In this paper an experimental study of exhaust gas parameters of a modern diesel engine is presented. The engine under study is developed for passenger car. It was used a flexible engine management system based on National Instruments real-time controller and LabVIEW code. However, basic settings of the engine calibration values were used over the test. The engine was tested at seventeen operating points which correspond to real operating mode in NEDC of the vehicle. In order to define the engine speed and load a vehicle driving model was used. Finally, exhaust mass flow and temperature were studied as well as exhaust enthalpy was estimated. The results revealed that waste heat recovery system can be applied in order to reduce fuel consumption in NEDC.
Author: Punov P.
COMPARATIVE ANALYSIS OF RANKINE CYCLE AND ORGANIC RANKINE CYCLE FOR WASTE HEAT RECOVERY IN INTERNAL COMBUSTION ENGINE
This paper presents numerical analysis of waste heat recovery from engine exhaust gases by means of Rankine cycle and Organic Rankine cycle. Both technologies are widely studied in combustion engines but there are still not solid statements which should be chosen.
The heat source in this study is the exhaust system of a modern diesel engine, developed for passenger car. Firstly, the engine was experimentally studied at stationary operating mode. Thus, exhaust gas parameters such as: mass flow rate, temperature and enthalpy were obtained at seventeen operating points which correspond to real operating mode of vehicle in NEDC. A simulation model of waste heat recovery system was developed. Based on that model, a numerical code was created in Python as CoolProp open-source platform was used to determine working fluid parameters. Lastly, Rankine cycle and Organic Rankine Cycle output power and efficiency were studied. The results revealed that Organic Rankine cycle using R245fa as working fluid provides better efficiency than steam Rankine cycle. Maximum recovered power was estimated to be 1.69kW while for the steam Rankine cycle it was 1.43kW.
The article presents a numerical study of pre-injection strategy in order to reduce the rate of heat release and pressure rise in a modern direct injection diesel engine, developed for passenger car. A model of the engine was built in advanced simulation code AVL BOOST. In order to determine the injection rate a supplementary model of the solenoid injector was built in AVL HYDSIM. A study of rate of heat release and pressure rise into combustion chamber was conducted at single operating point. The engine effective power was taken into consideration as well. The results revealed that pre-injection strategy is a promising approach for reducing the rate of heat released and the engine noise at low speed and load. However, a precise control of pre-injected mass and injection timing has to be realised by engine control system.
The article presents a modern approach for studying the combustion process in the DI Diesel engines developed for passenger car. The mixing controlled combustion model has been chosen for estimation the rate of heat released in the combustion chamber as well as the Arrhenius equation was used for ignition delay determination. The injection rate was calculated by means of constant injection pressure as well. Zero dimensional thermodynamic models have been used for estimation the in-cylinder parameters. All of the models were implemented as a computational code in Matlab. Finally, in-cylinder parameters variation such as pressure, temperature, rate of heat released etc., were studied at two engine operating points.