9,284 research outputs found
Design and development of auxiliary components for a new two-stroke, stratified-charge, lean-burn gasoline engine
A unique stepped-piston engine was developed by a group of research engineers at Universiti Teknologi Malaysia (UTM), from 2003 to 2005. The development work undertaken by them engulfs design, prototyping and evaluation over a predetermined period of time which was iterative and challenging in nature. The main objective of the program is to demonstrate local R&D capabilities on small engine work that is able to produce mobile powerhouse of comparable output, having low-fuel consumption and acceptable emission than its crankcase counterpart of similar displacement. A two-stroke engine work was selected as it posses a number of technological challenges, increase in its thermal efficiency, which upon successful undertakings will be useful in assisting the group in future powertrain undertakings in UTM. In its carbureted version, the single-cylinder aircooled engine incorporates a three-port transfer system and a dedicated crankcase breather. These features will enable the prototype to have high induction efficiency and to behave very much a two-stroke engine but equipped with a four-stroke crankcase lubrication system. After a series of analytical work the engine was subjected to a series of laboratory trials. It was also tested on a small watercraft platform with promising indication of its flexibility of use as a prime mover in mobile platform. In an effort to further enhance its technology features, the researchers have also embarked on the development of an add-on auxiliary system. The system comprises of an engine control unit (ECU), a directinjector unit, a dedicated lubricant dispenser unit and an embedded common rail fuel unit. This support system was incorporated onto the engine to demonstrate the finer points of environmental-friendly and fuel economy features. The outcome of this complete package is described in the report, covering the methodology and the final characteristics of the mobile power plant
Recalibration Methodology to Compensate for Changing Fluid Properties in an Individual Nozzle Direct Injection Systems
Limited advancement of direct injection pesticide application systems has been made in recent years, which has hindered further commercialization of this technology. One approach to solving the lag and mixing issues typically associated with injection-based systems is high-pressure individual nozzle injection. However, accurate monitoring of the chemical concentrate flow rate can pose a challenge due to the high pressure, low flow, and changing viscosities of the fluid. A methodology was developed for recalibrating high-pressure chemical concentrate injectors to compensate for fluid property variations and evaluate the performance of this technique for operating injectors in an open-loop configuration. Specific objectives were to (1) develop a method for continuous recalibration of the chemical concentrate injectors to ensure accurate metering of chemicals of varying viscosities and (2) evaluate the recalibration method for estimating individual injector flow rates from a system of multiple injectors to assess potential errors. Test results indicated that the recalibration method was able to compensate for changes in fluid kinematic viscosity (e.g., from temperature changes and/or product variation). Errors were less than 3.4% for the minimum injector duty cycle (DCi) (at 10%) and dropped 0.2% for the maximum DCi (at 90%) for temperature changes of up to 20°C. While larger temperature changes may be expected, these test results showed that the proposed method could be successfully implemented to meet desired injection rates. Because multiple injectors would be used in commercial deployment of this technology, a method was developed to calculate the desired injector flow rate using initial injector calibration factors. Using this multi-injector recalibration method, errors ranged from 0.23% to 0.66% between predicted and actual flow rates for all three injectors
Recalibration Methodology to Compensate for Changing Fluid Properties in an Individual Nozzle Direct Injection Systems
Limited advancement of direct injection pesticide application systems has been made in recent years, which has hindered further commercialization of this technology. One approach to solving the lag and mixing issues typically associated with injection-based systems is high-pressure individual nozzle injection. However, accurate monitoring of the chemical concentrate flow rate can pose a challenge due to the high pressure, low flow, and changing viscosities of the fluid. A methodology was developed for recalibrating high-pressure chemical concentrate injectors to compensate for fluid property variations and evaluate the performance of this technique for operating injectors in an open-loop configuration. Specific objectives were to (1) develop a method for continuous recalibration of the chemical concentrate injectors to ensure accurate metering of chemicals of varying viscosities and (2) evaluate the recalibration method for estimating individual injector flow rates from a system of multiple injectors to assess potential errors. Test results indicated that the recalibration method was able to compensate for changes in fluid kinematic viscosity (e.g., from temperature changes and/or product variation). Errors were less than 3.4% for the minimum injector duty cycle (DCi) (at 10%) and dropped 0.2% for the maximum DCi (at 90%) for temperature changes of up to 20°C. While larger temperature changes may be expected, these test results showed that the proposed method could be successfully implemented to meet desired injection rates. Because multiple injectors would be used in commercial deployment of this technology, a method was developed to calculate the desired injector flow rate using initial injector calibration factors. Using this multi-injector recalibration method, errors ranged from 0.23% to 0.66% between predicted and actual flow rates for all three injectors
