Browse

81 - 90 of 455 items :

  • Energy Engineering x
Clear All
A Study of Reduction for Combustion Products of a Gasoline Engine – Especially Effects of Multi Component Fuel Properties

Abstract

It is well known that the component proportion of gasoline varies depending on the extraction time of crude oil and the production country. Of course, there are effects of the engine performance and the emission on a little. So it is necessary to examine the effects of multi component fuel on the combustion characteristics and emissions. This study aims to examine the effects of fuel composition on the fuel properties and emission characteristics (HC, CO, NOx, etc.) by using multi component fuels in a small gasoline engine. Multi component fuels (model fuel) mixed with plural hydrocarbon compounds was used as fuel. The two kinds of main component fuel were used for the test base fuel (50 vol% Iso-Octane and 25-vol% Toluene). The other addition fuels were selected pure fuel (10 kinds of fuel: Iso-Octane, Toluene, Pentane, Hexane, Heptane, Octane, Di-Isobutylene, Methyl cyclohexane, P-Xylene, Ethanol), it was mixed 25 -vol% in the base fuel. The main conclusions are as follows, 1) The HC emissions decrease with increasing the evaporation velocity of addition fuels for normal chain paraffin. 2) The CO emissions monotonically decrease with increasing excess air ratio by using multi component fuels. 3) It is possible to control the HC, CO and NOx emissions by using the fuel of 25-vol% ethanol addition for a small gasoline engine.

Open access
Subjective Risk Estimation of the Rare Event

Abstract

In the safety engineering, the most frequently disadvantage in risk estimation is the lack of data. In such cases, we have to rely on subjective estimations made by persons with practical knowledge in the field of interest, i.e. experts. However, in some realistic situations, they may have uncertainty in the perceiving and evaluation of the problem considered or limited knowledge of the rare events, such as the consequences of the seagoing ship propulsion failures. The probabilistic models of the risk estimation turn out to be insufficient in modelling the subjective uncertainty. The fuzzy methods are viewed to be powerful in dealing with ambiguity and uncertainty that can be used to handle with the subjective estimation. This article addresses the intuitionistic fuzzy method in the subjective estimation of the ship propulsion failure consequences as rare event risk. In the article, a subjective model of the ship propulsion risk is developed as scenarios of the different subsequent consequences of loss of ship propulsion function until a seriously severe accident resulting in loss of seaworthiness. The model proposes an approach combining AHP method and intuitionistic fuzzy method to assess the occurrence probability and severe probability of these rare events based on the expert opinions. In order to show the applicability of the proposed model, a study case of the propulsion risk of the container carrier operating on the North Atlantic lines is conducted.

Open access
Thrust Control Systems of Propulsion and their Verification on Dynamically Positioned Vessels

Abstract

Thrust vector control systems of propulsion systems of dynamic positioning vessels are commonly applied on vessels with DP2 and DP3 class of DP. It was submitted the ways of providing information to dynamic positioning operator DPO about detecting of suspicion of failure in specific thruster and shown the ways of response in such situations. In the case of failure and shut down one of working thrusters, it must be done the possibility assessment of continuation of DP system safe operation. If such situation is not possible, it should be considered the work of DP system on limitations. It was indicated on safety threats during operation of DP systems resulting from system failure or even the design faults. It commonly applies the failure mode and effect analysis (FMEA or FMECA) from the design phase through sea trials until to the verification process during operation. It allows the elimination of majority of faults in the DP systems. It was communicated the basic conditions of safe operation of vessels with DP systems and the examples of conditions which releasing the readiness signal of DP propulsion system elements. Observed development of control and automatics systems will result in increasing the safety of DP systems operation.

