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Technical work packages

 

WP 1: Infrastructure to evaluate the measurement performance of flow meters deployed in fuel consumption measurements in road transport

The aim of this work package is to develop the metrological infrastructure needed to assess the performance of flow meters used in fuel consumption measurements of passenger cars and trucks. At present these flow meters are calibrated at test points and constant flow rates. Fuel flow meters are typically not calibrated down to low flows and the measurement performance at zero flow is not considered which both might result in non-negligible errors in the determination of fuel consumption. The test cycles and test equipment to be used are specified in the UN ECE.R49. Regarding the evaluation of the fuel consumption the standard recommends the performance specification for the measurement instruments only and not the complete measurement system. Further factors contributing to the measurement results such as e. g. from the environment are not clearly specified to be taken under consideration. Another open point concerns the influence of the test liquid on the measuring performance of the flow meter and thus on the measuring results. The question arises to what extent changes in the viscosity and density of the fuel affect this, esp. since the flow meter is calibrated with one specific test fluid. Variations in viscosity and density may arise from the use of different fuel types, or changes in temperature and pressure of the liquid.

This work package will develop the metrology essential for the evaluation of the measurement performance of flow meters deployed in fuel consumption measurements in the automotive sector taking into account real-world operation conditions. It will also report about the results of a first exemplary assessment of flow meter performance under conventional and dynamic test conditions based on test cycles such as e. g. WLTC, WHTC. Moreover, recommendations for such measurement procedures and a guide for the determination of a comprehensive uncertainty consideration for flow meters used for fuel consumption measurements will be provided.

 

WP 2: Infrastructure to characterize the measurement performance of flow meters deployed in the maritime sector

The aim of this work package is to develop the metrological infrastructure needed to assess the performance of flow meters used in fuel consumption measurements of ships. As is common practice, these flowmeters are also calibrated at test points and static flows using one test liquid (typically water). In the maritime sector, the question arises to a greater extent than in the automotive sector as to how the clearly different transport properties of the fuels affect the measuring behaviour of the flow meters. This is of particular relevance against the background of the wider variability of fuel properties. This is due to factors such as changes in fuel temperatures, different fuel quality depending on the port, transfer between different storage tanks and the associated mixing of fuels and, last but not least, the efforts to increase the use of alternative fuels in the maritime sector. Of further interest is a quantification of the measurement quality of the flow meters for variable flows as they occur in ECAs and there emission limits for NOx apply. The importance of fuel consumption measurement and its quality is illustrated among others by the fact that CO2 emissions are calculated directly from fuel consumption times an emission factor. As in the automotive sector, the question here is also how different ambient conditions affect flow meter performance.

This work package will develop the metrology essential for the evaluation of the measurement performance of flow meters deployed in fuel consumption measurements in shipping taking into account real-world operation conditions.

 

WP 3: Transport properties of alternative and synthetic fuels

The aim of this work package is to gain insights into the variability of transport parameters of alternative and synthetic fuels at reference temperature but in particular also changes in viscosity and density caused by temperature and pressure variations. This is essential input for a realistic uncertainty assessment of flow meters, the aim of the work carried out in WP4. The need for the transport-property data for the liquids is not so much for the conversion between mass and volume but to evaluate the impact changes in flow structure and liquid behaviour caused by differences in these properties have on flow measurements.

Furthermore, the work package will provide thermophysical property models for alternative fuels which can be used to extrapolate fuel properties and thus be deployed to assess flow meter performance under measurement conditions which cannot be easily realized with test rigs. The models will represent a useful ready-to-use tool for manufacturers and end users.

 

WP 4: Transfer of advanced flow meter calibrations to practical application

The aim of this work package is to prepare the floor for future advanced flow meter calibrations by providing the framework for dynamic calibrations of flow meters and addressing the issues of using different test liquids and the impact on the flow measurement resp. on the transfer of the calibration of a flow meter from one liquid to another. The question to which extent the influence on the measurement deviation is related to changes in the flow profile and how relevant the direct interaction between liquid and flow meter is will be dealt with taking into account different measurement principles of flow meters. By this a grasp on the quality and applicability of the Reynolds number approach (and associated uncertainties) for converting flow measurement results from one liquid to another will be obtained.

This work package will provide all documentation needed for an implementation of flow meter characterizations for dynamic flow regimes at stakeholder site. The documentation is also intended as input for the preparation of eventual standardization work. Moreover, this documentation will be complemented by a report with a focus on the influence of liquid properties (density, viscosity) and measurement conditions on the measurement performance of flow meters including uncertainty considerations. The documentation prepared in this work package is aimed at a target group that goes beyond the maritime sector and road transport. It includes calibration labs and technical committees at national and international level but is also meant to be of interest for parties related to other means of transport such as e. g. by aircrafts or inland waterway transport.