Analysis of the role of altitude on diesel engine performance and emissions using an atmosphere simulator

[EN] Forthcoming directives from European Commission will force homologation in altitude to approach standards to actual driving conditions in order to reduce the gap between regulated and real-life emissions. This work presents the use of a dedicated atmosphere simulator to analyse the impact of altitude on performance and emissions of a turbocharged diesel engine. The presented equipment provides engine intake and exhaust pressure to reproduce high-altitude conditions. The main advantages are related to cost savings with respect to round-robin testing campaigns ensuring controlled ambient conditions at the different altitudes. The paper shows the main features of the altitude simulator under steady-state and transient operation and the ability to control temperature at the same time that pressure according to International Standard Atmosphere (ISA) specifications. The experimental results highlight the need for specific testing facilities to perform calibration tasks as a key tool to comply with future emission standards in a cost-effective manner. In particular, regulated emissions measured at altitude are shown to clearly exceed that permitted at sea-level emphasizing the need to explore new dedicated engine control strategies for pollutant abatement under altitude operation.Bermúdez, V.; Serrano, J.; Piqueras, P.; Gómez-Gil, J.; Bender, S. (2017). Analysis of the role of altitude on diesel engine performance and emissions using an atmosphere simulator. International Journal of Engine Research. 18(1-2):105-117. doi:10.1177/1468087416679569S105117181-

Investigation of the effect of coal particle sizes on the interfacial and rheological properties of coal-water slurry fuels: Final report, July 1, 1994-June 30, 1996

The scope of the project is two fold: (1) examining particle size effect on interfacial properties of CWS fuels by measuring static and dynamic surface tension properties of specially prepared CWS samples containing different ranges of coal particle sizes, and (2) studying the effect of particle size on CWS atomization characteristics by measuring mean diameters of several different CWS sprays generated by sonic air blasting. The results show that both static and dynamic surface tensions decrease with increasing coal particle size and mean droplet diameter of CW-S sprays also decreases with increasing coal particle size. Based on the experimental evidence we conjecture that three different energies are competing in slurry atomization: (1) the internal capillary holding between particles and water, (2) the interfacial surface tensile energy at the slurry surface contacting air, and (3) the external air blast shear energy acting against the former two energies. The internal capillary holding force decreases with increasing particle size. This force is believed to play a major role in determining the effect of particle size on CWS atomization

Development and use of an apparatus to measure the dynamic surface properties of coal-water slurry fuels for applications to atomization characteristics

The Texas A M University (TAMU) has been awarded a DOE contract to study dynamic properties and atomization characteristics of coal-water slurry (CWS) fuels. Additives are essential for better mixing and stable suspension of coal powders and these additives change CWS properties. Dynamic properties will have major effects on CWS fuel atomization, which constitutes highly dynamic processes, and will determine the combustion as well as the pollutant formation behaviors. The dynamic surface tension of CWS fuels can be much higher than the corresponding static surface tension. Experimental study of correlating the atomization characteristics and dynamic properties of CWS fuels will be performed during the contract period. The research projects consists of five tasks. Task 1 selects appropriate additives and surfactants for CWS fuels by measuring the stabilizing characteristics and critical micelle concentrations (CMC). Task 2 implements the dynamic surface tensiometer operating based on the formation of maximum bubble pressure. Task 3 measures dynamic properties of CWS fuels as functions of bubble frequency while the fuel parameters are varied. The fuel parameters include coal loading, type of stabilizer and type of surfactant. Task 4 will devise a CWS fuel spray system and Task 5 will measure the spray droplet sizes using a laser diffraction technique

Fiscal Year 1996

Preliminary experiment has been made for cross injecting water sprays into a convective air stream to test the air-blast atomization system which has been constructed for CWS atomization in the future. A laser diffraction particle analyzing technique (the Malvern system) nonintrusively measured the drop size SMDs for various injection parameters including the convective air flow rate, flow rate of the injected liquid (distilled water), orifice diameter, and measurement locations along the two-dimensional spray plane. Buckingham-PI analysis finds the correlation of dimensionless parameters. A correlation of drop Sauter mean diameter (SMD) normalized to the orifice diameter is obtained from all the experimental data for the case of distilled water sprays

Investigation of the effect of coal particle sizes on the interfacial and rheological properties of coal-water slurry fuels. Quarterly report No. 3, January 1, 1995--March 31, 1995

Microscopic behavior of the bubble pressure has been investigated for selected aqueous solutions. The Kruss dynamic tensiometer has been modified so that the analog pressure readings of the instrument can be digitized through a computer interface for post data processing. Measurements of peak pressure, minimum pressure, surfactant diffusion time, and dead time are presented for DDBS-soft and 1840{minus}x aqueous solutions of surfactant concentrations of up to 1.0%. The implementation of the A-to-D data conversion also permits to examine the accuracy of the dynamic surface tension measurement which is based on the maximum bubble pressure principle

Investigation of the effect of coal particle sizes on the interfacial and rheological properties of coal-water slurry fuels. Quarterly report No. 3, January 1, 1996--March 31, 1996

A new sonic airblast atomization system has been designed and constructed to use in atomizing CWS fuels with two to three orders of magnitude higher viscosity values than water. Preliminary studies show that the new system successfully atomizes a glycerol/water solution that is one hundred times more viscous than pure water. This system, together with a constant displacement feed pump, will allow the study of CWS atomization under various surface tension properties, different coal loadings and particle sizes, and different surfactants. 4 figs., 1 tab

Investigation of the effect of coal particle sizes on the interfacial and rheological properties of coal-water slurry fuels. Quarterly report No. 2, October 1, 1995--December 31, 1995

Experiments have been performed to simulate the effects of high viscosity and surface tension of CWS fuel on its atomization. Aqueous solutions of glycerol simulated the high viscosity condition of CWS fuels and ethanol solutions allowed to separately investigate the effect of surface tension. A Fraunhofer diffraction particle sizing technique measured the spatial distribution of Sauter mean diameters (SMDs) for the cross injecting sprays which were previously described in the Quarterly Report No. 1. Experimentally determined parametric correlations reveals the dependence of the spray SMDs on the liquid viscosity, surface tension, the air flow rate, the liquid flow rate, the orifice nozzle diameter, and the measurement locations. This simulated correlation will provide important guidelines for the actual CWS spray experiment to be performed in the successive quarter

Investigation of the effect of coal particle sizes on the interfacial and rheological properties of coal-water slurry fuels. Quarterly report No. 4, April 1, 1995--June 30, 1995

Experiments were conducted to investigate the effect of particle size on coal-water slurry (CWS) surface tension properties. Two different coal powder samples of different size ranges were obtained through sieving of coal from the Upper Elkhorn Seam. The surfactant (anionic DDBS-soft, dodecylbenzene sulfonic acid) concentration varied from 0 to 1.0% in weight while the coal loading remained at 40% in weight for all the cases. A du Nouy ring tensiometer and a maximum bubble pressure tensiometer measured the static and dynamic surface tensions, respectively. The results show that both static and dynamic surface tensions tend to increase with decreasing coal particle sizes suspended in CWS fuels. Examination of the peak pressure, minimum pressure, surfactant diffusion time, and dead time were also made to correlate these microscopic pressure behavior with the macroscopic dynamic surface tension and to examine the accuracy of the experiment