Publication: Pressure loss model in fuel distribution system
Loading...
Identifiers
Publication date
2012
Defense date
2012-07-19
Authors
Tutors
Journal Title
Journal ISSN
Volume Title
Publisher
Impact
Export
Abstract
This final thesis work was performed at Volvocars, Gothenburg. The thesis was developed under Linköping University supervision and the complete duration of this work was 20 weeks. This work consists on building a model in GT Software, which would represent each of the components in the Diesel Distribution System and the interaction among them. These components include: the fuel tank, the filter, supply and return pipes and high pressure pump. In addition, experiments have been done to measure the pressure drops along the system components. These data will be used to support the software model in some components which complex geometry is more difficult to describe using the software. The experiments were developed using different viscosity fuels at different temperatures. It will be required to study the relation between diesel viscosity, temperature and its effects on pressure drops. The aim was building a model which will permit us to test different scenarios representing the real system. This model will be used as a tool to perform specific simulations and these simulation results would support the process of decision making. This model will be a useful tool to make simulations in a cost effective way, it enables simulating several driving conditions which implies significant cost reduction compared to the real simulation. For instance if it is known the vehicle consumption under certain conditions and the load, the simulation can be set to the precise flow rate and the model would yield the pressure drop for the complete temperature range and for any diesel viscosity. The main conclusions reached during this thesis work were: Simple models can be built in a very short time for different final objectives. For instance to test many design parameters which value slight variation might lead to a consequential impact in the system total pressure loss. GT Software can be used to build very simple models consisting on just one meter length pipe and allow us to build pressure drop graphs as a function of flow rate, temperature and diameter size. These graphs would be used for any pipe length by just multiplying the pressure drop by the actual length. Identification of the hose in the return flow circuit imposing the highest pressure drops, hose number 4 in the “Return Flow Simple Model”. After running different simulations varying the pipe length and the pipe diameter at different flows and temperatures it was concluded that the design parameter with a higher influence was the diameter dimension. The Y-connector angle in the steel return pipe does not have any influence on pressure drops for any flow rate or temperature value within the operating range. Past tests developed to verify its effect on pressure peaks meant a waste of resources which could have been avoided by using GT Software tool. A model representing the back flow circuit produced plots showing pressure values for the complete flow rate and temperature range. These plots will be used to see the different operating points, at a certain temperature and flow pumped the precise pressure values would be obtained. Thanks to the viscosity versus temperature plots it will be easy to determine the pressure values it would be obtained not just for the diesel samples used in this work but for any diesel viscosity in the market. A complete circuit model from the fuel tank to the filter and high pressure pump returning back to the fuel tank showing the pressure versus flow rate, temperature plots. This model would provide the pressure values at the different components and those hoses should be focused on to solve over pressure situations. Sensitive analysis of the deviation between the pressure drop values obtained during the real experiments and the pressure drop values produced by the model. Also it has been done a sensitive analysis of the deviation between pressure drop values when considering simple model return flow in comparison to the values produced when the 3D data was imported to the model (the model accounts for the bends and changes in diameters). The highest pressure difference value found was 9Kpa. Since the aim of the simulation was not obtaining absolute values but comparative values which would identify the main hoses that should be worked on, the simple model was concluded to be suitable for this purpose. The graph showing the total pressure drop through the complete circuit results from the real experiments, adjusts to the 3D Model pressure curve as it can be observed in the previous graph. There is not measurement data from the test for flow rate values over 165 l/h so this graph does not lead any conclusions regarding higher flow rate values. In the case of the Simple Complete circuit Model, the pressure drop values yield by the model are lower values, the reason for this is that the Simple Complete Model is including less information regarding changes in diameter and curves.
Description
Keywords
Combustibles, Sistemas de distribución de combustible, Tecnología automovilística, Mecánica de fluidos, Fuel, Simulación