Open access
Wavelet Transform in Vibroacoustic Diagnostic of Machines

Abstract

This article discusses the use of wavelet decomposition in the diagnostics of vibrometric signals of an engine. Apart from presenting the possibility of using wavelets in diagnostics, the authors take up the subject of the applicability range of processing for stationary signals, which until now has been reserved for non-stationary signals. A unified definition of signal stationarity has been proposed, which is not based on statistics. The authors presented methods of wavelet decomposition of a vibrometric signal of combustion engine vibrations, measured with the use of LDV (Laser Doppler Vibrometry). Laser measurements allows for studying an object without ‘touching’ its housing. Basing on the relative velocity of engine vibrations, the authors indicate how reliable vibrations are in diagnostics. Despite higher costs, this measurement method gives better results (for specific cases) than acoustic studies. Transform – wavelet decomposition is a solution hardly ever used in machine diagnostics; it is more often applied in medicine and image recognition. The authors presented the differences that can be obtained for different levels of decomposition, and also presented the impact on the engine condition assessment through the use of filtering (windowing) the signal before decomposition.

Open access
Advantages of Compressor Downstream Air Partial Bleed and Supplying It Downstream of the Turbine in a Turbojet Engine

Abstract

The research article discusses the advantages of using compressor downstream air partial bleed and supplying it downstream of the turbine, which was applied in a prototype of a “bypass” turbojet engine. The objective of such a turbo engine structural solution was discussed along with its elements and principle of operation. Further part of the article determines the impact of such partial air bleed on the value of achieved basic operating parameters of the engine, i.e., unit thrust and unit power consumption. The presented attempt to compare these parameters with the parameters achieved for a turbojet, single flow engine is very important; in the first case without air bleed, and in the second, with air bleed to the environment. Further sections of the article compared these parameters relative to a turbojet, turbofan engine with a jet mixer. Such comparisons enabled to determine the actual benefits of using compressor downstream air partial bleed and supplying it downstream of the turbine, which may constitute an intermediate solution between single flow turbine engines and turbo fan engines. Wide possibilities for the application of such structural solutions were shown, which was summarised in the conclusions.

Open access
Advantages of Using Hybrid Vehicles Based on Empirical Studies on the Chassis Dynamometer in the WLTC Test

Abstract

Vehicles powered in alternative ways have an increasing share in the car market. Their use is becoming more and more justified considering the ever more stringent standards for the emission of harmful substances from the exhaust systems of internal combustion engines and the introduction of restrictions on vehicle traffic in city centres. The possibility of using in the propulsion systems only an electric motor or its simultaneous use with the internal combustion engine enables a significant reduction of emission of harmful exhaust gas pollutants. This applies in particular to urban areas, where there are numerous exceedances of acceptable air quality standards. This problem is most noticeable in larger cities in Poland, where there is a lot of traffic. It is therefore legitimate to promote alternative vehicles powered in alternative ways. Their dual power system gives the opportunity to significantly reduce the emission of harmful substances. Therefore, the article presents own research, carried out on a chassis dynamometer, using two passenger cars, one with a spark-ignition combustion engine and the second with a hybrid drive system containing a spark-ignition engine and an electric motor (system without the possibility of recharging batteries from external sources). Vehicles were characterized by similar mass and the same displacement volumes of internal combustion engines. The results of the tests made it possible to compare cars in terms of exhaust emissions. For testing purposes, a chassis dynamometer was used, on which the WLTC homologation cycle was repeatedly reproduced. This is a new driving cycle, which replaces the NEDC cycle used so far in the type approval procedure in the European Union.

Open access
Analysis of Abrasive Wear of Selected Aircraft Materials in Various Abrasion Conditions

Abstract

The use of composite materials is continuously increasing in modern transport. This process is especially noticeable in aviation. The mass percentage of epoxy resin composites in contemporary aircraft constructions is usually higher than 50%, and these materials must meet increasingly demanding requirements. In these circumstances, in addition to mass and strength, it is necessary to predict other properties of the material, such as abrasion resistance. The article presents the analysis of the process of abrasion of carbon fibre reinforced polymers reinforced with various fillers. Straight carbon fibre mats were used for the tests. In addition, powders of pumice, alumina, silicon carbide, and glass microspheres at various concentrations in relation to the matrix were used as fillers. In order to investigate the influence of external factors on the abrasion process, each group of samples was subjected to abrasion under different external conditions: in an insulated environment, in the presence of water and loose abrasives: brown fused alumina (BFA) and white fused alumina (WFA). The measurements were carried out using a precision balance and an electron microscope. The results allow concluding on which kind of filler and in what concentration contributes to improvement of the abrasion resistance of the composite material the most. In addition, it was found that the conditions in which abrasion occurs have a very large impact on the course of this process.

