The potential of increased efficiency and power for a turbocharged PFI-SI engine through variable valve actuation and DEP

New legislation involving emissions from internal combustion engines are pushing the manu-facturers to develop new technology faster than ever before with the amount of greenhouse gases. To meet the standards new concepts need to be developed with lower fuel consumption and emissions. This thesis covers the implementation of a couple of methods to achieve this. These concepts are DEP with fully variable valves in a port fuel SI engine with high compres-sion ratio (CR). The results show an increase in efficiency followed by lowered fuel consump-tion. The improvements in fuel consumption are mainly found to be the result of raising the CR and because of decreases in pumping losses due to de-throttling via the Miller-cycle. The reduction in pumping losses by implementing the DEP concept was not as great as expected. The results show a decrease of fuel consumption of 9.5% at part load and 5 % at high load. The main improvement with the DEP concept was the reduction of the in-cylinder residual gases at 40 CAD before top dead centre firing (TDCF). This could be enough to be able to use such high CR that otherwise just wouldn´t be possible. The thesis reveals many of the difficulties involving combustion simulation and with no ex-perimental work available in particular. The thesis would gain a lot from implementing a pre-dicted combustion model to simulate EGR and the full capability of the DEP concept in terms of affecting the combustion, by for example changing the burn rate

Control of nitrous oxide in dental operatories

"Commercially available scavenging systems for the control of nitrous- oxide (10024972) in dental operatories were evaluated in the field and in the laboratory. The field study sites included two pediatric dental facilities, an oral surgical clinic, and a dental clinic for the developmentally disabled. Sampling methods employed to gather data included personal and area sampling, real time nitrous-oxide sampling, video recording and documentation of work practices and infrared thermography. None of the scavenging systems were found to be adequate to control nitrous-oxide exposures. Tests were conducted in the laboratory and the field to evaluate two new local exhaust systems intended to control patient mouth emissions of nitrous-oxide. Face mask leakage was the primary cause of emissions. The use of exhaust systems placed on the chin or chest, or in the mouth captured mouth emissions. The authors conclude that it is possible to control nitrous-oxide levels to the NIOSH recommended exposure limit of 25 parts per million or lower when engineering controls; proper nitrous-oxide equipment maintenance; good work practices; and effective local, auxiliary and general ventilation controls are in place. The authors recommend that the use of nitrous-oxide be reduced, and that scavenging systems, ventilation, work practices, and equipment maintenance be used to control exposures." - NIOSHTIC-2James D. McGlothlin, Keith G. Crouch, R. Leroy Mickelsen."September 1994.""Report no. ECTB 166-04"--T.p. verso.Includes bibliographical references

Prediction of hydrogen-heavy fuel combustion process with water addition in an adapted low speed two stroke diesel engine: Performance improvement

Article number 117250Despite their high thermal efficiency (>50%), large two-stroke (2 T) diesel engines burning very cheap heavy fuel oil (HFO) produce a high level of carbon dioxide (CO2). To achieve the low emission levels of greenhouse gases (GHG) that will be imposed by future legislation, the use of hydrogen (H2) as fuel in 2 T diesel engines is a viable option for reducing or almost eliminate CO2 emissions. In this work, from experimental data and system modelling, an analysis of dual combustion is carried out considering different strategies to supply H2 to the engine and for different H2 fractions in energy basis. Previously, a complete thermodynamic model of a 2 T diesel engine with an innovative scavenging model is developed and validated. The most important drawbacks of this type of engines are controlled in this work using dual combustion and water injection, reducing nitrogen oxides emissions (NOx), self-ignition and combustion knocking. The results show that the developed model matches engine performance data in diesel mode, achieving a higher efficiency and mean effective pressure (MEP) in hydrogen mode of 53% and 14.62 bar respectively.Consejería de Economía, Conocimiento, Empresas y Universidad(Junta de Andalucía) AT17_5934_U

Analysis of two stroke marine diesel engine operation including turbocharger cut-out by using a zero-dimensional model

In this article, the operation of a large two-stroke marine diesel engine including various cases with turbocharger cut-out was thoroughly investigated by using a modular zero-dimensional engine model built in MATLAB/Simulink environment. The model was developed by using as a basis an in-house modular mean value engine model, in which the existing cylinder block was replaced by a more detailed one that is capable of representing the scavenging ports-cylinder-exhaust valve processes. Simulation of the engine operation at steady state conditions was performed and the derived engine performance parameters were compared with the respective values obtained by the engine shop trials. The investigation of engine operation under turbocharger cut-out conditions in the region from 10% to 50% load was carried out and the influence of turbocharger cut-out on engine performance including the in-cylinder parameters was comprehensively studied. The recommended schedule for the combination of the turbocharger cut-out and blower activation was discussed for the engine operation under part load conditions. Finally, the influence of engine operating strategies on the annual fuel savings, CO2 emissions reduction and blower operating hours for a Panamax container ship operating at slow steaming conditions is presented and discussed

A study of high output two-stroke diesel engines - scavenging, supercharging and compounding

SIGLEAvailable from British Library Document Supply Centre- DSC:DX170889 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Adaptive Observer for Nonlinearly Parameterised Hammerstein System with Sensor Delay – Applied to Ship Emissions Reduction

Taking offspring in a problem of ship emission reduction by exhaust gas recirculation control for large diesel engines, an underlying generic estimation challenge is formulated as a problem of joint state and parameter estimation for a class of multiple-input single-output Hammerstein systems with first order dynamics, sensor delay and a bounded time-varying parameter in the nonlinear part. The paper suggests a novel scheme for this estimation problem that guarantees exponential convergence to an interval that depends on the sensitivity of the system. The system is allowed to be nonlinear parameterized and time dependent, which are characteristics of the industrial problem we study. The approach requires the input nonlinearity to be a sector nonlinearity in the time-varying parameter. Salient features of the approach include simplicity of design and implementation. The efficacy of the adaptive observer is shown on simulated cases, on tests with a large diesel engine on test bed and on tests with a container vessel