Engine Exhaust Gas Temperature Research Articles

Low-Load Dual-Fuel Compression Ignition (CI) Engine Operation with an On-Board Reformer and a Diesel Oxidation Catalyst: Effects on Engine Performance and Emissions

In the exhaust gas fuel-reforming method, part of the engine exhaust gas reacts with small amounts of engine fuel in a mini-reactor fitted in the exhaust gas recirculation (EGR) loop to produce gaseous fuel named reformed EGR (REGR). In this study, hot REGR (gas containing H2, CO, CH4, and CO2) was fed back to the engine inlet, so that the diesel engine in effect operated in dual fuel with inlet heating and EGR (CO2 existence). The effects of the diesel engine dual fueling with different REGR percentages on the engine performance and emissions have been examined. The study focused at low-load engine operation, where the conditions are not favorable for efficient gaseous fuel oxidation and engine combustion stability. The addition of the premixed gaseous fuel resulted in a remarkable reduction of both NOx and smoke engine emissions. Carbon monoxide and hydrogen oxidation efficiency can be improved by careful selection of REGR addition (e.g., premixed air/fuel ratio, inlet temperature, and reduced in-cylinder O2 concentration) and in-cylinder diesel injection timing. The use of Pt supported on Al2O3 as an oxidation catalyst at the engine exhaust can eliminate both CO and H2 at temperatures lower than the engine exhaust gas temperature at part loads. Preferably, in an actual engine reformer system, the uncombusted CO and H2 will be used to enhance the aftertreatment system (i.e., diesel particulate filter, NOx traps, and hydrocarbon-selective catalytic reduction of NOx) performance.

Improving the low temperature NO x reduction activity over a Ag-Al 2O 3 catalyst

Silver-alumina (Ag-Al 2O 3) catalysts are susceptible to deactivation by nitrates and/or carbon species deposition, especially at low temperatures. A prototype catalyst (PC) was used to cleanse the diesel exhaust by reducing potential catalyst poisoning species and possibly generate more reactive species which would aid the SCR catalyst NO x reduction activity. The PC was located upstream the SCR catalyst and its influence on the passive SCR catalyst NO x activity was dependant on the engine exhaust gas temperature, hydrogen concentration (50–5000 ppm) and space velocity (SV). Nevertheless, the PC was found to have significant influence on the reduction of HCs, CO and particulate matter (PM) across all engine operating conditions. During HC-SCR at low temperatures, there was sufficient HC species available for the reduction of NO x (peaking at ∼80%) over the Ag-Al 2O 3 catalyst. However, there was a decrease in NO x conversion at higher engine exhaust gas temperatures, attributed to the reduced HC concentrations relative to the NO x produced by the engine and also the HC oxidation reaction being more predominant over the HC-NO x reduction reaction. At these particular conditions the active injection of HC species (engine fuel) was necessary for improved NO x reduction activity over the Ag-based SCR catalyst. HC speciation in the exhaust gas shows that the PC reduces small chain HCs but has small influence in reduction of toluene and >C7 hydrocarbons. Of the three investigated space velocities, the best NO x conversion was observed for the medium value of ∼20,000 h −1. The lower (15,000 h −1) and higher (25,000 h −1) space velocities yielded results that were similar to those without the use of the PC. Hence, a careful balance between exhaust gas temperature, SV and reactants is therefore necessary for the best NO x reduction activity.

Promoting hydrocarbon-SCR of NOx in diesel engine exhaust by hydrogen and fuel reforming

A hydrocarbon-selective catalytic reduction (HC-SCR) silver–alumina monolith catalyst has been prepared and tested for NOx emissions control in a diesel engine. The work is based on ongoing laboratory experiments, catalyst research, and process development. Hydrogen and actual reformate (i.e. H2 and hydrocarbon species produced in a partial and exhaust gas fuel reformer) significantly improved the passive control (i.e. no externally added hydrocarbons) NOx reduction activity over the SCR catalyst using the whole engine exhaust gas from a single-cylinder diesel engine. Optimisation of the reforming process is required for various engine conditions in order to maximise H2 production and minimise fuel penalty. When diesel fuel partial oxidation and exhaust gas reforming for SCR were implemented, the calculated fuel penalty was in the range of 5–10%, which is relatively high, as both reformers were not optimised yet. During HC-SCR of NOx over silver–alumina, the known promoting effect of H2 has been found to be sensitive to various factors, especially the engine exhaust gas temperature, H2 concentration, HC concentration, HC:NOx ratio, and space velocity. Under active control (i.e. hydrocarbon injection) SCR operation, powdered Ag–Al2O3 catalysts gave significantly higher initial NOx reduction, but the catalyst activity deteriorated rapidly with time due to poisoning species adsorption (e.g. HCs, nitrates, particulate matter (PM), etc.), whilst for the Ag–Al2O3-coated monolithic catalysts, NOx reduction activity was lower but remained constant for the duration of the tests. The improved physical (mass transfer, filtering of C-containing species) and chemical (reaction kinetics) processes during HC-SCR over powders compared to monoliths led to better initial catalyst activity, but it also accelerated catalyst deactivation which led to increased diffusion limitations.

