David J. Timoney

The development of a semi-empirical model for rapid NOx concentration evaluation using measured in-cylinder pressure in diesel engines:

Continued legislative pressure to reduce NO x emissions from diesel engine combustion systems generates a desire for cycle-by-cycle emissions data, with a view to their use in a feedback control strategy, perhaps in conjunction with an exhaust catalytic reactor. While NOx sensors that provide fast, robust, reliable, and continuous measurements in a diesel exhaust at a reasonable price are currently the subject of much development, the present work focuses on an indirect approach. This has led to the development of a semi-empirical model that can be used to estimate NO x emissions, based on more easily measured input data, primarily in the form of instantaneous in-cylinder pressure as a function of crank angle. The model computations are based on fundamental thermodynamic principles, but key empirical constants have been derived with the aid of statistical techniques. The approach taken relied on the availability of an extensive bank of experimental data from three different designs of direct injection diesel engine, each utilizing common rail type fuel injection systems and, in some cases, with the use of multiple injections per cycle.

Some effects of air flow maldistribution on performance of a compact evaporator with R134a

Abstract An experimental facility has been constructed to enable the effects of air flow non-uniformity on the transfer performance of refrigerant evaporators to be investigated. This is based on an open-circuit wind tunnel, which is equipped with a single component traversing LDA system, capable of determining local mean velocities and turbulence levels. The refrigerant circuit uses R134a and has been designed to allow maximum flexibility in setting test conditions. Preliminary results are presented from tests on a single circuit finned-tube evaporator with 33 tubes, 300 mm long, arranged in an in-line matrix 4 rows deep, with 25 mm spacing. The height of the fin block was 225 mm, the fin spacing and tube external diameter were 4 mm and 9.5 mm respectively. Contrary to expectations, increases in heat transfer duty and overall heat transfer coefficients were recorded as air flow non-uniformities were artificially introduced, whilst a constant mean air velocity was maintained.

The Effect of a Three-Way Catalytic Converter on Particulate Matter from a Gasoline Direct-Injection Engine During Cold-Start

This work investigates the effect of a three-way catalytic converter and sampling dilution ratio on nano-scale exhaust particulate matter emissions from a gasoline direct-injection engine during cold-start and warm-up transients. Experimental results are presented from a four cylinder in-line, four stroke, wall-guided direct-injection, turbo-charged and inter-cooled 1.6 l gasoline engine. A fast-response particulate spectrometer for exhaust nano-particle measurement up to 1000 nm was utilised. It was observed that the three-way catalytic converter had a significant effect on particle number density, reducing the total particle number by up to 65 % over the duration of the cold-start test. The greatest change in particle number density occurred for particles less than 23 nm diameter, with reductions of up to 95 % being observed, whilst the number density for particles above 50 nm diameter exhibited a significant increase. The exhaust temperature plays a significant role on the influence of the catalytic converter on the nano-scale particulate matter. It is evident that the dilution ratio of the exhaust sample has a distinct effect on the particulate matter number and size distribution, influencing the engine-out PM more significantly than the tailpipe-out PM during cold-start engine operation. The catalytic converter also has a considerable effect on the estimated total particle mass.

Examination of Low-cost Systems for the Determination of Kinematic Driving Cycles and Engine Operating Conditions in Dublin, Ireland

With increased numbers of vehicles on Irish roads, there is now a need to be able to scientifically assess the quantity of pollutant material to which populations are exposed. Traditionally, emissions have been determined using kinematic (vehicle speed) data but recent studies have identified that other parameters are of interest. The work in this Paper focuses on the development and testing of a purpose-built software system to extract onboard diagnostic data from a vehicle in order to derive a driving cycle and to use other engine characteristic data to better inform local pollutant and energy consumption models for Dublin. Comparisons with GPS data shows the system to be cost effective (price and computing overhead) and reliable.

Problems with heat release analysis in D.I. diesels

Problemes poses par le calcul du degagement de chaleur dans les moteurs diesel a injection directe

Effect of operating condition on the particulate matter emission factor for a domestic biomass boiler

The effect of operating condition on the particulate matter emission factor for a domestic biomass boiler has been examined, with a view to improving emission inventories compiled under the Convention on Long-Range Transboundary Air Pollution (CLRTAP). It was found that the emission factor depended strongly on the boiler load, and that there were significant differences between the value used in current emission inventories and actual values found in a combustion installation from a typical domestic dwelling.

On the relative roles of fuel spray kinetic energy and engine speed in determining mixing rates in D.I. diesel engines

This paper describes an attempt to separate out and to quantify the relative importance of fuel injection characteristics and in-cylinder air motion as factors influencing the rate of fuel-air mixing and of combustion in high-speed Direct Injection (D.I.) diesel engines, where bulk swirling air motion is absent. Tests on a 121 mm bore x 139 mm stroke, 1.6 liter, single-cylinder engine at constant engine speed reveal substantially shorter fuel-air mixing times as the mean fuel injection kinetic energy (M.I.K.E.) is increased. Also, tests at constant injection kinetic energy but with varying engine speed (involving different fuel injection system builds at each speed) show that fuel-air mixing times are reduced at higher engine speeds. From these trends it is concluded that, while injection kinetic energy is the dominant factor in determining fuel-air mixing rates in D.I. diesels, small-scale turbulent air motions, the intensity and structure of which are related to engine speed, also exert an important influence on the mixing rate.

Context-Based Cyclist Intelligent Support: An Approach to e-Bike Control Based on Smartphone Sensors

Electrically assisted bicycles (e-bikes or pedelecs) have recently become popular as a means of personal transportation, particularly in cities. Pedelecs allow people to combine their muscular strength in varying proportions with the assistance of an electric engine. One of the challenges here is to determine the cyclist preferences, capabilities, and the context situation around the e-bike and, based on these, to make recommendations to the cyclist and also to control the degree of electrical assistance provided. The Smart Space concept is used here for context formation. The concept involves creation of a real-time model of the physical space that aids decision making about electrical engine utilization for the particular situation and generates a recommendation for the cyclist. An ontology-based publish/subscribe mechanism is used for information sharing in Smart Space.

Modelling Boiler Response to Co-Ordinate Reserve in Isolated Power Systems

Abstract This paper describes the details of a drum boiler model which is capable of predicting the dynamics in stored energy during a transient. Results show how changes in the stored energy of the boiler components, i.e. drum, riser, superheater, etc., contribute to the changing power output of the turbine. After validation it is intended to use this model and other models for once through boilers to co-ordinate reserve for small isolated power systems following a contingency.