Closed-cycle gas dynamic laser design investigation
A conceptual design study was made of a closed cycle gas-dynamic laser to provide definition of the major components in the laser loop. The system potential application is for long range power transmission by way of high power laser beams to provide satellite propulsion energy for orbit changing or station keeping. A parametric cycle optimization was conducted to establish the thermodynamic requirements for the system components. A conceptual design was conducted of the closed cycle system and the individual components to define physical characteristics and establish the system size and weight. Technology confirmation experimental demonstration programs were outlined to develop, evaluate, and demonstrate the technology base needed for this closed cycle GDL system
Direct injection systems for agricultural chemical applicators
An experimental laboratory-model direct chemical injection system was designed, constructed, and evaluated at The University of Tennessee Department of Agricultural Engineering in Knoxville, Tennessee. Evaluations consisted of determining the transient period between initiation of chemical injection and achievement of full chemical concentration at the nozzle. The laboratory sprayer apparatus was also used to determine variation in chemical concentration in nozzle effluent both from nozzle to nozzle across the boom and with time. Performance using three injection points was evaluated for this system. Points included injection immediately upstream of the system pump, injection immediately downstream of the system pump, and injection at the individual nozzles. Tests were conducted at system operating pressures of 171, 275, and 378 kilopascals. Three injection pumps were also evaluated at the upstream injection point, and two pumps at each pressure-side injection site. The three pumps included one peristaltic pump and two piston pumps. The two piston pumps were used for pressureside injection at both locations. A computer model for predicting transient times for low-pressure injection was also written and validated. Finally, flow characteristics within a conventional application system using a tank mix instead of direct injection were evaluated at the same three pressures to allow comparison with the different injection systems.
The sprayer was equipped with nine flat fan nozzles, and effluent samples were simultaneously taken from each nozzle. A potassium bromide solution formulated at a concentration of 28.3 grams per liter was used as the simulated pesticide to be injected into the diluent stream. Conductivity of the effluent solution caught at the nozzles was measured and related to chemical concentration based upon a calibration of the conductivity meter performed prior to each test.
Results of laboratory studies indicated that performance of the direct injection system was very dependent upon component selection and system configuration. Direct injection systems when used for low-pressure injection with any of the three pumps produced chemical concentrations in the nozzle effluent equal in uniformity to those achieved through conventional tank mixing.
Injection on the high-pressure side of the system pump was effective in reducing the transient period in comparison to injection on the low-pressure side of the system pump. However, mixing of the diluent and the concentrated chemical was reduced. The reduced level of mixing was probably due to the fact that the chemical did not pass through the sprayer system pump, which was found to be effective in thoroughly mixing the two fluids.
When injecting at the individual nozzles, high system operating pressures produced increased variation in chemical concentration in the nozzle effluent. Further, location of diluent entrance to the boom became a critical issue. Flow to both sides of the boom must be equal to achieve uniform chemical concentration from nozzle to nozzle across the boom
Definition of a resistojet control system for the Manned Orbital Research Laboratory. Volume 1 - Summary Final report
Resistojet control system for attitude control and orbit operations of Manned Orbital Research Laborator
Characteristics of Control Piston Motion and Pressure Inside of a Common Rail Diesel Injector
[EN] In this paper the experimental setup of a commercial third generation common rail solenoid injector with advanced
measurement is discussed. The motion of the control piston is measured while performing injection rate
investigations using a purpose-built injection rate analyzer of the Bosch type. At the same time fuel pressure in the
feed line of the nozzle is gauged and contrasted to fuel pressure before the inlet connector.
