climate chamber or vehicle. This speeds up the tests and lowers test costs.
The robust, high-quality, corrosion-resistant system measures 1,960 x 1,800 x 1,100 mm (HxWxD). It allows for the refuelling and defuelling of the test vehicle, along with a circulation and tempering of AdBlue®. The installation is fully cased and mounted on a movable base frame. It is composed of a non-pressurised aerated 190-litre stainless steel tank with a connected pump and temperature control unit. This makes it possible to circulate AdBlue® via a bypass during the heating or cooling process. Once the desired temperature has been reached, the pump is switched to output and the tank can be filled.
Optionally, a refuelling volume pre-selection and a volume flow control can be realised with a high level of accuracy. The flow rate is between 15 and 45 litres per minute depending on the tubing and the nozzle. The system is equipped with a level indicator and a level sensor mounted in the tank for level monitoring purposes. Heating takes place with an electric flow-type heater, and cooling is achieved with an air-cooled refrigeration unit with a direct evaporator. Depending on the design, the desired flow rate is set manually or digitally. The system is controlled by a Simpac process controller with a touch panel developed by Weiss. It is particularly easy to connect with the automation system of the SHED chamber, allowing the entire test unit to be operated with a computer.
All components in contact with AdBlue® – pump, control valve, heating, nozzle, tubing and all sensors – are made of urea-resistant materials. The plant, equipped with various safety devices, has a special sensor that measures the concentration of ammonia outside the system, and triggers an alarm or system shutdown when limits are exceeded. The plant is planned as a basic version and can be customised and extended; for example, by extending the temperature range or by increasing the flow rate up to 60 l/min. With its highly accessible maintenance area, the system ensures the shortest service times.