Improvement of measurement efficiency at the engine test bench

Abstract

The improvement of measurement efficiency in industry is getting more and more important. Faster measurement procedures lead to more experiments in less time and so reduce the costs. This master thesis is focusing on the improvement of the conditioning unit on one of the test bench equipped with a small turbocharged diesel engine. In order to test engine according to manufacturer specifications, the air going in the cylinder has to be at a certain temperature depending on the load and the speed of the engine. The intercooler, (exchanger air/air), being not present on a test bench, the intake air down-stream the turbocharger is cooled down by an air-water heat exchanger. This water is either warmed up by a heater or cooled down by a water-water heat exchanger. The temperature of the water in the cooling/heating system is controlled in order to get the desired intake air temperature. The cooling power is controlled by opening and closing a valve in a cooling circuit and the heating power is depending of the amount electricity consumed by the heater. Both of the cooling and heating units are controlled by one PI governor in a global control strategy. The cold hydraulic circuit has to be modified in order get a more precise flow in the water-water exchanger to be able to control the intake air temperature. The cooling power is the crucial part having more than 20 kW of cooling power regarding the 6 kW of heating power. Once this step achieved, experiments will be done in order to modify and optimize the control strategy to get the best performances of the system. Once this has been optimized, this control strategy will be adapted to other test benches with different engine size in order to get better and faster measurements.