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This paper describes a pressure and flow based control method of diesel engine air-path systems equipped with dual-loop exhaust gas recirculation (EGR) and variable geometry turbine (VGT). For the control of dual-loop EGR systems, fraction states are usually controlled, but how to select the control outputs is still controversial. In this paper, considering availability and reliability of sensors, pressure and mass flow states are selected as control targets instead of fraction states. A robust nonlinear control method, input-output linearization is applied for the states of intake manifold pressure, exhaust manifold pressure, and fresh air mass flow rate in order to satisfy the target emissions. The control performance is verified by simulation based on the valid model of a heavy-duty 6000cc engine air-path.

SUMMARYMagnetocaloric cooling is an alternative, high-efficiency cooling technology. In this paper, we present the design and fabrication of a micromachined magnetocaloric cooler and demonstrate its ability to work in a small magnetic field ð51:2 TÞ with a cooling test. The cooler was built by fabricating Si microfluidic channels, and it was integrated with a Gd 5 ðSi 2 Ge 2 Þ magnetocaloric refrigeration element. The magnetic properties of the Gd 5 ðSi 2 Ge 2 Þ material were characterized to calculate the magnetic entropy change at different ambient temperatures. Three different methods to integrate the channel layer and the magnetocaloric element were evaluated to test sealing and cooling performance. The cooling tests were performed by providing a magnetic field using an electromagnet. A test jig was constructed between the poles of an electromagnet to maintain a steady temperature during the test. Cooling tests were performed on the magnetocaloric element at ambient temperatures ranging from 258 to 280 K using a magnetic field of 1.2 T. Experimental results showed a maximum temperature change of 7 K on the magnetocaloric element alone at an ambient temperature of 258 K. Cooling tests of the fully integrated coolers were also performed. A solution of anti-freeze fluid (propylene glycol) and water was used as the coolant. The temperature of the working fluid decreased by 4.6 and 9 K for the glass and Si intermediate layers, respectively, confirming that the thermal conductivity of the materials is also an important factor in cooler performance.

This paper describes simplified burnt gas fraction estimation method for turbocharged diesel engine with dual loop exhaust gas recirculation (EGR) system. According to the strengthening emission gas regulation in diesel engine, burnt gas fraction has become principal factor for diesel engine air path system. Previous burnt gas fraction estimation method was valid only for a few operating point because of many assumptions used to prove the observability. Or it limits the condition which is not appropriate for practical use. By introducing a simplified burnt gas fraction dynamics, observability can be proved only with a single assumption. Asymptotic stability of the burnt gas fraction observer was proved by lyapunov analysis. The observer was validated on a 6L heavy duty diesel engine GT-POWER model with various engine operating points.