In contrast to the steady rise observed in a similar study, the motion of the control piston in this case is characterized
by a changing gradient in the upward movement. The magnitude of the negative displacement of the upper part of
the control piston due to the fuel pressure in the control volume corresponds to simulation results of the elastic
deformation.
Pressure before the inlet connector and pressure in the feed line exhibit a similar course with a difference in
magnitude that is rising with higher rail pressures. Precisely with the end of injection the pressure in the feed line
surpasses the pressure before the inlet connector for a short moment. The measurement results of control piston
motion and pressure inside the injector are of particular interest because these parameters are to serve as indicators
for changes in the injection rate caused by phenomena like wear and coking amongst others.The authors thank the German Research Foundation DFG for the funding of the project (reference number WA 2468/4-1) in which the here presented results originated. Furthermore, the authors thank Martin Niedermeier for the development the injector and Mario Meinhardt for the development of the data acquisition.Schuckert, S.; Wachtmeister, G. (2017). Characteristics of Control Piston Motion and Pressure Inside of a Common Rail Diesel Injector. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 569-577. https://doi.org/10.4995/ILASS2017.2017.6454OCS56957
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Control of NOx emissions from diesel engines using exhaust gas re-circulation
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The diesel engine currently accounts for 32 per cent of the new passenger car sales in
Europe. In the US, diesel-power is responsible for 94 per cent of all freight movement. Comparing European Stage III standard petrol and diesel passenger car emissions, diesel NOx emissions are still considered a concern. This thesis investigates the mechanisms by which oxides of nitrogen are formed during diesel combustion. It reviews the current methods of controlling NOx emissions, such as retarding fuel injection timing, exhaust gas re-circulation (EGR), water injection and
exhaust after-treatment. Modelling using a phenomenological model, is used to demonstrate the extended Zeldovich mechanism and formation trends, the effects of EGR and the significance of the Zeldovich mechanism rate constants. Modified Zeldovich rate constants are proposed to improve the correlation to measured data. Clearly, EGR is currently the most effective method of reducing NOx emissions from passenger car diesel engines. The way EGR works in suppressing NOx formation is reviewed in detail. Experimentation on a 1.8 litre inline 4-cylinder 4-valve per cylinder DI diesel with a variable nozzle turbine (VNT) turbocharger was used to demonstrate the concept of "additional" EGR on this small automotive engine. "Additional" EGR is the concept whereby a proportion of the EGR is added to the total charge, so that the volumetric efficiency increases as EGR is introduced. By using "additional" EGR, the benefits of lower NOx emissions combined with reduced particulates emissions and improved fuel consumption were clearly demonstrated at two test conditions. The reasons for achieving lower NOx emissions when using a VNT turbocharger and EGR have been explained. Finally, several methods of calculating EGR proportion were used and compared against true mass flow. The use of a CO2 balance was found to be the most accurate method.This study is funded by the Ford Motor Company
Nuclear light bulb
The nuclear light bulb engine is a closed cycle concept. The nuclear light bulb concept provides containment by keeping the nuclear fuel fluid mechanically suspended in a cylindrical geometry. Thermal heat passes through an internally cooled, fused-silica, transparent wall and heats hydrogen propellant. The seeded hydrogen propellant absorbs radiant energy and is expanded through a nozzle. Internal moderation was used in the configuration which resulted in a reduced critical density requirement. This result was supported by criticality experiments. A reference engine was designed that had seven cells and was sized to fit in what was then predicted to be the shuttle bay mass and volume limitations. There were studies done of nozzle throat cooling schemes to remove the radiant heat. Elements of the nuclear light bulb program included closed loop critical assembly tests done at Los Alamos with UF6 confined by argon buffer gas. It was shown that the fuel region could be seeded with constituents that would block UV radiation from the uranium plasma. A combination of calculations and experiments showed that internal moderation produced a critical mass reduction. Other aspects of the research are presented
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