Open access
Analysis of Changes in Traffic Rules and Assessment of Their Impact on Road Traffic Safety

Abstract

Road safety is an important social issue. Hence, changes in road traffic rules have a large influence on travel safety improvement. One of the major issues to be addressed is the speed limit of motor vehicles and radar speed measurements. Moreover, road traffic rules impose the obligation to wear safety belts during driving, carrying children in car safety seats and they put a ban on drink driving as well as driving under the influence of other intoxicating substances that have a negative influence on the driver’s physical condition and driving skills. This study analyses changes in traffic rules and provides assessment of the way they affect road traffic safety in Poland. The study presents an analysis of the issues connected with road vehicle operation and safety of the passengers including: wearing safety seat belts, use of children car safety seats, vehicle lighting, speed limit. Such issues as the proposed changes in breathalyzer use and implementation of safety systems to provide road users with safety have been addressed.

Open access
Analysis of Hazards Occurring During the Use of Hydrazine

Abstract

The article presents the safety issue bonded to the Polish Air Force F-16 multirole aircraft. The authors pointed out the issue of fuel used for emergency supply system of these aircrafts. The article emphasized the fact that these aircrafts require special fuel with designation H-70, which is 70% aqueous solution of toxic hydrazine. For this reason, the rescue services of Polish Air Force bases where Polish F-16 are stationed had to be adjusted accordingly. Just as importantly, authors noticed that in the event of an emergency landing of this aircraft at different airports could receive difficulties associated with the possible leakage of hydrazine, or its neutralization in the absence of specialized Hydrazine Response Team, which are part of the Airport Rescue Group. After the introduction of new aircraft for use in the Polish Air Force (in this case F-16 multirole aircraft), it is necessary to analyse the safety of their use in the context of potential places on which they can land. This is related, among others, to the safety of managing liquid fuels. In the case of F-16 aircraft, one must bear in mind besides the F-34 fuel, also hydrazine (H-70). The article presents a functional diagram of EPU system of emergency power supply EPS of F-16 multirole aircraft.

Open access
Analysis of LDV Operation Manner in Terms of its Environmental and Economical Indexes

Abstract

Environmental protection is becoming an increasingly important issue in every area of life. In recent times, a great emphasis has been placed on reducing the negative impact of automotive on human health at every stage of the vehicle's life. The most common impact of cars on the environment is the emission of pollutants from the exhaust system, created during the combustion of fuels in internal combustion engines. For this purpose, legislators introduce emission standards that must be met at the stage of vehicle approval for a given market. To meet these requirements, vehicle manufacturers modify the design of the drive units, body, and chassis to reduce weight and improve aerodynamic properties. This approach is methodologically correct because it is possible to compare the results obtained for different vehicles, but in real operation the level of harmful exhaust compounds, emissions and fuel consumption depend very much on the way the vehicle is used. As a manner of operation one can understand a variable load in the form of passengers or cargo, driving style, share of urban, extra-urban and motorway driving, terrain formation, ambient temperature and others. This article addresses issues related to the assessment of the impact of the light commercial vehicle operation manner on fuel consumption and the emission of harmful exhaust compounds. The problem was analysed in terms of the difference in vehicle load and driving style. Exhaust emission measurements were carried out using PEMS (Portable Emission Measurement System) analysers, which are state of the art devices for measuring exhaust emission in real operating conditions, called RDE (Real Driving Emissions).

Open access