Performance and exhaust emissions of a gasoline engine using artificial neural network

This study deals with artificial neural network (ANN) modelling of a gasoline engine to predict the brake specific fuel consumption, brake thermal efficiency, exhaust gas temperature and exhaust emissions of the engine. To acquire data for training and testing the proposed ANN, a four-cylinder, four-stroke test engine was fuelled with gasoline having various octane numbers (91, 93, 95 and 95.3), and operated at different engine speeds and torques. Using some of the experimental data for training, an ANN model based on standard back-propagation algorithm for the engine was developed. Then, the performance of the ANN predictions were measured by comparing the predictions with the experimental results which were not used in the training process. It was observed that the ANN model can predict the engine performance, exhaust emissions and exhaust gas temperature quite well with correlation coefficients in the range of 0.983–0.996, mean relative errors in the range of 1.41–6.66% and very low root mean square errors. This study shows that, as an alternative to classical modelling techniques, the ANN approach can be used to accurately predict the performance and emissions of internal combustion engines.

Engine and winter road test performances of used cooking oil originated biodiesel

Biodiesel is a renewable and environmentally friendly alternative fuel that can be used in Diesel engines with little or no modification. Low cost feedstocks, such as waste oils, used cooking oil and animal fats, are important for low cost biodiesel production. The objective of this study was to investigate the engine performance and the road performance of biodiesel fuel originated from used cooking oil in a Renault Mégane automobile and four stroke, four cylinder, F9Q732 code and 75 kW Renault Mégane Diesel engine in winter conditions for 7500 km road tests in urban and long distance traffic. The results were compared to those of No. 2 Diesel fuel. The results indicated that the torque and brake power output obtained during the used cooking oil originated biodiesel application were 3–5% less then those of No. 2 Diesel fuel. The engine exhaust gas temperature at each engine speed of biodiesel was less than that of No. 2 Diesel fuel. The injection pressures of both fuels were similar. Higher values of exhaust pressures were found for No. 2 Diesel fuel at each engine speed. As a result of the No. 2 Diesel fuel application, the engine injectors were normally carbonized. After the first period, as a result of winter conditions and insufficient combustion, carbonization of the injectors was observed with biodiesel usage. As a result of the second period, since the viscosity of the biodiesel was decreased, the injectors were observed to be cleaner. Also, no carbonization was observed on the surface of the cylinders and piston heads. The catalytic converter was plugged because of the viscosity in the first period. At the second period, no problem was observed with the catalytic converter.

Reversed flow converter for emission control after automotive engines

A concept of catalytic reversed flow converter (RFC) is discussed for three emerging areas of emission control after automotive engines. The first potential application concerns with oxidation of methane and CO emitted from dual fueled, natural gas/diesel engines (DDF). The behavior of RFC is studied under typical transient conditions of DDF engine exhaust using mathematical modeling and experiments with converter prototype. It was shown that the RFC with a single catalyst monolith can be well suited for this application. The second potential application is aimed at NO x emission control from diesel engines. An RFC comprising a catalyst bed flanked by two beds of inert material is discussed based on a lumped kinetics of NO x reduction over a noble metal lean-NO x catalyst. Contrary to a traditional converter, the RFC retains high efficiency of NO x reduction for long time after typical excursion of NO x concentration and temperature of engine exhaust gas. Finally, an idea of RFC combining catalyst and adsorbent is suggested for emission control during cold start of automotive engines.

Instantaneous exhaust-gas temperature and velocity for a diesel engine

An accurate knowledge of engine exhaust-gas temperatures and velocities is important for engine design and diagnostic efforts. This paper introduces a simple and reliable theoretical model for predicting the instantaneous exhaust-gas temperatures and velocities of a single-cylinder diesel engine. Comparisons of the calculated results with those obtained from experiment have shown good agreement. Based on this agreement, the influence of the engine operating conditions on the exhaust-gas temperatures and velocities can be studied and predicted easily with this model.

Safety Topics

A Boeing 757–200 took off from London Heathrow and commenced a climb to the south for Milan. Both the take‐off and climb were made using de‐rated engine power settings approriate to the aircraft all‐up weight and no abnormalities were noticed. At around 8700ft there was a bang immediately followed by indication of excessive No 1 engine Exhaust Gas Temperature (EGT). There was no engine fire warning and the engine was shut down and the aircraft returned to Heathrow without further incident.

Jet engine exhaust gas temperature measured

This paper is devoted to experimental study of capabilities and limitations of grindable thermocouples as applied to polymer materials sliding on metal. Chromel–alumel and chromel–copel grindable thermocouples have been developed and tested for wide ranges of contact pressure and sliding velocity. The background temperature of the sliding surface can be determined as the lower envelope of the signal from the grindable thermocouple. Steady and unsteady regimes of sliding have been investigated. For steady sliding, the accuracy of the temperature determination increases with measurement duration. In the case of unsteady sliding, accurate temperature determination requires multiple tests under the same conditions. The thickness of the thermocouple junction has been analyzed for correct comparison of experimental and calculated temperatures.