Model development and experimental validation of an exhaust brake supported dual loop exhaust gas recirculation on a medium duty Diesel engine

Abstract

Due to the new European emission norms internal combustion engines have to comply stricter rules. The new norms contain new requirements that were not included in previous regulations for example the decreased temperature of the cold start or the real driving emission part. The emission cycles for passenger vehicles are completely news, the stricter emission norms for commercial vehicles will follow them within a few years. Despite the increasing spread of alternative transmission systems in road transport Diesel engines are going to be remain in commercial vehicles in the next decades due to their good torque and fuel consumption performance. The emission of Diesel engines can be kept low by several way: by the modification of combustion processes, or by exhaust gas after treatment. To comply future regulations both of them seems to be necessary. By exhaust gas recirculation systems alternative Diesel combustion processes can be realized which can provide lower nitrogen-oxide emission and in several operation points also lower fuel consumption. Exhaust gas recirculation systems also can support the thermal management of a Diesel engine. To utilize the advantages of the recirculated exhaust gases a complex system is necessary to get a freedom in control possibilities: duel loop exhaust gas recirculated systems supplemented with supporter valves on the intake or on the exhaust side. In this paper a pressure and mass flow rate based control oriented engine model will be presented which contains high and low pressure exhaust gas recirculation systems and both of them are supported by exhaust brakes. The model considers four balance volumes and it has five state variables. The model is validated by an engine dyno measurements on a medium duty Diesel engine.

Verification and Comparison of Nine Exhaust Gas Recirculation Mass Flow Rate Estimation Methods

“…Engine models can be based on several physical properties in the air path system. One typical modeling type is based on the pressures and mass flow rates [2,3,15]. In these models, the EGR mass flow rate can be estimated by the orifice equation between the exhaust and the intake side [2].…”

“…In most of the articles, there are two types of engine mass flow rate estimations. The first one considers the cylinders' air consumption with the speed, the displacement, the intake air density and the volumetric efficiency [2,3]. The other one determines the engine mass flow rate by the oxygen fraction change between the intake and the exhaust side [23,25].…”

“…For the measurements, an engine dyno was used, equipped with a medium duty Diesel engine. This engine was included in several articles [2,3,5,6,23,26,27]. The operation of the engine was modelled in several ways, for example in Reference [26] a detailed engine model was published, where the burn rates, the friction loads and also the pressures and the temperatures in the air path system were validated.…”

“…The volumetric efficiency usually is a function of engine speed. In commercial vehicles, the engine speed range is smaller, for example, the volumetric efficiency can be modeled as a constant [3].…”

“…Due to the periodic operation, several parameters change effectively in the engine speed function-for example, the volumetric efficiency can have a significant change. A smaller speed range achieves that several parameters can be simplified to constants [2,3]. Thus, commercial vehicles' engines' modeling needs a different approach and has new research opportunities in model simplification [4].…”