Pipes are essential components in engines and therefore models of them are important. For example, the aftertreatment system for modern heavy-duty diesel engines consists of multiple components that are connected using pipes. The temperature in each of these components are important when determining the efficiency of the aftertreatment system and therefore models that accurately describe the temperature in the pipes between the components are important. Here, a dynamic pipe model that combines the adiabatic model of a control volume and that of a stationary one-dimensional flow with heat transfer in a pipe is developed and validated. The resulting model is a quasi-dimensional lumped parameter mean value model containing states for the temperature and pressure of the gas inside the pipe and the temperature of the pipe wall. The model uses the states and convective heat transfer models to calculate pressure at the inlet and outlet as well as temperature at the outlet, in a way that is physically correct under certain conditions. To validate the physical behavior of the model a detailed one-dimensional model is used, and to validate the practical applicability and accuracy of the model data from a passenger car gasoline engine is used to parameterize and validate the model.

Exhaust aftertreatment systems are essential components in modern powertrains, needed to reach the low legislated levels of NOx and soot emissions. A well designed diesel engine exhaust aftertreatment system can have NOx conversion rates above 95%. However, to achieve high conversion the aftertreatment system must be warm. Because of this, large parts of the total NOx emissions come from cold starts where the engine has been turned off long enough for the aftertreatment system to cool down and loose its capacity to reduce NOx. It is therefore important to understand how the aftertreatment cools down when the engine in turned off.Experimental data for a catalyst cool-down process is presented and analyzed. The analysis shows that it is important to capture the spatial distribution of temperatures both in axial and radial directions. The data and analysis are used to design a catalyst thermal model that can be used for model based catalyst temperature monitoring and control.

Hybridization is a promising and obvious way of reducing fuel consumption in automotive applications, however, its ability to reduce emissions in long haulage trucks is not so obvious. The complexity of the powertrain is also increased which makes well designed control systems needed to fully utilize the potential benefits of the hybridization. In this paper, a control strategy that takes advantage of the complex structure of the powertrain in a hybrid electric long haulage truck is developed and evaluated. The control system is based on equivalent consumption minimization strategy where an equivalence factor is used to compare fuel and battery power so that an optimal distribution of power between the components in the powertrain can be calculated. The proposed control system is evaluated in a driving scenario using a model of a complete hybrid electric truck, including an aftertreatment system, and the results are compared with a conventional, non-hybrid, vehicle. The hybridization leads to 31 % lower NOx emissions, primarily due to better thermal conditions in the exhaust system during braking, and at the same time, the fuel consumption was reduced by 3.8 % compared to the non-hybrid vehicle. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

Cold start emissions are the most significant contributor to the accumulated emissions of a vehicle and poses a critical design limit for the design of clean and efficient vehicles. The core reasons for the emissions are the initial low temperature and the thermal inertia of the exhaust aftertreatment systems. Moreover, it also costs fuel to perform the heating of the catalyst. It is therefore of high interest to develop efficient control schemes that can reduce the time to light off. To facilitate this a model structure and a method, based on the explicit solution to the catalyst differential equations are developed, that can be used to analyze both time and fuel optimal heating control strategies. The method is developed to be applicable to both gasoline and diesel aftertreatment systems. A case study is performed on a Diesel engine and the results show that the solutions exhibit a structured and simple two-phase pattern. There is a first heating phase, where the catalyst is fed with a high temperature gas, building up a high inlet temperature. Then in a second phase the flow is kept high and the temperature is pushed through the catalyst. The strategy is easy to understand and realize in a real time control system. (C) 2019, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

Green zones are challenging problems for the thermal management systems of hybrid vehicles. This is because within the green zone the engine is turned off, and the only way to keep the aftertreatment system warm is lost. This means that there is a risk of leaving the green zone with a cold and ineffective aftertreatment system, resulting in high emissions.A thermal management strategy that heats the aftertreatment system prior to turning off the engine, in an optimal way, to reduce the NOx emissions when the engine is restarted, is developed. The strategy is also used to evaluate under what conditions pre-heating is a suitable strategy, by evaluating the performance in simulations using a model of a heavy-duty diesel powertrain and scenario designed for this purpose.The results show that, for the studied vehicle, pre-heating of the aftertreatment system is an effective strategy to reduce NOx for engine-off events shorter than two hours, and is most effective for engine off events of around 1.5 hours. The results also show that for engine-off events longer than two hours, pre-heating quickly becomes an inefficient strategy. At this point, ammonia storage when the engine is turned off is more important, and pre-heating can even make the results worse, since an increased SCR temperature results in lower ammonia storage before turning off the engine, which is detrimental for NOx conversion during the restart.