Syed Wahiduzzaman

Experimental and analytical study of heat radiation in a diesel engine

An experimental study was conducted of the heat radiation in a single-cylinder direct injection 14 iota engine. The engine was operated at speeds ranging from 1000 to 2100 RPM and a variety of loads. The radiation was measured using a specially designed fiber optics probe operating on the two-color principle. The probe was located in the head at two different locations: in one location it faced the piston bowl and in the other it faced the piston crown. The data obtained from the probe was processed to deduce the apparent radiation temperature and soot volume concentration as a function of crank angle. The resultant profiles of radiation temperature and of the soot volume concentrations were compared with the predictions of a zonal heat radiation model imbedded in a detailed two-zone thermodynamic cycle code.

A diesel combustion bomb: proof of concept

A combustion bomb has been developed which allows simulation of diesel combustion without the need to heat the bomb to high temperatures. Simulation of the compression stroke is achieved by burning a lean precharge composed of acetylene, oxygen and nitrogen. By controlling the initial partial pressures of these constituents it is possible to burn them to a state with an oxygen concentration, temperature and pressure representative of conditions in a diesel engine at the start of fuel injection. Diesel fuel injected into these gases autoignites and burns in a manner typical of combustion in diesel engines. 22 references, 24 figures.

Heat Transfer Experiments in an Insulated Diesel

A set of heat flux data was obtained in a Cummins single cylinder NH-engine coated with zirconia plasma spray. Data were acquired at two locations on the head, at several speeds and several load levels, using a thin film Pt-Pt/Rh thermocouple plated onto the zirconia coating. The data showed that the peak heat flux was consistently reduced by insulation and by the increasing wall temperature. The results agree well with a previously developed flow-based heat transfer model. This indicates that the nature of the heat transfer process was unchanged by the increased wall temperature

Development of ECU Capable Grey-Box Models from Detailed Models—Application to a SCR Reactor

Selective catalytic reduction (SCR) of NOx with NH3 is a widely used after-treatment technology for reducing the NOx emissions from diesel engines. Mathematical models play an important role in analyzing and optimizing SCR reactors and also in controller design. Detailed mathematical models of SCR reactors consist of a number of coupled differential and algebraic equations, which can only be solved numerically. Due to the limited computational capability of engine control unit (ECU) and hardware-in-loop (HIL) systems, it is not practical to solve detailed model equations on these systems in real time, and hence, there is a need for reduced-order models. In this work, we provide a systematic procedure for deriving reduced-order models from detailed models of a SCR reactor. This systematic procedure consists of making reasonable assumptions, good input signal design, and system identification procedure. The reduced-order model consists of non-stiff system of equations which can be solved with an explicit solver, is two to three orders of magnitude faster than the detailed model, and has same level of accuracy as detailed model. The proposed model remains fundamental-based, with model parameters directly related to physical and chemical properties of the catalyst, and can be used on ECU and HIL systems to predict ammonia storage, NOx conversion efficiency, and ammonia slip during transient operating conditions. Moreover, it is shown that the model equations can be easily linearized around various operating points, thus allowing the development of advanced control strategies based on linear control theory. Although mainly demonstrated in the context of SCR reactors, the procedures can be applied to other monolith reactors as well.

A fuel injection transducer and controller

A fuel injection meter and controller has been developed which (1) measures the instantaneous injection rate and the total mass of fuel injected, and (2) controls the mass of fuel injected and injection pressure. The injection rate is computed from instantaneous measurements of the velocity of a pumping plunger and the pressure of fuel injection. A mathematical model of the meter and controller was developed to further the understanding of various design and operating parameters on the injection rate. Compressibility of the fuel is accounted for. Good agreement is realized between numerically computed injection pressure and rate histories with corresponding experimental results.

Efficient Solution of Washcoat Diffusion-Reaction Problem for Real-Time Simulations

As countries around the globe adapt more stringent emissions standards set by Real Driving Emissions (RDE) legislation, mathematical models are becoming ever more widely used as plant models for devising vehicle control strategies. It is important for the model to run on Hardware-in-Loop (HIL) and engine control unit (ECU) systems which have significantly less computational power and memory than modern personal computers. Washcoat diffusion limitations play a very important role in the efficient design of a catalytic converter. Numerical solution of aftertreatment models that include diffusion-reaction equations in the washcoat are computationally demanding. There are several simplified approaches proposed in the literature for the solution of diffusion-reaction equations in the washcoat to avoid the computational demand of the full numerical solution. In this paper, we use the recently proposed asymptotic solution and compare the results with that of the full numerical solution for the following aftertreatment reactor models with both single- and dual-layer washcoat configurations for the practical range of operating conditions; three-way catalyst (TWC), diesel oxidation catalyst (DOC), Selective Catalytic Reduction (SCR), and ammonia slip catalyst (ASC). These reactor models are constructed using published kinetic mechanisms and represent the global kinetics mechanisms (including non-linear reaction orders and inhibition functions) commonly used in the aftertreatment modeling community. We also discuss the importance of adaptive mesh, quasi-steady state assumption, and occurrence of concentration jumps in the simulation of aftertreatment reactors.

The effect of aspect ratio on heat loss from a swirling flow within a cylinder

Abstract Measurements have been made of the total rate of heat loss and the half radius swirl velocity of an unsteady, turbulent swirling flow within a cylinder for different aspect ratios. The instantaneous heat loss correlates with the half radius swirl velocity by a Nusselt-Reynolds number power law. The correlation is independent of aspect ratio if the filling of the cylinder results in a flow field which is axi-symmetric and shows no axial variation outside the boundary layers.